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Sample records for bold fmri hemodynamics

  1. Hemodynamic modelling of BOLD fMRI - A machine learning approach

    DEFF Research Database (Denmark)

    Jacobsen, Danjal Jakup

    2007-01-01

    This Ph.D. thesis concerns the application of machine learning methods to hemodynamic models for BOLD fMRI data. Several such models have been proposed by different researchers, and they have in common a basis in physiological knowledge of the hemodynamic processes involved in the generation...... of the BOLD signal. The BOLD signal is modelled as a non-linear function of underlying, hidden (non-measurable) hemodynamic state variables. The focus of this thesis work has been to develop methods for learning the parameters of such models, both in their traditional formulation, and in a state space...... formulation. In the latter, noise enters at the level of the hidden states, as well as in the BOLD measurements themselves. A framework has been developed to allow approximate posterior distributions of model parameters to be learned from real fMRI data. This is accomplished with Markov chain Monte Carlo...

  2. Re-examine tumor-induced alterations in hemodynamic responses of BOLD fMRI. Implications in presurgical brain mapping

    International Nuclear Information System (INIS)

    Wang, Liya; Ali, Shazia; Fa, Tianning; Mao, Hui; Dandan, Chen; Olson, Jeffrey

    2012-01-01

    Background: Blood oxygenation level dependent (BOLD) fMRI is used for presurgical functional mapping of brain tumor patients. Abnormal tumor blood supply may affect hemodynamic responses and BOLD fMRI signals. Purpose: To perform a multivariate and quantitative investigation of the effect of brain tumors on the hemodynamic responses and its impact on BOLD MRI signal time course, data analysis in order to better understand tumor-induced alterations in hemodynamic responses, and accurately mapping cortical regions in brain tumor patients. Material and Methods: BOLD fMRI data from 42 glioma patients who underwent presurgical mapping of the primary motor cortex (PMC) with a block designed finger tapping paradigm were analyzed, retrospectively. Cases were divided into high grade (n = 24) and low grade (n = 18) groups based on pathology. The tumor volume and distance to the activated PMCs were measured. BOLD signal time courses from selected regions of interest (ROIs) in the PMCs of tumor affected and contralateral unaffected hemispheres were obtained from each patient. Tumor-induced changes of BOLD signal intensity and time to peak (TTP) of BOLD signal time courses were analyzed statistically. Results: The BOLD signal intensity and TTP in the tumor-affected PMCs are altered when compared to that of the unaffected hemisphere. The average BOLD signal level is statistically significant lower in the affected PMCs. The average TTP in the affected PMCs is shorter in the high grade group, but longer in the low grade tumor group compared to the contralateral unaffected hemisphere. Degrees of alterations in BOLD signal time courses are related to both the distance to activated foci and tumor volume with the stronger effect in tumor distance to activated PMC. Conclusion: Alterations in BOLD signal time courses are strongly related to the tumor grade, the tumor volume, and the distance to the activated foci. Such alterations may impair accurate mapping of tumor-affected functional

  3. Mapping of the brain hemodynamic responses to sensorimotor stimulation in a rodent model: A BOLD fMRI study.

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    Salem Boussida

    Full Text Available Blood Oxygenation Level Dependent functional MRI (BOLD fMRI during electrical paw stimulation has been widely used in studies aimed at the understanding of the somatosensory network in rats. However, despite the well-established anatomical connections between cortical and subcortical structures of the sensorimotor system, most of these functional studies have been concentrated on the cortical effects of sensory electrical stimulation. BOLD fMRI study of the integration of a sensorimotor input across the sensorimotor network requires an appropriate methodology to elicit functional activation in cortical and subcortical areas owing to the regional differences in both neuronal and vascular architectures between these brain regions. Here, using a combination of low level anesthesia, long pulse duration of the electrical stimulation along with improved spatial and temporal signal to noise ratios, we provide a functional description of the main cortical and subcortical structures of the sensorimotor rat brain. With this calibrated fMRI protocol, unilateral non-noxious sensorimotor electrical hindpaw stimulation resulted in robust positive activations in the contralateral sensorimotor cortex and bilaterally in the sensorimotor thalamus nuclei, whereas negative activations were observed bilaterally in the dorsolateral caudate-putamen. These results demonstrate that, once the experimental setup allowing necessary spatial and temporal signal to noise ratios is reached, hemodynamic changes related to neuronal activity, as preserved by the combination of a soft anesthesia with a soft muscle relaxation, can be measured within the sensorimotor network. Moreover, the observed responses suggest that increasing pulse duration of the electrical stimulus adds a proprioceptive component to the sensory input that activates sensorimotor network in the brain, and that these activation patterns are similar to those induced by digits paw's movements. These findings may

  4. Nonlinear coupling between evoked rCBF and BOLD signals: a simulation study of hemodynamic responses.

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    Mechelli, A; Price, C J; Friston, K J

    2001-10-01

    The aim of this work was to investigate the dependence of BOLD responses on different patterns of stimulus input/neuronal changes. In an earlier report, we described an input-state-output model that combined (i) the Balloon/Windkessel model of nonlinear coupling between rCBF and BOLD signals, and (ii) a linear model of how regional flow changes with synaptic activity. In the present investigation, the input-state-output model was used to explore the dependence of simulated PET (rCBF) and fMRI (BOLD) signals on various parameters pertaining to experimental design. Biophysical simulations were used to estimate rCBF and BOLD responses as functions of (a) a prior stimulus, (b) epoch length (for a fixed SOA), (c) SOA (for a fixed number of events), and (d) stimulus amplitude. We also addressed the notion that a single neuronal response may differ, in terms of the relative contributions of early and late neural components, and investigated the effect of (e) the relative size of the late or "endogenous" neural component. We were interested in the estimated average rCBF and BOLD responses per stimulus or event, not in the statistical efficiency with which these responses are detected. The BOLD response was underestimated relative to rCBF with a preceding stimulus, increasing epoch length, and increasing SOA. Furthermore, the BOLD response showed some highly nonlinear behaviour when varying stimulus amplitude, suggesting some form of hemodynamic "rectification." Finally, the BOLD response was underestimated in the context of large late neuronal components. The difference between rCBF and BOLD is attributed to the nonlinear transduction of rCBF to BOLD signal. Our simulations support the idea that varying parameters that specify the experimental design may have differential effects in PET and fMRI. Moreover, they show that fMRI can be asymmetric in its ability to detect deactivations relative to activations when an absolute baseline is stipulated. Finally, our simulations

  5. Advances in High-Field BOLD fMRI

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    Markus Barth

    2011-11-01

    Full Text Available This review article examines the current state of BOLD fMRI at a high magnetic field strength of 7 Tesla. The following aspects are covered: a short description of the BOLD contrast, spatial and temporal resolution, BOLD sensitivity, localization and spatial specificity, technical challenges as well as an outlook on future developments are given. It is shown that the main technical challenges of performing BOLD fMRI at high magnetic field strengths—namely development of array coils, imaging sequences and parallel imaging reconstruction—have been solved successfully. The combination of these developments has lead to the availability of high-resolution BOLD fMRI protocols that are able to cover the whole brain with a repetition time (TR shorter than 3 s. The structural information available from these high-resolution fMRI images itself is already very detailed, which helps to co-localize structure and function. Potential future applications include whole-brain connectivity analysis on a laminar resolution and single subject examinations.

  6. Effects of glyceryl trinitrate and calcitonin-gene-related peptide on BOLD signal and arterial diameter –methodological studies by fMRI and MRA

    DEFF Research Database (Denmark)

    Asghar, Mohammed Sohail; Ashina, Messoud

    2013-01-01

    of measuring task-related hemodynamic changes. Pharmacological substances that induce hemodynamic changes can therefore potentially alter the BOLD-signal that in turn falsely can be interpreted as changes in neuronal activity. It is therefore important to characterize possible effects of a pharmacological...... substance on the BOLD-response per see before that substance can be used in an fMRI experiment. Furthermore MR-angiography is useful in determining the vascular site-of-action of vasoactive substances....

  7. Significant feed-forward connectivity revealed by high frequency components of BOLD fMRI signals.

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    Lin, Fa-Hsuan; Chu, Ying-Hua; Hsu, Yi-Cheng; Lin, Jo-Fu Lotus; Tsai, Kevin W-K; Tsai, Shang-Yueh; Kuo, Wen-Jui

    2015-11-01

    Granger causality analysis has been suggested as a method of estimating causal modulation without specifying the direction of information flow a priori. Using BOLD-contrast functional MRI (fMRI) data, such analysis has been typically implemented in the time domain. In this study, we used magnetic resonance inverse imaging, a method of fast fMRI enabled by massively parallel detection allowing up to 10 Hz sampling rate, to investigate the causal modulation at different frequencies up to 5 Hz. Using a visuomotor two-choice reaction-time task, both the spectral decomposition of Granger causality and isolated effective coherence revealed that the BOLD signal at frequency up to 3 Hz can still be used to estimate significant dominant directions of information flow consistent with results from the time-domain Granger causality analysis. We showed the specificity of estimated dominant directions of information flow at high frequencies by contrasting causality estimates using data collected during the visuomotor task and resting state. Our data suggest that hemodynamic responses carry physiological information related to inter-regional modulation at frequency higher than what has been commonly considered. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. Brain functional BOLD perturbation modelling for forward fMRI and inverse mapping

    Science.gov (United States)

    Robinson, Jennifer; Calhoun, Vince

    2018-01-01

    Purpose To computationally separate dynamic brain functional BOLD responses from static background in a brain functional activity for forward fMRI signal analysis and inverse mapping. Methods A brain functional activity is represented in terms of magnetic source by a perturbation model: χ = χ0 +δχ, with δχ for BOLD magnetic perturbations and χ0 for background. A brain fMRI experiment produces a timeseries of complex-valued images (T2* images), whereby we extract the BOLD phase signals (denoted by δP) by a complex division. By solving an inverse problem, we reconstruct the BOLD δχ dataset from the δP dataset, and the brain χ distribution from a (unwrapped) T2* phase image. Given a 4D dataset of task BOLD fMRI, we implement brain functional mapping by temporal correlation analysis. Results Through a high-field (7T) and high-resolution (0.5mm in plane) task fMRI experiment, we demonstrated in detail the BOLD perturbation model for fMRI phase signal separation (P + δP) and reconstructing intrinsic brain magnetic source (χ and δχ). We also provided to a low-field (3T) and low-resolution (2mm) task fMRI experiment in support of single-subject fMRI study. Our experiments show that the δχ-depicted functional map reveals bidirectional BOLD χ perturbations during the task performance. Conclusions The BOLD perturbation model allows us to separate fMRI phase signal (by complex division) and to perform inverse mapping for pure BOLD δχ reconstruction for intrinsic functional χ mapping. The full brain χ reconstruction (from unwrapped fMRI phase) provides a new brain tissue image that allows to scrutinize the brain tissue idiosyncrasy for the pure BOLD δχ response through an automatic function/structure co-localization. PMID:29351339

  9. Brain functional BOLD perturbation modelling for forward fMRI and inverse mapping.

    Science.gov (United States)

    Chen, Zikuan; Robinson, Jennifer; Calhoun, Vince

    2018-01-01

    To computationally separate dynamic brain functional BOLD responses from static background in a brain functional activity for forward fMRI signal analysis and inverse mapping. A brain functional activity is represented in terms of magnetic source by a perturbation model: χ = χ0 +δχ, with δχ for BOLD magnetic perturbations and χ0 for background. A brain fMRI experiment produces a timeseries of complex-valued images (T2* images), whereby we extract the BOLD phase signals (denoted by δP) by a complex division. By solving an inverse problem, we reconstruct the BOLD δχ dataset from the δP dataset, and the brain χ distribution from a (unwrapped) T2* phase image. Given a 4D dataset of task BOLD fMRI, we implement brain functional mapping by temporal correlation analysis. Through a high-field (7T) and high-resolution (0.5mm in plane) task fMRI experiment, we demonstrated in detail the BOLD perturbation model for fMRI phase signal separation (P + δP) and reconstructing intrinsic brain magnetic source (χ and δχ). We also provided to a low-field (3T) and low-resolution (2mm) task fMRI experiment in support of single-subject fMRI study. Our experiments show that the δχ-depicted functional map reveals bidirectional BOLD χ perturbations during the task performance. The BOLD perturbation model allows us to separate fMRI phase signal (by complex division) and to perform inverse mapping for pure BOLD δχ reconstruction for intrinsic functional χ mapping. The full brain χ reconstruction (from unwrapped fMRI phase) provides a new brain tissue image that allows to scrutinize the brain tissue idiosyncrasy for the pure BOLD δχ response through an automatic function/structure co-localization.

  10. Decoding neural events from fMRI BOLD signal: a comparison of existing approaches and development of a new algorithm.

    Science.gov (United States)

    Bush, Keith; Cisler, Josh

    2013-07-01

    Neuroimaging methodology predominantly relies on the blood oxygenation level dependent (BOLD) signal. While the BOLD signal is a valid measure of neuronal activity, variances in fluctuations of the BOLD signal are not only due to fluctuations in neural activity. Thus, a remaining problem in neuroimaging analyses is developing methods that ensure specific inferences about neural activity that are not confounded by unrelated sources of noise in the BOLD signal. Here, we develop and test a new algorithm for performing semiblind (i.e., no knowledge of stimulus timings) deconvolution of the BOLD signal that treats the neural event as an observable, but intermediate, probabilistic representation of the system's state. We test and compare this new algorithm against three other recent deconvolution algorithms under varied levels of autocorrelated and Gaussian noise, hemodynamic response function (HRF) misspecification and observation sampling rate. Further, we compare the algorithms' performance using two models to simulate BOLD data: a convolution of neural events with a known (or misspecified) HRF versus a biophysically accurate balloon model of hemodynamics. We also examine the algorithms' performance on real task data. The results demonstrated good performance of all algorithms, though the new algorithm generally outperformed the others (3.0% improvement) under simulated resting-state experimental conditions exhibiting multiple, realistic confounding factors (as well as 10.3% improvement on a real Stroop task). The simulations also demonstrate that the greatest negative influence on deconvolution accuracy is observation sampling rate. Practical and theoretical implications of these results for improving inferences about neural activity from fMRI BOLD signal are discussed. Copyright © 2013 Elsevier Inc. All rights reserved.

  11. The impact of temporal regularization on estimates of the BOLD hemodynamic response function: a comparative analysis.

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    Casanova, Ramon; Ryali, Srikanth; Serences, John; Yang, Lucie; Kraft, Robert; Laurienti, Paul J; Maldjian, Joseph A

    2008-05-01

    In fMRI data analysis it has been shown that for a wide range of situations the hemodynamic response function (HRF) can be reasonably characterized as the impulse response function of a linear and time invariant system. An accurate and robust extraction of the HRF is essential to infer quantitative information about the relative timing of the neuronal events in different brain regions. When no assumptions are made about the HRF shape, it is most commonly estimated using time windowed averaging or a least squares estimated general linear model based on either Fourier or delta basis functions. Recently, regularization methods have been employed to increase the estimation efficiency of the HRF; typically these methods produce more accurate HRF estimates than the least squares approach [Goutte, C., Nielsen, F.A., Hansen, L.K., 2000. Modeling the Haemodynamic Response in fMRI Using Smooth FIR Filters. IEEE Trans. Med. Imag. 19(12), 1188-1201.]. Here, we use simulations to clarify the relative merit of temporal regularization based methods compared to the least squares methods with respect to the accuracy of estimating certain characteristics of the HRF such as time to peak (TTP), height (HR) and width (W) of the response. We implemented a Bayesian approach proposed by Marrelec et al. [Marrelec, G., Benali, H., Ciuciu, P., Pelegrini-Issac, M., Poline, J.-B., 2003. Robust Estimation of the Hemodynamic Response Function in Event-Related BOLD fMRI Using Basic Physiological Information. Hum. Brain Mapp. 19, 1-17., Marrelec, G., Benali, H., Ciuciu, P., Poline, J.B. Bayesian estimation of the hemodynamic of the hemodynamic response function in functional MRI. In: R. F, editor; 2001; Melville. p 229-247.] and its deterministic counterpart based on a combination of Tikhonov regularization [Tikhonov, A.N., Arsenin, V.Y., 1977. Solution of ill-posed problems. Washington DC: W.H. Winston.] and generalized cross-validation (GCV) [Wahba, G., 1990. Spline Models for Observational Data

  12. Differentiating BOLD and non-BOLD signals in fMRI time series using multi-echo EPI.

    Science.gov (United States)

    Kundu, Prantik; Inati, Souheil J; Evans, Jennifer W; Luh, Wen-Ming; Bandettini, Peter A

    2012-04-15

    A central challenge in the fMRI based study of functional connectivity is distinguishing neuronally related signal fluctuations from the effects of motion, physiology, and other nuisance sources. Conventional techniques for removing nuisance effects include modeling of noise time courses based on external measurements followed by temporal filtering. These techniques have limited effectiveness. Previous studies have shown using multi-echo fMRI that neuronally related fluctuations are Blood Oxygen Level Dependent (BOLD) signals that can be characterized in terms of changes in R(2)* and initial signal intensity (S(0)) based on the analysis of echo-time (TE) dependence. We hypothesized that if TE-dependence could be used to differentiate BOLD and non-BOLD signals, non-BOLD signal could be removed to denoise data without conventional noise modeling. To test this hypothesis, whole brain multi-echo data were acquired at 3 TEs and decomposed with Independent Components Analysis (ICA) after spatially concatenating data across space and TE. Components were analyzed for the degree to which their signal changes fit models for R(2)* and S(0) change, and summary scores were developed to characterize each component as BOLD-like or not BOLD-like. These scores clearly differentiated BOLD-like "functional network" components from non BOLD-like components related to motion, pulsatility, and other nuisance effects. Using non BOLD-like component time courses as noise regressors dramatically improved seed-based correlation mapping by reducing the effects of high and low frequency non-BOLD fluctuations. A comparison with seed-based correlation mapping using conventional noise regressors demonstrated the superiority of the proposed technique for both individual and group level seed-based connectivity analysis, especially in mapping subcortical-cortical connectivity. The differentiation of BOLD and non-BOLD components based on TE-dependence was highly robust, which allowed for the

  13. Multimodal investigation of fMRI and fNIRS derived breath hold BOLD signals with an expanded balloon model

    International Nuclear Information System (INIS)

    Emir, U E; Ozturk, C; Akin, A

    2008-01-01

    Multimodal investigation of blood oxygenation level-dependent (BOLD) signals, using both functional near-infrared spectroscopy (fNIRS) and functional magnetic resonance imaging (fMRI), may give further insight to the underlying physiological principles and the detailed transient dynamics of the vascular response. Utilizing a breath hold task (BHT), we measured deoxy-hemoglobin (HbR) and oxy-hemoglobin (HbO) changes via fNIRS and blood oxygen level dependent (BOLD) changes by fMRI. Measurements were taken in four volunteers asynchronously and carefully aligned for comparative analysis. In order to describe the main stimulus in BHT, partial pressure of carbon dioxide (PaCO 2 ) parameter was integrated into the balloon model as the driving function of cerebral blood flow (CBF) which led to the development of an expanded balloon model (EBM). During BHT, the increase in HbR was observed later than the BOLD peak and coincided temporally with its post-stimulus undershoot. Further investigation of these transients with a PaCO 2 integrated balloon model suggests that post-stimulus undershoot measured by fMRI is dominated by slow return of cerebral blood volume (CBV). This was confirmed by fNIRS measurements. In addition, the BOLD signal decreased with the increase of the initial level of PaCO 2 derived from EBM, indicating an effect of basal CBF level on the BOLD signal. In conclusion, a multimodal approach with an appropriate biophysical model gave a comprehensive description of the hemodynamic response during BHT

  14. Impact of abnormal cerebrovascular reactivity on BOLD fMRI: a preliminary investigation of moyamoya disease.

    Science.gov (United States)

    Mazerolle, Erin L; Ma, Yuhan; Sinclair, David; Pike, G Bruce

    2018-01-01

    Blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) studies of patients with cerebrovascular disease have largely ignored the confounds associated with abnormal cerebral blood flow, vascular reactivity and neurovascular coupling. We studied BOLD fMRI activation and cerebrovascular reactivity in moyamoya disease. To characterize the impact of remote vascular demands on BOLD fMRI measurements, we varied the vascular territories engaged by manipulating the experimental task performed by the participants. Vascular territories affected by disease were identified using BOLD cerebrovascular reactivity. Preliminary evidence from two patients pre- and postrevascularization surgery and four controls indicates that neurovascular coupling in affected brain regions can be modulated by the task-related vascular demands in unaffected regions. In one patient studied, we observed that brain regions with improved cerebrovascular reactivity after surgery demonstrated normalized neurovascular coupling, that is the degree to which neurovascular coupling was modulated by task-related vascular demands was decreased. We propose that variations in task-dependent neurovascular coupling in patients with moyamoya disease are likely related to vascular steal. While preliminary, our findings are a proof of concept of the limitations of BOLD fMRI in cerebrovascular disease and suggest a role for assessment of cerebrovascular reactivity to improve interpretation of task-related BOLD fMRI activation. © 2016 The Authors. Clinical Physiology and Functional Imaging published by John Wiley & Sons Ltd on behalf of Scandinavian Society of Clinical Physiology and Nuclear Medicine.

  15. Blood Flow and Brain Function: Investigations of neurovascular coupling using BOLD fMRI at 7 tesla

    NARCIS (Netherlands)

    Siero, J.C.W.

    2013-01-01

    The advent of ultra high field (7 tesla) MRI systems has opened the possibility to probe biological processes of the human body in great detail. Especially for studying brain function using BOLD fMRI there is a large benefit from the increased magnetic field strength. BOLD fMRI is the working horse

  16. Hypercapnic normalization of BOLD fMRI: comparison across field strengths and pulse sequences

    DEFF Research Database (Denmark)

    Cohen, Eric R.; Rostrup, Egill; Sidaros, Karam

    2004-01-01

    The blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) signal response to neural stimulation is influenced by many factors that are unrelated to the stimulus. These factors are physiological, such as the resting venous cerebral blood volume (CBV(v)) and vessel s...

  17. Bayesian model comparison in nonlinear BOLD fMRI hemodynamics

    DEFF Research Database (Denmark)

    Jacobsen, Danjal Jakup; Hansen, Lars Kai; Madsen, Kristoffer Hougaard

    2008-01-01

    of the parameters conditioned on the data is estimated using Markov chain Monte Carlo techniques. Using a split-half resampling procedure (Strother, Anderson, & Hansen, 2002), we compare the generalization abilities of the models as well as their reproducibility for both synthetic and real data, recorded from two...

  18. Comparison of diffusion-weighted fMRI and BOLD fMRI responses in a verbal working memory task

    International Nuclear Information System (INIS)

    Aso, Toshihiko; Urayama, Shin-ichi; Fukuyama, Hidenao; Le Bihan, Denis

    2013-01-01

    Diffusion-weighted functional MRI (DfMRI) has been reported to have a different response pattern in the visual cortex than that of BOLD-fMRI. Especially, the DfMRI signal shows a constantly faster response at both onset and offset of the stimulus, suggesting that the DfMRI signal might be more directly linked to neuronal events than the hemodynamic response. However, because the DfMRI response also contains a residual sensitivity to BOLD this hypothesis has been challenged. Using a verbal working memory task we show that the DfMRI time-course features are preserved outside visual cortices, but also less liable to between-subject/between-regional variation than the BOLD response. The overall findings not only support the feasibility of DfMRI as an approach for functional brain imaging, but also strengthen the uniqueness of the DfMRI signal origin. (authors)

  19. Comparison of fMRI analysis methods for heterogeneous BOLD responses in block design studies.

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    Liu, Jia; Duffy, Ben A; Bernal-Casas, David; Fang, Zhongnan; Lee, Jin Hyung

    2017-02-15

    A large number of fMRI studies have shown that the temporal dynamics of evoked BOLD responses can be highly heterogeneous. Failing to model heterogeneous responses in statistical analysis can lead to significant errors in signal detection and characterization and alter the neurobiological interpretation. However, to date it is not clear that, out of a large number of options, which methods are robust against variability in the temporal dynamics of BOLD responses in block-design studies. Here, we used rodent optogenetic fMRI data with heterogeneous BOLD responses and simulations guided by experimental data as a means to investigate different analysis methods' performance against heterogeneous BOLD responses. Evaluations are carried out within the general linear model (GLM) framework and consist of standard basis sets as well as independent component analysis (ICA). Analyses show that, in the presence of heterogeneous BOLD responses, conventionally used GLM with a canonical basis set leads to considerable errors in the detection and characterization of BOLD responses. Our results suggest that the 3rd and 4th order gamma basis sets, the 7th to 9th order finite impulse response (FIR) basis sets, the 5th to 9th order B-spline basis sets, and the 2nd to 5th order Fourier basis sets are optimal for good balance between detection and characterization, while the 1st order Fourier basis set (coherence analysis) used in our earlier studies show good detection capability. ICA has mostly good detection and characterization capabilities, but detects a large volume of spurious activation with the control fMRI data. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. Pitfalls in Fractal Time Series Analysis: fMRI BOLD as an Exemplary Case

    Science.gov (United States)

    Eke, Andras; Herman, Peter; Sanganahalli, Basavaraju G.; Hyder, Fahmeed; Mukli, Peter; Nagy, Zoltan

    2012-01-01

    This article will be positioned on our previous work demonstrating the importance of adhering to a carefully selected set of criteria when choosing the suitable method from those available ensuring its adequate performance when applied to real temporal signals, such as fMRI BOLD, to evaluate one important facet of their behavior, fractality. Earlier, we have reviewed on a range of monofractal tools and evaluated their performance. Given the advance in the fractal field, in this article we will discuss the most widely used implementations of multifractal analyses, too. Our recommended flowchart for the fractal characterization of spontaneous, low frequency fluctuations in fMRI BOLD will be used as the framework for this article to make certain that it will provide a hands-on experience for the reader in handling the perplexed issues of fractal analysis. The reason why this particular signal modality and its fractal analysis has been chosen was due to its high impact on today’s neuroscience given it had powerfully emerged as a new way of interpreting the complex functioning of the brain (see “intrinsic activity”). The reader will first be presented with the basic concepts of mono and multifractal time series analyses, followed by some of the most relevant implementations, characterization by numerical approaches. The notion of the dichotomy of fractional Gaussian noise and fractional Brownian motion signal classes and their impact on fractal time series analyses will be thoroughly discussed as the central theme of our application strategy. Sources of pitfalls and way how to avoid them will be identified followed by a demonstration on fractal studies of fMRI BOLD taken from the literature and that of our own in an attempt to consolidate the best practice in fractal analysis of empirical fMRI BOLD signals mapped throughout the brain as an exemplary case of potentially wide interest. PMID:23227008

  1. Identification of non-linear models of neural activity in bold fmri

    DEFF Research Database (Denmark)

    Jacobsen, Daniel Jakup; Madsen, Kristoffer Hougaard; Hansen, Lars Kai

    2006-01-01

    Non-linear hemodynamic models express the BOLD signal as a nonlinear, parametric functional of the temporal sequence of local neural activity. Several models have been proposed for this neural activity. We identify one such parametric model by estimating the distribution of its parameters. These ....... These distributions are themselves stochastic, therefore we estimate their variance by epoch based leave-one-out cross validation, using a Metropolis-Hastings algorithm for sampling of the posterior parameter distribution....

  2. Pitfalls in fractal time series analysis: fMRI BOLD as an exemplary case

    Directory of Open Access Journals (Sweden)

    Andras eEke

    2012-11-01

    Full Text Available This article will be positioned on our previous work demonstrating the importance of adhering to a carefully selected set of criteria when choosing the suitable method from those available ensuring its adequate performance when applied to real temporal signals, such as fMRI BOLD, to evaluate one important facet of their behavior, fractality.Earlier, we have reviewed on a range of monofractal tools and evaluated their performance. Given the advance in the fractal field, in this article we will discuss the most widely used implementations of multifractal analyses, too.Our recommended flowchart for the fractal characterization of spontaneous, low frequency fluctuations in fMRI BOLD will be used as the framework for this article to make certain that it will provide a hands-on experience for the reader in handling the perplexed issues of fractal analysis. The reason why this particular signal modality and its fractal analysis has been chosen was due to its high impact on today's neuroscience given it had powerfully emerged as a new way of interpreting the complex functioning of the brain (see intrinsic activity.The reader will first be presented with the basic concepts of mono and multifractal time series analyses, followed by some of the most relevant implementations, characterization by numerical approaches. The notion of the dichotomy of fractional Gaussian noise (fGn and fractional Brownian motion (fBm signal classes and their impact on fractal time series analyses will be thoroughly discussed as the central theme of our application strategy. Sources of pitfalls and way how to avoid them will be identified followed by a demonstration on fractal studies of fMRI BOLD taken from the literature and that of our own in an attempt to consolidate the best practice in fractal analysis of empirical fMRI-BOLD signals mapped throughout the brain as an exemplary case of potentially wide interest.

  3. Development of visual cortical function in infant macaques: A BOLD fMRI study.

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    Tom J Van Grootel

    Full Text Available Functional brain development is not well understood. In the visual system, neurophysiological studies in nonhuman primates show quite mature neuronal properties near birth although visual function is itself quite immature and continues to develop over many months or years after birth. Our goal was to assess the relative development of two main visual processing streams, dorsal and ventral, using BOLD fMRI in an attempt to understand the global mechanisms that support the maturation of visual behavior. Seven infant macaque monkeys (Macaca mulatta were repeatedly scanned, while anesthetized, over an age range of 102 to 1431 days. Large rotating checkerboard stimuli induced BOLD activation in visual cortices at early ages. Additionally we used static and dynamic Glass pattern stimuli to probe BOLD responses in primary visual cortex and two extrastriate areas: V4 and MT-V5. The resulting activations were analyzed with standard GLM and multivoxel pattern analysis (MVPA approaches. We analyzed three contrasts: Glass pattern present/absent, static/dynamic Glass pattern presentation, and structured/random Glass pattern form. For both GLM and MVPA approaches, robust coherent BOLD activation appeared relatively late in comparison to the maturation of known neuronal properties and the development of behavioral sensitivity to Glass patterns. Robust differential activity to Glass pattern present/absent and dynamic/static stimulus presentation appeared first in V1, followed by V4 and MT-V5 at older ages; there was no reliable distinction between the two extrastriate areas. A similar pattern of results was obtained with the two analysis methods, although MVPA analysis showed reliable differential responses emerging at later ages than GLM. Although BOLD responses to large visual stimuli are detectable, our results with more refined stimuli indicate that global BOLD activity changes as behavioral performance matures. This reflects an hierarchical development of

  4. MEG and fMRI fusion for nonlinear estimation of neural and BOLD signal changes

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    Sergey M Plis

    2010-11-01

    Full Text Available The combined analysis of MEG/EEG and functional MRI measurements can lead to improvement in the description of the dynamical and spatial properties of brain activity. In this paper we empirically demonstrate this improvement using simulated and recorded task related MEG and fMRI activity. Neural activity estimates were derived using a dynamic Bayesian network with continuous real valued parameters by means of a sequential Monte Carlo technique. In synthetic data, we show that MEG and fMRI fusion improves estimation of the indirectly observed neural activity and smooths tracking of the BOLD response. In recordings of task related neural activity the combination of MEG and fMRI produces a result with greater SNR, that confirms the expectation arising from the nature of the experiment. The highly nonlinear model of the BOLD response poses a difficult inference problem for neural activity estimation; computational requirements are also high due to the time and space complexity. We show that joint analysis of the data improves the system's behavior by stabilizing the differential equations system and by requiring fewer computational resources.

  5. A novel approach to calibrate the Hemodynamic Model using functional Magnetic Resonance Imaging (fMRI) measurements

    KAUST Repository

    Khoram, Nafiseh

    2016-01-21

    Background The calibration of the hemodynamic model that describes changes in blood flow and blood oxygenation during brain activation is a crucial step for successfully monitoring and possibly predicting brain activity. This in turn has the potential to provide diagnosis and treatment of brain diseases in early stages. New Method We propose an efficient numerical procedure for calibrating the hemodynamic model using some fMRI measurements. The proposed solution methodology is a regularized iterative method equipped with a Kalman filtering-type procedure. The Newton component of the proposed method addresses the nonlinear aspect of the problem. The regularization feature is used to ensure the stability of the algorithm. The Kalman filter procedure is incorporated here to address the noise in the data. Results Numerical results obtained with synthetic data as well as with real fMRI measurements are presented to illustrate the accuracy, robustness to the noise, and the cost-effectiveness of the proposed method. Comparison with Existing Method(s) We present numerical results that clearly demonstrate that the proposed method outperforms the Cubature Kalman Filter (CKF), one of the most prominent existing numerical methods. Conclusion We have designed an iterative numerical technique, called the TNM-CKF algorithm, for calibrating the mathematical model that describes the single-event related brain response when fMRI measurements are given. The method appears to be highly accurate and effective in reconstructing the BOLD signal even when the measurements are tainted with high noise level (as high as 30%).

  6. Enhancement of Temporal Resolution and BOLD Sensitivity in Real-Time fMRI using Multi-Slab Echo-Volumar Imaging

    Science.gov (United States)

    Posse, Stefan; Ackley, Elena; Mutihac, Radu; Rick, Jochen; Shane, Matthew; Murray-Krezan, Cristina; Zaitsev, Maxim; Speck, Oliver

    2012-01-01

    In this study, a new approach to high-speed fMRI using multi-slab echo-volumar imaging (EVI) is developed that minimizes geometrical image distortion and spatial blurring, and enables nonaliased sampling of physiological signal fluctuation to increase BOLD sensitivity compared to conventional echo-planar imaging (EPI). Real-time fMRI using whole brain 4-slab EVI with 286 ms temporal resolution (4 mm isotropic voxel size) and partial brain 2-slab EVI with 136 ms temporal resolution (4×4×6 mm3 voxel size) was performed on a clinical 3 Tesla MRI scanner equipped with 12-channel head coil. Four-slab EVI of visual and motor tasks significantly increased mean (visual: 96%, motor: 66%) and maximum t-score (visual: 263%, motor: 124%) and mean (visual: 59%, motor: 131%) and maximum (visual: 29%, motor: 67%) BOLD signal amplitude compared with EPI. Time domain moving average filtering (2 s width) to suppress physiological noise from cardiac and respiratory fluctuations further improved mean (visual: 196%, motor: 140%) and maximum (visual: 384%, motor: 200%) t-scores and increased extents of activation (visual: 73%, motor: 70%) compared to EPI. Similar sensitivity enhancement, which is attributed to high sampling rate at only moderately reduced temporal signal-to-noise ratio (mean: − 52%) and longer sampling of the BOLD effect in the echo-time domain compared to EPI, was measured in auditory cortex. Two-slab EVI further improved temporal resolution for measuring task-related activation and enabled mapping of five major resting state networks (RSNs) in individual subjects in 5 min scans. The bilateral sensorimotor, the default mode and the occipital RSNs were detectable in time frames as short as 75 s. In conclusion, the high sampling rate of real-time multi-slab EVI significantly improves sensitivity for studying the temporal dynamics of hemodynamic responses and for characterizing functional networks at high field strength in short measurement times. PMID:22398395

  7. Somatosensory BOLD fMRI reveals close link between salient blood pressure changes and the murine neuromatrix.

    Science.gov (United States)

    Reimann, Henning Matthias; Todiras, Mihail; Hodge, Russ; Huelnhagen, Till; Millward, Jason Michael; Turner, Robert; Seeliger, Erdmann; Bader, Michael; Pohlmann, Andreas; Niendorf, Thoralf

    2018-05-15

    The neuromatrix, or "pain matrix", is a network of cortical brain areas which is activated by noxious as well as salient somatosensory stimulation. This has been studied in mice and humans using blood oxygenation level-dependent (BOLD) fMRI. Here we demonstrate that BOLD effects observed in the murine neuromatrix in response to salient somatosensory stimuli are prone to reflect mean arterial blood pressure (MABP) changes, rather than neural activity. We show that a standard electrostimulus typically used in murine somatosensory fMRI can induce substantial elevations in MABP. Equivalent drug-induced MABP changes - without somatosensory stimulation - evoked BOLD patterns in the neuromatrix strikingly similar to those evoked by electrostimulation. This constitutes a serious caveat for murine fMRI. The regional specificity of these BOLD patterns can be attributed to the co-localization of the neuromatrix with large draining veins. Based on these findings we propose a cardiovascular support mechanism whereby abrupt elevations in MABP provide additional energy supply to the neuromatrix and other essential brain areas in fight-or-flight situations. Copyright © 2018 Elsevier Inc. All rights reserved.

  8. Visual, Auditory, and Cross Modal Sensory Processing in Adults with Autism: An EEG Power and BOLD fMRI Investigation

    Science.gov (United States)

    Hames, Elizabeth’ C.; Murphy, Brandi; Rajmohan, Ravi; Anderson, Ronald C.; Baker, Mary; Zupancic, Stephen; O’Boyle, Michael; Richman, David

    2016-01-01

    Electroencephalography (EEG) and blood oxygen level dependent functional magnetic resonance imagining (BOLD fMRI) assessed the neurocorrelates of sensory processing of visual and auditory stimuli in 11 adults with autism (ASD) and 10 neurotypical (NT) controls between the ages of 20–28. We hypothesized that ASD performance on combined audiovisual trials would be less accurate with observable decreased EEG power across frontal, temporal, and occipital channels and decreased BOLD fMRI activity in these same regions; reflecting deficits in key sensory processing areas. Analysis focused on EEG power, BOLD fMRI, and accuracy. Lower EEG beta power and lower left auditory cortex fMRI activity were seen in ASD compared to NT when they were presented with auditory stimuli as demonstrated by contrasting the activity from the second presentation of an auditory stimulus in an all auditory block vs. the second presentation of a visual stimulus in an all visual block (AA2-VV2).We conclude that in ASD, combined audiovisual processing is more similar than unimodal processing to NTs. PMID:27148020

  9. Evaluating the impact of spatio-temporal smoothness constraints on the BOLD hemodynamic response function estimation: an analysis based on Tikhonov regularization

    International Nuclear Information System (INIS)

    Casanova, R; Yang, L; Hairston, W D; Laurienti, P J; Maldjian, J A

    2009-01-01

    Recently we have proposed the use of Tikhonov regularization with temporal smoothness constraints to estimate the BOLD fMRI hemodynamic response function (HRF). The temporal smoothness constraint was imposed on the estimates by using second derivative information while the regularization parameter was selected based on the generalized cross-validation function (GCV). Using one-dimensional simulations, we previously found this method to produce reliable estimates of the HRF time course, especially its time to peak (TTP), being at the same time fast and robust to over-sampling in the HRF estimation. Here, we extend the method to include simultaneous temporal and spatial smoothness constraints. This method does not need Gaussian smoothing as a pre-processing step as usually done in fMRI data analysis. We carried out two-dimensional simulations to compare the two methods: Tikhonov regularization with temporal (Tik-GCV-T) and spatio-temporal (Tik-GCV-ST) smoothness constraints on the estimated HRF. We focus our attention on quantifying the influence of the Gaussian data smoothing and the presence of edges on the performance of these techniques. Our results suggest that the spatial smoothing introduced by regularization is less severe than that produced by Gaussian smoothing. This allows more accurate estimates of the response amplitudes while producing similar estimates of the TTP. We illustrate these ideas using real data. (note)

  10. A statistical approach for segregating cognitive task stages from multivariate fMRI BOLD time series.

    Science.gov (United States)

    Demanuele, Charmaine; Bähner, Florian; Plichta, Michael M; Kirsch, Peter; Tost, Heike; Meyer-Lindenberg, Andreas; Durstewitz, Daniel

    2015-01-01

    Multivariate pattern analysis can reveal new information from neuroimaging data to illuminate human cognition and its disturbances. Here, we develop a methodological approach, based on multivariate statistical/machine learning and time series analysis, to discern cognitive processing stages from functional magnetic resonance imaging (fMRI) blood oxygenation level dependent (BOLD) time series. We apply this method to data recorded from a group of healthy adults whilst performing a virtual reality version of the delayed win-shift radial arm maze (RAM) task. This task has been frequently used to study working memory and decision making in rodents. Using linear classifiers and multivariate test statistics in conjunction with time series bootstraps, we show that different cognitive stages of the task, as defined by the experimenter, namely, the encoding/retrieval, choice, reward and delay stages, can be statistically discriminated from the BOLD time series in brain areas relevant for decision making and working memory. Discrimination of these task stages was significantly reduced during poor behavioral performance in dorsolateral prefrontal cortex (DLPFC), but not in the primary visual cortex (V1). Experimenter-defined dissection of time series into class labels based on task structure was confirmed by an unsupervised, bottom-up approach based on Hidden Markov Models. Furthermore, we show that different groupings of recorded time points into cognitive event classes can be used to test hypotheses about the specific cognitive role of a given brain region during task execution. We found that whilst the DLPFC strongly differentiated between task stages associated with different memory loads, but not between different visual-spatial aspects, the reverse was true for V1. Our methodology illustrates how different aspects of cognitive information processing during one and the same task can be separated and attributed to specific brain regions based on information contained in

  11. Vascular Reactivity Maps in Patients with Gliomas Using Breath-Holding BOLD fMRI.

    Science.gov (United States)

    Iranmahboob, Amir; Peck, Kyung K; Brennan, Nicole P; Karimi, Sasan; Fisicaro, Ryan; Hou, Bob; Holodny, Andrei I

    2016-01-01

    To evaluate whether breath-holding (BH) blood oxygenation level-dependent (BOLD) fMRI can quantify differences in vascular reactivity (VR), as there is a need for improved contrast mechanisms in gliomas. 16 patients (gliomas, grade II = 5, III = 2, IV = 9) were evaluated using the BH paradigm: 4-second single deep breath followed by 16 seconds of BH and 40 seconds of regular breathing for five cycles. VR was defined as the difference in BOLD signal between the minimal signal seen at the end of the deep breath and maximal signal seen at the end of BH (peak-to-trough). VR was measured for every voxel and compared for gray versus white matter and tumor versus normal contralateral brain. VR maps were compared to the areas of enhancement and FLAIR/T2 abnormality. VR was significantly lower in normal white matter than gray matter (P < .05) and in tumors compared to the normal, contralateral brain (P < 0.002). The area of abnormal VR (1103 ± 659 mm²) was significantly greater (P = .019) than the enhancement (543 ± 530 mm²), but significantly smaller (P = .0011) than the FLAIR abnormality (2363 ± 1232 mm²). However, the variability in the areas of gadolinium contrast enhancement versus VR abnormality indicates that the contrast mechanism elicited by BH (caused by abnormal arteriolar smooth muscles) appears to be fundamentally different from the contrast mechanism of gadolinium enhancement (caused by the presence of "leaky" gap junctions). BH maps based on peak-to-trough can be used to characterize VR in brain tumors. VR maps in brain tumor patients appear to be caused by a different mechanism than gadolinium enhancement.

  12. A statistical approach for segregating cognitive task stages from multivariate fMRI BOLD time series

    Directory of Open Access Journals (Sweden)

    Charmaine eDemanuele

    2015-10-01

    Full Text Available Multivariate pattern analysis can reveal new information from neuroimaging data to illuminate human cognition and its disturbances. Here, we develop a methodological approach, based on multivariate statistical/machine learning and time series analysis, to discern cognitive processing stages from fMRI blood oxygenation level dependent (BOLD time series. We apply this method to data recorded from a group of healthy adults whilst performing a virtual reality version of the delayed win-shift radial arm maze task. This task has been frequently used to study working memory and decision making in rodents. Using linear classifiers and multivariate test statistics in conjunction with time series bootstraps, we show that different cognitive stages of the task, as defined by the experimenter, namely, the encoding/retrieval, choice, reward and delay stages, can be statistically discriminated from the BOLD time series in brain areas relevant for decision making and working memory. Discrimination of these task stages was significantly reduced during poor behavioral performance in dorsolateral prefrontal cortex (DLPFC, but not in the primary visual cortex (V1. Experimenter-defined dissection of time series into class labels based on task structure was confirmed by an unsupervised, bottom-up approach based on Hidden Markov Models. Furthermore, we show that different groupings of recorded time points into cognitive event classes can be used to test hypotheses about the specific cognitive role of a given brain region during task execution. We found that whilst the DLPFC strongly differentiated between task stages associated with different memory loads, but not between different visual-spatial aspects, the reverse was true for V1. Our methodology illustrates how different aspects of cognitive information processing during one and the same task can be separated and attributed to specific brain regions based on information contained in multivariate patterns of voxel

  13. Effect of hypoxia on BOLD fMRI response and total cerebral blood flow in migraine with aura patients

    DEFF Research Database (Denmark)

    Arngrim, Nanna; Hougaard, Anders; Schytz, Henrik W

    2018-01-01

    was measured in the visual cortex ROIs V1-V5. Total cerebral blood flow (CBF) was calculated by measuring the blood velocity in the internal carotid arteries and the basilar artery using phase-contrast mapping (PCM) MRI. Hypoxia induced a greater decrease in BOLD response to visual stimulation in V1-V4 in MA......Experimentally induced hypoxia triggers migraine and aura attacks in patients suffering from migraine with aura (MA). We investigated the blood oxygenation level-dependent (BOLD) signal response to visual stimulation during hypoxia in MA patients and healthy volunteers. In a randomized double......-blind crossover study design, 15 MA patients were allocated to 180 min of normobaric poikilocapnic hypoxia (capillary oxygen saturation 70-75%) or sham (normoxia) on two separate days and 14 healthy volunteers were exposed to hypoxia. The BOLD functional MRI (fMRI) signal response to visual stimulation...

  14. An efficient multi-stage algorithm for full calibration of the hemodynamic model from BOLD signal responses

    KAUST Repository

    Zambri, Brian

    2017-02-22

    We propose a computational strategy that falls into the category of prediction/correction iterative-type approaches, for calibrating the hemodynamic model introduced by Friston et al. (2000). The proposed method is employed to estimate consecutively the values of the biophysiological system parameters and the external stimulus characteristics of the model. Numerical results corresponding to both synthetic and real functional Magnetic Resonance Imaging (fMRI) measurements for a single stimulus as well as for multiple stimuli are reported to highlight the capability of this computational methodology to fully calibrate the considered hemodynamic model. This article is protected by copyright. All rights reserved.

  15. Dataset for: An efficient multi-stage algorithm for full calibration of the hemodynamic model from BOLD signal responses

    KAUST Repository

    Djellouli, Rabia

    2017-01-01

    We propose a computational strategy that falls into the category of prediction/correction iterative-type approaches, for calibrating the hemodynamic model introduced by Friston et al. (2000). The proposed method is employed to estimate consecutively the values of the biophysiological system parameters and the external stimulus characteristics of the model. Numerical results corresponding to both synthetic and real functional Magnetic Resonance Imaging (fMRI) measurements for a single stimulus as well as for multiple stimuli are reported to highlight the capability of this computational methodology to fully calibrate the considered hemodynamic model.

  16. Reliable quantification of BOLD fMRI cerebrovascular reactivity despite poor breath-hold performance☆

    Science.gov (United States)

    Bright, Molly G.; Murphy, Kevin

    2013-01-01

    Cerebrovascular reactivity (CVR) can be mapped using BOLD fMRI to provide a clinical insight into vascular health that can be used to diagnose cerebrovascular disease. Breath-holds are a readily accessible method for producing the required arterial CO2 increases but their implementation into clinical studies is limited by concerns that patients will demonstrate highly variable performance of breath-hold challenges. This study assesses the repeatability of CVR measurements despite poor task performance, to determine if and how robust results could be achieved with breath-holds in patients. Twelve healthy volunteers were scanned at 3T. Six functional scans were acquired, each consisting of 6 breath-hold challenges (10, 15, or 20 s duration) interleaved with periods of paced breathing. These scans simulated the varying breath-hold consistency and ability levels that may occur in patient data. Uniform ramps, time-scaled ramps, and end-tidal CO2 data were used as regressors in a general linear model in order to measure CVR at the grey matter, regional, and voxelwise level. The intraclass correlation coefficient (ICC) quantified the repeatability of the CVR measurement for each breath-hold regressor type and scale of interest across the variable task performances. The ramp regressors did not fully account for variability in breath-hold performance and did not achieve acceptable repeatability (ICC  0.4). Further analysis of intra-subject CVR variability across the brain (ICCspatial and voxelwise correlation) supported the use of end-tidal CO2 data to extract robust whole-brain CVR maps, despite variability in breath-hold performance. We conclude that the incorporation of end-tidal CO2 monitoring into scanning enables robust, repeatable measurement of CVR that makes breath-hold challenges suitable for routine clinical practice. PMID:23845426

  17. Enhancement of temporal resolution and BOLD sensitivity in real-time fMRI using multi-slab echo-volumar imaging.

    Science.gov (United States)

    Posse, Stefan; Ackley, Elena; Mutihac, Radu; Rick, Jochen; Shane, Matthew; Murray-Krezan, Cristina; Zaitsev, Maxim; Speck, Oliver

    2012-05-15

    In this study, a new approach to high-speed fMRI using multi-slab echo-volumar imaging (EVI) is developed that minimizes geometrical image distortion and spatial blurring, and enables nonaliased sampling of physiological signal fluctuation to increase BOLD sensitivity compared to conventional echo-planar imaging (EPI). Real-time fMRI using whole brain 4-slab EVI with 286 ms temporal resolution (4mm isotropic voxel size) and partial brain 2-slab EVI with 136 ms temporal resolution (4×4×6 mm(3) voxel size) was performed on a clinical 3 Tesla MRI scanner equipped with 12-channel head coil. Four-slab EVI of visual and motor tasks significantly increased mean (visual: 96%, motor: 66%) and maximum t-score (visual: 263%, motor: 124%) and mean (visual: 59%, motor: 131%) and maximum (visual: 29%, motor: 67%) BOLD signal amplitude compared with EPI. Time domain moving average filtering (2s width) to suppress physiological noise from cardiac and respiratory fluctuations further improved mean (visual: 196%, motor: 140%) and maximum (visual: 384%, motor: 200%) t-scores and increased extents of activation (visual: 73%, motor: 70%) compared to EPI. Similar sensitivity enhancement, which is attributed to high sampling rate at only moderately reduced temporal signal-to-noise ratio (mean: -52%) and longer sampling of the BOLD effect in the echo-time domain compared to EPI, was measured in auditory cortex. Two-slab EVI further improved temporal resolution for measuring task-related activation and enabled mapping of five major resting state networks (RSNs) in individual subjects in 5 min scans. The bilateral sensorimotor, the default mode and the occipital RSNs were detectable in time frames as short as 75 s. In conclusion, the high sampling rate of real-time multi-slab EVI significantly improves sensitivity for studying the temporal dynamics of hemodynamic responses and for characterizing functional networks at high field strength in short measurement times. Copyright © 2012

  18. BOLD fMRI in infants under sedation: Comparing the impact of pentobarbital and propofol on auditory and language activation.

    Science.gov (United States)

    DiFrancesco, Mark W; Robertson, Sara A; Karunanayaka, Prasanna; Holland, Scott K

    2013-11-01

    To elucidate differences in the disruption of language network function, as measured by blood oxygenation level-dependent (BOLD) contrast functional MRI (fMRI), attributable to two common sedative agents administered to infants under clinical imaging protocols. The sedatives pentobarbital (Nembutal) and Propofol, administered clinically to infants at 1 year of age, were compared with respect to BOLD activation profiles in response to passive story-listening stimulation. An intermittent event-related imaging protocol was used with which the temporal evolution of language processing resulting from this stimulation was explored. Propofol and Nembutal were found to have distinct and complementary responses to story-listening. Propofol exhibited more activation in higher processing networks with increasing response toward the end of narrative stimulus. Nembutal, in contrast, had much more robust activation of primary and secondary sensory cortices but a decreasing response over time in fronto-parietal default-mode regions. This may suggest a breakdown of top-down feedback for Propofol versus the lack of bottom-up feed-forward processing for Nembutal. Two popular sedative agents for use in children for clinical fMRI were found to induce distinct alteration of activation patterns from a language stimulus. This has ramifications for clinical fMRI of sedated infants and encourages further study to build a framework for more confident interpretation. Copyright © 2013 Wiley Periodicals, Inc.

  19. Localization of cortical primary motor area of the hand using navigated transcranial magnetic stimulation, BOLD and arterial spin labeling fMRI.

    Science.gov (United States)

    Kallioniemi, Elisa; Pitkänen, Minna; Könönen, Mervi; Vanninen, Ritva; Julkunen, Petro

    2016-11-01

    Although the relationship between neuronavigated transcranial magnetic stimulation (nTMS) and functional magnetic resonance imaging (fMRI) has been widely studied in motor mapping, it is unknown how the motor response type or the choice of motor task affect this relationship. Centers of gravity (CoGs) and response maxima were measured with blood-oxygen-level dependent (BOLD) and arterial spin labeling (ASL) fMRI during motor tasks against nTMS CoGs and response maxima, which were mapped with motor evoked potentials (MEPs) and silent periods (SPs). No differences in motor representations (CoGs and response maxima) were observed in lateral-medial direction (p=0.265). fMRI methods localized the motor representation more posterior than nTMS (pmotor task (p>0.999) nor nTMS response type (p>0.999). ASL fMRI maxima did not differ from the nTMS nor BOLD fMRI CoGs (p≥0.070), but the ASL CoG was deeper in comparison to other methods (p≤0.042). The BOLD fMRI motor task did not influence the depth of the motor representation (p≥0.745). The median Euclidean distances between the nTMS and fMRI motor representations varied between 7.7mm and 14.5mm and did not differ between the methods (F≤1.23, p≥0.318). The relationship between fMRI and nTMS mapped excitatory (MEP) and inhibitory (SP) responses, and whether the choice of motor task affects this relationship, have not been studied before. The congruence between fMRI and nTMS is good. The choice of nTMS motor response type nor BOLD fMRI motor task had no effect on this relationship. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Nonlinear neural network for hemodynamic model state and input estimation using fMRI data

    KAUST Repository

    Karam, Ayman M.

    2014-11-01

    Originally inspired by biological neural networks, artificial neural networks (ANNs) are powerful mathematical tools that can solve complex nonlinear problems such as filtering, classification, prediction and more. This paper demonstrates the first successful implementation of ANN, specifically nonlinear autoregressive with exogenous input (NARX) networks, to estimate the hemodynamic states and neural activity from simulated and measured real blood oxygenation level dependent (BOLD) signals. Blocked and event-related BOLD data are used to test the algorithm on real experiments. The proposed method is accurate and robust even in the presence of signal noise and it does not depend on sampling interval. Moreover, the structure of the NARX networks is optimized to yield the best estimate with minimal network architecture. The results of the estimated neural activity are also discussed in terms of their potential use.

  1. The fMRI BOLD response to unisensory and multisensory smoking cues in nicotine-dependent adults.

    Science.gov (United States)

    Cortese, Bernadette M; Uhde, Thomas W; Brady, Kathleen T; McClernon, F Joseph; Yang, Qing X; Collins, Heather R; LeMatty, Todd; Hartwell, Karen J

    2015-12-30

    Given that the vast majority of functional magnetic resonance imaging (fMRI) studies of drug cue reactivity use unisensory visual cues, but that multisensory cues may elicit greater craving-related brain responses, the current study sought to compare the fMRI BOLD response to unisensory visual and multisensory, visual plus odor, smoking cues in 17 nicotine-dependent adult cigarette smokers. Brain activation to smoking-related, compared to neutral, pictures was assessed under cigarette smoke and odorless odor conditions. While smoking pictures elicited a pattern of activation consistent with the addiction literature, the multisensory (odor+picture) smoking cues elicited significantly greater and more widespread activation in mainly frontal and temporal regions. BOLD signal elicited by the multisensory, but not unisensory cues, was significantly related to participants' level of control over craving as well. Results demonstrated that the co-presentation of cigarette smoke odor with smoking-related visual cues, compared to the visual cues alone, elicited greater levels of craving-related brain activation in key regions implicated in reward. These preliminary findings support future research aimed at a better understanding of multisensory integration of drug cues and craving. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  2. Linear Discriminant Analysis Achieves High Classification Accuracy for the BOLD fMRI Response to Naturalistic Movie Stimuli.

    Science.gov (United States)

    Mandelkow, Hendrik; de Zwart, Jacco A; Duyn, Jeff H

    2016-01-01

    Naturalistic stimuli like movies evoke complex perceptual processes, which are of great interest in the study of human cognition by functional MRI (fMRI). However, conventional fMRI analysis based on statistical parametric mapping (SPM) and the general linear model (GLM) is hampered by a lack of accurate parametric models of the BOLD response to complex stimuli. In this situation, statistical machine-learning methods, a.k.a. multivariate pattern analysis (MVPA), have received growing attention for their ability to generate stimulus response models in a data-driven fashion. However, machine-learning methods typically require large amounts of training data as well as computational resources. In the past, this has largely limited their application to fMRI experiments involving small sets of stimulus categories and small regions of interest in the brain. By contrast, the present study compares several classification algorithms known as Nearest Neighbor (NN), Gaussian Naïve Bayes (GNB), and (regularized) Linear Discriminant Analysis (LDA) in terms of their classification accuracy in discriminating the global fMRI response patterns evoked by a large number of naturalistic visual stimuli presented as a movie. Results show that LDA regularized by principal component analysis (PCA) achieved high classification accuracies, above 90% on average for single fMRI volumes acquired 2 s apart during a 300 s movie (chance level 0.7% = 2 s/300 s). The largest source of classification errors were autocorrelations in the BOLD signal compounded by the similarity of consecutive stimuli. All classifiers performed best when given input features from a large region of interest comprising around 25% of the voxels that responded significantly to the visual stimulus. Consistent with this, the most informative principal components represented widespread distributions of co-activated brain regions that were similar between subjects and may represent functional networks. In light of these

  3. Hemodynamic traveling waves in human visual cortex.

    Directory of Open Access Journals (Sweden)

    Kevin M Aquino

    Full Text Available Functional MRI (fMRI experiments rely on precise characterization of the blood oxygen level dependent (BOLD signal. As the spatial resolution of fMRI reaches the sub-millimeter range, the need for quantitative modelling of spatiotemporal properties of this hemodynamic signal has become pressing. Here, we find that a detailed physiologically-based model of spatiotemporal BOLD responses predicts traveling waves with velocities and spatial ranges in empirically observable ranges. Two measurable parameters, related to physiology, characterize these waves: wave velocity and damping rate. To test these predictions, high-resolution fMRI data are acquired from subjects viewing discrete visual stimuli. Predictions and experiment show strong agreement, in particular confirming BOLD waves propagating for at least 5-10 mm across the cortical surface at speeds of 2-12 mm s-1. These observations enable fundamentally new approaches to fMRI analysis, crucial for fMRI data acquired at high spatial resolution.

  4. Quantification of fMRI BOLD signal and volume applied to the somatosensory cortex

    Energy Technology Data Exchange (ETDEWEB)

    Luedemann, L.; Wust, P. [Universitaetsklinikum Charite, CVK, Berlin (Germany). Klinik fuer Radiologie, Nuklearmedizin und Strahlenheilkunde; Foerschler, A.; Zimmer, C. [Universitaetsklinikum Leipzig (Germany). Abt. fuer Neuroradiologie

    2007-07-01

    Functional magnetic resonance imaging based on blood-oxygenation-level-dependent (BOLD) signal variations is clinically used to investigate the impact of neurological disorders on brain function. Such disorders effect not only the localization but also the amplitude and extent of the BOLD signal. Statistical methods are useful to localize the BOLD signal but fail to quantify functional activity because they rely on arbitrary thresholds. This article presents a method that uses a priori defined VOI (volume of interest) and independently quantifies the mean BOLD signal and extent of the activated volume. The technique is based on the separation of the VOI signal difference distribution into a noise and an activation contribution. The technique does not require any threshold and is nearly independent of the preselected VOI size. The technique was verified in a test group of 17 subjects performing bilateral finger tapping. The results were compared with those of conventional analysis based on statistical tools. A standard imaging technique using FID-EPI (free induction decay echo-planar imaging, TR = 4000 ms, TE = 66 ms, 60 images activation, 60 images rest) was employed. The activated volume, V, and signal difference, {delta}S, of the motor cortex were determined with an accuracy of {sigma}(V)=17.1% and {sigma}({delta}S)=3.6%, respectively. The activated volume of the left hemispheric motor area was significantly greater (P=0.025) then in the right hemispheric, V{sub L} = 7.35 {+-} 2.29 cm{sup 3} versus V{sub L} = 6.39 {+-} 2.34 cm{sup 3}. The result is consistent with the findings obtained by other techniques. On the other hand, the statistical methods did not yield any significant difference in activation between both hemispheres. The VOI-based method presented here is an additional tool to study the extent and amplitude of the BOLD signal. (orig.)

  5. Accounting for the role of hematocrit in between-subject variations of MRI-derived baseline cerebral hemodynamic parameters and functional BOLD responses.

    Science.gov (United States)

    Xu, Feng; Li, Wenbo; Liu, Peiying; Hua, Jun; Strouse, John J; Pekar, James J; Lu, Hanzhang; van Zijl, Peter C M; Qin, Qin

    2018-01-01

    Baseline hematocrit fraction (Hct) is a determinant for baseline cerebral blood flow (CBF) and between-subject variation of Hct thus causes variation in task-based BOLD fMRI signal changes. We first verified in healthy volunteers (n = 12) that Hct values can be derived reliably from venous blood T 1 values by comparison with the conventional lab test. Together with CBF measured using phase-contrast MRI, this noninvasive estimation of Hct, instead of using a population-averaged Hct value, enabled more individual determination of oxygen delivery (DO 2 ), oxygen extraction fraction (OEF), and cerebral metabolic rate of oxygen (CMRO 2 ). The inverse correlation of CBF and Hct explained about 80% of between-subject variation of CBF in this relatively uniform cohort of subjects, as expected based on the regulation of DO 2 to maintain constant CMRO 2 . Furthermore, we compared the relationships of visual task-evoked BOLD response with Hct and CBF. We showed that Hct and CBF contributed 22%-33% of variance in BOLD signal and removing the positive correlation with Hct and negative correlation with CBF allowed normalization of BOLD signal with 16%-22% lower variability. The results of this study suggest that adjustment for Hct effects is useful for studies of MRI perfusion and BOLD fMRI. Hum Brain Mapp 39:344-353, 2018. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  6. BOLD fMRI deactivation of limbic and temporal brain structures and mood enhancing effect by transcutaneous vagus nerve stimulation.

    Science.gov (United States)

    Kraus, T; Hösl, K; Kiess, O; Schanze, A; Kornhuber, J; Forster, C

    2007-01-01

    Direct vagus nerve stimulation (VNS) has proved to be an effective treatment for seizure disorder and major depression. However, since this invasive technique implies surgery, with its side-effects and relatively high financial costs, a non-invasive method to stimulate vagal afferences would be a great step forward. We studied effects of non-invasive electrical stimulation of the nerves in the left outer auditory canal in healthy subjects (n = 22), aiming to activate vagal afferences transcutaneously (t-VNS). Short-term changes in brain activation and subjective well-being induced by t-VNS were investigated by functional magnetic resonance imaging (fMRI) and psychometric assessment using the Adjective Mood Scale (AMS), a self-rating scale for current subjective feeling. Stimulation of the ear lobe served as a sham control. fMRI showed that robust t-VNS induced BOLD-signal decreases in limbic brain areas, including the amygdala, hippocampus, parahippocampal gyrus and the middle and superior temporal gyrus. Increased activation was seen in the insula, precentral gyrus and the thalamus. Psychometric assessment revealed significant improvement of well-being after t-VNS. Ear lobe stimulation as a sham control intervention did not show similar effects in either fMRI or psychometric assessment. No significant effects on heart rate, blood pressure or peripheral microcirculation could be detected during the stimulation procedure. Our study shows the feasibility and beneficial effects of transcutaneous nerve stimulation in the left auditory canal of healthy subjects. Brain activation patterns clearly share features with changes observed during invasive vagus nerve stimulation.

  7. Visual, Auditory, and Cross Modal Sensory Processing in Adults with Autism:An EEG Power and BOLD fMRI Investigation

    Directory of Open Access Journals (Sweden)

    Elizabeth C Hames

    2016-04-01

    Full Text Available Electroencephalography (EEG and Blood Oxygen Level Dependent Functional Magnetic Resonance Imagining (BOLD fMRI assessed the neurocorrelates of sensory processing of visual and auditory stimuli in 11 adults with autism (ASD and 10 neurotypical (NT controls between the ages of 20-28. We hypothesized that ASD performance on combined audiovisual trials would be less accurate with observable decreased EEG power across frontal, temporal, and occipital channels and decreased BOLD fMRI activity in these same regions; reflecting deficits in key sensory processing areas. Analysis focused on EEG power, BOLD fMRI, and accuracy. Lower EEG beta power and lower left auditory cortex fMRI activity were seen in ASD compared to NT when they were presented with auditory stimuli as demonstrated by contrasting the activity from the second presentation of an auditory stimulus in an all auditory block versus the second presentation of a visual stimulus in an all visual block (AA2­VV2. We conclude that in ASD, combined audiovisual processing is more similar than unimodal processing to NTs.

  8. Detection and Characterization of Single-Trial fMRI BOLD Responses : Paradigm Free Mapping

    NARCIS (Netherlands)

    Gaudes, Cesar Caballero; Petridou, Natalia; Dryden, Ian L.; Bai, Li; Francis, Susan T.; Gowland, Penny A.

    This work presents a novel method of mapping the brain's response to single stimuli in space and time without prior knowledge of the paradigm timing: paradigm free mapping (PFM). This method is based on deconvolution of the hemodynamic response from the voxel time series assuming a linear response

  9. Resting bold fMRI differentiates dementia with Lewy bodies vs Alzheimer disease

    Science.gov (United States)

    Price, J.L.; Yan, Z.; Morris, J.C.; Sheline, Y.I.

    2011-01-01

    Objective: Clinicopathologic phenotypes of dementia with Lewy bodies (DLB) and Alzheimer disease (AD) often overlap, making discrimination difficult. We performed resting state blood oxygen level–dependent (BOLD) functional connectivity MRI (fcMRI) to determine whether there were differences between AD and DLB. Methods: Participants (n = 88) enrolled in a longitudinal study of memory and aging underwent 3-T fcMRI. Clinical diagnoses of probable DLB (n = 15) were made according to published criteria. Cognitively normal control participants (n = 38) were selected for the absence of cerebral amyloid burden as imaged with Pittsburgh compound B (PiB). Probable AD cases (n = 35) met published criteria and had appreciable amyloid deposits with PiB imaging. Functional images were collected using a gradient spin-echo sequence sensitive to BOLD contrast (T2* weighting). Correlation maps selected a seed region in the combined bilateral precuneus. Results: Participants with DLB had a functional connectivity pattern for the precuneus seed region that was distinct from AD; both the DLB and AD groups had functional connectivity patterns that differed from the cognitively normal group. In the DLB group, we found increased connectivity between the precuneus and regions in the dorsal attention network and the putamen. In contrast, we found decreased connectivity between the precuneus and other task-negative default regions and visual cortices. There was also a reversal of connectivity in the right hippocampus. Conclusions: Changes in functional connectivity in DLB indicate patterns of activation that are distinct from those seen in AD and may improve discrimination of DLB from AD and cognitively normal individuals. Since patterns of connectivity differ between AD and DLB groups, measurements of BOLD functional connectivity can shed further light on neuroanatomic connections that distinguish DLB from AD. PMID:21525427

  10. Working memory in volunteers and schizophrenics using BOLD fMRI

    International Nuclear Information System (INIS)

    Giesel, F.L.; Hohmann, N.; Seidl, U.; Kress, K.R.; Schoenknecht, P.; Schroeder, J.; Kauczor, H.-U.; Essig, M.

    2005-01-01

    Functional magnetic resonance imaging uses the blood oxygen level-dependent effect (BOLD MRI) for noninvasive display of cerebral correlatives of cognitive function. The importance for the understanding of physiological and pathological processes is demonstrated by investigations of working memory in schizophrenics and healthy controls. Working memory is involved in processing rather than storage of information and therefore is linked to complex processes such as learning and problem solving. In schizophrenic psychosis, these functions are clearly restricted. Training effects in the working memory task follow an inverse U-shape function, suggesting that cerebral activation reaches a peak before economics of the brain find a more efficient method and activation decreases. (orig.) [de

  11. CNS BOLD fMRI effects of sham-controlled transcutaneous electrical nerve stimulation in the left outer auditory canal - a pilot study.

    Science.gov (United States)

    Kraus, Thomas; Kiess, Olga; Hösl, Katharina; Terekhin, Pavel; Kornhuber, Johannes; Forster, Clemens

    2013-09-01

    It has recently been shown that electrical stimulation of sensory afferents within the outer auditory canal may facilitate a transcutaneous form of central nervous system stimulation. Functional magnetic resonance imaging (fMRI) blood oxygenation level dependent (BOLD) effects in limbic and temporal structures have been detected in two independent studies. In the present study, we investigated BOLD fMRI effects in response to transcutaneous electrical stimulation of two different zones in the left outer auditory canal. It is hypothesized that different central nervous system (CNS) activation patterns might help to localize and specifically stimulate auricular cutaneous vagal afferents. 16 healthy subjects aged between 20 and 37 years were divided into two groups. 8 subjects were stimulated in the anterior wall, the other 8 persons received transcutaneous vagus nervous stimulation (tVNS) at the posterior side of their left outer auditory canal. For sham control, both groups were also stimulated in an alternating manner on their corresponding ear lobe, which is generally known to be free of cutaneous vagal innervation. Functional MR data from the cortex and brain stem level were collected and a group analysis was performed. In most cortical areas, BOLD changes were in the opposite direction when comparing anterior vs. posterior stimulation of the left auditory canal. The only exception was in the insular cortex, where both stimulation types evoked positive BOLD changes. Prominent decreases of the BOLD signals were detected in the parahippocampal gyrus, posterior cingulate cortex and right thalamus (pulvinar) following anterior stimulation. In subcortical areas at brain stem level, a stronger BOLD decrease as compared with sham stimulation was found in the locus coeruleus and the solitary tract only during stimulation of the anterior part of the auditory canal. The results of the study are in line with previous fMRI studies showing robust BOLD signal decreases in

  12. Olfactory responses to natal stream water in sockeye salmon by BOLD fMRI.

    Directory of Open Access Journals (Sweden)

    Hiroshi Bandoh

    Full Text Available Many studies have shown that juvenile salmon imprint olfactory memory of natal stream odors during downstream migration, and adults recall this stream-specific odor information to discriminate their natal stream during upstream migration for spawning. The odor information processing of the natal stream in the salmon brain, however, has not been clarified. We applied blood oxygenation level-dependent (BOLD functional magnetic resonance imaging to investigate the odor information processing of the natal stream in the olfactory bulb and telencephalon of lacustrine sockeye salmon (Oncorhynchus nerka. The strong responses to the natal stream water were mainly observed in the lateral area of dorsal telencephalon (Dl, which are homologous to the medial pallium (hippocampus in terrestrial vertebrates. Although the concentration of L-serine (1 mM in the control water was 20,000-times higher than that of total amino acid in the natal stream water (47.5 nM, the BOLD signals resulting from the natal stream water were stronger than those by L-serine in the Dl. We concluded that sockeye salmon could process the odor information of the natal stream by integrating information in the Dl area of the telencephalon.

  13. Impaired cerebral vasoreactivity to CO2 in Alzheimer's disease using BOLD fMRI.

    Science.gov (United States)

    Cantin, S; Villien, M; Moreaud, O; Tropres, I; Keignart, S; Chipon, E; Le Bas, J-F; Warnking, J; Krainik, A

    2011-09-15

    To evaluate the cerebral vasoreactivity using blood oxygenation level dependent functional MRI during carbogen inhalation with 7% CO(2) in Alzheimer's disease and amnestic mild cognitive impairment. Thirty nine subjects were included to be investigated using blood oxygenation level dependent (BOLD) functional MRI at 1.5T during a block-design carbogen inhalation paradigm, with a high concentration face-mask under physiological monitoring. Basal cerebral perfusion was measured using pulsed arterial spin labeling. Image analyses were conducted using Matlab® and SPM5 with physiological regressors and corrected for partial volume effect. Among selected participants, 12 subjects were excluded because of incomplete protocol, leaving for analysis 27 subjects without significant microangiopathy diagnosed for Alzheimer's disease (n=9), amnestic mild cognitive impairment (n=7), and matched controls (n=11). No adverse reaction related to the CO(2) challenge was reported. Carbogen inhalation induced a whole-brain signal increase, predominant in the gray matter. In patients, signal changes corrected for gray matter partial volume were decreased (0.36±0.13% BOLD/mmHg in Alzheimer's disease, 0.36±0.12 in patients with mild cognitive impairment, 0.62±0.20 in controls). Cerebral vasoreactivity impairments were diffuse but seemed predominant in posterior areas. The basal hypoperfusion in Alzheimer's disease was not significantly different from patients with mild cognitive impairment and controls. Among clinical and biological parameters, no effect of apoE4 genotype was detected. Cerebral vasoreactivity values were correlated with cognitive performances and hippocampal volumes. Among age and hippocampal atrophy, mean CVR was the best predictor of the mini-mental status examination. This BOLD functional MRI study on CO(2) challenge shows impaired cerebral vasoreactivity in patients with Alzheimer's disease and amnestic mild cognitive impairment at the individual level. These

  14. In contrast to BOLD: signal enhancement by extravascular water protons as an alternative mechanism of endogenous fMRI signal change.

    Science.gov (United States)

    Figley, Chase R; Leitch, Jordan K; Stroman, Patrick W

    2010-10-01

    Despite the popularity and widespread application of functional magnetic resonance imaging (fMRI) in recent years, the physiological bases of signal change are not yet fully understood. Blood oxygen level-dependant (BOLD) contrast - attributed to local changes in blood flow and oxygenation, and therefore magnetic susceptibility - has become the most prevalent means of functional neuroimaging. However, at short echo times, spin-echo sequences show considerable deviations from the BOLD model, implying a second, non-BOLD component of signal change. This has been dubbed "signal enhancement by extravascular water protons" (SEEP) and is proposed to result from proton-density changes associated with cellular swelling. Given that such changes are independent of magnetic susceptibility, SEEP may offer new and improved opportunities for carrying out fMRI in regions with close proximity to air-tissue and/or bone-tissue interfaces (e.g., the prefrontal cortex and spinal cord), as well as regions close to large blood vessels, which may not be ideally suited for BOLD imaging. However, because of the interdisciplinary nature of the literature, there has yet to be a thorough synthesis, tying together the various and sometimes disparate aspects of SEEP theory. As such, we aim to provide a concise yet comprehensive overview of SEEP, including recent and compelling evidence for its validity, its current applications and its future relevance to the rapidly expanding field of functional neuroimaging. Before presenting the evidence for a non-BOLD component of endogenous functional contrast, and to enable a more critical review for the nonexpert reader, we begin by reviewing the fundamental principles underlying BOLD theory. Copyright © 2010 Elsevier Inc. All rights reserved.

  15. PHYCAA: Data-driven measurement and removal of physiological noise in BOLD fMRI

    DEFF Research Database (Denmark)

    Churchill, Nathan W.; Yourganov, Grigori; Spring, Robyn

    2012-01-01

    challenge for identifying and removing such artifact. This paper presents a multivariate, data-driven method for the characterization and removal of physiological noise in fMRI data, termed PHYCAA (PHYsiological correction using Canonical Autocorrelation Analysis). The method identifies high frequency......, autocorrelated physiological noise sources with reproducible spatial structure, using an adaptation of Canonical Correlation Analysis performed in a split-half resampling framework. The technique is able to identify physiological effects with vascular-linked spatial structure, and an intrinsic dimensionality...... with physiological noise, and real data-driven model prediction and reproducibility, for both block and event-related task designs. This is demonstrated compared to no physiological noise correction, and to the widely used RETROICOR (Glover et al., 2000) physiological denoising algorithm, which uses externally...

  16. BOLD fMRI of C-Fiber Mediated Nociceptive Processing in Mouse Brain in Response to Thermal Stimulation of the Forepaws.

    Directory of Open Access Journals (Sweden)

    Simone C Bosshard

    Full Text Available Functional magnetic resonance imaging (fMRI in rodents enables non-invasive studies of brain function in response to peripheral input or at rest. In this study we describe a thermal stimulation paradigm using infrared laser diodes to apply noxious heat to the forepaw of mice in order to study nociceptive processing. Stimulation at 45 and 46°C led to robust BOLD signal changes in various brain structures including the somatosensory cortices and the thalamus. The BOLD signal amplitude scaled with the temperature applied but not with the area irradiated by the laser beam. To demonstrate the specificity of the paradigm for assessing nociceptive signaling we administered the quaternary lidocaine derivative QX-314 to the forepaws, which due to its positive charge cannot readily cross biological membranes. However, upon activation of TRPV1 channels following the administration of capsaicin the BOLD signal was largely abolished, indicative of a selective block of the C-fiber nociceptors due to QX-314 having entered the cells via the now open TRPV1 channels. This demonstrates that the cerebral BOLD response to thermal noxious paw stimulation is specifically mediated by C-fibers.

  17. Functional dissociation of transient and sustained fMRI BOLD components in human auditory cortex revealed with a streaming paradigm based on interaural time differences.

    Science.gov (United States)

    Schadwinkel, Stefan; Gutschalk, Alexander

    2010-12-01

    A number of physiological studies suggest that feature-selective adaptation is relevant to the pre-processing for auditory streaming, the perceptual separation of overlapping sound sources. Most of these studies are focused on spectral differences between streams, which are considered most important for streaming. However, spatial cues also support streaming, alone or in combination with spectral cues, but physiological studies of spatial cues for streaming remain scarce. Here, we investigate whether the tuning of selective adaptation for interaural time differences (ITD) coincides with the range where streaming perception is observed. FMRI activation that has been shown to adapt depending on the repetition rate was studied with a streaming paradigm where two tones were differently lateralized by ITD. Listeners were presented with five different ΔITD conditions (62.5, 125, 187.5, 343.75, or 687.5 μs) out of an active baseline with no ΔITD during fMRI. The results showed reduced adaptation for conditions with ΔITD ≥ 125 μs, reflected by enhanced sustained BOLD activity. The percentage of streaming perception for these stimuli increased from approximately 20% for ΔITD = 62.5 μs to > 60% for ΔITD = 125 μs. No further sustained BOLD enhancement was observed when the ΔITD was increased beyond ΔITD = 125 μs, whereas the streaming probability continued to increase up to 90% for ΔITD = 687.5 μs. Conversely, the transient BOLD response, at the transition from baseline to ΔITD blocks, increased most prominently as ΔITD was increased from 187.5 to 343.75 μs. These results demonstrate a clear dissociation of transient and sustained components of the BOLD activity in auditory cortex. © 2010 The Authors. European Journal of Neuroscience © 2010 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

  18. Music reduces pain and increases resting state fMRI BOLD signal amplitude in the left angular gyrus in fibromyalgia patients

    DEFF Research Database (Denmark)

    Garza-Villarreal, Eduardo A; Jiang, Zhiguo; Vuust, Peter

    2015-01-01

    Music reduces pain in fibromyalgia (FM), a chronic pain disease, but the functional neural correlates of music-induced analgesia (MIA) are still largely unknown. We recruited FM patients (n = 22) who listened to their preferred relaxing music and an auditory control (pink noise) for 5 min without...... external noise from fMRI image acquisition. Resting state fMRI was then acquired before and after the music and control conditions. A significant increase in the amplitude of low frequency fluctuations of the BOLD signal was evident in the left angular gyrus (lAnG) after listening to music, which in turn......, correlated to the analgesia reports. The post-hoc seed-based functional connectivity analysis of the lAnG showed found higher connectivity after listening to music with right dorsolateral prefrontal cortex (rdlPFC), the left caudate (lCau), and decreased connectivity with right anterior cingulate cortex (r...

  19. Working memory in volunteers and schizophrenics using BOLD fMRI; Das Arbeitsgedaechtnis bei Gesunden und bei Schizophrenen: Untersuchungen mit BOLD-fMRT

    Energy Technology Data Exchange (ETDEWEB)

    Giesel, F.L. [Deutsches Krebsforschungszentrum (DKFZ) Heidelberg, Abteilung Radiologie (Germany); Deutsches Krebsforschungszentrum (DKFZ), Abteilung Radiologie, Heidelberg (Germany); Hohmann, N. [Deutsches Krebsforschungszentrum (DKFZ) Heidelberg, Abteilung Radiologie (Germany); Psychiatrische Universitaetsklinik Heidelberg, Sektion Gerontopsychiatrie (Germany); Seidl, U.; Kress, K.R.; Schoenknecht, P.; Schroeder, J. [Psychiatrische Universitaetsklinik Heidelberg, Sektion Gerontopsychiatrie (Germany); Kauczor, H.-U.; Essig, M. [Deutsches Krebsforschungszentrum (DKFZ) Heidelberg, Abteilung Radiologie (Germany)

    2005-02-01

    Functional magnetic resonance imaging uses the blood oxygen level-dependent effect (BOLD MRI) for noninvasive display of cerebral correlatives of cognitive function. The importance for the understanding of physiological and pathological processes is demonstrated by investigations of working memory in schizophrenics and healthy controls. Working memory is involved in processing rather than storage of information and therefore is linked to complex processes such as learning and problem solving. In schizophrenic psychosis, these functions are clearly restricted. Training effects in the working memory task follow an inverse U-shape function, suggesting that cerebral activation reaches a peak before economics of the brain find a more efficient method and activation decreases. (orig.) [German] Die funktionelle Magnetresonanztomographie (fMRT) nutzt den ''blood oxygen level dependent effect'' (BOLD-Effekt) zur nichtinvasiven Darstellung zerebraler Korrelate kognitiver Funktionen. Die Bedeutung dieses Verfahrens fuer das Verstaendnis physiologischer und pathologischer Prozesse wird anhand von Untersuchungen zum Arbeitsgedaechtnis bei Schizophrenen und gesunden Kontrollpersonen verdeutlicht. Das Arbeitsgedaechtnis dient weniger der Speicherung, sondern vielmehr der Verarbeitung von Informationen und ist deshalb in komplexe Prozesse wie Lernen und Problemloesen eingebunden. Im Rahmen schizophrener Psychosen kommt es zu einer deutlichen Einschraenkung dieser Funktionen. Erwartungsgemaess zeigen sich unter Durchfuehrung eines Arbeitsgedaechtnisparadigmas Unterschiede in der zerebralen Aktivitaet, die jedoch bei den Erkrankten unter Therapie prinzipiell reversibel sind. Von Interesse sind auch Trainingseffekte bei Gesunden, wobei eine verminderte Aktivierung nach Training auf eine ''Oekonomisierung'' schliessen laesst. (orig.)

  20. BOLD fMRI in the white matter as a marker of aging and small vessel disease.

    Directory of Open Access Journals (Sweden)

    Ilia Makedonov

    Full Text Available Determine whether white matter signal fluctuation on T2* weighted BOLD contrast images are associated with aging and cerebral small vessel disease (SVD.Resting state BOLD data were collected with a 250 ms repetition time (TR to achieve unaliased, ungated cardiac sampled BOLD (cs-BOLD images on 11 young adult controls, 10 healthy older adult controls and 7 adults with extensive white matter hyperintensities (WMH from SVD. Tissue classes (WM and GM were segmented on T1 images. WMH were identified on FLAIR images in the SVD group. Raw physiological noise (σphysio and cardiac pulsatility (i.e. fluctuations at the cardiac frequency were calculated voxel wise and group differences were tested by ANOVA. It was also possible to calculate σphysio in 2s TR cardiac aliased whole-brain BOLD (wb-BOLD data (N = 84 obtained from the International Consortium for Brain Mapping.CS-BOLD metrics showed an aging and SVD effects (p<0.0005. Covariates such as thermal noise, WM volume and partial volume did not influence the significant aging effect seen on the cardiac pulsatility metric (p<0.017 but did influence the σphysio (p = 0.184. As a verification of the cs-BOLD findings, the wb-BOLD also showed a linear aging effect of σphysio in WM. In the SVD adults, cardiac pulsatility and σphysio were lower in WMH regions compared to normal appearing white matter (NAWM regions (p<0.0013 and p<0.002, respectively. Cardiac pulsatility was better able to distinguish WMH regions from NAWM than σphysio as measured by effect size (Cohen's d 2.2 and 0.88, respectively.NAWM was found to have graded increases in cardiac pulsations due to age and SVD, independently. Within SVD participants, WMH lesions had reduced physiological noise compared to NAWM. Cardiac pulsatility in resting BOLD data may provide a complementary dynamic measure of WM integrity to add to static FLAIR anatomical images.

  1. Quantitative aspects of brain perfusion dynamic induced by BOLD fMRI Aspectos quantitativos da dinâmica perfusional do cérebro induzida pelo BOLD fMRI

    Directory of Open Access Journals (Sweden)

    Katia C. Andrade

    2006-12-01

    Full Text Available The increase of relative cerebral blood flow (rCBF may contribute for a change in blood oxygenation level dependent signal (BOLD. The main purpose of this study is to investigate some aspects of perfusional alterations in the human brain in response to a uniform stimulation: hypercapnia induced by breath holding. It was observed that the BOLD signal increased globally during hypercapnia and that it is correlated with the time of breath holding. This signal increase shows a clear distinction between gray and white matter, being greater in the grey matter.O aumento relativo do fluxo cerebral sangüíneo (relative Cerebral Blood Flow - rCBF pode contribuir para uma mudança no sinal dependente da oxigenação do sangue (Blood Oxygenation Level Dependent - BOLD. O objetivo principal deste trabalho foi estudar alguns aspectos da alteração perfusional no cérebro humano em resposta a um estímulo uniforme: hipercapnia, causada por um estado de apnéia induzida. Foi observado um aumento global no sinal BOLD durante a hipercapnia. Este aumento é correlacionado com a duração da apnéia e mostra uma clara distinção entre a substância branca e cinzenta, sendo maior na substância cinzenta.

  2. Efficient solution methodology for calibrating the hemodynamic model using functional Magnetic Resonance Imaging (fMRI) measurements

    KAUST Repository

    Zambri, Brian

    2015-11-05

    Our aim is to propose a numerical strategy for retrieving accurately and efficiently the biophysiological parameters as well as the external stimulus characteristics corresponding to the hemodynamic mathematical model that describes changes in blood flow and blood oxygenation during brain activation. The proposed method employs the TNM-CKF method developed in [1], but in a prediction/correction framework. We present numerical results using both real and synthetic functional Magnetic Resonance Imaging (fMRI) measurements to highlight the performance characteristics of this computational methodology. © 2015 IEEE.

  3. Ghrelin modulates the fMRI BOLD response of homeostatic and hedonic brain centers regulating energy balance in the rat.

    Directory of Open Access Journals (Sweden)

    Miklós Sárvári

    Full Text Available The orexigenic gut-brain peptide, ghrelin and its G-protein coupled receptor, the growth hormone secretagogue receptor 1a (GHS-R1A are pivotal regulators of hypothalamic feeding centers and reward processing neuronal circuits of the brain. These systems operate in a cooperative manner and receive a wide array of neuronal hormone/transmitter messages and metabolic signals. Functional magnetic resonance imaging was employed in the current study to map BOLD responses to ghrelin in different brain regions with special reference on homeostatic and hedonic regulatory centers of energy balance. Experimental groups involved male, ovariectomized female and ovariectomized estradiol-replaced rats. Putative modulation of ghrelin signaling by endocannabinoids was also studied. Ghrelin-evoked effects were calculated as mean of the BOLD responses 30 minutes after administration. In the male rat, ghrelin evoked a slowly decreasing BOLD response in all studied regions of interest (ROI within the limbic system. This effect was antagonized by pretreatment with GHS-R1A antagonist JMV2959. The comparison of ghrelin effects in the presence or absence of JMV2959 in individual ROIs revealed significant changes in the prefrontal cortex, nucleus accumbens of the telencephalon, and also within hypothalamic centers like the lateral hypothalamus, ventromedial nucleus, paraventricular nucleus and suprachiasmatic nucleus. In the female rat, the ghrelin effects were almost identical to those observed in males. Ovariectomy and chronic estradiol replacement had no effect on the BOLD response. Inhibition of the endocannabinoid signaling by rimonabant significantly attenuated the response of the nucleus accumbens and septum. In summary, ghrelin can modulate hypothalamic and mesolimbic structures controlling energy balance in both sexes. The endocannabinoid signaling system contributes to the manifestation of ghrelin's BOLD effect in a region specific manner. In females, the

  4. Self-regulation strategy, feedback timing and hemodynamic properties modulate learning in a simulated fMRI neurofeedback environment.

    Science.gov (United States)

    Oblak, Ethan F; Lewis-Peacock, Jarrod A; Sulzer, James S

    2017-07-01

    Direct manipulation of brain activity can be used to investigate causal brain-behavior relationships. Current noninvasive neural stimulation techniques are too coarse to manipulate behaviors that correlate with fine-grained spatial patterns recorded by fMRI. However, these activity patterns can be manipulated by having people learn to self-regulate their own recorded neural activity. This technique, known as fMRI neurofeedback, faces challenges as many participants are unable to self-regulate. The causes of this non-responder effect are not well understood due to the cost and complexity of such investigation in the MRI scanner. Here, we investigated the temporal dynamics of the hemodynamic response measured by fMRI as a potential cause of the non-responder effect. Learning to self-regulate the hemodynamic response involves a difficult temporal credit-assignment problem because this signal is both delayed and blurred over time. Two factors critical to this problem are the prescribed self-regulation strategy (cognitive or automatic) and feedback timing (continuous or intermittent). Here, we sought to evaluate how these factors interact with the temporal dynamics of fMRI without using the MRI scanner. We first examined the role of cognitive strategies by having participants learn to regulate a simulated neurofeedback signal using a unidimensional strategy: pressing one of two buttons to rotate a visual grating that stimulates a model of visual cortex. Under these conditions, continuous feedback led to faster regulation compared to intermittent feedback. Yet, since many neurofeedback studies prescribe implicit self-regulation strategies, we created a computational model of automatic reward-based learning to examine whether this result held true for automatic processing. When feedback was delayed and blurred based on the hemodynamics of fMRI, this model learned more reliably from intermittent feedback compared to continuous feedback. These results suggest that different

  5. Self-regulation strategy, feedback timing and hemodynamic properties modulate learning in a simulated fMRI neurofeedback environment.

    Directory of Open Access Journals (Sweden)

    Ethan F Oblak

    2017-07-01

    Full Text Available Direct manipulation of brain activity can be used to investigate causal brain-behavior relationships. Current noninvasive neural stimulation techniques are too coarse to manipulate behaviors that correlate with fine-grained spatial patterns recorded by fMRI. However, these activity patterns can be manipulated by having people learn to self-regulate their own recorded neural activity. This technique, known as fMRI neurofeedback, faces challenges as many participants are unable to self-regulate. The causes of this non-responder effect are not well understood due to the cost and complexity of such investigation in the MRI scanner. Here, we investigated the temporal dynamics of the hemodynamic response measured by fMRI as a potential cause of the non-responder effect. Learning to self-regulate the hemodynamic response involves a difficult temporal credit-assignment problem because this signal is both delayed and blurred over time. Two factors critical to this problem are the prescribed self-regulation strategy (cognitive or automatic and feedback timing (continuous or intermittent. Here, we sought to evaluate how these factors interact with the temporal dynamics of fMRI without using the MRI scanner. We first examined the role of cognitive strategies by having participants learn to regulate a simulated neurofeedback signal using a unidimensional strategy: pressing one of two buttons to rotate a visual grating that stimulates a model of visual cortex. Under these conditions, continuous feedback led to faster regulation compared to intermittent feedback. Yet, since many neurofeedback studies prescribe implicit self-regulation strategies, we created a computational model of automatic reward-based learning to examine whether this result held true for automatic processing. When feedback was delayed and blurred based on the hemodynamics of fMRI, this model learned more reliably from intermittent feedback compared to continuous feedback. These results

  6. Self-regulation strategy, feedback timing and hemodynamic properties modulate learning in a simulated fMRI neurofeedback environment

    Science.gov (United States)

    Sulzer, James S.

    2017-01-01

    Direct manipulation of brain activity can be used to investigate causal brain-behavior relationships. Current noninvasive neural stimulation techniques are too coarse to manipulate behaviors that correlate with fine-grained spatial patterns recorded by fMRI. However, these activity patterns can be manipulated by having people learn to self-regulate their own recorded neural activity. This technique, known as fMRI neurofeedback, faces challenges as many participants are unable to self-regulate. The causes of this non-responder effect are not well understood due to the cost and complexity of such investigation in the MRI scanner. Here, we investigated the temporal dynamics of the hemodynamic response measured by fMRI as a potential cause of the non-responder effect. Learning to self-regulate the hemodynamic response involves a difficult temporal credit-assignment problem because this signal is both delayed and blurred over time. Two factors critical to this problem are the prescribed self-regulation strategy (cognitive or automatic) and feedback timing (continuous or intermittent). Here, we sought to evaluate how these factors interact with the temporal dynamics of fMRI without using the MRI scanner. We first examined the role of cognitive strategies by having participants learn to regulate a simulated neurofeedback signal using a unidimensional strategy: pressing one of two buttons to rotate a visual grating that stimulates a model of visual cortex. Under these conditions, continuous feedback led to faster regulation compared to intermittent feedback. Yet, since many neurofeedback studies prescribe implicit self-regulation strategies, we created a computational model of automatic reward-based learning to examine whether this result held true for automatic processing. When feedback was delayed and blurred based on the hemodynamics of fMRI, this model learned more reliably from intermittent feedback compared to continuous feedback. These results suggest that different

  7. Brain activation by short-term nicotine exposure in anesthetized wild-type and beta2-nicotinic receptors knockout mice: a BOLD fMRI study

    Energy Technology Data Exchange (ETDEWEB)

    Suarez, S.V.; Changeux, J.P.; Granon, S. [Unite de Neurobiologie Integrative du Systeme Cholinergique, URA CNRS 2182, Institut Pasteur, Departement de Neuroscience, 25 rue du Dr Roux, 75015 Paris (France); Amadon, A.; Giacomini, E.; Le Bihan, D. [Service Hospitalier Frederic Joliot, 4 place du general Leclerc, 91400 Orsay (France); Wiklund, A. [Section of Anaesthesiology and Intensive Care Medicine, Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm (Sweden)

    2009-07-01

    Rationale: The behavioral effects of nicotine and the role of the beta2-containing nicotinic receptors in these behaviors are well documented. However, the behaviors altered by nicotine rely on the functioning on multiple brain circuits where the high-affinity {beta}2-containing nicotinic receptors ({beta}2*nAChRs) are located. Objectives We intend to see which brain circuits are activated when nicotine is given in animals naive for nicotine and whether the {beta}2*nAChRs are needed for its activation of the blood oxygen level dependent (BOLD) signal in all brain areas. Materials and methods: We used functional magnetic resonance imaging (fMRI) to measure the brain activation evoked by nicotine (1 mg/kg delivered at a slow rate for 45 min) in anesthetized C57BL/6J mice and {beta}2 knockout (KO) mice. Results: Acute nicotine injection results in a significant increased activation in anterior frontal, motor, and somatosensory cortices and in the ventral tegmental area and the substantia nigra. Anesthetized mice receiving no nicotine injection exhibited a major decreased activation in all cortical and subcortical structures, likely due to prolonged anesthesia. At a global level, {beta}2 KO mice were not rescued from the globally declining BOLD signal. However, nicotine still activated regions of a meso-cortico-limbic circuit likely via {alpha}7 nicotinic receptors. Conclusions: Acute nicotine exposure compensates for the drop in brain activation due to anesthesia through the meso-cortico-limbic network via the action of nicotine on {beta}2*nAChRs. The developed fMRI method is suitable for comparing responses in wild-type and mutant mice. (authors)

  8. Brain activation by short-term nicotine exposure in anesthetized wild-type and beta2-nicotinic receptors knockout mice: a BOLD fMRI study

    International Nuclear Information System (INIS)

    Suarez, S.V.; Changeux, J.P.; Granon, S.; Amadon, A.; Giacomini, E.; Le Bihan, D.; Wiklund, A.

    2009-01-01

    Rationale: The behavioral effects of nicotine and the role of the beta2-containing nicotinic receptors in these behaviors are well documented. However, the behaviors altered by nicotine rely on the functioning on multiple brain circuits where the high-affinity β2-containing nicotinic receptors (β2*nAChRs) are located. Objectives We intend to see which brain circuits are activated when nicotine is given in animals naive for nicotine and whether the β2*nAChRs are needed for its activation of the blood oxygen level dependent (BOLD) signal in all brain areas. Materials and methods: We used functional magnetic resonance imaging (fMRI) to measure the brain activation evoked by nicotine (1 mg/kg delivered at a slow rate for 45 min) in anesthetized C57BL/6J mice and β2 knockout (KO) mice. Results: Acute nicotine injection results in a significant increased activation in anterior frontal, motor, and somatosensory cortices and in the ventral tegmental area and the substantia nigra. Anesthetized mice receiving no nicotine injection exhibited a major decreased activation in all cortical and subcortical structures, likely due to prolonged anesthesia. At a global level, β2 KO mice were not rescued from the globally declining BOLD signal. However, nicotine still activated regions of a meso-cortico-limbic circuit likely via α7 nicotinic receptors. Conclusions: Acute nicotine exposure compensates for the drop in brain activation due to anesthesia through the meso-cortico-limbic network via the action of nicotine on β2*nAChRs. The developed fMRI method is suitable for comparing responses in wild-type and mutant mice. (authors)

  9. Simultaneous estimation of population receptive field and hemodynamic parameters from single point BOLD responses using Metropolis-Hastings sampling.

    Science.gov (United States)

    Adaszewski, Stanisław; Slater, David; Melie-Garcia, Lester; Draganski, Bogdan; Bogorodzki, Piotr

    2018-01-30

    We introduce a new approach to Bayesian pRF model estimation using Markov Chain Monte Carlo (MCMC) sampling for simultaneous estimation of pRF and hemodynamic parameters. To obtain high performance on commonly accessible hardware we present a novel heuristic consisting of interpolation between precomputed responses for predetermined stimuli and a large cross-section of receptive field parameters. We investigate the validity of the proposed approach with respect to MCMC convergence, tuning and biases. We compare different combinations of pRF - Compressive Spatial Summation (CSS), Dumoulin-Wandell (DW) and hemodynamic (5-parameter and 3-parameter Balloon-Windkessel) models within our framework with and without the usage of the new heuristic. We evaluate estimation consistency and log probability across models. We perform as well a comparison of one model with and without lookup table within the RStan framework using its No-U-Turn Sampler. We present accelerated computation of whole-ROI parameters for one subject. Finally, we discuss risks and limitations associated with the usage of the new heuristic as well as the means of resolving them. We found that the new algorithm is a valid sampling approach to joint pRF/hemodynamic parameter estimation and that it exhibits very high performance. Copyright © 2018. Published by Elsevier Inc.

  10. Music reduces pain and increases resting state fMRI BOLD signal amplitude in the left angular gyrus in fibromyalgia patients.

    Science.gov (United States)

    Garza-Villarreal, Eduardo A; Jiang, Zhiguo; Vuust, Peter; Alcauter, Sarael; Vase, Lene; Pasaye, Erick H; Cavazos-Rodriguez, Roberto; Brattico, Elvira; Jensen, Troels S; Barrios, Fernando A

    2015-01-01

    Music reduces pain in fibromyalgia (FM), a chronic pain disease, but the functional neural correlates of music-induced analgesia (MIA) are still largely unknown. We recruited FM patients (n = 22) who listened to their preferred relaxing music and an auditory control (pink noise) for 5 min without external noise from fMRI image acquisition. Resting state fMRI was then acquired before and after the music and control conditions. A significant increase in the amplitude of low frequency fluctuations of the BOLD signal was evident in the left angular gyrus (lAnG) after listening to music, which in turn, correlated to the analgesia reports. The post-hoc seed-based functional connectivity analysis of the lAnG showed found higher connectivity after listening to music with right dorsolateral prefrontal cortex (rdlPFC), the left caudate (lCau), and decreased connectivity with right anterior cingulate cortex (rACC), right supplementary motor area (rSMA), precuneus and right precentral gyrus (rPreG). Pain intensity (PI) analgesia was correlated (r = 0.61) to the connectivity of the lAnG with the rPreG. Our results show that MIA in FM is related to top-down regulation of the pain modulatory network by the default mode network (DMN).

  11. Satiation attenuates BOLD activity in brain regions involved in reward and increases activity in dorsolateral prefrontal cortex: an fMRI study in healthy volunteers.

    Science.gov (United States)

    Thomas, Jason M; Higgs, Suzanne; Dourish, Colin T; Hansen, Peter C; Harmer, Catherine J; McCabe, Ciara

    2015-04-01

    Neural responses to rewarding food cues are significantly different in the fed vs. fasted (>8 h food-deprived) state. However, the effect of eating to satiety after a shorter (more natural) intermeal interval on neural responses to both rewarding and aversive cues has not been examined. With the use of a novel functional magnetic resonance imaging (fMRI) task, we investigated the effect of satiation on neural responses to both rewarding and aversive food tastes and pictures. Sixteen healthy participants (8 men, 8 women) were scanned on 2 separate test days, before and after eating a meal to satiation or after not eating for 4 h (satiated vs. premeal). fMRI blood oxygen level-dependent (BOLD) signals to the sight and/or taste of the stimuli were recorded. A whole-brain cluster-corrected analysis (P analysis showed that the vmPFC was more highly connected to the dlPFC when individuals were exposed to food stimuli when satiated than when not satiated. These results suggest that natural satiation attenuates activity in reward-related brain regions and increases activity in the dlPFC, which may reflect a "top down" cognitive influence on satiation. This trial was registered at clinicaltrials.gov as NCT02298049. © 2015 American Society for Nutrition.

  12. Music reduces pain and increases resting state fMRI BOLD signal amplitude in the left angular gyrus in fibromyalgia patients

    Directory of Open Access Journals (Sweden)

    Eduardo A. Garza-Villarreal

    2015-07-01

    Full Text Available Music reduces pain in fibromyalgia (FM, a chronic pain disease, but the functional neural correlates of music-induced analgesia are still largely unknown. We recruited FM patients (n = 22 who listened to their preferred relaxing music and an auditory control (pink noise for 5 minutes without external noise from fMRI image acquisition. Resting state fMRI was then acquired before and after the music and control conditions. A significant increase in the amplitude of low frequency fluctuations of the BOLD signal was evident in the left angular gyrus after listening to music, which in turn, correlated to the analgesia reports. The post-hoc seed-based functional connectivity analysis of the left angular gyrus showed found higher connectivity after listening to music with right dorsolateral prefrontal cortex, the left caudate, and decreased connectivity with right anterior cingulate cortex, right supplementary motor area, precuneus and right precentral gyrus. Pain intensity analgesia was correlated (r = .61 to the connectivity of the left angular gyrus with the right precentral gyrus. Our results show that music-induced analgesia in FM is related to top-down regulation of the pain modulatory network by the default-mode network.

  13. Generate the scale-free brain music from BOLD signals.

    Science.gov (United States)

    Lu, Jing; Guo, Sijia; Chen, Mingming; Wang, Weixia; Yang, Hua; Guo, Daqing; Yao, Dezhong

    2018-01-01

    Many methods have been developed to translate a human electroencephalogram (EEG) into music. In addition to EEG, functional magnetic resonance imaging (fMRI) is another method used to study the brain and can reflect physiological processes. In 2012, we established a method to use simultaneously recorded fMRI and EEG signals to produce EEG-fMRI music, which represents a step toward scale-free brain music. In this study, we used a neural mass model, the Jansen-Rit model, to simulate activity in several cortical brain regions. The interactions between different brain regions were represented by the average normalized diffusion tensor imaging (DTI) structural connectivity with a coupling coefficient that modulated the coupling strength. Seventy-eight brain regions were adopted from the Automated Anatomical Labeling (AAL) template. Furthermore, we used the Balloon-Windkessel hemodynamic model to transform neural activity into a blood-oxygen-level dependent (BOLD) signal. Because the fMRI BOLD signal changes slowly, we used a sampling rate of 250 Hz to produce the temporal series for music generation. Then, the BOLD music was generated for each region using these simulated BOLD signals. Because the BOLD signal is scale free, these music pieces were also scale free, which is similar to classic music. Here, to simulate the case of an epileptic patient, we changed the parameter that determined the amplitude of the excitatory postsynaptic potential (EPSP) in the neural mass model. Finally, we obtained BOLD music for healthy and epileptic patients. The differences in levels of arousal between the 2 pieces of music may provide a potential tool for discriminating the different populations if the differences can be confirmed by more real data. Copyright © 2017 The Authors. Published by Wolters Kluwer Health, Inc. All rights reserved.

  14. Distinct BOLD fMRI Responses of Capsaicin-Induced Thermal Sensation Reveal Pain-Related Brain Activation in Nonhuman Primates.

    Directory of Open Access Journals (Sweden)

    Abu Bakar Ali Asad

    Full Text Available Approximately 20% of the adult population suffer from chronic pain that is not adequately treated by current therapies, highlighting a great need for improved treatment options. To develop effective analgesics, experimental human and animal models of pain are critical. Topically/intra-dermally applied capsaicin induces hyperalgesia and allodynia to thermal and tactile stimuli that mimics chronic pain and is a useful translation from preclinical research to clinical investigation. Many behavioral and self-report studies of pain have exploited the use of the capsaicin pain model, but objective biomarker correlates of the capsaicin augmented nociceptive response in nonhuman primates remains to be explored.Here we establish an aversive capsaicin-induced fMRI model using non-noxious heat stimuli in Cynomolgus monkeys (n = 8. BOLD fMRI data were collected during thermal challenge (ON:20 s/42°C; OFF:40 s/35°C, 4-cycle at baseline and 30 min post-capsaicin (0.1 mg, topical, forearm application. Tail withdrawal behavioral studies were also conducted in the same animals using 42°C or 48°C water bath pre- and post- capsaicin application (0.1 mg, subcutaneous, tail.Group comparisons between pre- and post-capsaicin application revealed significant BOLD signal increases in brain regions associated with the 'pain matrix', including somatosensory, frontal, and cingulate cortices, as well as the cerebellum (paired t-test, p<0.02, n = 8, while no significant change was found after the vehicle application. The tail withdrawal behavioral study demonstrated a significant main effect of temperature and a trend towards capsaicin induced reduction of latency at both temperatures.These findings provide insights into the specific brain regions involved with aversive, 'pain-like', responses in a nonhuman primate model. Future studies may employ both behavioral and fMRI measures as translational biomarkers to gain deeper understanding of pain processing and evaluate

  15. Regional differences in the CBF and BOLD responses to hypercapnia: a combined PET and fMRI study

    DEFF Research Database (Denmark)

    Rostrup, Egill; Law, I; Blinkenberg, M

    2000-01-01

    Previous fMRI studies of the cerebrovascular response to hypercapnia have shown signal change in cerebral gray matter, but not in white matter. Therefore, the objective of the present study was to compare (15)O PET and T *(2)-weighted MRI during a hypercapnic challenge. The measurements were perf...

  16. BOLD contrast fMRI of whole rodent tumour during air or carbogen breathing using echo-planar imaging at 1.5 T

    Energy Technology Data Exchange (ETDEWEB)

    Landuyt, W.; Bogaert, W. van den; Lambin, P. [Lab. of Experimental Radiobiology and Department of Radiotherapy/Oncology,Univ. Hospitals Leuven (Belgium); Hermans, R.; Bosmans, H.; Sunaert, S.; Beatse, E.; Farina, D.; Meijerink, M.; Zhang, H.; Marchal, G. [University Hospital, Leuven (Belgium). Dept. of Radiology

    2001-11-01

    The aim of this study was to evaluate the feasibility of functional MR imaging (fMRI) at 1.5 T, exploiting blood oxygenation level-dependent (BOLD) contrast, for detecting changes in whole-tumour oxygenation induced by carbogen (5% CO{sub 2}+95% O{sub 2}) inhalation of the host. Adult WAG/Rij rats with rhabdomyosarcomas growing subcutaneously in the lower flank were imaged when tumours reached sizes between 1 and 11 cm{sup 3} (n=12). Air and carbogen were alternatively supplied at 2 l/min using a snout mask. Imaging was done on a 1.5-T MR scanner using a T2*-weighted gradient-echo, echo-planar imaging (GE-EPI) sequence. Analysis of the whole-tumour EPI images was based on statistical parametric maps. Voxels with and without signal intensity changes (SIC) were recorded. Significance thresholds were set at p<0.05, corrected for multiple comparisons. In continuous air breathing condition, 3 of 12 tumours showed significant negative SIC and 1 tumour had a clear-cut positive SIC. The remaining tumours showed very little or no change. When switching to carbogen breathing, the SIC were significantly positive in 10 of 12 tumours. Negative SIC were present in 4 tumours, of which three were simultaneously characterised by positive SIC. The overall analysis indicated that 6 of the 12 tumours could be considered as strong positive responders to carbogen. Our research demonstrates the applicability of fMRI GE-EPI at 1.5 T to study whole-tumour oxygenation non-invasively. The observed negative SIC during air condition may reflect the presence of transient hypoxia during these measurements. Selection of tumours on the basis of their individual response to carbogen is possible, indicating a role of such non-invasive measurements for using tailor-made treatments. (orig.)

  17. Differential Localization of Pain-Related and Pain-Unrelated Neural Responses for Acupuncture at BL60 Using BOLD fMRI

    Directory of Open Access Journals (Sweden)

    Na-Hee Kim

    2013-01-01

    Full Text Available The objective of this study was to differentiate between pain-related and pain-unrelated neural responses of acupuncture at BL60 to investigate the specific effects of acupuncture. A total of 19 healthy volunteers were evaluated. fMRI was performed with sham or verum acupuncture stimulation at the left BL60 before and after local anesthesia. To investigate the relative BOLD signal effect for each session, a one-sample t-test was performed for individual contrast maps, and a paired t-test to investigate the differences between the pre- and post-anesthetic signal effects. Regarding verum acupuncture, areas that were more activated before local anesthesia included the superior, middle, and medial frontal gyri, inferior parietal lobule, superior temporal gyrus, thalamus, middle temporal gyrus, cingulate gyrus, culmen, and cerebellar tonsil. The postcentral gyrus was more deactivated before local anesthesia. After local anesthesia, the middle occipital gyrus, inferior temporal gyrus, postcentral gyrus, precuneus, superior parietal lobule, and declive were deactivated. Pre-anesthetic verum acupuncture at BL60 activated areas of vision and pain transmission. Post-anesthetic verum acupuncture deactivated brain areas of visual function, which is considered to be a pain-unrelated acupuncture response. It indicates that specific effects of acupoint BL60 are to control vision sense as used in the clinical setting.

  18. Application of fMRI to obesity research: differences in reward pathway activation measured with fMRI BOLD during visual presentation of high and low calorie foods

    Science.gov (United States)

    Tsao, Sinchai; Adam, Tanja C.; Goran, Michael I.; Singh, Manbir

    2012-03-01

    The factors behind the neural mechanisms that motivate food choice and obesity are not well known. Furthermore, it is not known when these neural mechanisms develop and how they are influenced by both genetic and environmental factors. This study uses fMRI together with clinical data to shed light on the aforementioned questions by investigating how appetite-related activation in the brain changes with low versus high caloric foods in pre-pubescent girls. Previous studies have shown that obese adults have less striatal D2 receptors and thus reduced Dopamine (DA) signaling leading to the reward-deficit theory of obesity. However, overeating in itself reduces D2 receptor density, D2 sensitivity and thus reward sensitivity. The results of this study will show how early these neural mechanisms develop and what effect the drastic endocrinological changes during puberty has on these mechanisms. Our preliminary results showed increased activations in the Putamen, Insula, Thalamus and Hippocampus when looking at activations where High Calorie > Low Calorie. When comparing High Calorie > Control and Low Calorie > Control, the High > Control test showed increased significant activation in the frontal lobe. The Low > Control also yielded significant activation in the Left and Right Fusiform Gyrus, which did not appear in the High > Control test. These results indicate that the reward pathway activations previously shown in post-puberty and adults are present in pre-pubescent teens. These results may suggest that some of the preferential neural mechanisms of reward are already present pre-puberty.

  19. Modeling the hemodynamic response in fMRI using smooth FIR filters

    DEFF Research Database (Denmark)

    Goutte, Cyril; Nielsen, Finn Årup; Hansen, Lars Kai

    2000-01-01

    -parameters using the evidence framework, or sampling using a Markov Chain Monte Carlo (MCMC) approach. The authors present a comparison of their model with standard hemodynamic response kernels on simulated data, and perform a full analysis of data acquired during an experiment involving visual stimulation.......-parametric approach based on finite impulse response (FIR) filters. In order to cope with the increase in the number of degrees of freedom, the authors introduce a Gaussian process prior on the filter parameters. They show how to carry on the analysis by incorporating prior knowledge on the filters, optimizing hyper...

  20. Fixation-related FMRI analysis in the domain of reading research: using self-paced eye movements as markers for hemodynamic brain responses during visual letter string processing.

    Science.gov (United States)

    Richlan, Fabio; Gagl, Benjamin; Hawelka, Stefan; Braun, Mario; Schurz, Matthias; Kronbichler, Martin; Hutzler, Florian

    2014-10-01

    The present study investigated the feasibility of using self-paced eye movements during reading (measured by an eye tracker) as markers for calculating hemodynamic brain responses measured by functional magnetic resonance imaging (fMRI). Specifically, we were interested in whether the fixation-related fMRI analysis approach was sensitive enough to detect activation differences between reading material (words and pseudowords) and nonreading material (line and unfamiliar Hebrew strings). Reliable reading-related activation was identified in left hemisphere superior temporal, middle temporal, and occipito-temporal regions including the visual word form area (VWFA). The results of the present study are encouraging insofar as fixation-related analysis could be used in future fMRI studies to clarify some of the inconsistent findings in the literature regarding the VWFA. Our study is the first step in investigating specific visual word recognition processes during self-paced natural sentence reading via simultaneous eye tracking and fMRI, thus aiming at an ecologically valid measurement of reading processes. We provided the proof of concept and methodological framework for the analysis of fixation-related fMRI activation in the domain of reading research. © The Author 2013. Published by Oxford University Press.

  1. The 5-HT2Creceptor agonist meta-chlorophenylpiperazine (mCPP) reduces palatable food consumption and BOLD fMRI responses to food images in healthy female volunteers.

    Science.gov (United States)

    Thomas, Jason M; Dourish, Colin T; Tomlinson, Jeremy; Hassan-Smith, Zaki; Hansen, Peter C; Higgs, Suzanne

    2018-01-01

    Brain 5-HT 2C receptors form part of a neural network that controls eating behaviour. 5-HT 2C receptor agonists decrease food intake by activating proopiomelanocortin (POMC) neurons in the arcuate nucleus of the hypothalamus, but recent research in rodents has suggested that 5-HT 2C receptor agonists may also act via dopaminergic circuitry to reduce the rewarding value of food and other reinforcers. No mechanistic studies on the effects of 5-HT 2C agonists on food intake in humans have been conducted to date. The present study examined the effects of the 5-HT 2C receptor agonist meta-chlorophenylpiperazine (mCPP) on food consumption, eating microstructure and blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) responses to food pictures in healthy female volunteers. In a double-blind, placebo-controlled, crossover design, participants were randomized immediately after screening to receive oral mCPP (30mg) in a single morning dose, or placebo, in a counterbalanced order. Test foods were served from a Universal Eating Monitor (UEM) that measured eating rate and fMRI BOLD signals to the sight of food and non-food images were recorded. mCPP decreased rated appetite and intake of a palatable snack eaten in the absence of hunger but had no significant effect on the consumption of a pasta lunch (although pasta eating rate was reduced). mCPP also decreased BOLD fMRI responses to the sight of food pictures in areas of reward-associated circuitry. A post hoc analysis identified individual variability in the response to mCPP (exploratory responder-non-responder analysis). Some participants did not reduce their cookie intake after treatment with mCPP and this lack of response was associated with enhanced ratings of cookie pleasantness and enhanced baseline BOLD responses to food images in key reward and appetite circuitry. These results suggest that 5-HT 2C receptor activation in humans inhibits food reward-related responding and that further

  2. Acute Nicotine Administration Increases BOLD fMRI Signal in Brain Regions Involved in Reward Signaling and Compulsive Drug Intake in Rats

    Science.gov (United States)

    Alexander, Jon C.; Perez, Pablo D.; Bauzo-Rodriguez, Rayna; Hall, Gabrielle; Klausner, Rachel; Guerra, Valerie; Zeng, Huadong; Igari, Moe; Febo, Marcelo

    2015-01-01

    Background: Acute nicotine administration potentiates brain reward function and enhances motor and cognitive function. These studies investigated which brain areas are being activated by a wide range of doses of nicotine, and if this is diminished by pretreatment with the nonselective nicotinic receptor antagonist mecamylamine. Methods: Drug-induced changes in brain activity were assessed by measuring changes in the blood oxygen level dependent (BOLD) signal using an 11.1-Tesla magnetic resonance scanner. In the first experiment, nicotine naïve rats were mildly anesthetized and the effect of nicotine (0.03–0.6mg/kg) on the BOLD signal was investigated for 10min. In the second experiment, the effect of mecamylamine on nicotine-induced brain activity was investigated. Results: A high dose of nicotine increased the BOLD signal in brain areas implicated in reward signaling, such as the nucleus accumbens shell and the prelimbic area. Nicotine also induced a dose-dependent increase in the BOLD signal in the striato-thalamo-orbitofrontal circuit, which plays a role in compulsive drug intake, and in the insular cortex, which contributes to nicotine craving and relapse. In addition, nicotine induced a large increase in the BOLD signal in motor and somatosensory cortices. Mecamylamine alone did not affect the BOLD signal in most brain areas, but induced a negative BOLD response in cortical areas, including insular, motor, and somatosensory cortices. Pretreatment with mecamylamine completely blocked the nicotine-induced increase in the BOLD signal. Conclusions: These studies demonstrate that acute nicotine administration activates brain areas that play a role in reward signaling, compulsive behavior, and motor and cognitive function. PMID:25552431

  3. Patterns of cortical oscillations organize neural activity into whole-brain functional networks evident in the fMRI BOLD signal

    Directory of Open Access Journals (Sweden)

    Jennifer C Whitman

    2013-03-01

    Full Text Available Recent findings from electrophysiology and multimodal neuroimaging have elucidated the relationship between patterns of cortical oscillations evident in EEG / MEG and the functional brain networks evident in the BOLD signal. Much of the existing literature emphasized how high-frequency cortical oscillations are thought to coordinate neural activity locally, while low-frequency oscillations play a role in coordinating activity between more distant brain regions. However, the assignment of different frequencies to different spatial scales is an oversimplification. A more informative approach is to explore the arrangements by which these low- and high-frequency oscillations work in concert, coordinating neural activity into whole-brain functional networks. When relating such networks to the BOLD signal, we must consider how the patterns of cortical oscillations change at the same speed as cognitive states, which often last less than a second. Consequently, the slower BOLD signal may often reflect the summed neural activity of several transient network configurations. This temporal mismatch can be circumvented if we use spatial maps to assess correspondence between oscillatory networks and BOLD networks.

  4. Spatiotemporal dynamics of the brain at rest--exploring EEG microstates as electrophysiological signatures of BOLD resting state networks.

    Science.gov (United States)

    Yuan, Han; Zotev, Vadim; Phillips, Raquel; Drevets, Wayne C; Bodurka, Jerzy

    2012-05-01

    Neuroimaging research suggests that the resting cerebral physiology is characterized by complex patterns of neuronal activity in widely distributed functional networks. As studied using functional magnetic resonance imaging (fMRI) of the blood-oxygenation-level dependent (BOLD) signal, the resting brain activity is associated with slowly fluctuating hemodynamic signals (~10s). More recently, multimodal functional imaging studies involving simultaneous acquisition of BOLD-fMRI and electroencephalography (EEG) data have suggested that the relatively slow hemodynamic fluctuations of some resting state networks (RSNs) evinced in the BOLD data are related to much faster (~100 ms) transient brain states reflected in EEG signals, that are referred to as "microstates". To further elucidate the relationship between microstates and RSNs, we developed a fully data-driven approach that combines information from simultaneously recorded, high-density EEG and BOLD-fMRI data. Using independent component analysis (ICA) of the combined EEG and fMRI data, we identified thirteen microstates and ten RSNs that are organized independently in their temporal and spatial characteristics, respectively. We hypothesized that the intrinsic brain networks that are active at rest would be reflected in both the EEG data and the fMRI data. To test this hypothesis, the rapid fluctuations associated with each microstate were correlated with the BOLD-fMRI signal associated with each RSN. We found that each RSN was characterized further by a specific electrophysiological signature involving from one to a combination of several microstates. Moreover, by comparing the time course of EEG microstates to that of the whole-brain BOLD signal, on a multi-subject group level, we unraveled for the first time a set of microstate-associated networks that correspond to a range of previously described RSNs, including visual, sensorimotor, auditory, attention, frontal, visceromotor and default mode networks. These

  5. Self-regulation strategy, feedback timing and hemodynamic properties modulate learning in a simulated fMRI neurofeedback environment

    OpenAIRE

    Oblak, Ethan F.; Lewis-Peacock, Jarrod A.; Sulzer, James S.

    2017-01-01

    Direct manipulation of brain activity can be used to investigate causal brain-behavior relationships. Current noninvasive neural stimulation techniques are too coarse to manipulate behaviors that correlate with fine-grained spatial patterns recorded by fMRI. However, these activity patterns can be manipulated by having people learn to self-regulate their own recorded neural activity. This technique, known as fMRI neurofeedback, faces challenges as many participants are unable to self-regulate...

  6. fMRI BOLD Response in High-risk College Students (Part 1): During Exposure to Alcohol, Marijuana, Polydrug and Emotional Picture Cues†

    OpenAIRE

    Ray, Suchismita; Hanson, Catherine; Hanson, Stephen J.; Bates, Marsha E.

    2010-01-01

    Aim: This functional magnetic resonance imaging (fMRI) study examined reactivity to alcohol, polydrug, marijuana and emotional picture cues in students who were referred to a college alcohol and drug assistance program. Methods: The fMRI data of 10 participants (5 females; 5 males) were collected while they viewed standardized emotional and appetitive cues. Results: Positive and negative emotional cues produced greater activity than neutral cues in the expected brain areas. Compared with neut...

  7. Quantitative comparisons on hand motor functional areas determined by resting state and task BOLD fMRI and anatomical MRI for pre-surgical planning of patients with brain tumors

    Directory of Open Access Journals (Sweden)

    Bob L. Hou

    2016-01-01

    Full Text Available For pre-surgical planning we present quantitative comparison of the location of the hand motor functional area determined by right hand finger tapping BOLD fMRI, resting state BOLD fMRI, and anatomically using high resolution T1 weighted images. Data were obtained on 10 healthy subjects and 25 patients with left sided brain tumors. Our results show that there are important differences in the locations (i.e., >20 mm of the determined hand motor voxels by these three MR imaging methods. This can have significant effect on the pre-surgical planning of these patients depending on the modality used. In 13 of the 25 cases (i.e., 52% the distances between the task-determined and the rs-fMRI determined hand areas were more than 20 mm; in 13 of 25 cases (i.e., 52% the distances between the task-determined and anatomically determined hand areas were >20 mm; and in 16 of 25 cases (i.e., 64% the distances between the rs-fMRI determined and anatomically determined hand areas were more than 20 mm. In just three cases, the distances determined by all three modalities were within 20 mm of each other. The differences in the location or fingerprint of the hand motor areas, as determined by these three MR methods result from the different underlying mechanisms of these three modalities and possibly the effects of tumors on these modalities.

  8. Layer-Specific fMRI Responses to Excitatory and Inhibitory Neuronal Activities in the Olfactory Bulb.

    Science.gov (United States)

    Poplawsky, Alexander John; Fukuda, Mitsuhiro; Murphy, Matthew; Kim, Seong-Gi

    2015-11-18

    High-resolution functional magnetic resonance imaging (fMRI) detects localized neuronal activity via the hemodynamic response, but it is unclear whether it accurately identifies neuronal activity specific to individual layers. To address this issue, we preferentially evoked neuronal activity in superficial, middle, and deep layers of the rat olfactory bulb: the glomerular layer by odor (5% amyl acetate), the external plexiform layer by electrical stimulation of the lateral olfactory tract (LOT), and the granule cell layer by electrical stimulation of the anterior commissure (AC), respectively. Electrophysiology, laser-Doppler flowmetry of cerebral blood flow (CBF), and blood oxygenation level-dependent (BOLD) and cerebral blood volume-weighted (CBV) fMRI at 9.4 T were performed independently. We found that excitation of inhibitory granule cells by stimulating LOT and AC decreased the spontaneous multi-unit activities of excitatory mitral cells and subsequently increased CBF, CBV, and BOLD signals. Odor stimulation also increased the hemodynamic responses. Furthermore, the greatest CBV fMRI responses were discretely separated into the same layers as the evoked neuronal activities for all three stimuli, whereas BOLD was poorly localized with some exception to the poststimulus undershoot. In addition, the temporal dynamics of the fMRI responses varied depending on the stimulation pathway, even within the same layer. These results indicate that the vasculature is regulated within individual layers and CBV fMRI has a higher fidelity to the evoked neuronal activity compared with BOLD. Our findings are significant for understanding the neuronal origin and spatial specificity of hemodynamic responses, especially for the interpretation of laminar-resolution fMRI. Functional magnetic resonance imaging (fMRI) is a noninvasive, in vivo technique widely used to map function of the entire brain, including deep structures, in animals and humans. However, it measures neuronal

  9. Comparison of fMRI BOLD Response Patterns by Electrical Stimulation of the Ventroposterior Complex and Medial Thalamus of the Rat

    Science.gov (United States)

    Yang, Pai-Feng; Chen, You-Yin; Chen, Der-Yow; Hu, James W.; Chen, Jyh-Horng; Yen, Chen-Tung

    2013-01-01

    The objective of this study was to compare the functional connectivity of the lateral and medial thalamocortical pain pathways by investigating the blood oxygen level-dependent (BOLD) activation patterns in the forebrain elicited by direct electrical stimulation of the ventroposterior (VP) and medial (MT) thalamus. An MRI-compatible stimulation electrode was implanted in the VP or MT of α-chloralose-anesthetized rats. Electrical stimulation was applied to the VP or MT at various intensities (50 µA to 300 µA) and frequencies (1 Hz to 12 Hz). BOLD responses were analyzed in the ipsilateral forelimb region of the primary somatosensory cortex (iS1FL) after VP stimulation and in the ipsilateral cingulate cortex (iCC) after MT stimulation. When stimulating the VP, the strongest activation occurred at 3 Hz. The stimulation intensity threshold was 50 µA and the response rapidly peaked at 100 µA. When stimulating the MT, The optimal frequency for stimulation was 9 Hz or 12 Hz, the stimulation intensity threshold was 100 µA and we observed a graded increase in the BOLD response following the application of higher intensity stimuli. We also evaluated c-Fos expression following the application of a 200-µA stimulus. Ventroposterior thalamic stimulation elicited c-Fos-positivity in few cells in the iS1FL and caudate putamen (iCPu). Medial thalamic stimulation, however, produced numerous c-Fos-positive cells in the iCC and iCPu. The differential BOLD responses and c-Fos expressions elicited by VP and MT stimulation indicate differences in stimulus-response properties of the medial and lateral thalamic pain pathways. PMID:23826146

  10. Comparison of fMRI BOLD response patterns by electrical stimulation of the ventroposterior complex and medial thalamus of the rat.

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    Pai-Feng Yang

    Full Text Available The objective of this study was to compare the functional connectivity of the lateral and medial thalamocortical pain pathways by investigating the blood oxygen level-dependent (BOLD activation patterns in the forebrain elicited by direct electrical stimulation of the ventroposterior (VP and medial (MT thalamus. An MRI-compatible stimulation electrode was implanted in the VP or MT of α-chloralose-anesthetized rats. Electrical stimulation was applied to the VP or MT at various intensities (50 µA to 300 µA and frequencies (1 Hz to 12 Hz. BOLD responses were analyzed in the ipsilateral forelimb region of the primary somatosensory cortex (iS1FL after VP stimulation and in the ipsilateral cingulate cortex (iCC after MT stimulation. When stimulating the VP, the strongest activation occurred at 3 Hz. The stimulation intensity threshold was 50 µA and the response rapidly peaked at 100 µA. When stimulating the MT, The optimal frequency for stimulation was 9 Hz or 12 Hz, the stimulation intensity threshold was 100 µA and we observed a graded increase in the BOLD response following the application of higher intensity stimuli. We also evaluated c-Fos expression following the application of a 200-µA stimulus. Ventroposterior thalamic stimulation elicited c-Fos-positivity in few cells in the iS1FL and caudate putamen (iCPu. Medial thalamic stimulation, however, produced numerous c-Fos-positive cells in the iCC and iCPu. The differential BOLD responses and c-Fos expressions elicited by VP and MT stimulation indicate differences in stimulus-response properties of the medial and lateral thalamic pain pathways.

  11. BOLD-fMRI response vs. transcranial magnetic stimulation (TMS) pulse-train length: testing for linearity.

    Science.gov (United States)

    Bohning, Daryl E; Shastri, Ananda; Lomarev, Mikhail P; Lorberbaum, Jeffrey P; Nahas, Ziad; George, Mark S

    2003-03-01

    To measure motor and auditory cortex blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) response to impulse-like transcranial magnetic stimulation (TMS) pulses as a function of train length. Interleaved with fMRI at 1.5 T, TMS pulses 0.3-msec long were applied at 1 Hz to the motor cortex area for thumb. Six subjects were studied in a TR = 1 second session administering trains of 1, 2, 4, 8, and 16 pulses, and a TR = 3 seconds session administering trains of 1, 2, 4, 8, 16, and 24 pulses. A simple hemodynamic model with finite recovery and saturation was used to quantitatively characterize the BOLD-fMRI response as a function of train length. In both the activations directly induced in motor cortex by TMS and the indirect activations in auditory cortex caused by the sound of the TMS coil firing, the BOLD-fMRI responses to multiple pulses were well described by a summation of single-pulse impulse functions. Up to 24 discrete pulses, BOLD-fMRI response to 1 Hz TMS in both motor cortex and auditory cortex were consistent with a linear increase in amplitude and length with train length, possibly suggesting that stimuli of 1 to 2 seconds may be too long to represent impulses. Copyright 2003 Wiley-Liss, Inc.

  12. Interictal functional connectivity of human epileptic networks assessed by intracerebral EEG and BOLD signal fluctuations.

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    Gaelle Bettus

    Full Text Available In this study, we aimed to demonstrate whether spontaneous fluctuations in the blood oxygen level dependent (BOLD signal derived from resting state functional magnetic resonance imaging (fMRI reflect spontaneous neuronal activity in pathological brain regions as well as in regions spared by epileptiform discharges. This is a crucial issue as coherent fluctuations of fMRI signals between remote brain areas are now widely used to define functional connectivity in physiology and in pathophysiology. We quantified functional connectivity using non-linear measures of cross-correlation between signals obtained from intracerebral EEG (iEEG and resting-state functional MRI (fMRI in 5 patients suffering from intractable temporal lobe epilepsy (TLE. Functional connectivity was quantified with both modalities in areas exhibiting different electrophysiological states (epileptic and non affected regions during the interictal period. Functional connectivity as measured from the iEEG signal was higher in regions affected by electrical epileptiform abnormalities relative to non-affected areas, whereas an opposite pattern was found for functional connectivity measured from the BOLD signal. Significant negative correlations were found between the functional connectivities of iEEG and BOLD signal when considering all pairs of signals (theta, alpha, beta and broadband and when considering pairs of signals in regions spared by epileptiform discharges (in broadband signal. This suggests differential effects of epileptic phenomena on electrophysiological and hemodynamic signals and/or an alteration of the neurovascular coupling secondary to pathological plasticity in TLE even in regions spared by epileptiform discharges. In addition, indices of directionality calculated from both modalities were consistent showing that the epileptogenic regions exert a significant influence onto the non epileptic areas during the interictal period. This study shows that functional

  13. Modeling the BOLD correlates of competitive neural dynamics.

    Science.gov (United States)

    Bonaiuto, James; Arbib, Michael A

    2014-01-01

    Winner-take-all models are commonly used to model decision-making tasks where one outcome must be selected from several competing options. Related random walk and diffusion models have been used to explain such processes and apply them to psychometric and neurophysiological data. Recent model-based fMRI studies have sought to find the neural correlates of decision-making processes. However, due to the fact that hemodynamic responses likely reflect synaptic rather than spiking activity, the expected BOLD signature of winner-take-all circuits is not clear. A powerful way to integrate data from neurophysiology and brain imaging is by developing biologically plausible neural network models constrained and testable by neural and behavioral data, and then using Synthetic Brain Imaging - transforming the output of simulations with the model to make predictions testable against neuroimaging data. We developed a biologically realistic spiking winner-take-all model comprised of coupled excitatory and inhibitory neural populations. We varied the difficulty of a decision-making task by adjusting the contrast, or relative strength of inputs representing two response options. Synthetic brain imaging was used to estimate the BOLD response of the model and analyze its peak as a function of input contrast. We performed a parameter space analysis to determine values for which the model performs the task accurately, and given accurate performance, the distribution of the input contrast-BOLD response relationship. This underscores the need for models grounded in neurophysiological data for brain imaging analyses which attempt to localize the neural correlates of cognitive processes based on predicted BOLD responses. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. fMRI BOLD response in high-risk college students (Part 1): during exposure to alcohol, marijuana, polydrug and emotional picture cues.

    Science.gov (United States)

    Ray, Suchismita; Hanson, Catherine; Hanson, Stephen J; Bates, Marsha E

    2010-01-01

    This functional magnetic resonance imaging (fMRI) study examined reactivity to alcohol, polydrug, marijuana and emotional picture cues in students who were referred to a college alcohol and drug assistance program. The fMRI data of 10 participants (5 females; 5 males) were collected while they viewed standardized emotional and appetitive cues. Positive and negative emotional cues produced greater activity than neutral cues in the expected brain areas. Compared with neutral cues, alcohol cues produced greater brain activation in the right insula, left anterior cingulate, left caudate and left prefrontal cortex (Z = 2.01, 1.86, 1.82, 1.81, respectively; P marijuana cues activating left anterior cingulate. Students at-risk for alcohol abuse showed neural reactivity to alcohol cues in four brain regions, which is consistent with their greater use of alcohol. Insula activation to appetitive cues may be an early marker of risk for progression to alcohol/drug abuse.

  15. Does the individual adaption of standardized speech paradigmas for clinical functional Magnetic Resonance Imaging (fMRI) effect the localization of the language-dominant hemisphere and of Broca's and Wernicke's areas

    International Nuclear Information System (INIS)

    Konrad, F.; Nennig, E.; Kress, B.; Sartor, K.; Stippich, C.; Ochmann, H.

    2005-01-01

    Purpose: Functional magnetic resonance imaging (fMRI) localizes Broca's area (B) and Wernicke's area (W) and the hemisphere dominant for language. In clinical fMRI, adapting the stimulation paradigms to each patient's individual cognitive capacity is crucial for diagnostic success. To interpret clinical fMRI findings correctly, we studied the effect of varying frequency and number of stimuli on functional localization, determination of language dominance and BOLD signals. Materials and Methods: Ten volunteers (VP) were investigated at 1.5 Tesla during visually triggered sentence generation using a standardized block design. In four different measurements, the stimuli were presented to each VP with frequencies of (1/1)s, (1/2)s,(1/3)s and (1/6)s. Results: The functional localizations and the correlations of the measured BOLD signals to the applied hemodynamic reference function (r) were almost independent from frequency and number of the stimuli in both hemispheres, whereas the relative BOLD signal changes (ΔS) in B and W increased with the stimulation rate, which also changed the lateralization indices. The strongest BOLD activations were achieved with the highest stimulation rate or with the maximum language production task, respectively. Conclusion: The adaptation of language paradigms necessary in clinical fMRI does not alter the functional localizations but changes the BOLD signals and language lateralization which should not be attributed to the underlying brain pathology. (orig.)

  16. [Does the individual adaptation of standardized speech paradigmas for clinical functional magnetic resonance imaging (fMRI) effect the localization of the language-dominant hemisphere and of Broca's and Wernicke's areas].

    Science.gov (United States)

    Konrad, F; Nennig, E; Ochmann, H; Kress, B; Sartor, K; Stippich, C

    2005-03-01

    Functional magnetic resonance imaging (fMRI) localizes Broca's area (B) and Wernicke's area (W) and the hemisphere dominant for language. In clinical fMRI, adapting the stimulation paradigms to each patient's individual cognitive capacity is crucial for diagnostic success. To interpret clinical fMRI findings correctly, we studied the effect of varying frequency and number of stimuli on functional localization, determination of language dominance and BOLD signals. Ten volunteers (VP) were investigated at 1.5 Tesla during visually triggered sentence generation using a standardized block design. In four different measurements, the stimuli were presented to each VP with frequencies of 1/1 s, (1/2) s, (1/3) s and (1/6) s. The functional localizations and the correlations of the measured BOLD signals to the applied hemodynamic reference function (r) were almost independent from frequency and number of the stimuli in both hemispheres, whereas the relative BOLD signal changes (DeltaS) in B and W increased with the stimulation rate, which also changed the lateralization indices. The strongest BOLD activations were achieved with the highest stimulation rate or with the maximum language production task, respectively. The adaptation of language paradigms necessary in clinical fMRI does not alter the functional localizations but changes the BOLD signals and language lateralization which should not be attributed to the underlying brain pathology.

  17. fMRI BOLD response of high-risk college students (Part 2): during memory priming of alcohol, marijuana and polydrug picture cues.

    Science.gov (United States)

    Ray, Suchismita; Hanson, Catherine; Hanson, Stephen J; Rahman, Rifaquat M; Bates, Marsha E

    2010-01-01

    This study examined brain activity using functional magnetic resonance imaging (fMRI) and reaction time (RT) during an implicit repetition priming memory task involving alcohol, polydrug, marijuana and emotional picture cues. Participants were 5 male and 5 female high-risk college students who had just participated in a cue exposure study (Ray et al., this issue). fMRI and RT data were collected while participants made decisions about previously seen and new picture cues. Both behavioral RT and brain imaging data revealed strong memory priming for drug and alcohol cues. Neurologically, a repetition priming effect (suppression in neural activity for repeated cues) was observed in response to alcohol cues in the left prefrontal, bilateral occipital, and bilateral occipitotemporal regions, as well as right insula and right precuneus (Z ranged from 3.03 to 3.31 P marijuana cues in the occipital area. Prefrontal and insular cortex involvement both in reactivity to alcohol cues (Ray et al., this issue) and subsequent implicit memory processing of these cues, as found in this study, suggests their potential role in the maintenance of high-risk alcohol use behaviors.

  18. BMI not WHR modulates BOLD fMRI responses in a sub-cortical reward network when participants judge the attractiveness of human female bodies.

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    Ian E Holliday

    Full Text Available In perceptual terms, the human body is a complex 3d shape which has to be interpreted by the observer to judge its attractiveness. Both body mass and shape have been suggested as strong predictors of female attractiveness. Normally body mass and shape co-vary, and it is difficult to differentiate their separate effects. A recent study suggested that altering body mass does not modulate activity in the reward mechanisms of the brain, but shape does. However, using computer generated female body-shaped greyscale images, based on a Principal Component Analysis of female bodies, we were able to construct images which covary with real female body mass (indexed with BMI and not with body shape (indexed with WHR, and vice versa. Twelve observers (6 male and 6 female rated these images for attractiveness during an fMRI study. The attractiveness ratings were correlated with changes in BMI and not WHR. Our primary fMRI results demonstrated that in addition to activation in higher visual areas (such as the extrastriate body area, changing BMI also modulated activity in the caudate nucleus, and other parts of the brain reward system. This shows that BMI, not WHR, modulates reward mechanisms in the brain and we infer that this may have important implications for judgements of ideal body size in eating disordered individuals.

  19. fMRI BOLD Response of High-risk College Students (Part 2): During Memory Priming of Alcohol, Marijuana and Polydrug Picture Cues

    Science.gov (United States)

    Ray, Suchismita; Hanson, Catherine; Hanson, Stephen J.; Rahman, Rifaquat M.; Bates, Marsha E.

    2010-01-01

    Aims: This study examined brain activity using functional magnetic resonance imaging (fMRI) and reaction time (RT) during an implicit repetition priming memory task involving alcohol, polydrug, marijuana and emotional picture cues. Methods: Participants were 5 male and 5 female high-risk college students who had just participated in a cue exposure study (Ray et al., this issue). fMRI and RT data were collected while participants made decisions about previously seen and new picture cues. Results: Both behavioral RT and brain imaging data revealed strong memory priming for drug and alcohol cues. Neurologically, a repetition priming effect (suppression in neural activity for repeated cues) was observed in response to alcohol cues in the left prefrontal, bilateral occipital, and bilateral occipitotemporal regions, as well as right insula and right precuneus (Z ranged from 3.03 to 3.31 P < 0.05). Polydrug cues elicited priming in the occipital and temporal areas, and marijuana cues in the occipital area. Conclusions: Prefrontal and insular cortex involvement both in reactivity to alcohol cues (Ray et al., this issue) and subsequent implicit memory processing of these cues, as found in this study, suggests their potential role in the maintenance of high-risk alcohol use behaviors. PMID:20729527

  20. Exploiting magnetic resonance angiography imaging improves model estimation of BOLD signal.

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    Zhenghui Hu

    Full Text Available The change of BOLD signal relies heavily upon the resting blood volume fraction ([Formula: see text] associated with regional vasculature. However, existing hemodynamic data assimilation studies pretermit such concern. They simply assign the value in a physiologically plausible range to get over ill-conditioning of the assimilation problem and fail to explore actual [Formula: see text]. Such performance might lead to unreliable model estimation. In this work, we present the first exploration of the influence of [Formula: see text] on fMRI data assimilation, where actual [Formula: see text] within a given cortical area was calibrated by an MR angiography experiment and then was augmented into the assimilation scheme. We have investigated the impact of [Formula: see text] on single-region data assimilation and multi-region data assimilation (dynamic cause modeling, DCM in a classical flashing checkerboard experiment. Results show that the employment of an assumed [Formula: see text] in fMRI data assimilation is only suitable for fMRI signal reconstruction and activation detection grounded on this signal, and not suitable for estimation of unobserved states and effective connectivity study. We thereby argue that introducing physically realistic [Formula: see text] in the assimilation process may provide more reliable estimation of physiological information, which contributes to a better understanding of the underlying hemodynamic processes. Such an effort is valuable and should be well appreciated.

  1. An Ensemble of Classifiers based Approach for Prediction of Alzheimer's Disease using fMRI Images based on Fusion of Volumetric, Textural and Hemodynamic Features

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    MALIK, F.

    2018-02-01

    Full Text Available Alzheimer's is a neurodegenerative disease caused by the destruction and death of brain neurons resulting in memory loss, impaired thinking ability, and in certain behavioral changes. Alzheimer disease is a major cause of dementia and eventually death all around the world. Early diagnosis of the disease is crucial which can help the victims to maintain their level of independence for comparatively longer time and live a best life possible. For early detection of Alzheimer's disease, we are proposing a novel approach based on fusion of multiple types of features including hemodynamic, volumetric and textural features of the brain. Our approach uses non-invasive fMRI with ensemble of classifiers, for the classification of the normal controls and the Alzheimer patients. For performance evaluation, ten-fold cross validation is used. Individual feature sets and fusion of features have been investigated with ensemble classifiers for successful classification of Alzheimer's patients from normal controls. It is observed that fusion of features resulted in improved results for accuracy, specificity and sensitivity.

  2. Spatial attention related SEP amplitude modulations covary with BOLD signal in S1--a simultaneous EEG--fMRI study.

    Science.gov (United States)

    Schubert, Ruth; Ritter, Petra; Wüstenberg, Torsten; Preuschhof, Claudia; Curio, Gabriel; Sommer, Werner; Villringer, Arno

    2008-11-01

    Recent studies investigating the influence of spatial-selective attention on primary somatosensory processing have produced inconsistent results. The aim of this study was to explore the influence of tactile spatial-selective attention on spatiotemporal aspects of evoked neuronal activity in the primary somatosensory cortex (S1). We employed simultaneous electroencephalography (EEG)-functional magnetic resonance imaging (fMRI) in 14 right-handed subjects during bilateral index finger Braille stimulation to investigate the relationship between attentional effects on somatosensory evoked potential (SEP) components and the blood oxygenation level-dependent (BOLD) signal. The 1st reliable EEG response following left tactile stimulation (P50) was significantly enhanced by spatial-selective attention, which has not been reported before. FMRI analysis revealed increased activity in contralateral S1. Remarkably, the effect of attention on the P50 component as well as long-latency SEP components starting at 190 ms for left stimuli correlated with attentional effects on the BOLD signal in contralateral S1. The implications are 2-fold: First, the correlation between early and long-latency SEP components and the BOLD effect suggest that spatial-selective attention enhances processing in S1 at 2 time points: During an early passage of the signal and during a later passage, probably via re-entrant feedback from higher cortical areas. Second, attentional modulations of the fast electrophysiological signals and the slow hemodynamic response are linearly related in S1.

  3. Does the individual adaption of standardized speech paradigmas for clinical functional Magnetic Resonance Imaging (fMRI) effect the localization of the language-dominant hemisphere and of Broca's and Wernicke's areas; Beeinflusst die individuelle Anpassung standardisierter Sprachparadigmen fuer die klinische funktionelle Magnetresonanztomographie (fMRT) die Lokalisation der sprachdominanten Hemisphaere, des Broca- und des Wernicke-Sprachzentrums?

    Energy Technology Data Exchange (ETDEWEB)

    Konrad, F.; Nennig, E.; Kress, B.; Sartor, K.; Stippich, C. [Abteilung Neuroradiologie, Neurologische Klinik, Universitaetsklinikum Heidelberg (Germany); Ochmann, H. [Neurochirurgische Klinik, Universitaetsklinikum Heidelberg (Germany)

    2005-03-01

    Purpose: Functional magnetic resonance imaging (fMRI) localizes Broca's area (B) and Wernicke's area (W) and the hemisphere dominant for language. In clinical fMRI, adapting the stimulation paradigms to each patient's individual cognitive capacity is crucial for diagnostic success. To interpret clinical fMRI findings correctly, we studied the effect of varying frequency and number of stimuli on functional localization, determination of language dominance and BOLD signals. Materials and Methods: Ten volunteers (VP) were investigated at 1.5 Tesla during visually triggered sentence generation using a standardized block design. In four different measurements, the stimuli were presented to each VP with frequencies of (1/1)s, (1/2)s,(1/3)s and (1/6)s. Results: The functional localizations and the correlations of the measured BOLD signals to the applied hemodynamic reference function (r) were almost independent from frequency and number of the stimuli in both hemispheres, whereas the relative BOLD signal changes ({delta}S) in B and W increased with the stimulation rate, which also changed the lateralization indices. The strongest BOLD activations were achieved with the highest stimulation rate or with the maximum language production task, respectively. Conclusion: The adaptation of language paradigms necessary in clinical fMRI does not alter the functional localizations but changes the BOLD signals and language lateralization which should not be attributed to the underlying brain pathology. (orig.)

  4. The 'where' and the 'when' of the BOLD response to pain in the insular cortex. Discussion on amplitudes and latencies.

    Science.gov (United States)

    Pomares, Florence B; Faillenot, Isabelle; Barral, Fabrice Guy; Peyron, Roland

    2013-01-01

    The operculo-insular cortex has been recently pointed out to be the main area of the pain matrix to be involved in the integration of pain intensity. This fMRI study specified the pattern of response to laser stimuli by focusing on this cortical area, by optimizing the temporal sampling and by investigating pain-related differences in the amplitudes and latencies of the BOLD responses. Canonical and temporal derivative hemodynamic response function (HRF) and finite impulse response (FIR) modeling provided consistent results. Amplitude of BOLD response discriminated painful from non-painful conditions in posterior and mid-insular cortices, bilaterally. Pain conditions were characterized by a shortened latency (as compared to non-painful conditions) in the anterior insula. In the functional organization of the insula, these results suggest a double dissociation that can be summarized as the 'where' and the 'when' of the BOLD response to pain. These results suggest that differences in the amplitude of the BOLD activity in the posterior and in the mid-insular cortices as well as shortened latency of the response in the anterior insula deal with discriminative processes related to painful conditions. Copyright © 2012 Elsevier Inc. All rights reserved.

  5. Interpreting BOLD: towards a dialogue between cognitive and cellular neuroscience.

    Science.gov (United States)

    Hall, Catherine N; Howarth, Clare; Kurth-Nelson, Zebulun; Mishra, Anusha

    2016-10-05

    Cognitive neuroscience depends on the use of blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) to probe brain function. Although commonly used as a surrogate measure of neuronal activity, BOLD signals actually reflect changes in brain blood oxygenation. Understanding the mechanisms linking neuronal activity to vascular perfusion is, therefore, critical in interpreting BOLD. Advances in cellular neuroscience demonstrating differences in this neurovascular relationship in different brain regions, conditions or pathologies are often not accounted for when interpreting BOLD. Meanwhile, within cognitive neuroscience, the increasing use of high magnetic field strengths and the development of model-based tasks and analyses have broadened the capability of BOLD signals to inform us about the underlying neuronal activity, but these methods are less well understood by cellular neuroscientists. In 2016, a Royal Society Theo Murphy Meeting brought scientists from the two communities together to discuss these issues. Here, we consolidate the main conclusions arising from that meeting. We discuss areas of consensus about what BOLD fMRI can tell us about underlying neuronal activity, and how advanced modelling techniques have improved our ability to use and interpret BOLD. We also highlight areas of controversy in understanding BOLD and suggest research directions required to resolve these issues.This article is part of the themed issue 'Interpreting BOLD: a dialogue between cognitive and cellular neuroscience'. © 2016 The Author(s).

  6. BOLD correlates of EEG topography reveal rapid resting-state network dynamics.

    Science.gov (United States)

    Britz, Juliane; Van De Ville, Dimitri; Michel, Christoph M

    2010-10-01

    Resting-state functional connectivity studies with fMRI showed that the brain is intrinsically organized into large-scale functional networks for which the hemodynamic signature is stable for about 10s. Spatial analyses of the topography of the spontaneous EEG also show discrete epochs of stable global brain states (so-called microstates), but they remain quasi-stationary for only about 100 ms. In order to test the relationship between the rapidly fluctuating EEG-defined microstates and the slowly oscillating fMRI-defined resting states, we recorded 64-channel EEG in the scanner while subjects were at rest with their eyes closed. Conventional EEG-microstate analysis determined the typical four EEG topographies that dominated across all subjects. The convolution of the time course of these maps with the hemodynamic response function allowed to fit a linear model to the fMRI BOLD responses and revealed four distinct distributed networks. These networks were spatially correlated with four of the resting-state networks (RSNs) that were found by the conventional fMRI group-level independent component analysis (ICA). These RSNs have previously been attributed to phonological processing, visual imagery, attention reorientation, and subjective interoceptive-autonomic processing. We found no EEG-correlate of the default mode network. Thus, the four typical microstates of the spontaneous EEG seem to represent the neurophysiological correlate of four of the RSNs and show that they are fluctuating much more rapidly than fMRI alone suggests. Copyright 2010 Elsevier Inc. All rights reserved.

  7. Estimation of the neuronal activation using fMRI data: An observer-based approach

    KAUST Repository

    Laleg-Kirati, Taous-Meriem

    2013-06-01

    This paper deals with the estimation of the neuronal activation and some unmeasured physiological information using the Blood Oxygenation Level Dependent (BOLD) signal measured using functional Magnetic Resonance Imaging (fMRI). We propose to use an observer-based approach applied to the balloon hemodynamic model. The latter describes the relation between the neural activity and the BOLD signal. The balloon model can be expressed in a nonlinear state-space representation where the states, the parameters and the input (neuronal activation), are unknown. This study focuses only on the estimation of the hidden states and the neuronal activation. The model is first linearized around the equilibrium and an observer is applied to this linearized version. Numerical results performed on synthetic data are presented.

  8. A Sensitivity Analysis of fMRI Balloon Model

    KAUST Repository

    Zayane, Chadia

    2015-04-22

    Functional magnetic resonance imaging (fMRI) allows the mapping of the brain activation through measurements of the Blood Oxygenation Level Dependent (BOLD) contrast. The characterization of the pathway from the input stimulus to the output BOLD signal requires the selection of an adequate hemodynamic model and the satisfaction of some specific conditions while conducting the experiment and calibrating the model. This paper, focuses on the identifiability of the Balloon hemodynamic model. By identifiability, we mean the ability to estimate accurately the model parameters given the input and the output measurement. Previous studies of the Balloon model have somehow added knowledge either by choosing prior distributions for the parameters, freezing some of them, or looking for the solution as a projection on a natural basis of some vector space. In these studies, the identification was generally assessed using event-related paradigms. This paper justifies the reasons behind the need of adding knowledge, choosing certain paradigms, and completing the few existing identifiability studies through a global sensitivity analysis of the Balloon model in the case of blocked design experiment.

  9. Resting-state functional MRI as a tool for evaluating brain hemodynamic responsiveness to external stimuli in rats.

    Science.gov (United States)

    Paasonen, Jaakko; Salo, Raimo A; Huttunen, Joanna K; Gröhn, Olli

    2017-09-01

    Anesthesia is a major confounding factor in functional MRI (fMRI) experiments attributed to its effects on brain function. Recent evidence suggests that parameters obtained with resting-state fMRI (rs-fMRI) are coupled with anesthetic depth. Therefore, we investigated whether parameters obtained with rs-fMRI, such as functional connectivity (FC), are also directly related to blood-oxygen-level-dependent (BOLD) responses. A simple rs-fMRI protocol was implemented in a pharmacological fMRI study to evaluate the coupling between hemodynamic responses and FC under five anesthetics (α-chloralose, isoflurane, medetomidine, thiobutabarbital, and urethane). Temporal change in the FC was evaluated at 1-hour interval. Supplementary forepaw stimulation experiments were also conducted. Under thiobutabarbital anesthesia, FC was clearly coupled with nicotine-induced BOLD responses. Good correlation values were also obtained under isoflurane and medetomidine anesthesia. The observations in the thiobutabarbital group were supported by forepaw stimulation experiments. Additionally, the rs-fMRI protocol revealed significant temporal changes in the FC in the α-chloralose, thiobutabarbital, and urethane groups. Our results suggest that FC can be used to estimate brain hemodynamic responsiveness to stimuli and evaluate the level and temporal changes of anesthesia. Therefore, analysis of the fMRI baseline signal may be highly valuable tool for controlling the outcome of preclinical fMRI experiments. Magn Reson Med 78:1136-1146, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  10. fMRI activation patterns in an analytic reasoning task: consistency with EEG source localization

    Science.gov (United States)

    Li, Bian; Vasanta, Kalyana C.; O'Boyle, Michael; Baker, Mary C.; Nutter, Brian; Mitra, Sunanda

    2010-03-01

    Functional magnetic resonance imaging (fMRI) is used to model brain activation patterns associated with various perceptual and cognitive processes as reflected by the hemodynamic (BOLD) response. While many sensory and motor tasks are associated with relatively simple activation patterns in localized regions, higher-order cognitive tasks may produce activity in many different brain areas involving complex neural circuitry. We applied a recently proposed probabilistic independent component analysis technique (PICA) to determine the true dimensionality of the fMRI data and used EEG localization to identify the common activated patterns (mapped as Brodmann areas) associated with a complex cognitive task like analytic reasoning. Our preliminary study suggests that a hybrid GLM/PICA analysis may reveal additional regions of activation (beyond simple GLM) that are consistent with electroencephalography (EEG) source localization patterns.

  11. Initiation of voluntary movements at free will and ongoing 0.1-Hz BOLD oscillations in the insula – a pilot study

    Directory of Open Access Journals (Sweden)

    Gert ePfurtscheller

    2014-12-01

    Full Text Available Recently we hypothesized that the intention to initiate a voluntary movement at free will may be related to the dynamics of hemodynamic variables, which may be supported by the intertwining of networks for the timing of voluntary movements and the control of cardiovascular variables in the insula. In the present study voluntary movements of 3 healthy subjects were analyzed using fMRI scans at 1.83-s intervals along with the time course of slow hemodynamic changes in sensorimotor networks. For the analyses of BOLD time courses the Wavelet transform coherence (WTC and calculation of phase-locking values were used. Analyzed was the frequency band between 0.07 and 0.13 Hz in the supplementary motor area (SMA and insula, two widely separated regions co-active in motor behavior. BOLD signals displayed slow fluctuations, concentrated around 0.1 Hz whereby the intrinsic oscillations in the insula preceded those in the SMA by 0.5 to 1 seconds. These preliminary results suggest that slow hemodynamic changes in SMA and insula may condition the initiation of a voluntary movement at free will.

  12. Positive Allosteric Modulator of GABA Lowers BOLD Responses in the Cingulate Cortex.

    Directory of Open Access Journals (Sweden)

    Susanna A Walter

    Full Text Available Knowledge about the neural underpinnings of the negative blood oxygen level dependent (BOLD responses in functional magnetic resonance imaging (fMRI is still limited. We hypothesized that pharmacological GABAergic modulation attenuates BOLD responses, and that blood concentrations of a positive allosteric modulator of GABA correlate inversely with BOLD responses in the cingulate cortex. We investigated whether or not pure task-related negative BOLD responses were co-localized with pharmacologically modulated BOLD responses. Twenty healthy adults received either 5 mg diazepam or placebo in a double blind, randomized design. During fMRI the subjects performed a working memory task. Results showed that BOLD responses in the cingulate cortex were inversely correlated with diazepam blood concentrations; that is, the higher the blood diazepam concentration, the lower the BOLD response. This inverse correlation was most pronounced in the pregenual anterior cingulate cortex and the anterior mid-cingulate cortex. For subjects with diazepam plasma concentration > 0.1 mg/L we observed negative BOLD responses with respect to fixation baseline. There was minor overlap between cingulate regions with task-related negative BOLD responses and regions where the BOLD responses were inversely correlated with diazepam concentration. We interpret that the inverse correlation between the BOLD response and diazepam was caused by GABA-related neural inhibition. Thus, this study supports the hypothesis that GABA attenuates BOLD responses in fMRI. The minimal overlap between task-related negative BOLD responses and responses attenuated by diazepam suggests that these responses might be caused by different mechanisms.

  13. Reproducibility of BOLD signal change induced by breath holding.

    Science.gov (United States)

    Magon, Stefano; Basso, Gianpaolo; Farace, Paolo; Ricciardi, Giuseppe Kenneth; Beltramello, Alberto; Sbarbati, Andrea

    2009-04-15

    Blood oxygen level dependent (BOLD) contrast is influenced by some physiological factors such as blood flow and blood volume that can be a source of variability in fMRI analysis. Previous studies proposed to use the cerebrovascular response data to normalize or calibrate BOLD maps in order to reduce variability of fMRI data both among brain areas in single subject analysis and across subjects. Breath holding is one of the most widely used methods to investigate the vascular reactivity. However, little is known about the robustness and reproducibility of this procedure. In this study we investigated three different breath holding periods. Subjects were asked to hold their breath for 9, 15 or 21 s in three separate runs and the fMRI protocol was repeated after 15 to 20 days. Our data show that the BOLD response to breath holding after inspiration results in a complex shape due to physiological factors that influence the signal variation with a timing that is highly reproducible. Nevertheless, the reproducibility of the magnitude of the cerebrovascular response to CO(2), expressed as amplitude of BOLD signal and number of responding voxels, strongly depends on duration of breath holding periods. Breath holding period of 9 s results in high variability of the magnitude of the response while longer breath holding durations produce more robust and reproducible BOLD responses.

  14. Acute Alcohol Effects on Contextual Memory BOLD Response: Differences Based on Fragmentary Blackout History

    Science.gov (United States)

    Wetherill, Reagan R.; Schnyer, David M.; Fromme, Kim

    2011-01-01

    Background Contextual memory, or memory for source details, is an important aspect of episodic memory and has been implicated in alcohol-induced fragmentary blackouts (FB). Little is known, however, about how neural functioning during contextual memory processes may differ between individuals with and without a history of fragmentary blackouts. This study examined whether neural activation during a contextual memory task differed by history of fragmentary blackout and acute alcohol consumption. Methods Twenty-four matched individuals with (FB+; n = 12) and without (FB−; n = 12) a history of FBs were recruited from a longitudinal study of alcohol use and behavioral risks and completed a laboratory beverage challenge followed by two functional magnetic resonance imaging (fMRI) sessions under no alcohol and alcohol [breath alcohol concentration (BrAC) = 0.08%] conditions. Task performance and brain hemodynamic activity during a block design contextual memory task were examined across 48 fMRI sessions. Results Groups demonstrated no differences in performance on the contextual memory task, yet exhibited different brain response patterns after alcohol intoxication. A significant FB group by beverage interaction emerged in bilateral dorsolateral prefrontal cortex and posterior parietal cortex with FB− individuals showing greater BOLD response after alcohol exposure (p blackouts. PMID:22420742

  15. A NO way to BOLD?

    DEFF Research Database (Denmark)

    Aamand, Rasmus; Dalsgaard, Thomas; Ho, Yi-Ching Lynn

    2013-01-01

    Neurovascular coupling links neuronal activity to vasodilation. Nitric oxide (NO) is a potent vasodilator, and in neurovascular coupling NO production from NO synthases plays an important role. However, another pathway for NO production also exists, namely the nitrate-nitrite-NO pathway. On this ......Neurovascular coupling links neuronal activity to vasodilation. Nitric oxide (NO) is a potent vasodilator, and in neurovascular coupling NO production from NO synthases plays an important role. However, another pathway for NO production also exists, namely the nitrate-nitrite-NO pathway...... to stimuli. A faster and smaller BOLD response, with less variation across local cortex, is consistent with an enhanced hemodynamic coupling during elevated nitrate intake. These findings suggest that dietary patterns, via the nitrate-nitrite-NO pathway, may be a potential way to affect key properties....... On this basis, we hypothesized that dietary nitrate (NO3-) could influence the brain's hemodynamic response to neuronal stimulation. In the present study, 20 healthy male participants were given either sodium nitrate (NaNO3) or sodium chloride (NaCl) (saline placebo) in a crossover study and were shown visual...

  16. Multiband multi-echo simultaneous ASL/BOLD for task-induced functional MRI.

    Directory of Open Access Journals (Sweden)

    Alexander D Cohen

    Full Text Available Typical simultaneous blood oxygenation-level dependent (BOLD and arterial spin labeling (ASL sequences acquire two echoes, one perfusion-sensitive and one BOLD-sensitive. However, for ASL, spatial resolution and brain coverage are limited due to the T1 decay of the labeled blood. This study applies a sequence combining a multiband acquisition with four echoes for simultaneous BOLD and pseudo-continuous ASL (pCASL echo planar imaging (MBME ASL/BOLD for block-design task-fMRI. A multiband acceleration of four was employed to increase brain coverage and reduce slice-timing effects on the ASL signal. Multi-echo independent component analysis (MEICA was implemented to automatically denoise the BOLD signal by regressing non-BOLD components. This technique led to increased temporal signal-to-noise ratio (tSNR and BOLD sensitivity. The MEICA technique was also modified to denoise the ASL signal by regressing artifact and BOLD signals from the first echo time-series. The MBME ASL/BOLD sequence was applied to a finger-tapping task functional MRI (fMRI experiment. Signal characteristics and activation were evaluated using single echo BOLD, combined ME BOLD, combined ME BOLD after MEICA denoising, perfusion-weighted (PW, and perfusion-weighted after MEICA denoising time-series. The PW data was extracted using both surround subtraction and high-pass filtering followed by demodulation. In addition, the CBF/BOLD response ratio and CBF/BOLD coupling were analyzed. Results showed that the MEICA denoising procedure significantly improved the BOLD signal, leading to increased BOLD sensitivity, tSNR, and activation statistics compared to conventional single echo BOLD data. At the same time, the denoised PW data showed increased tSNR and activation statistics compared to the non-denoised PW data. CBF/BOLD coupling was also increased using the denoised ASL and BOLD data. Our preliminary data suggest that the MBME ASL/BOLD sequence can be employed to collect whole

  17. Non-parametric temporal modeling of the hemodynamic response function via a liquid state machine.

    Science.gov (United States)

    Avesani, Paolo; Hazan, Hananel; Koilis, Ester; Manevitz, Larry M; Sona, Diego

    2015-10-01

    Standard methods for the analysis of functional MRI data strongly rely on prior implicit and explicit hypotheses made to simplify the analysis. In this work the attention is focused on two such commonly accepted hypotheses: (i) the hemodynamic response function (HRF) to be searched in the BOLD signal can be described by a specific parametric model e.g., double-gamma; (ii) the effect of stimuli on the signal is taken to be linearly additive. While these assumptions have been empirically proven to generate high sensitivity for statistical methods, they also limit the identification of relevant voxels to what is already postulated in the signal, thus not allowing the discovery of unknown correlates in the data due to the presence of unexpected hemodynamics. This paper tries to overcome these limitations by proposing a method wherein the HRF is learned directly from data rather than induced from its basic form assumed in advance. This approach produces a set of voxel-wise models of HRF and, as a result, relevant voxels are filterable according to the accuracy of their prediction in a machine learning framework. This approach is instantiated using a temporal architecture based on the paradigm of Reservoir Computing wherein a Liquid State Machine is combined with a decoding Feed-Forward Neural Network. This splits the modeling into two parts: first a representation of the complex temporal reactivity of the hemodynamic response is determined by a universal global "reservoir" which is essentially temporal; second an interpretation of the encoded representation is determined by a standard feed-forward neural network, which is trained by the data. Thus the reservoir models the temporal state of information during and following temporal stimuli in a feed-back system, while the neural network "translates" this data to fit the specific HRF response as given, e.g. by BOLD signal measurements in fMRI. An empirical analysis on synthetic datasets shows that the learning process can

  18. Risk assessment of aggressive behavior in Chinese patients with schizophrenia by fMRI and COMT gene

    Directory of Open Access Journals (Sweden)

    Tang X

    2017-02-01

    Full Text Available Xiaoli Tang,1 Jun Jin,1 Yi Tang,1 Jinbo Cao,1 Junjie Huang2 1Department of Radiology, Shekou People’s Hospital, Shenzhen, 2Department of Medicine, Shenzhen University, Guangdong, People’s Republic of China Background: Blood–oxygen-level dependent functional magnetic resonance imaging (BOLD-fMRI maps cerebral activity by the hemodynamic response. Catechol-O-methyltransferase (COMT gene is involved in the metabolism of dopamine. It is reported that both of these can be used to assess the aggression risk in patients with schizophrenia. However, these methods to assess the aggression risk patients with schizophrenia have not been established in China. Therefore, we deliver here a systematic review and meta-analysis based on the studies dealing with Chinese patients. Method: Nine fMRI studies and 12 gene studies were included. The data of each study were extracted and summarized. Odds ratios with 95% confidence intervals were estimated on allele, dominant, and recessive models. Publication bias was evaluated by Begg’s funnel plot. Results: Positive BOLD-fMRI values in the lower central neural system (CNS and negative values in the high-level CNS were observed in the patients with aggression risk. A strong association was derived from the recessive gene model of COMT polymorphism rs4680 and risk in aggression behavior (odds ratio =2.10. No significant publication bias was identified. Conclusion: Aggression behavior in patients with schizophrenia can be indicated by positive BOLD-fMRI values in the lower CNS and negative values in the high-level CNS and by a recessive gene model in COMT polymorphism rs4680. A combined test of fMRI and COMT gene could increase the predictive value. Keywords: aggression, schizophrenia, Chinese, fMRI, COMT, meta-analysis

  19. fMRI. Basics and clinical applications

    Energy Technology Data Exchange (ETDEWEB)

    Ulmer, Stephan; Jansen, Olav (eds.) [University Hospital of Schleswig-Holstein, Kiel (Germany). Inst. of Neuroradiology, Neurocenter

    2010-07-01

    Functional MRI (fMRI) and the basic method of BOLD imaging were introduced in 1993 by Seiji Ogawa. From very basic experiments, fMRI has evolved into a clinical application for daily routine brain imaging. There have been various improvements in both the imaging technique as such as well as in the statistical analysis. In this volume, experts in the field share their knowledge and point out possible technical barriers and problems explaining how to solve them. Starting from the very basics on the origin of the BOLD signal, the book covers technical issues, anatomical landmarks, presurgical applications, and special issues in various clinical fields. Other modalities for brain mapping such as PET, TMS, and MEG are also compared with fMRI. This book is intended to give a state-of-the-art overview and to serve as a reference and guide for clinical applications of fMRI. (orig.)

  20. Cerebrovascular reactivity among native-raised high altitude residents: an fMRI study

    Directory of Open Access Journals (Sweden)

    Zhang Jiaxing

    2011-09-01

    Full Text Available Abstract Background The impact of long term residence on high altitude (HA on human brain has raised concern among researchers in recent years. This study investigated the cerebrovascular reactivity among native-born high altitude (HA residents as compared to native sea level (SL residents. The two groups were matched on the ancestral line, ages, gender ratios, and education levels. A visual cue guided maximum inspiration task with brief breath holding was performed by all the subjects while Blood-Oxygenation-Level-Dependent (BOLD functional Magnetic Resonance Imaging (fMRI data were acquired from them. Results Compared to SL controls, the HA group showed generally decreased cerebrovascular reactivity and longer delay in hemodynamic response. Clusters showing significant differences in the former aspect were located at the bilateral primary motor cortex, the right somatosensory association cortex, the right thalamus and the right caudate, the bilateral precuneus, the right cingulate gyrus and the right posterior cingulate cortex, as well as the left fusiform gyrus and the right lingual cortex; clusters showing significant differences in the latter aspect were located at the precuneus, the insula, the superior frontal and temporal gyrus, the somatosensory cortex (the postcentral gyrus and the cerebellar tonsil. Inspiratory reserve volume (IRV, which is an important aspect of pulmonary function, demonstrated significant correlation with the amount of BOLD signal change in multiple brain regions, particularly at the bilateral insula among the HA group. Conclusions Native-born HA residents generally showed reduced cerebrovascular reactivity as demonstrated in the hemodynamic response during a visual cue guided maximum inspiration task conducted with BOLD-fMRI. This effect was particularly manifested among brain regions that are typically involved in cerebral modulation of respiration.

  1. Cortical layers, rhythms and BOLD signals.

    Science.gov (United States)

    Scheeringa, René; Fries, Pascal

    2017-11-03

    This review investigates how laminar fMRI can complement insights into brain function derived from the study of rhythmic neuronal synchronization. Neuronal synchronization in various frequency bands plays an important role in neuronal communication between brain areas, and it does so on the backbone of layer-specific interareal anatomical projections. Feedforward projections originate predominantly in supragranular cortical layers and terminate in layer 4, and this pattern is reflected in inter-laminar and interareal directed gamma-band influences. Thus, gamma-band synchronization likely subserves feedforward signaling. By contrast, anatomical feedback projections originate predominantly in infragranular layers and terminate outside layer 4, and this pattern is reflected in inter-laminar and interareal directed alpha- and/or beta-band influences. Thus, alpha-beta band synchronization likely subserves feedback signaling. Furthermore, these rhythms explain part of the BOLD signal, with independent contributions of alpha-beta and gamma. These findings suggest that laminar fMRI can provide us with a potentially useful method to test some of the predictions derived from the study of neuronal synchronization. We review central findings regarding the role of layer-specific neuronal synchronization for brain function, and regarding the link between neuronal synchronization and the BOLD signal. We discuss the role that laminar fMRI could play by comparing it to invasive and non-invasive electrophysiological recordings. Compared to direct electrophysiological recordings, this method provides a metric of neuronal activity that is slow and indirect, but that is uniquely non-invasive and layer-specific with potentially whole brain coverage. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  2. Bayesian spatiotemporal model of fMRI data using transfer functions.

    Science.gov (United States)

    Quirós, Alicia; Diez, Raquel Montes; Wilson, Simon P

    2010-09-01

    This research describes a new Bayesian spatiotemporal model to analyse BOLD fMRI studies. In the temporal dimension, we describe the shape of the hemodynamic response function (HRF) with a transfer function model. The spatial continuity and local homogeneity of the evoked responses are modelled by a Gaussian Markov random field prior on the parameter indicating activations. The proposal constitutes an extension of the spatiotemporal model presented in a previous approach [Quirós, A., Montes Diez, R. and Gamerman, D., 2010. Bayesian spatiotemporal model of fMRI data, Neuroimage, 49: 442-456], offering more flexibility in the estimation of the HRF and computational advantages in the resulting MCMC algorithm. Simulations from the model are performed in order to ascertain the performance of the sampling scheme and the ability of the posterior to estimate model parameters, as well as to check the model sensitivity to signal to noise ratio. Results are shown on synthetic data and on a real data set from a block-design fMRI experiment. Copyright (c) 2010 Elsevier Inc. All rights reserved.

  3. Assessment of Cortical Visual Impairment in Infants with Periventricular Leukomalacia: a Pilot Event-Related fMRI Study

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Bing; Guo, Qiyong [Shengjing Hospital of China Medical University, Shenyang (China); Fan, Guoguang [The First Hospital of China Medical University, Shenyang (China); Liu, Na [Greater China Region of Philips, Shanghai (China)

    2011-08-15

    We wanted to investigate the usefulness of event-related (ER) functional MRI (fMRI) for the assessment of cortical visual impairment in infants with periventricular leukomalacia (PVL). FMRI data were collected from 24 infants who suffered from PVL and from 12 age-matched normal controls. Slow ER fMRI was performed using a 3.0T MR scanner while visual stimuli were being presented. Data analysis was performed using Statistical Parametric Mapping software (SPM2), the SPM toolbox MarsBar was used to analyze the region of interest data, and the time to peak (TTP) of hemodynamic response functions (HRFs) was estimated for the surviving voxels. The number of activated voxels and the TTP values of HRFs were compared. Pearson correlation analysis was performed to compare visual impairment evaluated by using Teller Acuity Cards (TAC) with the number of activated voxels in the occipital lobes in all patients. In all 12 control infants, the blood oxygenation level-dependent (BOLD) signal was negative and the maximum response was located in the anterior and superior part of the calcarine fissure, and this might correspond to the anterior region of the primary visual cortex (PVC). In contrast, for the 24 cases of PVL, there were no activated pixels in the PVC in four subjects, small and weak activations in six subjects, deviated activations in seven subjects and both small and deviated activations in three subjects. The number of active voxels in the occipital lobe was significantly correlated with the TAC-evaluated visual impairment (p < 0.001). The mean TTP of the HRFs was significantly delayed in the cases of PVL as compared with that of the normal controls. Determining the characteristics of both the BOLD response and the ER fMRI activation may play an important role in the cortical visual assessment of infants with PVL.

  4. Assessment of Cortical Visual Impairment in Infants with Periventricular Leukomalacia: a Pilot Event-Related fMRI Study

    International Nuclear Information System (INIS)

    Yu, Bing; Guo, Qiyong; Fan, Guoguang; Liu, Na

    2011-01-01

    We wanted to investigate the usefulness of event-related (ER) functional MRI (fMRI) for the assessment of cortical visual impairment in infants with periventricular leukomalacia (PVL). FMRI data were collected from 24 infants who suffered from PVL and from 12 age-matched normal controls. Slow ER fMRI was performed using a 3.0T MR scanner while visual stimuli were being presented. Data analysis was performed using Statistical Parametric Mapping software (SPM2), the SPM toolbox MarsBar was used to analyze the region of interest data, and the time to peak (TTP) of hemodynamic response functions (HRFs) was estimated for the surviving voxels. The number of activated voxels and the TTP values of HRFs were compared. Pearson correlation analysis was performed to compare visual impairment evaluated by using Teller Acuity Cards (TAC) with the number of activated voxels in the occipital lobes in all patients. In all 12 control infants, the blood oxygenation level-dependent (BOLD) signal was negative and the maximum response was located in the anterior and superior part of the calcarine fissure, and this might correspond to the anterior region of the primary visual cortex (PVC). In contrast, for the 24 cases of PVL, there were no activated pixels in the PVC in four subjects, small and weak activations in six subjects, deviated activations in seven subjects and both small and deviated activations in three subjects. The number of active voxels in the occipital lobe was significantly correlated with the TAC-evaluated visual impairment (p < 0.001). The mean TTP of the HRFs was significantly delayed in the cases of PVL as compared with that of the normal controls. Determining the characteristics of both the BOLD response and the ER fMRI activation may play an important role in the cortical visual assessment of infants with PVL.

  5. Analysis of time and space invariance of BOLD responses in the rat visual system

    DEFF Research Database (Denmark)

    Bailey, Christopher; Sanganahalli, Basavaraju G; Herman, Peter

    2013-01-01

    superior colliculus (SC) and primary visual cortex (V1) in rat brain--regions with different basal blood flow and energy demand. Our goal was to assess neurovascular coupling in V1 and SC as reflected by temporal/spatial variances of impulse response functions (IRFs) and assess, if any, implications......Neuroimaging studies of functional magnetic resonance imaging (fMRI) and electrophysiology provide the linkage between neural activity and the blood oxygenation level-dependent (BOLD) response. Here, BOLD responses to light flashes were imaged at 11.7T and compared with neural recordings from...... for general linear modeling (GLM) of BOLD responses. Light flashes induced high magnitude neural/BOLD responses reproducibly from both regions. However, neural/BOLD responses from SC and V1 were markedly different. SC signals followed the boxcar shape of the stimulation paradigm at all flash rates, whereas V1...

  6. Controlled inspiration depth reduces variance in breath-holding induced BOLD signal

    Science.gov (United States)

    Thomason, Moriah E.; Glover, Gary H.

    2007-01-01

    Recent studies have shown that Blood Oxygen Level Dependent (BOLD) response amplitude during short periods of breath holding (BH) measured by functional Magnetic Resonance Imaging (fMRI) can be an effective metric for intersubject calibration procedures. However, inconsistency in the depth of inspiration during the BH scan may account for a portion of BOLD variation observed in such scans, and it is likely to reduce the effectiveness of the calibration measurement. While modulation of BOLD signal has been correlated with end-tidal CO2 and other measures of breathing, fluctuations in performance of BH have not been studied in the context of their impact on BOLD signal. Here, we studied the degree to which inspiration depth corresponds to BOLD signal change, and tested the effectiveness of a method designed to control inspiration level through visual cues during the BH task paradigm. We observed reliable differences in BOLD signal amplitude corresponding to the depth of inspiration. It was determined that variance in BOLD signal response to BH could be significantly reduced when subjects were given visual feedback during task inspiration periods. The implications of these findings for routine BH studies of BOLD-derived neurovascular response are discussed. PMID:17905599

  7. Controlled inspiration depth reduces variance in breath-holding-induced BOLD signal.

    Science.gov (United States)

    Thomason, Moriah E; Glover, Gary H

    2008-01-01

    Recent studies have shown that blood oxygen level dependent (BOLD) response amplitude during short periods of breath holding (BH) measured by functional magnetic resonance imaging (fMRI) can be an effective metric for intersubject calibration procedures. However, inconsistency in the depth of inspiration during the BH scan may account for a portion of BOLD variation observed in such scans, and it is likely to reduce the effectiveness of the calibration measurement. While modulation of BOLD signal has been correlated with end-tidal CO2 and other measures of breathing, fluctuations in performance of BH have not been studied in the context of their impact on BOLD signal. Here, we studied the degree to which inspiration depth corresponds to BOLD signal change and tested the effectiveness of a method designed to control inspiration level through visual cues during the BH task paradigm. We observed reliable differences in BOLD signal amplitude corresponding to the depth of inspiration. It was determined that variance in BOLD signal response to BH could be significantly reduced when subjects were given visual feedback during task inspiration periods. The implications of these findings for routine BH studies of BOLD-derived neurovascular response are discussed.

  8. Tactile and non-tactile sensory paradigms for fMRI and neurophysiologic studies in rodents

    OpenAIRE

    Sanganahalli, Basavaraju G.; Bailey, Christopher J.; Herman, Peter; Hyder, Fahmeed

    2009-01-01

    Functional magnetic resonance imaging (fMRI) has become a popular functional imaging tool for human studies. Future diagnostic use of fMRI depends, however, on a suitable neurophysiologic interpretation of the blood oxygenation level dependent (BOLD) signal change. This particular goal is best achieved in animal models primarily due to the invasive nature of other methods used and/or pharmacological agents applied to probe different nuances of neuronal (and glial) activity coupled to the BOLD...

  9. Identifying and characterizing systematic temporally-lagged BOLD artifacts.

    Science.gov (United States)

    Byrge, Lisa; Kennedy, Daniel P

    2018-05-01

    Residual noise in the BOLD signal remains problematic for fMRI - particularly for techniques such as functional connectivity, where findings can be spuriously influenced by noise sources that can covary with individual differences. Many such potential noise sources - for instance, motion and respiration - can have a temporally lagged effect on the BOLD signal. Thus, here we present a tool for assessing residual lagged structure in the BOLD signal that is associated with nuisance signals, using a construction similar to a peri-event time histogram. Using this method, we find that framewise displacements - both large and very small - were followed by structured, prolonged, and global changes in the BOLD signal that depend on the magnitude of the preceding displacement and extend for tens of seconds. This residual lagged BOLD structure was consistent across datasets, and independently predicted considerable variance in the global cortical signal (as much as 30-40% in some subjects). Mean functional connectivity estimates varied similarly as a function of displacements occurring many seconds in the past, even after strict censoring. Similar patterns of residual lagged BOLD structure were apparent following respiratory fluctuations (which covaried with framewise displacements), implicating respiration as one likely mechanism underlying the displacement-linked structure observed. Global signal regression largely attenuates this artifactual structure. These findings suggest the need for caution in interpreting results of individual difference studies where noise sources might covary with the individual differences of interest, and highlight the need for further development of preprocessing techniques for mitigating such structure in a more nuanced and targeted manner. Copyright © 2018 Elsevier Inc. All rights reserved.

  10. Noninvasive fMRI investigation of interaural level difference processing in the rat auditory subcortex.

    Directory of Open Access Journals (Sweden)

    Condon Lau

    Full Text Available OBJECTIVE: Interaural level difference (ILD is the difference in sound pressure level (SPL between the two ears and is one of the key physical cues used by the auditory system in sound localization. Our current understanding of ILD encoding has come primarily from invasive studies of individual structures, which have implicated subcortical structures such as the cochlear nucleus (CN, superior olivary complex (SOC, lateral lemniscus (LL, and inferior colliculus (IC. Noninvasive brain imaging enables studying ILD processing in multiple structures simultaneously. METHODS: In this study, blood oxygenation level-dependent (BOLD functional magnetic resonance imaging (fMRI is used for the first time to measure changes in the hemodynamic responses in the adult Sprague-Dawley rat subcortex during binaural stimulation with different ILDs. RESULTS AND SIGNIFICANCE: Consistent responses are observed in the CN, SOC, LL, and IC in both hemispheres. Voxel-by-voxel analysis of the change of the response amplitude with ILD indicates statistically significant ILD dependence in dorsal LL, IC, and a region containing parts of the SOC and LL. For all three regions, the larger amplitude response is located in the hemisphere contralateral from the higher SPL stimulus. These findings are supported by region of interest analysis. fMRI shows that ILD dependence occurs in both hemispheres and multiple subcortical levels of the auditory system. This study is the first step towards future studies examining subcortical binaural processing and sound localization in animal models of hearing.

  11. A Mixed L2 Norm Regularized HRF Estimation Method for Rapid Event-Related fMRI Experiments

    Directory of Open Access Journals (Sweden)

    Yu Lei

    2013-01-01

    Full Text Available Brain state decoding or “mind reading” via multivoxel pattern analysis (MVPA has become a popular focus of functional magnetic resonance imaging (fMRI studies. In brain decoding, stimulus presentation rate is increased as fast as possible to collect many training samples and obtain an effective and reliable classifier or computational model. However, for extremely rapid event-related experiments, the blood-oxygen-level-dependent (BOLD signals evoked by adjacent trials are heavily overlapped in the time domain. Thus, identifying trial-specific BOLD responses is difficult. In addition, voxel-specific hemodynamic response function (HRF, which is useful in MVPA, should be used in estimation to decrease the loss of weak information across voxels and obtain fine-grained spatial information. Regularization methods have been widely used to increase the efficiency of HRF estimates. In this study, we propose a regularization framework called mixed L2 norm regularization. This framework involves Tikhonov regularization and an additional L2 norm regularization term to calculate reliable HRF estimates. This technique improves the accuracy of HRF estimates and significantly increases the classification accuracy of the brain decoding task when applied to a rapid event-related four-category object classification experiment. At last, some essential issues such as the impact of low-frequency fluctuation (LFF and the influence of smoothing are discussed for rapid event-related experiments.

  12. Evidence that neurovascular coupling underlying the BOLD effect increases with age during childhood.

    Science.gov (United States)

    Schmithorst, Vincent J; Vannest, Jennifer; Lee, Gregory; Hernandez-Garcia, Luis; Plante, Elena; Rajagopal, Akila; Holland, Scott K

    2015-01-01

    Functional MRI using blood-oxygen-level-dependent (BOLD) imaging has provided unprecedented insights into the maturation of the human brain. Task-based fMRI studies have shown BOLD signal increases with age during development (ages 5-18) for many cognitive domains such as language and executive function, while functional connectivity (resting-state) fMRI studies investigating regionally synchronous BOLD fluctuations have revealed a developing functional organization of the brain from a local into a more distributed architecture. However, interpretation of these results is confounded by the fact that the BOLD signal is directly related to blood oxygenation driven by changes in blood flow and only indirectly related to neuronal activity, and may thus be affected by changing neuronal-vascular coupling. BOLD signal and cerebral blood flow (CBF) were measured simultaneously in a cohort of 113 typically developing awake participants ages 3-18 performing a narrative comprehension task. Using a novel voxelwise wild bootstrap analysis technique, an increased ratio of BOLD signal to relative CBF signal change with age (indicative of increased neuronal-vascular coupling) was seen in the middle temporal gyri and the left inferior frontal gyrus. Additionally, evidence of decreased relative oxygen metabolism (indicative of decreased neuronal activity) with age was found in the same regions. These findings raise concern that results of developmental BOLD studies cannot be unambiguously attributed to neuronal activity. Astrocytes and astrocytic processes may significantly affect the maturing functional architecture of the brain, consistent with recent research demonstrating a key role for astrocytes in mediating increased CBF following neuronal activity and for astrocyte processes in modulating synaptic connectivity. © 2014 Wiley Periodicals, Inc.

  13. Latencies in BOLD response during visual attention processes.

    Science.gov (United States)

    Kellermann, Thilo; Reske, Martina; Jansen, Andreas; Satrapi, Peyman; Shah, N Jon; Schneider, Frank; Habel, Ute

    2011-04-22

    One well-investigated division of attentional processes focuses on alerting, orienting and executive control, which can be assessed applying the attentional network test (ANT). The goal of the present study was to add further knowledge about the temporal dynamics of relevant neural correlates. As a right hemispheric dominance for alerting and orienting has previously been reported for intrinsic but not for phasic alertness, we additionally addressed a potential impact of this lateralization of attention by employing a lateralized version of the ANT, capturing phasic alertness processes. Sixteen healthy subjects underwent event-related functional magnetic resonance imaging (fMRI) while performing the ANT. Analyses of BOLD magnitude replicated the engagement of a fronto-parietal network in the attentional subsystems. The amplitudes of the attentional contrasts interacted with visual field presentation in the sense that the thalamus revealed a greater involvement for spatially cued items presented in the left visual field. Comparisons of BOLD latencies in visual cortices, first, verified faster BOLD responses following contra-lateral stimulus presentation. Second and more importantly, we identified attention-modulated activation in secondary visual and anterior cingulate cortices. Results are discussed in terms of bottom-up and lateralization processes. Although intrinsic and phasic alertness are distinct cognitive processes, we propose that neural substrates of intrinsic alertness may be accessed by phasic alertness provided that the attention-dominant (i.e., the right) hemisphere is activated directly by a warning stimulus. Copyright © 2011 Elsevier B.V. All rights reserved.

  14. BOLD delay times using group delay in sickle cell disease

    Science.gov (United States)

    Coloigner, Julie; Vu, Chau; Bush, Adam; Borzage, Matt; Rajagopalan, Vidya; Lepore, Natasha; Wood, John

    2016-03-01

    Sickle cell disease (SCD) is an inherited blood disorder that effects red blood cells, which can lead to vasoocclusion, ischemia and infarct. This disease often results in neurological damage and strokes, leading to morbidity and mortality. Functional Magnetic Resonance Imaging (fMRI) is a non-invasive technique for measuring and mapping the brain activity. Blood Oxygenation Level-Dependent (BOLD) signals contain also information about the neurovascular coupling, vascular reactivity, oxygenation and blood propagation. Temporal relationship between BOLD fluctuations in different parts of the brain provides also a mean to investigate the blood delay information. We used the induced desaturation as a label to profile transit times through different brain areas, reflecting oxygen utilization of tissue. In this study, we aimed to compare blood flow propagation delay times between these patients and healthy subjects in areas vascularized by anterior, middle and posterior cerebral arteries. In a group comparison analysis with control subjects, BOLD changes in these areas were found to be almost simultaneous and shorter in the SCD patients, because of their increased brain blood flow. Secondly, the analysis of a patient with a stenosis on the anterior cerebral artery indicated that signal of the area vascularized by this artery lagged the MCA signal. These findings suggest that sickle cell disease causes blood propagation modifications, and that these changes could be used as a biomarker of vascular damage.

  15. Advantages and disadvantages of a fast fMRI sequence in the context of EEG-fMRI investigation of epilepsy patients: A realistic simulation study.

    Science.gov (United States)

    Safi-Harb, Mouna; Proulx, Sébastien; von Ellenrieder, Nicolas; Gotman, Jean

    2015-10-01

    EEG-fMRI is an established technique to allow mapping BOLD changes in response to interictal discharges recorded in the EEG of epilepsy patients. Traditional fMRI experiments rely on an echo planar imaging (EPI) sequence with a time resolution given by its time-to-repetition (TR) of ~2 s. Recently, multiple fast fMRI sequences have been developed to get around the limited temporal resolution of the EPI sequence, and achieved a TR in the 100 ms range or lower. One such sequence is called Magnetic Resonance EncephaloGraphy (MREG). Its high temporal resolution should offer increased detection sensitivity and statistical power in the context of epilepsy studies and in fMRI experiments in general. The aim of this work was to investigate the advantages and disadvantages offered by MREG. This was done by superimposing artificial event-related BOLD responses on EPI and MREG background signals, from 5 epileptic patients, that were free of epileptic discharges (spikes) on simultaneously recorded EEG. These functional datasets simulated different spiking rates and hemodynamic response amplitudes, and were analyzed with the commonly used General Linear Model (GLM) with the canonical hemodynamic response function (HRF) as a fixed model of the response. Robustness to violation of the assumptions of the GLM was additionally assessed with similar simulations using variable spike-to-spike response amplitudes and 8 non-canonical HRFs. Consistent with previous work, MREG yields higher maximum statistical t-values than EPI, but our simulations showed these statistics to be inflated, as the false positive rate at a standard threshold was high. At thresholds set to appropriately control specificity, EPI showed better true positive rate and larger cluster size than MREG. However, the lack of an appropriate calibration of the amplitude of the responses across the sequences precludes definitive judgment on their relative sensitivity. In addition, we show that a mismatch between the assumed

  16. Fast joint detection-estimation of evoked brain activity in event-related FMRI using a variational approach

    Science.gov (United States)

    Chaari, Lotfi; Vincent, Thomas; Forbes, Florence; Dojat, Michel; Ciuciu, Philippe

    2013-01-01

    In standard within-subject analyses of event-related fMRI data, two steps are usually performed separately: detection of brain activity and estimation of the hemodynamic response. Because these two steps are inherently linked, we adopt the so-called region-based Joint Detection-Estimation (JDE) framework that addresses this joint issue using a multivariate inference for detection and estimation. JDE is built by making use of a regional bilinear generative model of the BOLD response and constraining the parameter estimation by physiological priors using temporal and spatial information in a Markovian model. In contrast to previous works that use Markov Chain Monte Carlo (MCMC) techniques to sample the resulting intractable posterior distribution, we recast the JDE into a missing data framework and derive a Variational Expectation-Maximization (VEM) algorithm for its inference. A variational approximation is used to approximate the Markovian model in the unsupervised spatially adaptive JDE inference, which allows automatic fine-tuning of spatial regularization parameters. It provides a new algorithm that exhibits interesting properties in terms of estimation error and computational cost compared to the previously used MCMC-based approach. Experiments on artificial and real data show that VEM-JDE is robust to model mis-specification and provides computational gain while maintaining good performance in terms of activation detection and hemodynamic shape recovery. PMID:23096056

  17. Negative BOLD signal changes in ipsilateral primary somatosensory cortex are associated with perfusion decreases and behavioral evidence for functional inhibition

    DEFF Research Database (Denmark)

    Schäfer, Katharina; Blankenburg, Felix; Kupers, Ron

    2012-01-01

    We used functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) to study the negative blood oxygenation level dependent (BOLD) signal and its underlying blood flow changes in healthy human subjects. This was combined with psychophysiological measurements to test that t...

  18. Effective Connectivity of Cortical Sensorimotor Networks During Finger Movement Tasks: A Simultaneous fNIRS, fMRI, EEG Study.

    Science.gov (United States)

    Anwar, A R; Muthalib, M; Perrey, S; Galka, A; Granert, O; Wolff, S; Heute, U; Deuschl, G; Raethjen, J; Muthuraman, Muthuraman

    2016-09-01

    Recently, interest has been growing to understand the underlying dynamic directional relationship between simultaneously activated regions of the brain during motor task performance. Such directionality analysis (or effective connectivity analysis), based on non-invasive electrophysiological (electroencephalography-EEG) and hemodynamic (functional near infrared spectroscopy-fNIRS; and functional magnetic resonance imaging-fMRI) neuroimaging modalities can provide an estimate of the motor task-related information flow from one brain region to another. Since EEG, fNIRS and fMRI modalities achieve different spatial and temporal resolutions of motor-task related activation in the brain, the aim of this study was to determine the effective connectivity of cortico-cortical sensorimotor networks during finger movement tasks measured by each neuroimaging modality. Nine healthy subjects performed right hand finger movement tasks of different complexity (simple finger tapping-FT, simple finger sequence-SFS, and complex finger sequence-CFS). We focused our observations on three cortical regions of interest (ROIs), namely the contralateral sensorimotor cortex (SMC), the contralateral premotor cortex (PMC) and the contralateral dorsolateral prefrontal cortex (DLPFC). We estimated the effective connectivity between these ROIs using conditional Granger causality (GC) analysis determined from the time series signals measured by fMRI (blood oxygenation level-dependent-BOLD), fNIRS (oxygenated-O2Hb and deoxygenated-HHb hemoglobin), and EEG (scalp and source level analysis) neuroimaging modalities. The effective connectivity analysis showed significant bi-directional information flow between the SMC, PMC, and DLPFC as determined by the EEG (scalp and source), fMRI (BOLD) and fNIRS (O2Hb and HHb) modalities for all three motor tasks. However the source level EEG GC values were significantly greater than the other modalities. In addition, only the source level EEG showed a

  19. Negative BOLD response and serotonin concentration within rostral subgenual portion of the anterior cingulate cortex for long-allele carriers during perceptual processing of emotional tasks

    Science.gov (United States)

    Hadi, Shamil M.; Siadat, Mohamad R.; Babajani-Feremi, Abbas

    2012-03-01

    We investigated the effect of synaptic serotonin concentration on hemodynamic responses. The stimuli paradigm involved the presentation of fearful and threatening facial expressions to a set of 24 subjects who were either5HTTLPR long- or short-allele carriers (12 of each type in each group). The BOLD signals of the rACC from subjects of each group were averaged to increase the signal-to-noise ratio. We used a Bayesian approach to estimate the parameters of the underlying hemodynamic model. Our results, during this perceptual processing of emotional task, showed a negative BOLD signal in the rACC in the subjects with long-alleles. In contrast, the subjects with short-alleles showed positive BOLD signals in the rACC. These results suggest that high synaptic serotonin concentration in the rACC inhibits neuronal activity in a fashion similar to GABA, and a consequent negative BOLD signal ensues.

  20. Luminance contrast of a visual stimulus modulates the BOLD response more than the cerebral blood flow response in the human brain

    OpenAIRE

    Liang, Christine L.; Ances, Beau M.; Perthen, Joanna E.; Moradi, Farshad; Liau, Joy; Buracas, Giedrius T.; Hopkins, Susan R.; Buxton, Richard B.

    2012-01-01

    The blood oxygenation level dependent (BOLD) response measured with functional magnetic resonance imaging (fMRI) depends on the evoked changes in cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2) in response to changes in neural activity. This response is strongly modulated by the CBF/CMRO2 coupling relationship with activation, defined as n, the ratio of the fractional changes. The reliability of the BOLD signal as a quantitative reflection of underlying physiological c...

  1. Co-localization between the BOLD response and epileptiform discharges recorded by simultaneous intracranial EEG-fMRI at 3 T

    Directory of Open Access Journals (Sweden)

    Yahya Aghakhani

    2015-01-01

    Conclusions: iEEG-fMRI is a feasible and low-risk method for assessment of hemodynamic changes of very focal IEDs that may not be recorded by scalp EEG. A high concordance rate between the location of the BOLD response and IEDs was seen for mesial temporal (6/7 IEDs. Significant BOLD activation was also seen in areas distant from the active electrode and these sites exhibited maximal BOLD activation in the majority of cases. This implies that iEEG-fMRI may further describe the areas involved in the generation of IEDs beyond the vicinity of the electrode(s.

  2. Optimal experimental designs for fMRI via circulant biased weighing designs

    OpenAIRE

    Cheng, Ching-Shui; Kao, Ming-Hung

    2015-01-01

    Functional magnetic resonance imaging (fMRI) technology is popularly used in many fields for studying how the brain reacts to mental stimuli. The identification of optimal fMRI experimental designs is crucial for rendering precise statistical inference on brain functions, but research on this topic is very lacking. We develop a general theory to guide the selection of fMRI designs for estimating a hemodynamic response function (HRF) that models the effect over time of the mental stimulus, and...

  3. "Extreme Bold" in the Faculty Ranks

    Science.gov (United States)

    Kuusisto, Stephen

    2013-01-01

    Boldness, defense, and the necessity of talking back remain as central to life with disability in one's time as in Francis Bacon's age. "Therefore all deformed persons are extreme bold," Bacon wrote, "first, as in their own defence, as being exposed to scorn, but in process of time, by a general habit." Perhaps no word carries…

  4. fMRI. Basics and clinical applications. 2. ed.

    Energy Technology Data Exchange (ETDEWEB)

    Ulmer, Stephan [Medizinisch Radiologisces Institut (MRI), Zuerich (Switzerland); Universitaetsklinikum Schleswig-Holstein, Kiel (Germany). Inst. fuer Neuroradiologie; Jansen, Olav (eds.) [Universitaetsklinikum Schleswig-Holstein, Kiel (Germany). Inst. fuer Neuroradiologie

    2013-11-01

    State of the art overview of fMRI. Covers technical issues, methods of statistical analysis, and the full range of clinical applications. Revised and expanded edition including discussion of novel aspects of analysis and further important applications. Includes comparisons with other brain mapping techniques and discussion of potential combined uses. Since functional MRI (fMRI) and the basic method of BOLD imaging were introduced in 1993 by Seiji Ogawa, fMRI has evolved into an invaluable clinical tool for routine brain imaging, and there have been substantial improvements in both the imaging technique itself and the associated statistical analysis. This book provides a state of the art overview of fMRI and its use in clinical practice. Experts in the field share their knowledge and explain how to overcome diverse potential technical barriers and problems. Starting from the very basics on the origin of the BOLD signal, the book covers technical issues, anatomical landmarks, the full range of clinical applications, methods of statistical analysis, and special issues in various clinical fields. Comparisons are made with other brain mapping techniques, such as DTI, PET, TMS, EEG, and MEG, and their combined use with fMRI is also discussed. Since the first edition, original chapters have been updated and new chapters added, covering both novel aspects of analysis and further important clinical applications.

  5. Luminance contrast of a visual stimulus modulates the BOLD response more than the cerebral blood flow response in the human brain.

    Science.gov (United States)

    Liang, Christine L; Ances, Beau M; Perthen, Joanna E; Moradi, Farshad; Liau, Joy; Buracas, Giedrius T; Hopkins, Susan R; Buxton, Richard B

    2013-01-01

    The blood oxygenation level dependent (BOLD) response measured with functional magnetic resonance imaging (fMRI) depends on the evoked changes in cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO(2)) in response to changes in neural activity. This response is strongly modulated by the CBF/CMRO(2) coupling relationship with activation, defined as n, the ratio of the fractional changes. The reliability of the BOLD signal as a quantitative reflection of underlying physiological changes depends on the stability of n in response to different stimuli. The effect of visual stimulus contrast on this coupling ratio was tested in 9 healthy human subjects, measuring CBF and BOLD responses to a flickering checkerboard at four visual contrast levels. The theory of the BOLD effect makes a robust prediction-independent of details of the model-that if the CBF/CMRO(2) coupling ratio n remains constant, then the response ratio between the lowest and highest contrast levels should be higher for the BOLD response than the CBF response because of the ceiling effect on the BOLD response. Instead, this response ratio was significantly lower for the BOLD response (BOLD response: 0.23 ± 0.13, mean ± SD; CBF response: 0.42 ± 0.18; p=0.0054). This data is consistent with a reduced dynamic range (strongest/weakest response ratio) of the CMRO(2) response (~1.7-fold) compared to that of the CBF response (~2.4-fold) as luminance contrast increases, corresponding to an increase of n from 1.7 at the lowest contrast level to 2.3 at the highest contrast level. The implication of these results for fMRI studies is that the magnitude of the BOLD response does not accurately reflect the magnitude of underlying physiological processes. Copyright © 2012 Elsevier Inc. All rights reserved.

  6. Developmental changes of BOLD signal correlations with global human EEG power and synchronization during working memory.

    Directory of Open Access Journals (Sweden)

    Lars Michels

    Full Text Available In humans, theta band (5-7 Hz power typically increases when performing cognitively demanding working memory (WM tasks, and simultaneous EEG-fMRI recordings have revealed an inverse relationship between theta power and the BOLD (blood oxygen level dependent signal in the default mode network during WM. However, synchronization also plays a fundamental role in cognitive processing, and the level of theta and higher frequency band synchronization is modulated during WM. Yet, little is known about the link between BOLD, EEG power, and EEG synchronization during WM, and how these measures develop with human brain maturation or relate to behavioral changes. We examined EEG-BOLD signal correlations from 18 young adults and 15 school-aged children for age-dependent effects during a load-modulated Sternberg WM task. Frontal load (in-dependent EEG theta power was significantly enhanced in children compared to adults, while adults showed stronger fMRI load effects. Children demonstrated a stronger negative correlation between global theta power and the BOLD signal in the default mode network relative to adults. Therefore, we conclude that theta power mediates the suppression of a task-irrelevant network. We further conclude that children suppress this network even more than adults, probably from an increased level of task-preparedness to compensate for not fully mature cognitive functions, reflected in lower response accuracy and increased reaction time. In contrast to power, correlations between instantaneous theta global field synchronization and the BOLD signal were exclusively positive in both age groups but only significant in adults in the frontal-parietal and posterior cingulate cortices. Furthermore, theta synchronization was weaker in children and was--in contrast to EEG power--positively correlated with response accuracy in both age groups. In summary we conclude that theta EEG-BOLD signal correlations differ between spectral power and

  7. Test-retest reliability of longitudinal task-based fMRI: Implications for developmental studies.

    Science.gov (United States)

    Herting, Megan M; Gautam, Prapti; Chen, Zhanghua; Mezher, Adam; Vetter, Nora C

    2017-07-13

    Great advances have been made in functional Magnetic Resonance Imaging (fMRI) studies, including the use of longitudinal design to more accurately identify changes in brain development across childhood and adolescence. While longitudinal fMRI studies are necessary for our understanding of typical and atypical patterns of brain development, the variability observed in fMRI blood-oxygen-level dependent (BOLD) signal and its test-retest reliability in developing populations remain a concern. Here we review the current state of test-retest reliability for child and adolescent fMRI studies (ages 5-18 years) as indexed by intraclass correlation coefficients (ICC). In addition to highlighting ways to improve fMRI test-retest reliability in developmental cognitive neuroscience research, we hope to open a platform for dialogue regarding longitudinal fMRI study designs, analyses, and reporting of results. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  8. Concordance of Epileptic Networks Associated with Epileptic Spikes Measured by High-Density EEG and Fast fMRI.

    Directory of Open Access Journals (Sweden)

    Vera Jäger

    Full Text Available The present study aims to investigate whether a newly developed fast fMRI called MREG (magnetic resonance encephalography measures metabolic changes related to interictal epileptic discharges (IED. For this purpose BOLD changes are correlated with the IED distribution and variability.Patients with focal epilepsy underwent EEG-MREG using a 64 channel cap. IED voltage maps were generated using 32 and 64 channels and compared regarding their correspondence to the BOLD response. The extents of IEDs (defined as number of channels with >50% of maximum IED negativity were correlated with the extents of positive and negative BOLD responses. Differences in inter-spike variability were investigated between interictal epileptic discharges (IED sets with and without concordant positive or negative BOLD responses.17 patients showed 32 separate IED types. In 50% of IED types the BOLD changes could be confirmed by another independent imaging method. The IED extent significantly correlated with the positive BOLD extent (p = 0.04. In 6 patients the 64-channel EEG voltage maps better reflected the positive or negative BOLD response than the 32-channel EEG; in all others no difference was seen. Inter-spike variability was significantly lower in IED sets with than without concordant positive or negative BOLD responses (with p = 0.04.Higher density EEG and fast fMRI seem to improve the value of EEG-fMRI in epilepsy. The correlation of positive BOLD and IED extent could suggest that widespread BOLD responses reflect the IED network. Inter-spike variability influences the likelihood to find IED concordant positive or negative BOLD responses, which is why single IED analysis may be promising.

  9. Resting BOLD fluctuations in the primary somatosensory cortex correlate with tactile acuity.

    Science.gov (United States)

    Haag, Lauren M; Heba, Stefanie; Lenz, Melanie; Glaubitz, Benjamin; Höffken, Oliver; Kalisch, Tobias; Puts, Nicholaas A; Edden, Richard A E; Tegenthoff, Martin; Dinse, Hubert; Schmidt-Wilcke, Tobias

    2015-03-01

    Sensory perception, including 2-point discrimination (2 ptD), is tightly linked to cortical processing of tactile stimuli in primary somatosensory cortices. While the role of cortical activity in response to a tactile stimulus has been widely investigated, the role of baseline cortical activity is largely unknown. Using resting state fMRI we investigated the relationship between local BOLD fluctuations in the primary somatosensory cortex (the representational field of the hand) and 2 ptD of the corresponding index finger (right and left). Cortical activity was measured using fractional amplitudes of the low frequency BOLD fluctuations (fALFF) and synchronicity using regional homogeneity (ReHo) of the S1 hand region during rest. 2 ptD correlated with higher ReHo values in the representational areas of the contralateral S1 cortex (left hand: p = .028; right hand: p = .049). 2 ptD additionally correlated with higher fALFF in the representational area of the left hand (p = .007) and showed a trend for a significant correlation in the representational area of the right hand (p = .051). Thus, higher BOLD amplitudes and synchronicity at rest, as measures of cortical activity and synchronicity, respectively, are related to better tactile discrimination abilities of the contralateral hand. Our findings extend the relationship seen between spontaneous BOLD fluctuations and sensory perception. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Dorsal root ganglion stimulation attenuates the BOLD signal response to noxious sensory input in specific brain regions: Insights into a possible mechanism for analgesia.

    Science.gov (United States)

    Pawela, Christopher P; Kramer, Jeffery M; Hogan, Quinn H

    2017-02-15

    Targeted dorsal root ganglion (DRG) electrical stimulation (i.e. ganglionic field stimulation - GFS) is an emerging therapeutic approach to alleviate chronic pain. Here we describe blood oxygen-level dependent (BOLD) functional magnetic resonance imaging (fMRI) responses to noxious hind-limb stimulation in a rat model that replicates clinical GFS using an electrode implanted adjacent to the DRG. Acute noxious sensory stimulation in the absence of GFS caused robust BOLD fMRI response in brain regions previously associated with sensory and pain-related response, such as primary/secondary somatosensory cortex, retrosplenial granular cortex, thalamus, caudate putamen, nucleus accumbens, globus pallidus, and amygdala. These regions differentially demonstrated either positive or negative correlation to the acute noxious stimulation paradigm, in agreement with previous rat fMRI studies. Therapeutic-level GFS significantly attenuated the global BOLD response to noxious stimulation in these regions. This BOLD signal attenuation persisted for 20minutes after the GFS was discontinued. Control experiments in sham-operated animals showed that the attenuation was not due to the effect of repetitive noxious stimulation. Additional control experiments also revealed minimal BOLD fMRI response to GFS at therapeutic intensity when presented in a standard block-design paradigm. High intensity GFS produced a BOLD signal map similar to acute noxious stimulation when presented in a block-design. These findings are the first to identify the specific brain region responses to neuromodulation at the DRG level and suggest possible mechanisms for GFS-induced treatment of chronic pain. Copyright © 2016 Elsevier Inc. All rights reserved.

  11. Disentangling resting-state BOLD variability and PCC functional connectivity in 22q11.2 deletion syndrome.

    Science.gov (United States)

    Zöller, Daniela; Schaer, Marie; Scariati, Elisa; Padula, Maria Carmela; Eliez, Stephan; Van De Ville, Dimitri

    2017-04-01

    Although often ignored in fMRI studies, moment-to-moment variability of blood oxygenation level dependent (BOLD) signals reveals important information about brain function. Indeed, higher brain signal variability has been associated with better cognitive performance in young adults compared to children and elderly adults. Functional connectivity, a very common approach in resting-state fMRI analysis, is scaled for variance. Thus, alterations might be confounded or driven by BOLD signal variance alterations. Chromosome 22q11.2 deletion syndrome (22q11.2DS) is a neurodevelopmental disorder that is associated with a vast cognitive and clinical phenotype. To date, several resting-state fMRI studies reported altered functional connectivity in 22q11.2DS, however BOLD signal variance has not yet been analyzed. Here, we employed PLS correlation analysis to reveal multivariate patterns of diagnosis-related alterations and age-relationship throughout the cortex of 50 patients between 9 and 25 years old and 50 healthy controls in the same age range. To address how functional connectivity in the default mode network is influenced by BOLD signal fluctuations, we conducted the same analysis on seed-to-voxel connectivity of the posterior cingulate cortex (PCC) and compared resulting brain patterns. BOLD signal variance was lower mainly in regions of the default mode network and in the dorsolateral prefrontal cortex, but higher in large parts of the temporal lobes. In those regions, BOLD signal variance was correlated with age in healthy controls, but not in patients, suggesting deviant developmental trajectories from child- to adulthood. Positive connectivity of the PCC within the default mode network as well as negative connectivity towards the frontoparietal network were weaker in patients with 22q11.2DS. We furthermore showed that lower functional connectivity of the PCC was not driven by higher BOLD signal variability. Our results confirm the strong implication of BOLD

  12. Non-white noise in fMRI: Does modelling have an impact?

    DEFF Research Database (Denmark)

    Lund, Torben Ellegaard; Madsen, Kristoffer Hougaard; Sidaros, Karam

    2006-01-01

    The sources of non-white noise in Blood Oxygenation Level Dependent (BOLD) functional magnetic resonance imaging (fMRI) are many. Familiar sources include low-frequency drift due to hardware imperfections, oscillatory noise due to respiration and cardiac pulsation and residual movement artefacts ...

  13. Distinct BOLD activation profiles following central and peripheral oxytocin administration in awake rats

    Directory of Open Access Journals (Sweden)

    Craig F Ferris

    2015-09-01

    Full Text Available A growing body of literature has suggested that intranasal oxytocin (OT or other systemic routes of administration can alter prosocial behavior, presumably by directly activating OT sensitive neural circuits in the brain. Yet there is no clear evidence that OT given peripherally can cross the blood-brain-barrier at levels sufficient to engage the OT receptor. To address this issue we examined changes in blood oxygen level dependent (BOLD signal intensity in response to peripheral OT injections (0.1, 0.5 or 2.5 mg/kg during functional magnetic resonance (fMRI in awake rats imaged at 7.0 tesla. These data were compared to OT (1ug/5 µl given directly to the brain via the lateral cerebroventricle. Using a 3D annotated MRI atlas of the rat brain segmented into 171 brain areas and computational analysis we reconstructed the distributed integrated neural circuits identified with BOLD fMRI following central and peripheral OT. Both routes of administration caused significant changes in BOLD signal within the first 10 min of administration. As expected, central OT activated a majority of brain areas known to express a high density of OT receptors e.g., lateral septum, subiculum, shell of the accumbens, bed nucleus of the stria terminalis. This profile of activation was not matched by peripheral OT. The change in BOLD signal to peripheral OT did not show any discernible dose-response. Interestingly, peripheral OT affected all subdivisions of the olfactory bulb, in addition to the cerebellum and several brainstem areas relevant to the autonomic nervous system, including the solitary tract nucleus. The results from this imaging study do not support a direct central action of peripheral OT on the brain. Instead, the patterns of brain activity suggest that peripheral OT may interact at the level of the olfactory bulb and through sensory afferents from the autonomic nervous system to influence brain activity.

  14. Unsupervised Myocardial Segmentation for Cardiac BOLD.

    Science.gov (United States)

    Oksuz, Ilkay; Mukhopadhyay, Anirban; Dharmakumar, Rohan; Tsaftaris, Sotirios A

    2017-11-01

    A fully automated 2-D+time myocardial segmentation framework is proposed for cardiac magnetic resonance (CMR) blood-oxygen-level-dependent (BOLD) data sets. Ischemia detection with CINE BOLD CMR relies on spatio-temporal patterns in myocardial intensity, but these patterns also trouble supervised segmentation methods, the de facto standard for myocardial segmentation in cine MRI. Segmentation errors severely undermine the accurate extraction of these patterns. In this paper, we build a joint motion and appearance method that relies on dictionary learning to find a suitable subspace. Our method is based on variational pre-processing and spatial regularization using Markov random fields, to further improve performance. The superiority of the proposed segmentation technique is demonstrated on a data set containing cardiac phase-resolved BOLD MR and standard CINE MR image sequences acquired in baseline and ischemic condition across ten canine subjects. Our unsupervised approach outperforms even supervised state-of-the-art segmentation techniques by at least 10% when using Dice to measure accuracy on BOLD data and performs at par for standard CINE MR. Furthermore, a novel segmental analysis method attuned for BOLD time series is utilized to demonstrate the effectiveness of the proposed method in preserving key BOLD patterns.

  15. Impact of Global Normalization in fMRI Acupuncture Studies

    Directory of Open Access Journals (Sweden)

    Jinbo Sun

    2012-01-01

    Full Text Available Global normalization is often used as a preprocessing step for dispelling the “nuisance effects.” However, it has been shown in cognitive and emotion tasks that this preprocessing step might greatly distort statistical results when the orthogonality assumption of global normalization is violated. The present study examines this issue in fMRI acupuncture studies. Thirty healthy subjects were recruited to evaluate the impacts of the global normalization on the BOLD responses evoked by acupuncture stimulation during De-qi sensation and tactile stimulation during nonpainful sensations. To this end, we compared results by conducting global normalization (PSGS and not conducting global normalization (NO PSGS based on a proportional scaling model. The orthogonality assumption of global normalization was violated, and significant changes between BOLD responses for NO PSGS and PSGS were shown in most subjects. Extensive deactivations of acupuncture in fMRI were the non-specifically pernicious consequences of global normalization. The central responses of acupuncture during De-qi are non-specifically activation-dominant at the somatosensory-related brain network, whose statistical power is specifically enhanced by PSGS. In conclusion, PSGS should be unjustified for acupuncture studies in fMRI. The differences including the global normalization or not may partly contribute to conflicting results and interpretations in previous fMRI acupuncture studies.

  16. Occupational exposure in hemodynamic

    International Nuclear Information System (INIS)

    Silva, Amanda J.; Fernandes, Ivani M.; Silva, Paula P. Nou; Sordi, Gian Maria A.A.; Carneiro, Janete C.G.G.

    2011-01-01

    This paper has an objective to perform a radiometric survey at a hemodynamic service. Besides, it was intended to evaluate the effective dose of health professionals and to provide data which can contribute with minimization of exposures during the realization of hemodynamic procedure. The radiometric survey was realized in the real environment of work simulating the conditions of a hemodynamic study with a ionization chamber

  17. Effects of age on negative BOLD signal changes in the primary somatosensory cortex.

    Science.gov (United States)

    Gröschel, Sonja; Sohns, Jan Martin; Schmidt-Samoa, Carsten; Baudewig, Jürgen; Becker, Lars; Dechent, Peter; Kastrup, Andreas

    2013-05-01

    In addition to a contralateral activation of the primary and secondary somatosensory cortices, peripheral sensory stimulation has been shown to elicit responses in the ipsilateral primary somatosensory cortex (SI). In particular, evidence is accumulating that processes of interhemispheric inhibition as depicted by negative blood oxygenation level dependent (BOLD) signal changes are part of somatosensory processes. The aim of the study was to analyze age-related differences in patterns of cerebral activation in the somatosensory system in general and processes of interhemispheric inhibition in particular. For this, a functional magnetic resonance imaging (fMRI) study was performed including 14 younger (mean age 23.3±0.9years) and 13 healthy older participants (mean age 73.2±8.3years). All subjects were scanned during peripheral electrical median nerve stimulation (40Hz) to obtain BOLD responses in the somatosensory system. Moreover, the individual current perception threshold (CPT) as a quantitative measure of sensory function was determined in a separate psychophysical testing. Significant increases in BOLD signal across the entire group could be measured within the contralateral SI, in the bilateral secondary somatosensory cortex (SII), the contralateral supplementary motor area and the insula. Negative BOLD signal changes were delineated in ipsilateral SI/MI as well as in the ipsilateral thalamus and basal ganglia. After comparing the two groups, only the cortical deactivation in ipsilateral SI in the early stimulation phase as well as the activation in contralateral SI and SII in the late stimulation block remained as statistically significant differences between the two groups. The psychophysical experiments yielded a significant age-dependent effect of CPT change with less difference in the older group which is in line with the significantly smaller alterations in maximal BOLD signal change in the contra- and ipsilateral SI found between the two groups

  18. Functional connectivity analysis of the brain network using resting-state fMRI

    International Nuclear Information System (INIS)

    Hayashi, Toshihiro

    2011-01-01

    Spatial patterns of spontaneous fluctuations in blood oxygenation level-dependent (BOLD) signals reflect the underlying neural architecture. The study of the brain network based on these self-organized patterns is termed resting-state functional MRI (fMRI). This review article aims at briefly reviewing a basic concept of this technology and discussing its implications for neuropsychological studies. First, the technical aspects of resting-state fMRI, including signal sources, physiological artifacts, image acquisition, and analytical methods such as seed-based correlation analysis and independent component analysis, are explained, followed by a discussion on the major resting-state networks, including the default mode network. In addition, the structure-function correlation studied using diffuse tensor imaging and resting-state fMRI is briefly discussed. Second, I have discussed the reservations and potential pitfalls of 2 major imaging methods: voxel-based lesion-symptom mapping and task fMRI. Problems encountered with voxel-based lesion-symptom mapping can be overcome by using resting-state fMRI and evaluating undamaged brain networks in patients. Regarding task fMRI in patients, I have also emphasized the importance of evaluating the baseline brain activity because the amplitude of activation in BOLD fMRI is hard to interpret as the same baseline cannot be assumed for both patient and normal groups. (author)

  19. Mapping transient hyperventilation induced alterations with estimates of the multi-scale dynamics of BOLD signal.

    Directory of Open Access Journals (Sweden)

    Vesa J Kiviniemi

    2009-07-01

    Full Text Available Temporal blood oxygen level dependent (BOLD contrast signals in functional MRI during rest may be characterized by power spectral distribution (PSD trends of the form 1/f α. Trends with 1/f characteristics comprise fractal properties with repeating oscillation patterns in multiple time scales. Estimates of the fractal properties enable the quantification of phenomena that may otherwise be difficult to measure, such as transient, non-linear changes. In this study it was hypothesized that the fractal metrics of 1/f BOLD signal trends can map changes related to dynamic, multi-scale alterations in cerebral blood flow (CBF after a transient hyperventilation challenge. Twenty-three normal adults were imaged in a resting-state before and after hyperventilation. Different variables (1/f trend constant α, fractal dimension Df, and, Hurst exponent H characterizing the trends were measured from BOLD signals. The results show that fractal metrics of the BOLD signal follow the fractional Gaussian noise model, even during the dynamic CBF change that follows hyperventilation. The most dominant effect on the fractal metrics was detected in grey matter, in line with previous hyperventilation vaso-reactivity studies. The α was able to differentiate also blood vessels from grey matter changes. Df was most sensitive to grey matter. H correlated with default mode network areas before hyperventilation but this pattern vanished after hyperventilation due to a global increase in H. In the future, resting-state fMRI combined with fractal metrics of the BOLD signal may be used for analyzing multi-scale alterations of cerebral blood flow.

  20. Neurochemical and BOLD responses during neuronal activation measured in the human visual cortex at 7 Tesla.

    Science.gov (United States)

    Bednařík, Petr; Tkáč, Ivan; Giove, Federico; DiNuzzo, Mauro; Deelchand, Dinesh K; Emir, Uzay E; Eberly, Lynn E; Mangia, Silvia

    2015-03-31

    Several laboratories have consistently reported small concentration changes in lactate, glutamate, aspartate, and glucose in the human cortex during prolonged stimuli. However, whether such changes correlate with blood oxygenation level-dependent functional magnetic resonance imaging (BOLD-fMRI) signals have not been determined. The present study aimed at characterizing the relationship between metabolite concentrations and BOLD-fMRI signals during a block-designed paradigm of visual stimulation. Functional magnetic resonance spectroscopy (fMRS) and fMRI data were acquired from 12 volunteers. A short echo-time semi-LASER localization sequence optimized for 7 Tesla was used to achieve full signal-intensity MRS data. The group analysis confirmed that during stimulation lactate and glutamate increased by 0.26 ± 0.06 μmol/g (~30%) and 0.28 ± 0.03 μmol/g (~3%), respectively, while aspartate and glucose decreased by 0.20 ± 0.04 μmol/g (~5%) and 0.19 ± 0.03 μmol/g (~16%), respectively. The single-subject analysis revealed that BOLD-fMRI signals were positively correlated with glutamate and lactate concentration changes. The results show a linear relationship between metabolic and BOLD responses in the presence of strong excitatory sensory inputs, and support the notion that increased functional energy demands are sustained by oxidative metabolism. In addition, BOLD signals were inversely correlated with baseline γ-aminobutyric acid concentration. Finally, we discussed the critical importance of taking into account linewidth effects on metabolite quantification in fMRS paradigms.

  1. BOLD-specific cerebral blood volume and blood flow changes during neuronal activation in humans.

    Science.gov (United States)

    Chen, J Jean; Pike, G Bruce

    2009-12-01

    To understand and predict the blood-oxygenation level-dependent (BOLD) fMRI signal, an accurate knowledge of the relationship between cerebral blood flow (DeltaCBF) and volume (DeltaCBV) changes is critical. Currently, this relationship is widely assumed to be characterized by Grubb's power-law, derived from primate data, where the power coefficient (alpha) was found to be 0.38. The validity of this general formulation has been examined previously, and an alpha of 0.38 has been frequently cited when calculating the cerebral oxygen metabolism change (DeltaCMRo(2)) using calibrated BOLD. However, the direct use of this relationship has been the subject of some debate, since it is well established that the BOLD signal is primarily modulated by changes in 'venous' CBV (DeltaCBV(v), comprising deoxygenated blood in the capillary, venular, and to a lesser extent, in the arteriolar compartments) instead of total CBV, and yet DeltaCBV(v) measurements in humans have been extremely scarce. In this work, we demonstrate reproducible DeltaCBV(v) measurements at 3 T using venous refocusing for the volume estimation (VERVE) technique, and report on steady-state DeltaCBV(v) and DeltaCBF measurements in human subjects undergoing graded visual and sensorimotor stimulation. We found that: (1) a BOLD-specific flow-volume power-law relationship is described by alpha = 0.23 +/- 0.05, significantly lower than Grubb's constant of 0.38 for total CBV; (2) this power-law constant was not found to vary significantly between the visual and sensorimotor areas; and (3) the use of Grubb's value of 0.38 in gradient-echo BOLD modeling results in an underestimation of DeltaCMRo(2).

  2. Opposing BOLD responses to reciprocated and unreciprocated altruism in putative reward pathways.

    Science.gov (United States)

    Rilling, James K; Sanfey, Alan G; Aronson, Jessica A; Nystrom, Leigh E; Cohen, Jonathan D

    2004-11-15

    Mesencephalic dopamine neurons are believed to facilitate reward-dependent learning by computing errors in reward predictions. We used fMRI to test whether this system was activated as expected in response to errors in predictions about whether a social partner would reciprocate an act of altruism. Nineteen subjects received fMRI scans as they played a series of single-shot Prisoner's Dilemma games with partners who were outside the scanner. In both ventromedial prefrontal cortex and ventral striatum, reciprocated and unreciprocated cooperation were associated with positive and negative BOLD responses, respectively. Our results are consistent with the hypothesis that mesencephalic dopamine projection sites carry information about errors in reward prediction that allow us to learn who can and cannot be trusted to reciprocate favors.

  3. Spatial Mnemonic Encoding: Theta Power Decreases and Medial Temporal Lobe BOLD Increases Co-Occur during the Usage of the Method of Loci.

    Science.gov (United States)

    Fellner, Marie-Christin; Volberg, Gregor; Wimber, Maria; Goldhacker, Markus; Greenlee, Mark W; Hanslmayr, Simon

    2016-01-01

    The method of loci is one, if not the most, efficient mnemonic encoding strategy. This spatial mnemonic combines the core cognitive processes commonly linked to medial temporal lobe (MTL) activity: spatial and associative memory processes. During such processes, fMRI studies consistently demonstrate MTL activity, while electrophysiological studies have emphasized the important role of theta oscillations (3-8 Hz) in the MTL. However, it is still unknown whether increases or decreases in theta power co-occur with increased BOLD signal in the MTL during memory encoding. To investigate this question, we recorded EEG and fMRI separately, while human participants used the spatial method of loci or the pegword method, a similarly associative but nonspatial mnemonic. The more effective spatial mnemonic induced a pronounced theta power decrease source localized to the left MTL compared with the nonspatial associative mnemonic strategy. This effect was mirrored by BOLD signal increases in the MTL. Successful encoding, irrespective of the strategy used, elicited decreases in left temporal theta power and increases in MTL BOLD activity. This pattern of results suggests a negative relationship between theta power and BOLD signal changes in the MTL during memory encoding and spatial processing. The findings extend the well known negative relation of alpha/beta oscillations and BOLD signals in the cortex to theta oscillations in the MTL.

  4. Effect of fMRI acoustic noise on non-auditory working memory task: comparison between continuous and pulsed sound emitting EPI.

    Science.gov (United States)

    Haller, Sven; Bartsch, Andreas J; Radue, Ernst W; Klarhöfer, Markus; Seifritz, Erich; Scheffler, Klaus

    2005-11-01

    Conventional blood oxygenation level-dependent (BOLD) based functional magnetic resonance imaging (fMRI) is accompanied by substantial acoustic gradient noise. This noise can influence the performance as well as neuronal activations. Conventional fMRI typically has a pulsed noise component, which is a particularly efficient auditory stimulus. We investigated whether the elimination of this pulsed noise component in a recent modification of continuous-sound fMRI modifies neuronal activations in a cognitively demanding non-auditory working memory task. Sixteen normal subjects performed a letter variant n-back task. Brain activity and psychomotor performance was examined during fMRI with continuous-sound fMRI and conventional fMRI. We found greater BOLD responses in bilateral medial frontal gyrus, left middle frontal gyrus, left middle temporal gyrus, left hippocampus, right superior frontal gyrus, right precuneus and right cingulate gyrus with continuous-sound compared to conventional fMRI. Conversely, BOLD responses were greater in bilateral cingulate gyrus, left middle and superior frontal gyrus and right lingual gyrus with conventional compared to continuous-sound fMRI. There were no differences in psychomotor performance between both scanning protocols. Although behavioral performance was not affected, acoustic gradient noise interferes with neuronal activations in non-auditory cognitive tasks and represents a putative systematic confound.

  5. Searching for Conservation Laws in Brain Dynamics—BOLD Flux and Source Imaging

    Directory of Open Access Journals (Sweden)

    Henning U. Voss

    2014-07-01

    Full Text Available Blood-oxygen-level-dependent (BOLD imaging is the most important noninvasive tool to map human brain function. It relies on local blood-flow changes controlled by neurovascular coupling effects, usually in response to some cognitive or perceptual task. In this contribution we ask if the spatiotemporal dynamics of the BOLD signal can be modeled by a conservation law. In analogy to the description of physical laws, which often can be derived from some underlying conservation law, identification of conservation laws in the brain could lead to new models for the functional organization of the brain. Our model is independent of the nature of the conservation law, but we discuss possible hints and motivations for conservation laws. For example, globally limited blood supply and local competition between brain regions for blood might restrict the large scale BOLD signal in certain ways that could be observable. One proposed selective pressure for the evolution of such conservation laws is the closed volume of the skull limiting the expansion of brain tissue by increases in blood volume. These ideas are demonstrated on a mental motor imagery fMRI experiment, in which functional brain activation was mapped in a group of volunteers imagining themselves swimming. In order to search for local conservation laws during this complex cognitive process, we derived maps of quantities resulting from spatial interaction of the BOLD amplitudes. Specifically, we mapped fluxes and sources of the BOLD signal, terms that would appear in a description by a continuity equation. Whereas we cannot present final answers with the particular analysis of this particular experiment, some results seem to be non-trivial. For example, we found that during task the group BOLD flux covered more widespread regions than identified by conventional BOLD mapping and was always increasing during task. It is our hope that these results motivate more work towards the search for conservation

  6. Functional brain activation differences in stuttering identified with a rapid fMRI sequence

    Science.gov (United States)

    Kraft, Shelly Jo; Choo, Ai Leen; Sharma, Harish; Ambrose, Nicoline G.

    2011-01-01

    The purpose of this study was to investigate whether brain activity related to the presence of stuttering can be identified with rapid functional MRI (fMRI) sequences that involved overt and covert speech processing tasks. The long-term goal is to develop sensitive fMRI approaches with developmentally appropriate tasks to identify deviant speech motor and auditory brain activity in children who stutter closer to the age at which recovery from stuttering is documented. Rapid sequences may be preferred for individuals or populations who do not tolerate long scanning sessions. In this report, we document the application of a picture naming and phoneme monitoring task in three minute fMRI sequences with adults who stutter (AWS). If relevant brain differences are found in AWS with these approaches that conform to previous reports, then these approaches can be extended to younger populations. Pairwise contrasts of brain BOLD activity between AWS and normally fluent adults indicated the AWS showed higher BOLD activity in the right inferior frontal gyrus (IFG), right temporal lobe and sensorimotor cortices during picture naming and and higher activity in the right IFG during phoneme monitoring. The right lateralized pattern of BOLD activity together with higher activity in sensorimotor cortices is consistent with previous reports, which indicates rapid fMRI sequences can be considered for investigating stuttering in younger participants. PMID:22133409

  7. Relationship between saccadic eye movements and cortical activity as measured by fMRI

    DEFF Research Database (Denmark)

    Kimmig, H.; Greenlee, M.W.; Gondan, Matthias

    2001-01-01

    quantitative changes in cortical activity associated with qualitative changes in the saccade task for comparable levels of saccadic activity. All experiments required the simultaneous acquisition of eye movement and fMRI data. For this purpose we used a new high-resolution limbus-tracking technique...... that repeated processing of saccades is integrated over time in the BOLD response. In contrast, there was no comparable BOLD change with variation of saccade amplitude. This finding speaks for a topological rather than activity-dependent coding of saccade amplitudes in most cortical regions. In the experiments...

  8. Comparison between subjects with long- and short-allele carriers in the BOLD signal within amygdala during emotional tasks

    Science.gov (United States)

    Hadi, Shamil; Siadat, Mohamad R.; Babajani-Feremi, Abbas

    2012-03-01

    Emotional tasks may result in a strong blood oxygen level-dependent (BOLD) signal in the amygdala in 5- HTTLRP short-allele. Reduced anterior cingulate cortex (ACC)-amygdala connectivity in short-allele provides a potential mechanistic account for the observed increase in amygdala activity. In our study, fearful and threatening facial expressions were presented to two groups of 12 subjects with long- and short-allele carriers. The BOLD signals of the left amygdala of each group were averaged to increase the signal-to-noise ratio. A Bayesian approach was used to estimate the model parameters to elucidate the underlying hemodynamic mechanism. Our results showed a positive BOLD signal in the left amygdala for short-allele individuals, and a negative BOLD signal in the same region for long-allele individuals. This is due to the fact that short-allele is associated with lower availability of serotonin transporter (5-HTT) and this leads to an increase of serotonin (5-HT) concentration in the cACC-amygdala synapse.

  9. Corticostriatal and Dopaminergic Response to Beer Flavor with Both fMRI and [(11) C]raclopride Positron Emission Tomography.

    Science.gov (United States)

    Oberlin, Brandon G; Dzemidzic, Mario; Harezlak, Jaroslaw; Kudela, Maria A; Tran, Stella M; Soeurt, Christina M; Yoder, Karmen K; Kareken, David A

    2016-09-01

    Cue-evoked drug-seeking behavior likely depends on interactions between frontal activity and ventral striatal (VST) dopamine (DA) transmission. Using [(11) C]raclopride (RAC) positron emission tomography (PET), we previously demonstrated that beer flavor (absent intoxication) elicited VST DA release in beer drinkers, inferred by RAC displacement. Here, a subset of subjects from this previous RAC-PET study underwent a similar paradigm during functional magnetic resonance imaging (fMRI) to test how orbitofrontal cortex (OFC) and VST blood oxygenation level-dependent (BOLD) responses to beer flavor are related to VST DA release and motivation to drink. Male beer drinkers (n = 28, age = 24 ± 2, drinks/wk = 16 ± 10) from our previous PET study participated in a similar fMRI paradigm wherein subjects tasted their most frequently consumed brand of beer and Gatorade(®) (appetitive control). We tested for correlations between BOLD activation in fMRI and VST DA responses in PET, and drinking-related variables. Compared to Gatorade, beer flavor increased wanting and desire to drink, and induced BOLD responses in bilateral OFC and right VST. Wanting and desire to drink correlated with both right VST and medial OFC BOLD activation to beer flavor. Like the BOLD findings, beer flavor (relative to Gatorade) again induced right VST DA release in this fMRI subject subset, but there was no correlation between DA release and the magnitude of BOLD responses in frontal regions of interest. Both imaging modalities showed a right-lateralized VST response (BOLD and DA release) to a drug-paired conditioned stimulus, whereas fMRI BOLD responses in the VST and medial OFC also reflected wanting and desire to drink. The data suggest the possibility that responses to drug-paired cues may be rightward biased in the VST (at least in right-handed males) and that VST and OFC responses in this gustatory paradigm reflect stimulus wanting. Copyright © 2016 by the Research Society on

  10. Entry Mistakes, Entrepreneurial Boldness and Optimism

    OpenAIRE

    Brocas, Isabelle; Carrillo, Juan D

    1999-01-01

    We analyze the investment decision of a population of time inconsistent entrepreneurs who overweight current payoffs relative to future returns. We show that, in order to avoid inefficient procrastination, agents may find it optimal to keep optimistic priors about their chances of success and 'blindly invest'. This explains entrepreneurial boldness and entry mistakes (or an excessive level of investment in the economy) without assuming the existence of boundedly rational, 'intrinsically optim...

  11. Intersession reliability of fMRI activation for heat pain and motor tasks

    Directory of Open Access Journals (Sweden)

    Raimi L. Quiton

    2014-01-01

    Full Text Available As the practice of conducting longitudinal fMRI studies to assess mechanisms of pain-reducing interventions becomes more common, there is a great need to assess the test–retest reliability of the pain-related BOLD fMRI signal across repeated sessions. This study quantitatively evaluated the reliability of heat pain-related BOLD fMRI brain responses in healthy volunteers across 3 sessions conducted on separate days using two measures: (1 intraclass correlation coefficients (ICC calculated based on signal amplitude and (2 spatial overlap. The ICC analysis of pain-related BOLD fMRI responses showed fair-to-moderate intersession reliability in brain areas regarded as part of the cortical pain network. Areas with the highest intersession reliability based on the ICC analysis included the anterior midcingulate cortex, anterior insula, and second somatosensory cortex. Areas with the lowest intersession reliability based on the ICC analysis also showed low spatial reliability; these regions included pregenual anterior cingulate cortex, primary somatosensory cortex, and posterior insula. Thus, this study found regional differences in pain-related BOLD fMRI response reliability, which may provide useful information to guide longitudinal pain studies. A simple motor task (finger-thumb opposition was performed by the same subjects in the same sessions as the painful heat stimuli were delivered. Intersession reliability of fMRI activation in cortical motor areas was comparable to previously published findings for both spatial overlap and ICC measures, providing support for the validity of the analytical approach used to assess intersession reliability of pain-related fMRI activation. A secondary finding of this study is that the use of standard ICC alone as a measure of reliability may not be sufficient, as the underlying variance structure of an fMRI dataset can result in inappropriately high ICC values; a method to eliminate these false positive results

  12. Hemodynamic Support in Sepsis

    Directory of Open Access Journals (Sweden)

    Fatih Yildiz

    2014-04-01

    Full Text Available Sepsis is called systemic inflammatory response syndrome due to infection. When added to organs failure and perfusion abnormality is defined in severe sepsis, Hypotension that do not respond to fluid therapy is as defined septic shock. Fluid resuscitation is a most important parts of the treatment in patients with septic shock. Ongoing hypotension that despite of the adequate fluid therapy, vasopressor support initiation is required. Sepsis and septic shock, hemodynamic support is often understood as the hemodynamic support. The different approaches to the development of methods to track and objective comes up. Patients with severe sepsis and septic shock should be follow in the intensive care unit and rapid fluid replacement and effectual hemodynamic support should be provided.

  13. Ecological nuances in functional magnetic resonance imaging (fMRI): psychological stressors, posture, and hydrostatics.

    Science.gov (United States)

    Raz, Amir; Lieber, Baruch; Soliman, Fatima; Buhle, Jason; Posner, Jonathan; Peterson, Bradley S; Posner, Michael I

    2005-03-01

    Brain imaging techniques such as functional magnetic resonance imaging (fMRI) have forged an impressive link between psychology and neuroscience. Whereas most experiments in cognitive psychology require participants to perform while sitting upright in front of display devices, fMRI obliges participants to perform cognitive tasks while lying supine and motionless inside a narrow bore. In addition to introducing psychological and physical stressors, such as loud thumps and head restraints, fMRI procedures also alter brain hydrostatics. The ecological factors associated with current fMRI technology, such as supine posture, may skew cognitive processing and influence hemodynamic and electrophysiological measurements, especially in extreme age groups and pathological populations. Recognizing the central role of fMRI in unraveling the neural mechanisms of cognition, we outline ways to address these limitations.

  14. Hemodynamic Profiling in Complicated Pregnancies

    NARCIS (Netherlands)

    J.M.J. Cornette (Jérôme)

    2016-01-01

    textabstractIn order to permit a successful pregnancy outcome, the cardiovascular system must undergo substantial changes. This thesis addresses the hemodynamics in several pregnancy complications. A general overview of normal hemodynamic adaptation to pregnancy is provided . Several techniques of

  15. Is fMRI ?noise? really noise? Resting state nuisance regressors remove variance with network structure

    OpenAIRE

    Bright, Molly G.; Murphy, Kevin

    2015-01-01

    Noise correction is a critical step towards accurate mapping of resting state BOLD fMRI connectivity. Noise sources related to head motion or physiology are typically modelled by nuisance regressors, and a generalised linear model is applied to regress out the associated signal variance. In this study, we use independent component analysis (ICA) to characterise the data variance typically discarded in this pre-processing stage in a cohort of 12 healthy volunteers. The signal variance removed ...

  16. Multivoxel Pattern Analysis for fMRI Data: A Review

    Directory of Open Access Journals (Sweden)

    Abdelhak Mahmoudi

    2012-01-01

    Full Text Available Functional magnetic resonance imaging (fMRI exploits blood-oxygen-level-dependent (BOLD contrasts to map neural activity associated with a variety of brain functions including sensory processing, motor control, and cognitive and emotional functions. The general linear model (GLM approach is used to reveal task-related brain areas by searching for linear correlations between the fMRI time course and a reference model. One of the limitations of the GLM approach is the assumption that the covariance across neighbouring voxels is not informative about the cognitive function under examination. Multivoxel pattern analysis (MVPA represents a promising technique that is currently exploited to investigate the information contained in distributed patterns of neural activity to infer the functional role of brain areas and networks. MVPA is considered as a supervised classification problem where a classifier attempts to capture the relationships between spatial pattern of fMRI activity and experimental conditions. In this paper , we review MVPA and describe the mathematical basis of the classification algorithms used for decoding fMRI signals, such as support vector machines (SVMs. In addition, we describe the workflow of processing steps required for MVPA such as feature selection, dimensionality reduction, cross-validation, and classifier performance estimation based on receiver operating characteristic (ROC curves.

  17. Multivoxel Pattern Analysis for fMRI Data: A Review

    Science.gov (United States)

    Takerkart, Sylvain; Regragui, Fakhita; Boussaoud, Driss; Brovelli, Andrea

    2012-01-01

    Functional magnetic resonance imaging (fMRI) exploits blood-oxygen-level-dependent (BOLD) contrasts to map neural activity associated with a variety of brain functions including sensory processing, motor control, and cognitive and emotional functions. The general linear model (GLM) approach is used to reveal task-related brain areas by searching for linear correlations between the fMRI time course and a reference model. One of the limitations of the GLM approach is the assumption that the covariance across neighbouring voxels is not informative about the cognitive function under examination. Multivoxel pattern analysis (MVPA) represents a promising technique that is currently exploited to investigate the information contained in distributed patterns of neural activity to infer the functional role of brain areas and networks. MVPA is considered as a supervised classification problem where a classifier attempts to capture the relationships between spatial pattern of fMRI activity and experimental conditions. In this paper , we review MVPA and describe the mathematical basis of the classification algorithms used for decoding fMRI signals, such as support vector machines (SVMs). In addition, we describe the workflow of processing steps required for MVPA such as feature selection, dimensionality reduction, cross-validation, and classifier performance estimation based on receiver operating characteristic (ROC) curves. PMID:23401720

  18. Mapping of cognitive functions in chronic intractable epilepsy: Role of fMRI

    International Nuclear Information System (INIS)

    Chaudhary, Kapil; Kumaran, S Senthil; Chandra, Sarat P; Wadhawan, Ashima Nehra; Tripathi, Manjari

    2014-01-01

    Functional magnetic resonance imaging (fMRI), a non-invasive technique with high spatial resolution and blood oxygen level dependent (BOLD) contrast, has been applied to localize and map cognitive functions in the clinical condition of chronic intractable epilepsy. fMRI was used to map the language and memory network in patients of chronic intractable epilepsy pre- and post-surgery. After obtaining approval from the institutional ethics committee, six patients with intractable epilepsy with an equal number of age-matched controls were recruited in the study. A 1.5 T MR scanner with 12-channel head coil, integrated with audio-visual fMRI accessories was used. Echo planar imaging sequence was used for BOLD studies. There were two sessions in TLE (pre- and post-surgery). In TLE patients, BOLD activation increased post-surgery in comparison of pre-surgery in inferior frontal gyrus (IFG), middle frontal gyrus (MFG), and superior temporal gyrus (STG), during semantic lexical, judgment, comprehension, and semantic memory tasks. Functional MRI is useful to study the basic concepts related to language and memory lateralization in TLE and guide surgeons for preservation of important brain areas during ATLR. This will help in understanding future directions for the diagnosis and treatment of such disease

  19. Feature-space-based FMRI analysis using the optimal linear transformation.

    Science.gov (United States)

    Sun, Fengrong; Morris, Drew; Lee, Wayne; Taylor, Margot J; Mills, Travis; Babyn, Paul S

    2010-09-01

    The optimal linear transformation (OLT), an image analysis technique of feature space, was first presented in the field of MRI. This paper proposes a method of extending OLT from MRI to functional MRI (fMRI) to improve the activation-detection performance over conventional approaches of fMRI analysis. In this method, first, ideal hemodynamic response time series for different stimuli were generated by convolving the theoretical hemodynamic response model with the stimulus timing. Second, constructing hypothetical signature vectors for different activity patterns of interest by virtue of the ideal hemodynamic responses, OLT was used to extract features of fMRI data. The resultant feature space had particular geometric clustering properties. It was then classified into different groups, each pertaining to an activity pattern of interest; the applied signature vector for each group was obtained by averaging. Third, using the applied signature vectors, OLT was applied again to generate fMRI composite images with high SNRs for the desired activity patterns. Simulations and a blocked fMRI experiment were employed for the method to be verified and compared with the general linear model (GLM)-based analysis. The simulation studies and the experimental results indicated the superiority of the proposed method over the GLM-based analysis in detecting brain activities.

  20. Distributed BOLD-response in association cortex vector state space predicts reaction time during selective attention.

    Science.gov (United States)

    Musso, Francesco; Konrad, Andreas; Vucurevic, Goran; Schäffner, Cornelius; Friedrich, Britta; Frech, Peter; Stoeter, Peter; Winterer, Georg

    2006-02-15

    Human cortical information processing is thought to be dominated by distributed activity in vector state space (Churchland, P.S., Sejnowski, T.J., 1992. The Computational Brain. MIT Press, Cambridge.). In principle, it should be possible to quantify distributed brain activation with independent component analysis (ICA) through vector-based decomposition, i.e., through a separation of a mixture of sources. Using event-related functional magnetic resonance imaging (fMRI) during a selective attention-requiring task (visual oddball), we explored how the number of independent components within activated cortical areas is related to reaction time. Prior to ICA, the activated cortical areas were determined on the basis of a General linear model (GLM) voxel-by-voxel analysis of the target stimuli (checkerboard reversal). Two activated cortical areas (temporoparietal cortex, medial prefrontal cortex) were further investigated as these cortical regions are known to be the sites of simultaneously active electromagnetic generators which give rise to the compound event-related potential P300 during oddball task conditions. We found that the number of independent components more strongly predicted reaction time than the overall level of "activation" (GLM BOLD-response) in the left temporoparietal area whereas in the medial prefrontal cortex both ICA and GLM predicted reaction time equally well. Comparable correlations were not seen when principle components were used instead of independent components. These results indicate that the number of independently activated components, i.e., a high level of cortical activation complexity in cortical vector state space, may index particularly efficient information processing during selective attention-requiring tasks. To our best knowledge, this is the first report describing a potential relationship between neuronal generators of cognitive processes, the associated electrophysiological evidence for the existence of distributed networks

  1. Crosslinking EEG time-frequency decomposition and fMRI in error monitoring.

    Science.gov (United States)

    Hoffmann, Sven; Labrenz, Franziska; Themann, Maria; Wascher, Edmund; Beste, Christian

    2014-03-01

    Recent studies implicate a common response monitoring system, being active during erroneous and correct responses. Converging evidence from time-frequency decompositions of the response-related ERP revealed that evoked theta activity at fronto-central electrode positions differentiates correct from erroneous responses in simple tasks, but also in more complex tasks. However, up to now it is unclear how different electrophysiological parameters of error processing, especially at the level of neural oscillations are related, or predictive for BOLD signal changes reflecting error processing at a functional-neuroanatomical level. The present study aims to provide crosslinks between time domain information, time-frequency information, MRI BOLD signal and behavioral parameters in a task examining error monitoring due to mistakes in a mental rotation task. The results show that BOLD signal changes reflecting error processing on a functional-neuroanatomical level are best predicted by evoked oscillations in the theta frequency band. Although the fMRI results in this study account for an involvement of the anterior cingulate cortex, middle frontal gyrus, and the Insula in error processing, the correlation of evoked oscillations and BOLD signal was restricted to a coupling of evoked theta and anterior cingulate cortex BOLD activity. The current results indicate that although there is a distributed functional-neuroanatomical network mediating error processing, only distinct parts of this network seem to modulate electrophysiological properties of error monitoring.

  2. Wavelet entropy of BOLD time series: An application to Rolandic epilepsy.

    Science.gov (United States)

    Gupta, Lalit; Jansen, Jacobus F A; Hofman, Paul A M; Besseling, René M H; de Louw, Anton J A; Aldenkamp, Albert P; Backes, Walter H

    2017-12-01

    To assess the wavelet entropy for the characterization of intrinsic aberrant temporal irregularities in the time series of resting-state blood-oxygen-level-dependent (BOLD) signal fluctuations. Further, to evaluate the temporal irregularities (disorder/order) on a voxel-by-voxel basis in the brains of children with Rolandic epilepsy. The BOLD time series was decomposed using the discrete wavelet transform and the wavelet entropy was calculated. Using a model time series consisting of multiple harmonics and nonstationary components, the wavelet entropy was compared with Shannon and spectral (Fourier-based) entropy. As an application, the wavelet entropy in 22 children with Rolandic epilepsy was compared to 22 age-matched healthy controls. The images were obtained by performing resting-state functional magnetic resonance imaging (fMRI) using a 3T system, an 8-element receive-only head coil, and an echo planar imaging pulse sequence ( T2*-weighted). The wavelet entropy was also compared to spectral entropy, regional homogeneity, and Shannon entropy. Wavelet entropy was found to identify the nonstationary components of the model time series. In Rolandic epilepsy patients, a significantly elevated wavelet entropy was observed relative to controls for the whole cerebrum (P = 0.03). Spectral entropy (P = 0.41), regional homogeneity (P = 0.52), and Shannon entropy (P = 0.32) did not reveal significant differences. The wavelet entropy measure appeared more sensitive to detect abnormalities in cerebral fluctuations represented by nonstationary effects in the BOLD time series than more conventional measures. This effect was observed in the model time series as well as in Rolandic epilepsy. These observations suggest that the brains of children with Rolandic epilepsy exhibit stronger nonstationary temporal signal fluctuations than controls. 2 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2017;46:1728-1737. © 2017 International Society for Magnetic

  3. Visual BOLD Response in Late Blind Subjects with Argus II Retinal Prosthesis.

    Directory of Open Access Journals (Sweden)

    E Castaldi

    2016-10-01

    Full Text Available Retinal prosthesis technologies require that the visual system downstream of the retinal circuitry be capable of transmitting and elaborating visual signals. We studied the capability of plastic remodeling in late blind subjects implanted with the Argus II Retinal Prosthesis with psychophysics and functional MRI (fMRI. After surgery, six out of seven retinitis pigmentosa (RP blind subjects were able to detect high-contrast stimuli using the prosthetic implant. However, direction discrimination to contrast modulated stimuli remained at chance level in all of them. No subject showed any improvement of contrast sensitivity in either eye when not using the Argus II. Before the implant, the Blood Oxygenation Level Dependent (BOLD activity in V1 and the lateral geniculate nucleus (LGN was very weak or absent. Surprisingly, after prolonged use of Argus II, BOLD responses to visual input were enhanced. This is, to our knowledge, the first study tracking the neural changes of visual areas in patients after retinal implant, revealing a capacity to respond to restored visual input even after years of deprivation.

  4. On the characterization of single-event related brain activity from functional Magnetic Resonance Imaging (fMRI) measurements

    KAUST Repository

    Khoram, Nafiseh

    2014-08-01

    We propose an efficient numerical technique for calibrating the mathematical model that describes the singleevent related brain response when fMRI measurements are given. This method employs a regularized Newton technique in conjunction with a Kalman filtering procedure. We have applied this method to estimate the biophysiological parameters of the Balloon model that describes the hemodynamic brain responses. Illustrative results obtained with both synthetic and real fMRI measurements are presented. © 2014 IEEE.

  5. Hemodynamic monitoring during CPR.

    Science.gov (United States)

    Ornato, J P

    1993-02-01

    Real-time hemodynamic monitoring provides useful information that can be used to assess and optimize mechanical and pharmacological interventions during CPR. The standard algorithms should always be the initial approach to resuscitation, because they offer a rapid, logical, coordinated series of treatments with proven success. Pressure and flow measurements during conventional, closed-chest CPR in humans indicate that the technique typically produces a hemodynamic state resembling profound cardiogenic shock, with a low systemic arterial pressure, markedly reduced cardiac output, and high intravascular filling pressures. End-tidal carbon dioxide monitoring provides useful, noninvasive information during clinical resuscitation. A low end-tidal carbon dioxide value during resuscitation should alert the rescuers that something is wrong with ventilation, perfusion, and/or carbon dioxide production and should prompt a search for correctable causes. If one or more hemodynamic parameters are being monitored at the time the patient develops cardiac arrest (eg, an intensive care unit patient who has an arterial line and a pulmonary artery catheter in place), it is appropriate for the resuscitation team to pay attention to the data that are generated during the resuscitation, particularly if the initial algorithm approach is not successful. For patients who are not being monitored at the time of their arrest, end-tidal carbon dioxide measurements provide noninvasive, semiquantitative information that can help the team detect and troubleshoot problems during resuscitation. Further research and better, more affordable technologies are needed to provide in- and out-of-hospital resuscitation teams feedback on the hemodynamic effectiveness of their resuscitative efforts.

  6. A sliding mode observer for hemodynamic characterization under modeling uncertainties

    KAUST Repository

    Zayane, Chadia

    2014-06-01

    This paper addresses the case of physiological states reconstruction in a small region of the brain under modeling uncertainties. The misunderstood coupling between the cerebral blood volume and the oxygen extraction fraction has lead to a partial knowledge of the so-called balloon model describing the hemodynamic behavior of the brain. To overcome this difficulty, a High Order Sliding Mode observer is applied to the balloon system, where the unknown coupling is considered as an internal perturbation. The effectiveness of the proposed method is illustrated through a set of synthetic data that mimic fMRI experiments.

  7. Antipsychotic Drug Effects in Schizophrenia: A Review of Longitudinal fMRI Investigations and Neural Interpretations

    Science.gov (United States)

    Abbott, C.C.; Jaramillo, A.; Wilcox, C.E.; Hamilton, D.A.

    2013-01-01

    The evidence that antipsychotics improve brain function and reduce symptoms in schizophrenia is unmistakable, but how antipsychotics change brain function is poorly understood, especially within neuronal systems. In this review, we investigated the hypothesized normalization of the functional magnetic resonance imaging (fMRI) blood oxygen level dependent signal in the context of antipsychotic treatment. First, we conducted a systematic PubMed search to identify eight fMRI investigations that met the following inclusion criteria: case-control, longitudinal design; pre- and post-treatment contrasts with a healthy comparison group; and antipsychotic-free or antipsychotic-naïve patients with schizophrenia at the start of the investigation. We hypothesized that aberrant activation patterns or connectivity between patients with schizophrenia and healthy comparisons at the first imaging assessment would no longer be apparent or “normalize” at the second imaging assessment. The included studies differed by analysis method and fMRI task but demonstrated normalization of fMRI activation or connectivity during the treatment interval. Second, we reviewed putative mechanisms from animal studies that support normalization of the BOLD signal in schizophrenia. We provided several neuronal-based interpretations of these changes of the BOLD signal that may be attributable to long-term antipsychotic administration. PMID:23157635

  8. Mapping and characterization of positive and negative BOLD responses to visual stimulation in multiple brain regions at 7T.

    Science.gov (United States)

    Jorge, João; Figueiredo, Patrícia; Gruetter, Rolf; van der Zwaag, Wietske

    2018-02-20

    External stimuli and tasks often elicit negative BOLD responses in various brain regions, and growing experimental evidence supports that these phenomena are functionally meaningful. In this work, the high sensitivity available at 7T was explored to map and characterize both positive (PBRs) and negative BOLD responses (NBRs) to visual checkerboard stimulation, occurring in various brain regions within and beyond the visual cortex. Recently-proposed accelerated fMRI techniques were employed for data acquisition, and procedures for exclusion of large draining vein contributions, together with ICA-assisted denoising, were included in the analysis to improve response estimation. Besides the visual cortex, significant PBRs were found in the lateral geniculate nucleus and superior colliculus, as well as the pre-central sulcus; in these regions, response durations increased monotonically with stimulus duration, in tight covariation with the visual PBR duration. Significant NBRs were found in the visual cortex, auditory cortex, default-mode network (DMN) and superior parietal lobule; NBR durations also tended to increase with stimulus duration, but were significantly less sustained than the visual PBR, especially for the DMN and superior parietal lobule. Responses in visual and auditory cortex were further studied for checkerboard contrast dependence, and their amplitudes were found to increase monotonically with contrast, linearly correlated with the visual PBR amplitude. Overall, these findings suggest the presence of dynamic neuronal interactions across multiple brain regions, sensitive to stimulus intensity and duration, and demonstrate the richness of information obtainable when jointly mapping positive and negative BOLD responses at a whole-brain scale, with ultra-high field fMRI. © 2018 Wiley Periodicals, Inc.

  9. Natriuretic peptides and cerebral hemodynamics

    DEFF Research Database (Denmark)

    Guo, Song; Barringer, Filippa; Zois, Nora Elisabeth

    2014-01-01

    in decompensated disease. In contrast, their biological effects on the cerebral hemodynamics are poorly understood. In this mini-review, we summarize the hemodynamic effects of the natriuretic peptides with a focus on the cerebral hemodynamics. In addition, we will discuss its potential implications in diseases...... where alteration of the cerebral hemodynamics plays a role such as migraine and acute brain injury including stroke. We conclude that a possible role of the peptides is feasible as evaluated from animal and in vitro studies, but more research is needed in humans to determine the precise response...

  10. Effect of repetitive arm cycling following botulinum toxin injection for poststroke spasticity: evidence from FMRI.

    Science.gov (United States)

    Diserens, Karin; Ruegg, Dieter; Kleiser, Raimund; Hyde, Sandrine; Perret, Nicolas; Vuadens, Philippe; Fornari, Eleonora; Vingerhoets, Francois; Seitz, Rüdiger J

    2010-10-01

    Investigations were performed to establish if repetitive arm cycling training enhances the antispastic effect of intramuscular botulinum toxin (BTX) injections in postischemic spastic hemiparesis. Effects on cerebral activation were evaluated by functional magnetic resonance imaging (fMRI). Eight chronic spastic hemisyndrome patients (49 ± 10 years) after middle cerebral artery infarction (5.5 ± 2.7 years) were investigated. BTX was injected into the affected arm twice, 6 months apart. Spasticity was assessed using the Ashworth Scale and range of motion before and 3 months after BTX injections. Images were analyzed using Brain Voyager QX 1.8, and fMRI signal changes were corrected for multiple comparisons. During passive movements of affected and nonaffected hands, fMRI activity was increased bilaterally in the sensorimotor cortex (MISI), secondary somatosensory areas (SII), and supplementary motor area predominantly in the contralesional hemisphere, compared with the rest. Following repetitive arm cycling, fMRI activity increased further in MISI of the lesioned hemisphere and SII of the contralesional hemisphere. For patients with residual motor activity, treatment-related fMRI activity increases were associated with reduced spasticity; in completely plegic patients, there was no fMRI activity change in SII but increased spasticity after training. Increased activity in SII of the contralesional hemisphere and in MISI of the lesioned hemisphere reflect a treatment-induced effect in the paretic arm. It is hypothesized that the increased BOLD activity results from increased afferent information related to the antispastic BTX effect reinforced by training.

  11. Interleaved quantitative BOLD: Combining extravascular R2' - and intravascular R2-measurements for estimation of deoxygenated blood volume and hemoglobin oxygen saturation.

    Science.gov (United States)

    Lee, Hyunyeol; Englund, Erin K; Wehrli, Felix W

    2018-03-23

    Quantitative BOLD (qBOLD), a non-invasive MRI method for assessment of hemodynamic and metabolic properties of the brain in the baseline state, provides spatial maps of deoxygenated blood volume fraction (DBV) and hemoglobin oxygen saturation (HbO 2 ) by means of an analytical model for the temporal evolution of free-induction-decay signals in the extravascular compartment. However, mutual coupling between DBV and HbO 2 in the signal model results in considerable estimation uncertainty precluding achievement of a unique set of solutions. To address this problem, we developed an interleaved qBOLD method (iqBOLD) that combines extravascular R 2 ' and intravascular R 2 mapping techniques so as to obtain prior knowledge for the two unknown parameters. To achieve these goals, asymmetric spin echo and velocity-selective spin-labeling (VSSL) modules were interleaved in a single pulse sequence. Prior to VSSL, arterial blood and CSF signals were suppressed to produce reliable estimates for cerebral venous blood volume fraction (CBV v ) as well as venous blood R 2 (to yield HbO 2 ). Parameter maps derived from the VSSL module were employed to initialize DBV and HbO 2 in the qBOLD processing. Numerical simulations and in vivo experiments at 3 T were performed to evaluate the performance of iqBOLD in comparison to the parent qBOLD method. Data obtained in eight healthy subjects yielded plausible values averaging 60.1 ± 3.3% for HbO 2 and 3.1 ± 0.5 and 2.0 ± 0.4% for DBV in gray and white matter, respectively. Furthermore, the results show that prior estimates of CBV v and HbO 2 from the VSSL component enhance the solution stability in the qBOLD processing, and thus suggest the feasibility of iqBOLD as a promising alternative to the conventional technique for quantifying neurometabolic parameters. Copyright © 2018. Published by Elsevier Inc.

  12. BOLD temporal dynamics of rat superior colliculus and lateral geniculate nucleus following short duration visual stimulation.

    Directory of Open Access Journals (Sweden)

    Condon Lau

    Full Text Available BACKGROUND: The superior colliculus (SC and lateral geniculate nucleus (LGN are important subcortical structures for vision. Much of our understanding of vision was obtained using invasive and small field of view (FOV techniques. In this study, we use non-invasive, large FOV blood oxygenation level-dependent (BOLD fMRI to measure the SC and LGN's response temporal dynamics following short duration (1 s visual stimulation. METHODOLOGY/PRINCIPAL FINDINGS: Experiments are performed at 7 tesla on Sprague Dawley rats stimulated in one eye with flashing light. Gradient-echo and spin-echo sequences are used to provide complementary information. An anatomical image is acquired from one rat after injection of monocrystalline iron oxide nanoparticles (MION, a blood vessel contrast agent. BOLD responses are concentrated in the contralateral SC and LGN. The SC BOLD signal measured with gradient-echo rises to 50% of maximum amplitude (PEAK 0.2±0.2 s before the LGN signal (p<0.05. The LGN signal returns to 50% of PEAK 1.4±1.2 s before the SC signal (p<0.05. These results indicate the SC signal rises faster than the LGN signal but settles slower. Spin-echo results support these findings. The post-MION image shows the SC and LGN lie beneath large blood vessels. This subcortical vasculature is similar to that in the cortex, which also lies beneath large vessels. The LGN lies closer to the large vessels than much of the SC. CONCLUSIONS/SIGNIFICANCE: The differences in response timing between SC and LGN are very similar to those between deep and shallow cortical layers following electrical stimulation, which are related to depth-dependent blood vessel dilation rates. This combined with the similarities in vasculature between subcortex and cortex suggest the SC and LGN timing differences are also related to depth-dependent dilation rates. This study shows for the first time that BOLD responses in the rat SC and LGN following short duration visual stimulation are

  13. Measurement of oxygen extraction fraction (OEF): An optimized BOLD signal model for use with hypercapnic and hyperoxic calibration.

    Science.gov (United States)

    Merola, Alberto; Murphy, Kevin; Stone, Alan J; Germuska, Michael A; Griffeth, Valerie E M; Blockley, Nicholas P; Buxton, Richard B; Wise, Richard G

    2016-04-01

    Several techniques have been proposed to estimate relative changes in cerebral metabolic rate of oxygen consumption (CMRO2) by exploiting combined BOLD fMRI and cerebral blood flow data in conjunction with hypercapnic or hyperoxic respiratory challenges. More recently, methods based on respiratory challenges that include both hypercapnia and hyperoxia have been developed to assess absolute CMRO2, an important parameter for understanding brain energetics. In this paper, we empirically optimize a previously presented "original calibration model" relating BOLD and blood flow signals specifically for the estimation of oxygen extraction fraction (OEF) and absolute CMRO2. To do so, we have created a set of synthetic BOLD signals using a detailed BOLD signal model to reproduce experiments incorporating hypercapnic and hyperoxic respiratory challenges at 3T. A wide range of physiological conditions was simulated by varying input parameter values (baseline cerebral blood volume (CBV0), baseline cerebral blood flow (CBF0), baseline oxygen extraction fraction (OEF0) and hematocrit (Hct)). From the optimization of the calibration model for estimation of OEF and practical considerations of hypercapnic and hyperoxic respiratory challenges, a new "simplified calibration model" is established which reduces the complexity of the original calibration model by substituting the standard parameters α and β with a single parameter θ. The optimal value of θ is determined (θ=0.06) across a range of experimental respiratory challenges. The simplified calibration model gives estimates of OEF0 and absolute CMRO2 closer to the true values used to simulate the experimental data compared to those estimated using the original model incorporating literature values of α and β. Finally, an error propagation analysis demonstrates the susceptibility of the original and simplified calibration models to measurement errors and potential violations in the underlying assumptions of isometabolism

  14. Convergence of human brain mapping tools: neuronavigated TMS parameters and fMRI activity in the hand motor area.

    Science.gov (United States)

    Sarfeld, Anna-Sophia; Diekhoff, Svenja; Wang, Ling E; Liuzzi, Gianpiero; Uludağ, Kamil; Eickhoff, Simon B; Fink, Gereon R; Grefkes, Christian

    2012-05-01

    Functional magnetic resonance imaging (fMRI) and transcranial magnetic stimulation (TMS) are well-established tools for investigating the human motor system in-vivo. We here studied the relationship between movement-related fMRI signal changes in the primary motor cortex (M1) and electrophysiological properties of the hand motor area assessed with neuronavigated TMS in 17 healthy subjects. The voxel showing the highest task-related BOLD response in the left hand motor area during right hand movements was identified for each individual subject. This fMRI peak voxel in M1 served as spatial target for coil positioning during neuronavigated TMS. We performed correlation analyses between TMS parameters, BOLD signal estimates and effective connectivity parameters of M1 assessed with dynamic causal modeling (DCM). The results showed a negative correlation between the movement-related BOLD signal in left M1 and resting as well as active motor threshold (MT) obtained for left M1. The DCM analysis revealed that higher excitability of left M1 was associated with a stronger coupling between left supplementary motor area (SMA) and M1. Furthermore, BOLD activity in left M1 correlated with ipsilateral silent period (ISP), i.e. the stronger the task-related BOLD response in left M1, the higher interhemispheric inhibition effects targeting right M1. DCM analyses revealed a positive correlation between the coupling of left SMA with left M1 and the duration of ISP. The data show that TMS parameters assessed for the hand area of M1 do not only reflect the intrinsic properties at the stimulation site but also interactions with remote areas in the human motor system. Copyright © 2011 Wiley-Liss, Inc.

  15. Fitness Consequences of Boldness in Juvenile and Adult Largemouth Bass.

    Science.gov (United States)

    Ballew, Nicholas G; Mittelbach, Gary G; Scribner, Kim T

    2017-04-01

    To date, most studies investigating the relationship between personality traits and fitness have focused on a single measure of fitness (such as survival) at a specific life stage. However, many personality traits likely have multiple effects on fitness, potentially operating across different functional contexts and stages of development. Here, we address the fitness consequences of boldness, under seminatural conditions, across life stages and functional contexts in largemouth bass (Micropterus salmoides). Specifically, we report the effect of boldness on (1) juvenile survivorship in an outdoor pond containing natural prey and predators and (2) adult reproductive success in three outdoor ponds across three reproductive seasons (years). Juvenile survival was negatively affected by boldness, with bolder juveniles having a lower probability of survival than shyer juveniles. In contrast, bolder adult male bass had greater reproductive success than their shyer male counterparts. Female reproductive success was not affected by boldness. These findings demonstrate that boldness can affect fitness differently across life stages. Further, boldness was highly consistent across years and significantly heritable, which suggests that boldness has a genetic component. Thus, our results support theory suggesting that fitness trade-offs across life stages may contribute to the maintenance of personality variation within populations.

  16. Identifying fMRI Model Violations with Lagrange Multiplier Tests

    Science.gov (United States)

    Cassidy, Ben; Long, Christopher J; Rae, Caroline; Solo, Victor

    2013-01-01

    The standard modeling framework in Functional Magnetic Resonance Imaging (fMRI) is predicated on assumptions of linearity, time invariance and stationarity. These assumptions are rarely checked because doing so requires specialised software, although failure to do so can lead to bias and mistaken inference. Identifying model violations is an essential but largely neglected step in standard fMRI data analysis. Using Lagrange Multiplier testing methods we have developed simple and efficient procedures for detecting model violations such as non-linearity, non-stationarity and validity of the common Double Gamma specification for hemodynamic response. These procedures are computationally cheap and can easily be added to a conventional analysis. The test statistic is calculated at each voxel and displayed as a spatial anomaly map which shows regions where a model is violated. The methodology is illustrated with a large number of real data examples. PMID:22542665

  17. Anatomical and functional assemblies of brain BOLD oscillations

    Science.gov (United States)

    Baria, Alexis T.; Baliki, Marwan N.; Parrish, Todd; Apkarian, A. Vania

    2011-01-01

    Brain oscillatory activity has long been thought to have spatial properties, the details of which are unresolved. Here we examine spatial organizational rules for the human brain oscillatory activity as measured by blood oxygen level-dependent (BOLD). Resting state BOLD signal was transformed into frequency space (Welch’s method), averaged across subjects, and its spatial distribution studied as a function of four frequency bands, spanning the full bandwidth of BOLD. The brain showed anatomically constrained distribution of power for each frequency band. This result was replicated on a repository dataset of 195 subjects. Next, we examined larger-scale organization by parceling the neocortex into regions approximating Brodmann Areas (BAs). This indicated that BAs of simple function/connectivity (unimodal), vs. complex properties (transmodal), are dominated by low frequency BOLD oscillations, and within the visual ventral stream we observe a graded shift of power to higher frequency bands for BAs further removed from the primary visual cortex (increased complexity), linking frequency properties of BOLD to hodology. Additionally, BOLD oscillation properties for the default mode network demonstrated that it is composed of distinct frequency dependent regions. When the same analysis was performed on a visual-motor task, frequency-dependent global and voxel-wise shifts in BOLD oscillations could be detected at brain sites mostly outside those identified with general linear modeling. Thus, analysis of BOLD oscillations in full bandwidth uncovers novel brain organizational rules, linking anatomical structures and functional networks to characteristic BOLD oscillations. The approach also identifies changes in brain intrinsic properties in relation to responses to external inputs. PMID:21613505

  18. Oxytocin modulates hemodynamic responses to monetary incentives in humans.

    Science.gov (United States)

    Mickey, Brian J; Heffernan, Joseph; Heisel, Curtis; Peciña, Marta; Hsu, David T; Zubieta, Jon-Kar; Love, Tiffany M

    2016-12-01

    Oxytocin is a neuropeptide widely recognized for its role in regulating social and reproductive behavior. Increasing evidence from animal models suggests that oxytocin also modulates reward circuitry in non-social contexts, but evidence in humans is lacking. We examined the effects of oxytocin administration on reward circuit function in 18 healthy men as they performed a monetary incentive task. The blood oxygenation level-dependent (BOLD) signal was measured using functional magnetic resonance imaging in the context of a randomized, double-blind, placebo-controlled, crossover trial of intranasal oxytocin. We found that oxytocin increases the BOLD signal in the midbrain (substantia nigra and ventral tegmental area) during the late phase of the hemodynamic response to incentive stimuli. Oxytocin's effects on midbrain responses correlated positively with its effects on positive emotional state. We did not detect an effect of oxytocin on responses in the nucleus accumbens. Whole-brain analyses revealed that oxytocin attenuated medial prefrontal cortical deactivation specifically during anticipation of loss. Our findings demonstrate that intranasal administration of oxytocin modulates human midbrain and medial prefrontal function during motivated behavior. These findings suggest that endogenous oxytocin is a neurochemical mediator of reward behaviors in humans-even in a non-social context-and that the oxytocinergic system is a potential target of pharmacotherapy for psychiatric disorders that involve dysfunction of reward circuitry.

  19. Oxytocin modulates hemodynamic responses to monetary incentives in humans

    Science.gov (United States)

    Mickey, Brian J.; Heffernan, Joseph; Heisel, Curtis; Peciña, Marta; Hsu, David T.; Zubieta, Jon-Kar; Love, Tiffany M.

    2016-01-01

    Oxytocin is a neuropeptide widely recognized for its role in regulating social and reproductive behavior. Increasing evidence from animal models suggests that oxytocin also modulates reward circuitry in non-social contexts, but evidence in humans is lacking. Here we examined the effects of oxytocin administration on reward circuit function in 18 healthy men as they performed a monetary incentive task. The blood oxygenation level dependent (BOLD) signal was measured using functional magnetic resonance imaging in the context of a randomized, double-blind, placebo-controlled, crossover trial of intranasal oxytocin. We found that oxytocin increases the BOLD signal in the midbrain (substantia nigra and ventral tegmental area) during the late phase of the hemodynamic response to incentive stimuli. Oxytocin’s effects on midbrain responses correlated positively with its effects on positive emotional state. We did not detect an effect of oxytocin on responses in the nucleus accumbens. Whole-brain analyses revealed that oxytocin attenuated medial prefrontal cortical deactivation specifically during anticipation of loss. Our findings demonstrate that intranasal administration of oxytocin modulates human midbrain and medial prefrontal function during motivated behavior. These findings suggest that endogenous oxytocin is a neurochemical mediator of reward behaviors in humans – even in a non-social context – and that the oxytocinergic system is a potential target of pharmacotherapy for psychiatric disorders that involve dysfunction of reward circuitry. PMID:27614896

  20. Activation of dorsolateral prefrontal cortex in a dual neuropsychological screening test: An fMRI approach

    Directory of Open Access Journals (Sweden)

    Tachibana Atsumichi

    2012-05-01

    Full Text Available Abstract Background The Kana Pick-out Test (KPT, which uses Kana or Japanese symbols that represent syllables, requires parallel processing of discrete (pick-out and continuous (reading dual tasks. As a dual task, the KPT is thought to test working memory and executive function, particularly in the prefrontal cortex (PFC, and is widely used in Japan as a clinical screen for dementia. Nevertheless, there has been little neurological investigation into PFC activity during this test. Methods We used functional magnetic resonance imaging (fMRI to evaluate changes in the blood oxygenation level-dependent (BOLD signal in young healthy adults during performance of a computerized KPT dual task (comprised of reading comprehension and picking out vowels and compared it to its single task components (reading or vowel pick-out alone. Results Behavioral performance of the KPT degraded compared to its single task components. Performance of the KPT markedly increased BOLD signal intensity in the PFC, and also activated sensorimotor, parietal association, and visual cortex areas. In conjunction analyses, bilateral BOLD signal in the dorsolateral PFC (Brodmann's areas 45, 46 was present only in the KPT. Conclusions Our results support the central bottleneck theory and suggest that the dorsolateral PFC is an important mediator of neural activity for both short-term storage and executive processes. Quantitative evaluation of the KPT with fMRI in healthy adults is the first step towards understanding the effects of aging or cognitive impairment on KPT performance.

  1. Cerebral hemodynamics in migraine

    DEFF Research Database (Denmark)

    Hachinski, V C; Olesen, Jes; Norris, J W

    1977-01-01

    Clinical and angiographic findings in migraine are briefly reviewed in relation to cerebral hemodynamic changes shown by regional cerebral blood flow (rCBF) studies. Three cases of migraine studied by the intracarotid xenon 133 method during attacks are reported. In classic migraine, with typical...... prodromal symptoms, a decrease in cerebral blood flow has been demonstrated during the aura. Occasionally, this flow decrease persists during the headache phase. In common migraine, where such prodromata are not seen, a flow decrease has not been demonstrated. During the headache phase of both types...... of migraine, rCBF has usually been found to be normal or in the high range of normal values. The high values may represent postischemic hyperemia, but are probably more frequently secondary to arousal caused by pain. Thus, during the headache phase rCBF may be subnormal, normal or high. These findings do...

  2. 17 CFR 232.307 - Bold face type.

    Science.gov (United States)

    2010-04-01

    ... an electronic format document by presenting such information in capital letters. (b) Paragraph (a) of this section does not apply to HTML documents. ...-GENERAL RULES AND REGULATIONS FOR ELECTRONIC FILINGS Preparation of Electronic Submissions § 232.307 Bold...

  3. Neurovascular and neurometabolic couplings in dynamic calibrated fMRI: transient oxidative neuroenergetics for block-design and event-related paradigms

    Directory of Open Access Journals (Sweden)

    D. S. Fahmeed Hyder

    2010-08-01

    Full Text Available Functional magnetic resonance imaging (fMRI with blood-oxygenation level dependent (BOLD contrast is an important tool for mapping brain activity. Interest in quantitative fMRI has renewed awareness in importance of oxidative neuroenergetics, as reflected by cerebral metabolic rate of oxygen consumption (CMRO2, for supporting brain function. Relationships between BOLD signal and the underlying neurophysiological parameters have been elucidated to allow determination of dynamic changes in CMRO2 by “calibrated fMRI”, which require multi-modal measurements of BOLD signal along with cerebral blood flow (CBF and volume (CBV. But how do CMRO2 changes, steady-state or transient, derived from calibrated fMRI compare with neural activity recordings of local field potential (LFP and/or multi-unit activity (MUA? Here we discuss recent findings primarily from animal studies which allow high magnetic fields studies for superior BOLD sensitivity as well as multi-modal CBV and CBF measurements in conjunction with LFP and MUA recordings from activated sites. A key observation is that while relationships between neural activity and sensory stimulus features range from linear to non-linear, associations between hyperemic components (BOLD, CBF, CBV and neural activity (LFP, MUA are almost always linear. More importantly, the results demonstrate good agreement between the changes in CMRO2 and independent measures of LFP or MUA. The tight neurovascular and neurometabolic couplings, observed from steady-state conditions to events separated by <200 ms, suggest rapid oxygen equilibration between blood and tissue pools and thus calibrated fMRI at high magnetic fields can provide high spatiotemporal mapping of CMRO2 changes.

  4. Robust resting state fMRI processing for studies on typical brain development based on multi-echo EPI acquisition.

    Science.gov (United States)

    Kundu, Prantik; Benson, Brenda E; Baldwin, Katherine L; Rosen, Dana; Luh, Wen-Ming; Bandettini, Peter A; Pine, Daniel S; Ernst, Monique

    2015-03-01

    Several methodological challenges affect the study of typical brain development based on resting state blood oxygenation level dependent (BOLD) functional MRI (fMRI). One such challenge is mitigating artifacts such as those from head motion, known to be more substantial in younger subjects than older subjects. Other challenges include controlling for potential age-dependence in cerebrospinal fluid (CSF) volume affecting anatomical-functional coregistration; in vascular density affecting BOLD contrast-to-noise; and in CSF pulsation creating time series artifacts. Historically, these confounds have been approached through incorporating artifact-specific temporal and/or spatial filtering into preprocessing pipelines. However, such paths often come with new confounds or limitations. In this study we take the approach of a bottom-up revision of fMRI methodology based on acquisition of multi-echo fMRI and comprehensive utilization of the information in the TE-domain to enhance several aspects of fMRI analysis in the context of a developmental study. We show in a cohort of 25 healthy subjects, aged 9 to 43 years, that the analysis of multi-echo fMRI data eliminates a number of arbitrary processing steps such as bandpass filtering and spatial smoothing, while enabling procedures such as [Formula: see text] mapping, BOLD contrast normalization and signal dropout recovery, precise anatomical-functional coregistration based on [Formula: see text] measurements, automatic denoising through removing subject motion, scanner-related signal drifts and physiology, as well as statistical inference for seed-based connectivity. These enhancements are of both theoretical significance and practical benefit in the study of typical brain development.

  5. Adaptation of a haptic robot in a 3T fMRI.

    Science.gov (United States)

    Snider, Joseph; Plank, Markus; May, Larry; Liu, Thomas T; Poizner, Howard

    2011-10-04

    Functional magnetic resonance imaging (fMRI) provides excellent functional brain imaging via the BOLD signal with advantages including non-ionizing radiation, millimeter spatial accuracy of anatomical and functional data, and nearly real-time analyses. Haptic robots provide precise measurement and control of position and force of a cursor in a reasonably confined space. Here we combine these two technologies to allow precision experiments involving motor control with haptic/tactile environment interaction such as reaching or grasping. The basic idea is to attach an 8 foot end effecter supported in the center to the robot allowing the subject to use the robot, but shielding it and keeping it out of the most extreme part of the magnetic field from the fMRI machine (Figure 1). The Phantom Premium 3.0, 6DoF, high-force robot (SensAble Technologies, Inc.) is an excellent choice for providing force-feedback in virtual reality experiments, but it is inherently non-MR safe, introduces significant noise to the sensitive fMRI equipment, and its electric motors may be affected by the fMRI's strongly varying magnetic field. We have constructed a table and shielding system that allows the robot to be safely introduced into the fMRI environment and limits both the degradation of the fMRI signal by the electrically noisy motors and the degradation of the electric motor performance by the strongly varying magnetic field of the fMRI. With the shield, the signal to noise ratio (SNR: mean signal/noise standard deviation) of the fMRI goes from a baseline of ~380 to ~330, and ~250 without the shielding. The remaining noise appears to be uncorrelated and does not add artifacts to the fMRI of a test sphere (Figure 2). The long, stiff handle allows placement of the robot out of range of the most strongly varying parts of the magnetic field so there is no significant effect of the fMRI on the robot. The effect of the handle on the robot's kinematics is minimal since it is lightweight (~2

  6. Interneuronal systems of the cervical spinal cord assessed with BOLD imaging at 1.5 T

    Energy Technology Data Exchange (ETDEWEB)

    Stracke, C.P.; Schoth, F.; Moeller-Hartmann, W.; Krings, T. [University Hospital of the University of Technology, Departments of Neuroradiology and Diagnostic Radiology, Aachen (Germany); Pettersson, L.G. [University of Goeteborg, Department of Physiology, Goeteborg (Sweden)

    2005-02-01

    The purpose of this study was to investigate if functional activity with spinal cord somatosensory stimulation can be visualized using BOLD fMRI. We investigated nine healthy volunteers using a somatosensory stimulus generator. The stimuli were applied in three different runs at the first, third, and fifth finger tip of the right hand, respectively, corresponding to dermatomes c6, c7, and c8. The stimuli gave an increase of BOLD signal (activation) in three different locations of the spinal cord and brain stem. First, activations could be seen in the spinal segment corresponding to the stimulated dermatome in seven out of nine volunteers for c6 stimulation, two out of eight for c7, and three out of eight for c8. These activations were located close to the posterior margin of the spinal cord, presumably reflecting synaptic transmission to dorsal horn interneurons. Second, activation in the medulla oblongata was evident in four subjects, most likely corresponding to the location of the nucleus cuneatus. The third location of activation, which was the strongest and most reliable observed was inside the spinal cord in the c3 and c4 segments. Activation at these spinal levels was almost invariably observed independently of the dermatome stimulated (9/9 for c6, 8/8 for c7, and 7/8 for c8 stimulation). These activations may pertain to an interneuronal system at this spinal level. The results are discussed in relation to neurophysiological studies on cervical spinal interneuronal pathways in animals and humans. (orig.)

  7. Pre-stimulus BOLD-network activation modulates EEG spectral activity during working memory retention

    Directory of Open Access Journals (Sweden)

    Mara eKottlow

    2015-05-01

    Full Text Available Working memory (WM processes depend on our momentary mental state and therefore exhibit considerable fluctuations. Here, we investigate the interplay of task-preparatory and task-related brain activity as represented by pre-stimulus BOLD-fluctuations and spectral EEG from the retention periods of a visual WM task. Visual WM is used to maintain sensory information in the brain enabling the performance of cognitive operations and is associated with mental health.We tested 22 subjects simultaneously with EEG and fMRI while performing a visuo-verbal Sternberg task with two different loads, allowing for the temporal separation of preparation, encoding, retention and retrieval periods.Four temporally coherent networks - the default mode network (DMN, the dorsal attention, the right and the left WM network - were extracted from the continuous BOLD data by means of a group ICA. Subsequently, the modulatory effect of these networks’ pre-stimulus activation upon retention-related EEG activity in the theta, alpha and beta frequencies was analyzed. The obtained results are informative in the context of state-dependent information processing.We were able to replicate two well-known load-dependent effects: the frontal-midline theta increase during the task and the decrease of pre-stimulus DMN activity. As our main finding, these two measures seem to depend on each other as the significant negative correlations at frontal-midline channels suggested. Thus, suppressed pre-stimulus DMN levels facilitated later task related frontal midline theta increases. In general, based on previous findings that neuronal coupling in different frequency bands may underlie distinct functions in WM retention, our results suggest that processes reflected by spectral oscillations during retention seem not only to be online synchronized with activity in different attention-related networks but are also modulated by activity in these networks during preparation intervals.

  8. Interneuronal systems of the cervical spinal cord assessed with BOLD imaging at 1.5 T

    International Nuclear Information System (INIS)

    Stracke, C.P.; Schoth, F.; Moeller-Hartmann, W.; Krings, T.; Pettersson, L.G.

    2005-01-01

    The purpose of this study was to investigate if functional activity with spinal cord somatosensory stimulation can be visualized using BOLD fMRI. We investigated nine healthy volunteers using a somatosensory stimulus generator. The stimuli were applied in three different runs at the first, third, and fifth finger tip of the right hand, respectively, corresponding to dermatomes c6, c7, and c8. The stimuli gave an increase of BOLD signal (activation) in three different locations of the spinal cord and brain stem. First, activations could be seen in the spinal segment corresponding to the stimulated dermatome in seven out of nine volunteers for c6 stimulation, two out of eight for c7, and three out of eight for c8. These activations were located close to the posterior margin of the spinal cord, presumably reflecting synaptic transmission to dorsal horn interneurons. Second, activation in the medulla oblongata was evident in four subjects, most likely corresponding to the location of the nucleus cuneatus. The third location of activation, which was the strongest and most reliable observed was inside the spinal cord in the c3 and c4 segments. Activation at these spinal levels was almost invariably observed independently of the dermatome stimulated (9/9 for c6, 8/8 for c7, and 7/8 for c8 stimulation). These activations may pertain to an interneuronal system at this spinal level. The results are discussed in relation to neurophysiological studies on cervical spinal interneuronal pathways in animals and humans. (orig.)

  9. Investigating the Group-Level Impact of Advanced Dual-Echo fMRI Combinations

    Directory of Open Access Journals (Sweden)

    Adam Kettinger

    2016-12-01

    Full Text Available Multi-echo fMRI data acquisition has been widely investigated and suggested to optimize sensitivity for detecting the BOLD signal. Several methods have also been proposed for the combination of data with different echo times. The aim of the present study was to investigate how these advance echo combination methods provide advantages over the simple averaging of echoes when state-of-the-art group-level random-effect analyses are performed. Both resting-state and task-based dual-echo fMRI data were collected from 27 healthy adult individuals (14 male, mean age = 25.75 years using standard echo-planar acquisition methods at 3T. Both resting-state and task-based data were subjected to a standard image pre-processing pipeline. Subsequently the two echoes were combined as a weighted average, using four different strategies for calculating the weights: (1 simple arithmetic averaging, (2 BOLD sensitivity weighting, (3 temporal-signal-to-noise ratio weighting and (4 temporal BOLD sensitivity weighting. Our results clearly show that the simple averaging of data with the different echoes is sufficient. Advanced echo combination methods may provide advantages on a single-subject level but when considering random-effects group level statistics they provide no benefit regarding sensitivity (i.e. group-level t-values compared to the simple echo-averaging approach. One possible reason for the lack of clear advantages may be that apart from increasing the average BOLD sensitivity at the single-subject level, the advanced weighted averaging methods also inflate the inter-subject variance. As the echo combination methods provide very similar results, the recommendation is to choose between them depending on the availability of time for collecting additional resting-state data or whether subject-level or group-level analyses are planned.

  10. Gender differences in brain areas involved in silent counting by means of fMRI

    OpenAIRE

    ?veljo, Olivera B; Kopriv?ek, Katarina M; Lu?i?, Milo? A; Prvulovi?, Mladen B; ?uli?, Milka

    2010-01-01

    Background Pattern of brain asymmetries varies with handedness, gender, age, and with variety of genetic and social factors. Large-scale neuroimaging analyses can optimize the detection of asymmetric features and confirm the factors that might modulate pattern of brain asymmetries. We attempted to evaluate eventual differences between genders in hemodynamic responses to a simple language task. Methods 12 healthy right-handed volunteers (age 24-46), 6 men and 6 women underwent fMRI scanning wh...

  11. Self-Regulation of Amygdala Activation Using Real-Time fMRI Neurofeedback

    Science.gov (United States)

    Phillips, Raquel; Alvarez, Ruben P.; Simmons, W. Kyle; Bellgowan, Patrick; Drevets, Wayne C.; Bodurka, Jerzy

    2011-01-01

    Real-time functional magnetic resonance imaging (rtfMRI) with neurofeedback allows investigation of human brain neuroplastic changes that arise as subjects learn to modulate neurophysiological function using real-time feedback regarding their own hemodynamic responses to stimuli. We investigated the feasibility of training healthy humans to self-regulate the hemodynamic activity of the amygdala, which plays major roles in emotional processing. Participants in the experimental group were provided with ongoing information about the blood oxygen level dependent (BOLD) activity in the left amygdala (LA) and were instructed to raise the BOLD rtfMRI signal by contemplating positive autobiographical memories. A control group was assigned the same task but was instead provided with sham feedback from the left horizontal segment of the intraparietal sulcus (HIPS) region. In the LA, we found a significant BOLD signal increase due to rtfMRI neurofeedback training in the experimental group versus the control group. This effect persisted during the Transfer run without neurofeedback. For the individual subjects in the experimental group the training effect on the LA BOLD activity correlated inversely with scores on the Difficulty Identifying Feelings subscale of the Toronto Alexithymia Scale. The whole brain data analysis revealed significant differences for Happy Memories versus Rest condition between the experimental and control groups. Functional connectivity analysis of the amygdala network revealed significant widespread correlations in a fronto-temporo-limbic network. Additionally, we identified six regions — right medial frontal polar cortex, bilateral dorsomedial prefrontal cortex, left anterior cingulate cortex, and bilateral superior frontal gyrus — where the functional connectivity with the LA increased significantly across the rtfMRI neurofeedback runs and the Transfer run. The findings demonstrate that healthy subjects can learn to regulate their amygdala

  12. Tactile and non-tactile sensory paradigms for fMRI and neurophysiologic studies in rodents.

    Science.gov (United States)

    Sanganahalli, Basavaraju G; Bailey, Christopher J; Herman, Peter; Hyder, Fahmeed

    2009-01-01

    Functional magnetic resonance imaging (fMRI) has become a popular functional imaging tool for human studies. Future diagnostic use of fMRI depends, however, on a suitable neurophysiologic interpretation of the blood oxygenation level dependent (BOLD) signal change. This particular goal is best achieved in animal models primarily due to the invasive nature of other methods used and/or pharmacological agents applied to probe different nuances of neuronal (and glial) activity coupled to the BOLD signal change. In the last decade, we have directed our efforts towards the development of stimulation protocols for a variety of modalities in rodents with fMRI. Cortical perception of the natural world relies on the formation of multi-dimensional representation of stimuli impinging on the different sensory systems, leading to the hypothesis that a sensory stimulus may have very different neurophysiologic outcome(s) when paired with a near simultaneous event in another modality. Before approaching this level of complexity, reliable measures must be obtained of the relatively small changes in the BOLD signal and other neurophysiologic markers (electrical activity, blood flow) induced by different peripheral stimuli. Here we describe different tactile (i.e., forepaw, whisker) and non-tactile (i.e., olfactory, visual) sensory paradigms applied to the anesthetized rat. The main focus is on development and validation of methods for reproducible stimulation of each sensory modality applied independently or in conjunction with one another, both inside and outside the magnet. We discuss similarities and/or differences across the sensory systems as well as advantages they may have for studying essential neuroscientific questions. We envisage that the different sensory paradigms described here may be applied directly to studies of multi-sensory interactions in anesthetized rats, en route to a rudimentary understanding of the awake functioning brain where various sensory cues presumably

  13. Aging effects on functional auditory and visual processing using fMRI with variable sensory loading.

    Science.gov (United States)

    Cliff, Michael; Joyce, Dan W; Lamar, Melissa; Dannhauser, Thomas; Tracy, Derek K; Shergill, Sukhwinder S

    2013-05-01

    Traditionally, studies investigating the functional implications of age-related structural brain alterations have focused on higher cognitive processes; by increasing stimulus load, these studies assess behavioral and neurophysiological performance. In order to understand age-related changes in these higher cognitive processes, it is crucial to examine changes in visual and auditory processes that are the gateways to higher cognitive functions. This study provides evidence for age-related functional decline in visual and auditory processing, and regional alterations in functional brain processing, using non-invasive neuroimaging. Using functional magnetic resonance imaging (fMRI), younger (n=11; mean age=31) and older (n=10; mean age=68) adults were imaged while observing flashing checkerboard images (passive visual stimuli) and hearing word lists (passive auditory stimuli) across varying stimuli presentation rates. Younger adults showed greater overall levels of temporal and occipital cortical activation than older adults for both auditory and visual stimuli. The relative change in activity as a function of stimulus presentation rate showed differences between young and older participants. In visual cortex, the older group showed a decrease in fMRI blood oxygen level dependent (BOLD) signal magnitude as stimulus frequency increased, whereas the younger group showed a linear increase. In auditory cortex, the younger group showed a relative increase as a function of word presentation rate, while older participants showed a relatively stable magnitude of fMRI BOLD response across all rates. When analyzing participants across all ages, only the auditory cortical activation showed a continuous, monotonically decreasing BOLD signal magnitude as a function of age. Our preliminary findings show an age-related decline in demand-related, passive early sensory processing. As stimulus demand increases, visual and auditory cortex do not show increases in activity in older

  14. Assessment of language lateralization with functional magnetic resonance imaging (fMRI)

    International Nuclear Information System (INIS)

    Salagierska-Barwinska, A.; Goraj, B.

    2004-01-01

    fMRI offers powerful methods to delineate which brain regions are engaged in language processing in the intact brain. Until now hemisphere dominance for language has been usually assessed by means of the intraoperative methods: the Wada test or electrocortical stimulation mapping. Recently functional MRI becomes the valuable method in determining hemisphere dominance for language. fMRI study was proved to be concordant with invasive measures. fMRI was carried out in 30 healthy selected participants (15 females: 10 strongly right-handed and 5 strongly left-handed; 15 males: 10 strongly right-handed and 5 strongly left-handed). The subject's handedness was assessed by standardized psychological tests inter alia the 'lateralization inventory'. Two different language tasks were used: a verb generation task and a phonological task. Subjects were scanned,while performing experimental block. The block contained alternately 8 active (language task) and 8 control conditions. Statistical analysis of evoked blood oxygenation level-dependent BOLD) responses, measured with echo planar imagining (1.5 T) were used. During a verb generation task in strongly right or left handed subjects the inferior frontal region was activated on the side opposite to the subject's handedness determined by the psychological test. Our fMRI studies demonstrated no gender effects on brain during these language tasks. Our study suggests that fMRI is a good device for the study of the language organization. The advantage of fMRI is its capacity for exact localization of activated areas. fMRI together with adequate neurolinguistic test could be promising routine preoperative tool in identification hemisphere dominance for language. These results encourage to further investigation for evaluating correlation in patients with brain injuries. (author)

  15. fMRI of the auditory system: understanding the neural basis of auditory gestalt.

    Science.gov (United States)

    Di Salle, Francesco; Esposito, Fabrizio; Scarabino, Tommaso; Formisano, Elia; Marciano, Elio; Saulino, Claudio; Cirillo, Sossio; Elefante, Raffaele; Scheffler, Klaus; Seifritz, Erich

    2003-12-01

    Functional magnetic resonance imaging (fMRI) has rapidly become the most widely used imaging method for studying brain functions in humans. This is a result of its extreme flexibility of use and of the astonishingly detailed spatial and temporal information it provides. Nevertheless, until very recently, the study of the auditory system has progressed at a considerably slower pace compared to other functional systems. Several factors have limited fMRI research in the auditory field, including some intrinsic features of auditory functional anatomy and some peculiar interactions between fMRI technique and audition. A well known difficulty arises from the high intensity acoustic noise produced by gradient switching in echo-planar imaging (EPI), as well as in other fMRI sequences more similar to conventional MR sequences. The acoustic noise interacts in an unpredictable way with the experimental stimuli both from a perceptual point of view and in the evoked hemodynamics. To overcome this problem, different approaches have been proposed recently that generally require careful tailoring of the experimental design and the fMRI methodology to the specific requirements posed by the auditory research. The novel methodological approaches can make the fMRI exploration of auditory processing much easier and more reliable, and thus may permit filling the gap with other fields of neuroscience research. As a result, some fundamental neural underpinnings of audition are being clarified, and the way sound stimuli are integrated in the auditory gestalt are beginning to be understood.

  16. Resting-state fMRI: A window into human brain plasticity

    OpenAIRE

    Guerra-Carrillo, B; MacKey, AP; Bunge, SA

    2014-01-01

    © The Author(s) 2014. Although brain plasticity is greatest in the first few years of life, the brain continues to be shaped by experience throughout adulthood. Advances in fMRI have enabled us to examine the plasticity of large-scale networks using blood oxygen level-dependent (BOLD) correlations measured at rest. Resting-state functional connectivity analysis makes it possible to measure task-independent changes in brain function and therefore could provide unique insights into experience-d...

  17. Metabolic Changes Underlying Bold Signal Variations after Administration of Zolpidem

    International Nuclear Information System (INIS)

    Rodriguez-Rojas, Rafael; Machado, Calixto; Alvarez, Lazaro; Carballo, Maylen; Perez-Nellar, Jesus; Estevez, Mario; Pavon, Nancy; Chinchilla, Mauricio

    2010-12-01

    Zolpidem is a non-benzodiazepine drug belonging to the imidazopiridine class, which has selectivity for stimulating the effect of gamma aminobutyric acid [GABA] and is used for the therapy of insomnia. Nonetheless, several reports have been published over recent years about a paradoxical arousing effect of Zolpidem in patients with severe brain damage. We studied a PVS case using 1 H-MRS and BOLD signal, before and after Zolpidem administration. Significantly increased BOLD signal was localized in left frontal superior cortex, bilateral cingulated areas, left thalamus and right head of the caudate nucleus. A transient activation was observed in frontal cortex, comprising portions of anterior cingulate, medial, and orbito-frontal cortices. Additionally, significant pharmacological activation in sensory-motor cortex is observed 1 hour after Zolpidem intake. Significant linear correlations of BOLD signal changes were found with primary concentrations of NAA, Glx and Lac in the right frontal cortex. We discussed that when Zolpidem attaches to the modified GABA receptors of the neurodormant cells, dormancy is switched off, inducing brain activation. This might explain the significant correlations of BOLD signal changes and 1 H-MRS metabolites in our patient. We concluded that 1 H-MRS and BOLD signal assessment might contribute to study neurovascular coupling in PVS cases after Zolpidem administration. Although this is a report of a single case, considering our results we recommend to apply this methodology in series of PVS and MCS patients. (author)

  18. Graph Theoretical Analysis of BOLD Functional Connectivity during Human Sleep without EEG Monitoring.

    Directory of Open Access Journals (Sweden)

    Jun Lv

    Full Text Available Functional brain networks of human have been revealed to have small-world properties by both analyzing electroencephalogram (EEG and functional magnetic resonance imaging (fMRI time series.In our study, by using graph theoretical analysis, we attempted to investigate the changes of paralimbic-limbic cortex between wake and sleep states. Ten healthy young people were recruited to our experiment. Data from 2 subjects were excluded for the reason that they had not fallen asleep during the experiment. For each subject, blood oxygen level dependency (BOLD images were acquired to analyze brain network, and peripheral pulse signals were obtained continuously to identify if the subject was in sleep periods. Results of fMRI showed that brain networks exhibited stronger small-world characteristics during sleep state as compared to wake state, which was in consistent with previous studies using EEG synchronization. Moreover, we observed that compared with wake state, paralimbic-limbic cortex had less connectivity with neocortical system and centrencephalic structure in sleep.In conclusion, this is the first study, to our knowledge, has observed that small-world properties of brain functional networks altered when human sleeps without EEG synchronization. Moreover, we speculate that paralimbic-limbic cortex organization owns an efficient defense mechanism responsible for suppressing the external environment interference when humans sleep, which is consistent with the hypothesis that the paralimbic-limbic cortex may be functionally disconnected from brain regions which directly mediate their interactions with the external environment. Our findings also provide a reasonable explanation why stable sleep exhibits homeostasis which is far less susceptible to outside world.

  19. Graph Theoretical Analysis of BOLD Functional Connectivity during Human Sleep without EEG Monitoring.

    Science.gov (United States)

    Lv, Jun; Liu, Dongdong; Ma, Jing; Wang, Xiaoying; Zhang, Jue

    2015-01-01

    Functional brain networks of human have been revealed to have small-world properties by both analyzing electroencephalogram (EEG) and functional magnetic resonance imaging (fMRI) time series. In our study, by using graph theoretical analysis, we attempted to investigate the changes of paralimbic-limbic cortex between wake and sleep states. Ten healthy young people were recruited to our experiment. Data from 2 subjects were excluded for the reason that they had not fallen asleep during the experiment. For each subject, blood oxygen level dependency (BOLD) images were acquired to analyze brain network, and peripheral pulse signals were obtained continuously to identify if the subject was in sleep periods. Results of fMRI showed that brain networks exhibited stronger small-world characteristics during sleep state as compared to wake state, which was in consistent with previous studies using EEG synchronization. Moreover, we observed that compared with wake state, paralimbic-limbic cortex had less connectivity with neocortical system and centrencephalic structure in sleep. In conclusion, this is the first study, to our knowledge, has observed that small-world properties of brain functional networks altered when human sleeps without EEG synchronization. Moreover, we speculate that paralimbic-limbic cortex organization owns an efficient defense mechanism responsible for suppressing the external environment interference when humans sleep, which is consistent with the hypothesis that the paralimbic-limbic cortex may be functionally disconnected from brain regions which directly mediate their interactions with the external environment. Our findings also provide a reasonable explanation why stable sleep exhibits homeostasis which is far less susceptible to outside world.

  20. Fractal analysis of spontaneous fluctuations of the BOLD signal in the human brain networks.

    Science.gov (United States)

    Li, Yi-Chia; Huang, Yun-An

    2014-05-01

    To investigate what extent brain regions are continuously interacting during resting-state, independent component analyses (ICA) was applied to analyze resting-state functional MRI (RS-fMRI) data. According to the analyzed results, it was surprisingly found that low frequency fluctuations (LFFs), which belong to the 1/f signal (a signal with power spectrum whose power spectral density is inversely proportional to the frequency), have been classified into groups using ICA; furthermore, the spatial distributions of these groups within the brain were found to resemble the spatial distributions of different networks, which manifests that the signal characteristics of RS LFFs are distinct across networks. In our work, we applied the 1/f model in the fractal analyses to further investigate this distinction. Twenty healthy participants got involved in this study. They were scanned to acquire the RS-fMRI data. The acquired data were first processed with ICA to obtain the networks of the resting brain. Afterward, the blood-oxygenation level dependent (BOLD) signals of these networks were processed with the fractal analyses for obtaining the fractal parameter α. α was found to significantly vary across networks, which reveals that the fractal characteristic of LFFs differs across networks. According to prior literatures, this difference could be brought by the discrepancy of hemodynamic response amplitude (HRA) between networks. Hence, in our work, we also performed the computational simulation to discover the relationship between α and HRA. Based on the simulation results, HRA is highly linear-correlated with the fractal characteristics of LFFs which is revealed by α. Our results support that the origin of RS-fMRI signals contains arterial fluctuations. Hence, in addition to the commonly used method such as synchrony analysis and power spectral analysis, another approach, the fractal analysis, is suggested for acquiring the information of hemodynamic responses by means

  1. Improving effect size estimation and statistical power with multi-echo fMRI and its impact on understanding the neural systems supporting mentalizing.

    Science.gov (United States)

    Lombardo, Michael V; Auyeung, Bonnie; Holt, Rosemary J; Waldman, Jack; Ruigrok, Amber N V; Mooney, Natasha; Bullmore, Edward T; Baron-Cohen, Simon; Kundu, Prantik

    2016-11-15

    Functional magnetic resonance imaging (fMRI) research is routinely criticized for being statistically underpowered due to characteristically small sample sizes and much larger sample sizes are being increasingly recommended. Additionally, various sources of artifact inherent in fMRI data can have detrimental impact on effect size estimates and statistical power. Here we show how specific removal of non-BOLD artifacts can improve effect size estimation and statistical power in task-fMRI contexts, with particular application to the social-cognitive domain of mentalizing/theory of mind. Non-BOLD variability identification and removal is achieved in a biophysical and statistically principled manner by combining multi-echo fMRI acquisition and independent components analysis (ME-ICA). Without smoothing, group-level effect size estimates on two different mentalizing tasks were enhanced by ME-ICA at a median rate of 24% in regions canonically associated with mentalizing, while much more substantial boosts (40-149%) were observed in non-canonical cerebellar areas. Effect size boosting occurs via reduction of non-BOLD noise at the subject-level and consequent reductions in between-subject variance at the group-level. Smoothing can attenuate ME-ICA-related effect size improvements in certain circumstances. Power simulations demonstrate that ME-ICA-related effect size enhancements enable much higher-powered studies at traditional sample sizes. Cerebellar effects observed after applying ME-ICA may be unobservable with conventional imaging at traditional sample sizes. Thus, ME-ICA allows for principled design-agnostic non-BOLD artifact removal that can substantially improve effect size estimates and statistical power in task-fMRI contexts. ME-ICA could mitigate some issues regarding statistical power in fMRI studies and enable novel discovery of aspects of brain organization that are currently under-appreciated and not well understood. Copyright © 2016 The Authors. Published

  2. Regional homogeneity changes in prelingually deafened patients: a resting-state fMRI study

    Science.gov (United States)

    Li, Wenjing; He, Huiguang; Xian, Junfang; Lv, Bin; Li, Meng; Li, Yong; Liu, Zhaohui; Wang, Zhenchang

    2010-03-01

    Resting-state functional magnetic resonance imaging (fMRI) is a technique that measures the intrinsic function of brain and has some advantages over task-induced fMRI. Regional homogeneity (ReHo) assesses the similarity of the time series of a given voxel with its nearest neighbors on a voxel-by-voxel basis, which reflects the temporal homogeneity of the regional BOLD signal. In the present study, we used the resting state fMRI data to investigate the ReHo changes of the whole brain in the prelingually deafened patients relative to normal controls. 18 deaf patients and 22 healthy subjects were scanned. Kendall's coefficient of concordance (KCC) was calculated to measure the degree of regional coherence of fMRI time courses. We found that regional coherence significantly decreased in the left frontal lobe, bilateral temporal lobes and right thalamus, and increased in the postcentral gyrus, cingulate gyrus, left temporal lobe, left thalamus and cerebellum in deaf patients compared with controls. These results show that the prelingually deafened patients have higher degree of regional coherence in the paleocortex, and lower degree in neocortex. Since neocortex plays an important role in the development of auditory, these evidences may suggest that the deaf persons reorganize the paleocortex to offset the loss of auditory.

  3. Simultaneously estimating the task-related and stimulus-evoked components of hemodynamic imaging measurements.

    Science.gov (United States)

    Herman, Max Charles; Cardoso, Mariana M B; Lima, Bruss; Sirotin, Yevgeniy B; Das, Aniruddha

    2017-07-01

    Task-related hemodynamic responses contribute prominently to functional magnetic resonance imaging (fMRI) recordings. They reflect behaviorally important brain states, such as arousal and attention, and can dominate stimulus-evoked responses, yet they remain poorly understood. To help characterize these responses, we present a method for parametrically estimating both stimulus-evoked and task-related components of hemodynamic responses from subjects engaged in temporally predictable tasks. The stimulus-evoked component is modeled by convolving a hemodynamic response function (HRF) kernel with spiking. The task-related component is modeled by convolving a Fourier-series task-related function (TRF) kernel with task timing. We fit this model with simultaneous electrode recordings and intrinsic-signal optical imaging from the primary visual cortex of alert, task-engaged monkeys. With high [Formula: see text], the model returns HRFs that are consistent across experiments and recording sites for a given animal and TRFs that entrain to task timing independent of stimulation or local spiking. When the task schedule conflicts with that of stimulation, the TRF remains locked to the task emphasizing its behavioral origins. The current approach is strikingly more robust to fluctuations than earlier ones and gives consistently, if modestly, better fits. This approach could help parse the distinct components of fMRI recordings made in the context of a task.

  4. [Hemodynamic changes in hypoglycemic shock].

    Science.gov (United States)

    Gutiérrez, C; Piza, R; Chousleb, A; Hidalgo, M A; Ortigosa, J L

    1977-01-01

    Severe hypoglycemia may be present in seriously ill patients; if it is not corrected opportunely a series of neuroendocrinal mechanisms take place aimed at correcting metabolic alterations. These mechanisms can produce hemodynamic alterations as well. Nine mongrel dogs were studied with continuous registration of: blood pressure, central venous pressure, cardiac frequency, respiratory frequency, electrocardiogram and first derivative (Dp/Dt). Six dogs received crystalline (fast acting) insuline intravenously (group 1). After hemodynamic changes were registered hypoglycemia was corrected with 50 per cent glucose solution. Complementary insuline doses were administered to three dogs (group 2); in this group hypoglycemia was not corrected. In group 1 during hypoglycemia there was an increase in blood pressure, central venous pressure, cardiac frequency, respiratory frequency and Dp/Dt, and changes in QT and T wave on the EKG; these changes were partially reversible after hypoglycemia was corrected. The above mentioned alterations persisted in group 2, breathing became irregular irregular and respiratory arrest supervened. It can be inferred that the hemodynamic response to hypoglycemia is predominantly adrenergic. The role of catecolamines, glucocorticoides, glucagon, insuline, cyclic AMP in metabolic and hemodynamic alterations consecutive to hypoglycemia are discussed.

  5. Discovering frequency sensitive thalamic nuclei from EEG microstate informed resting state fMRI.

    Science.gov (United States)

    Schwab, Simon; Koenig, Thomas; Morishima, Yosuke; Dierks, Thomas; Federspiel, Andrea; Jann, Kay

    2015-09-01

    Microstates (MS), the fingerprints of the momentarily and time-varying states of the brain derived from electroencephalography (EEG), are associated with the resting state networks (RSNs). However, using MS fluctuations along different EEG frequency bands to model the functional MRI (fMRI) signal has not been investigated so far, or elucidated the role of the thalamus as a fundamental gateway and a putative key structure in cortical functional networks. Therefore, in the current study, we used MS predictors in standard frequency bands to predict blood oxygenation level dependent (BOLD) signal fluctuations. We discovered that multivariate modeling of BOLD-fMRI using six EEG-MS classes in eight frequency bands strongly correlated with thalamic areas and large-scale cortical networks. Thalamic nuclei exhibited distinct patterns of correlations for individual MS that were associated with specific EEG frequency bands. Anterior and ventral thalamic nuclei were sensitive to the beta frequency band, medial nuclei were sensitive to both alpha and beta frequency bands, and posterior nuclei such as the pulvinar were sensitive to delta and theta frequency bands. These results demonstrate that EEG-MS informed fMRI can elucidate thalamic activity not directly observable by EEG, which may be highly relevant to understand the rapid formation of thalamocortical networks. Copyright © 2015 Elsevier Inc. All rights reserved.

  6. Calibrated fMRI for mapping absolute CMRO2: Practicalities and prospects.

    Science.gov (United States)

    Germuska, M; Wise, R G

    2018-03-29

    Functional magnetic resonance imaging (fMRI) is an essential workhorse of modern neuroscience, providing valuable insight into the functional organisation of the brain. The physiological mechanisms underlying the blood oxygenation level dependent (BOLD) effect are complex and preclude a straightforward interpretation of the signal. However, by employing appropriate calibration of the BOLD signal, quantitative measurements can be made of important physiological parameters including the absolute rate of cerebral metabolic oxygen consumption or oxygen metabolism (CMRO 2 ) and oxygen extraction (OEF). The ability to map such fundamental parameters has the potential to greatly expand the utility of fMRI and to broaden its scope of application in clinical research and clinical practice. In this review article we discuss some of the practical issues related to the calibrated-fMRI approach to the measurement of CMRO 2 . We give an overview of the necessary precautions to ensure high quality data acquisition, and explore some of the pitfalls and challenges that must be considered as it is applied and interpreted in a widening array of diseases and research questions. Copyright © 2018 Elsevier Inc. All rights reserved.

  7. Presurgical motor, somatosensory and language fMRI: Technical feasibility and limitations in 491 patients over 13 years

    International Nuclear Information System (INIS)

    Tyndall, Anthony J.; Reinhardt, Julia; Stippich, Christoph; Tronnier, Volker; Mariani, Luigi

    2017-01-01

    To analyse the long-term feasibility and limitations of presurgical fMRI in a cohort of tumour and epilepsy patients with different MR-scanners at 1.5 and 3.0 T. Four hundred and ninety-one consecutive patients undergoing presurgical fMRI between 2000 and 2012 on five different MR-scanners using established paradigms and semi-automated data processing were included. Success rates of task performance and BOLD-activation were determined for motor and somatosensory somatotopic mapping and language localisation. Procedural success, failures and imaging artifacts were analysed. MR-field strengths were compared. Two thousand three hundred fifteen of 2348 (98.6 %) attempted paradigms (1033 motor, 1220 speech, 95 somatosensory) were successfully performed. 100 paradigms (4.3 %) were repetition runs. 23 speech, 6 motor and 2 sensory paradigms failed for non-compliance and technical issues. Most language paradigm failures were noted in overt sentence generation. Average significant BOLD-activation was higher for motor than language paradigms (95.8 vs. 81.6 %). Most language paradigms showed significantly higher activation rates at 3 T compared to 1.5 T, whereas no significant difference was found for motor paradigms. fMRI proved very robust for the presurgical localisation of the different motor and somatosensory body representations, as well as Broca's and Wernicke's language areas across different MR-scanners at 1.5 and 3.0 T over 13 years. (orig.)

  8. Presurgical motor, somatosensory and language fMRI: Technical feasibility and limitations in 491 patients over 13 years

    Energy Technology Data Exchange (ETDEWEB)

    Tyndall, Anthony J.; Reinhardt, Julia; Stippich, Christoph [University Hospital Basel, Division of Diagnostic and Interventional Neuroradiology, Basel (Switzerland); Tronnier, Volker [University Hospital Schleswig-Holstein, Luebeck Campus, Department of Neurosurgery, Luebeck (Germany); Mariani, Luigi [University Hospitals Basel, Department of Neurosurgery, Basel (Switzerland)

    2017-01-15

    To analyse the long-term feasibility and limitations of presurgical fMRI in a cohort of tumour and epilepsy patients with different MR-scanners at 1.5 and 3.0 T. Four hundred and ninety-one consecutive patients undergoing presurgical fMRI between 2000 and 2012 on five different MR-scanners using established paradigms and semi-automated data processing were included. Success rates of task performance and BOLD-activation were determined for motor and somatosensory somatotopic mapping and language localisation. Procedural success, failures and imaging artifacts were analysed. MR-field strengths were compared. Two thousand three hundred fifteen of 2348 (98.6 %) attempted paradigms (1033 motor, 1220 speech, 95 somatosensory) were successfully performed. 100 paradigms (4.3 %) were repetition runs. 23 speech, 6 motor and 2 sensory paradigms failed for non-compliance and technical issues. Most language paradigm failures were noted in overt sentence generation. Average significant BOLD-activation was higher for motor than language paradigms (95.8 vs. 81.6 %). Most language paradigms showed significantly higher activation rates at 3 T compared to 1.5 T, whereas no significant difference was found for motor paradigms. fMRI proved very robust for the presurgical localisation of the different motor and somatosensory body representations, as well as Broca's and Wernicke's language areas across different MR-scanners at 1.5 and 3.0 T over 13 years. (orig.)

  9. Identification of Voxels Confounded by Venous Signals Using Resting-State fMRI Functional Connectivity Graph Clustering

    Directory of Open Access Journals (Sweden)

    Klaudius eKalcher

    2015-12-01

    Full Text Available Identifying venous voxels in fMRI datasets is important to increase the specificity of fMRI analyses to microvasculature in the vicinity of the neural processes triggering the BOLD response. This is, however, difficult to achieve in particular in typical studies where magnitude images of BOLD EPI are the only data available. In this study, voxelwise functional connectivity graphs were computed on minimally preprocessed low TR (333 ms multiband resting-state fMRI data, using both high positive and negative correlations to define edges between nodes (voxels. A high correlation threshold for binarization ensures that most edges in the resulting sparse graph reflect the high coherence of signals in medium to large veins. Graph clustering based on the optimization of modularity was then employed to identify clusters of coherent voxels in this graph, and all clusters of 50 or more voxels were then interpreted as corresponding to medium to large veins. Indeed, a comparison with SWI reveals that 75.6 ± 5.9% of voxels within these large clusters overlap with veins visible in the SWI image or lie outside the brain parenchyma. Some of the remainingdifferences between the two modalities can be explained by imperfect alignment or geometric distortions between the two images. Overall, the graph clustering based method for identifying venous voxels has a high specificity as well as the additional advantages of being computed in the same voxel grid as the fMRI dataset itself and not needingany additional data beyond what is usually acquired (and exported in standard fMRI experiments.

  10. SU-E-J-223: A BOLD Contrast Imaging Sequence to Evaluate Oxygenation Changes Due to Breath Holding for Breast Radiotherapy: A Pilot Study

    International Nuclear Information System (INIS)

    Adamson, J; Chang, Z; Cai, J; Palta, M; Horton, J; Yin, F; Blitzblau, R

    2015-01-01

    Purpose: To develop a robust MRI sequence to measure BOLD breath hold induced contrast in context of breast radiotherapy. Methods: Two sequences were selected from prior studies as candidates to measure BOLD contrast attributable to breath holding within the breast: (1) T2* based Gradient Echo EPI (TR/TE = 500/41ms, flip angle = 60°), and (2) T2 based Single Shot Fast Spin Echo (SSFSE) (TR/TE = 3000/60ms). We enrolled ten women post-lumpectomy for breast cancer who were undergoing treatment planning for whole breast radiotherapy. Each session utilized a 1.5T GE MRI and 4 channel breast coil with the subject immobilized prone on a custom board. For each sequence, 1–3 planes of the lumpectomy breast were imaged continuously during a background measurement (1min) and intermittent breath holds (20–40s per breath hold, 3–5 holds per sequence). BOLD contrast was quantified as correlation of changes in per-pixel intensity with the breath hold schedule convolved with a hemodynamic response function. Subtle motion was corrected using a deformable registration algorithm. Correlation with breath-holding was considered significant if p<0.001. Results: The percentage of the breast ROI with positive BOLD contrast measured by the two sequences were in agreement with a correlation coefficient of R=0.72 (p=0.02). While both sequences demonstrated areas with strong BOLD response, the response was more systematic throughout the breast for the SSFSE (T2) sequence (% breast with response in the same direction: 51.2%±0.7% for T2* vs. 68.1%±16% for T2). In addition, the T2 sequence was less prone to magnetic susceptibility artifacts, especially in presence of seroma, and provided a more robust image with little distortion or artifacts. Conclusion: A T2 SSFSE sequence shows promise for measuring BOLD contrast in the context of breast radiotherapy utilizing a breath hold technique. Further study in a larger patient cohort is warranted to better refine this novel technique

  11. SU-E-J-223: A BOLD Contrast Imaging Sequence to Evaluate Oxygenation Changes Due to Breath Holding for Breast Radiotherapy: A Pilot Study

    Energy Technology Data Exchange (ETDEWEB)

    Adamson, J; Chang, Z; Cai, J; Palta, M; Horton, J; Yin, F; Blitzblau, R [Duke University Medical Center, Durham, NC (United States)

    2015-06-15

    Purpose: To develop a robust MRI sequence to measure BOLD breath hold induced contrast in context of breast radiotherapy. Methods: Two sequences were selected from prior studies as candidates to measure BOLD contrast attributable to breath holding within the breast: (1) T2* based Gradient Echo EPI (TR/TE = 500/41ms, flip angle = 60°), and (2) T2 based Single Shot Fast Spin Echo (SSFSE) (TR/TE = 3000/60ms). We enrolled ten women post-lumpectomy for breast cancer who were undergoing treatment planning for whole breast radiotherapy. Each session utilized a 1.5T GE MRI and 4 channel breast coil with the subject immobilized prone on a custom board. For each sequence, 1–3 planes of the lumpectomy breast were imaged continuously during a background measurement (1min) and intermittent breath holds (20–40s per breath hold, 3–5 holds per sequence). BOLD contrast was quantified as correlation of changes in per-pixel intensity with the breath hold schedule convolved with a hemodynamic response function. Subtle motion was corrected using a deformable registration algorithm. Correlation with breath-holding was considered significant if p<0.001. Results: The percentage of the breast ROI with positive BOLD contrast measured by the two sequences were in agreement with a correlation coefficient of R=0.72 (p=0.02). While both sequences demonstrated areas with strong BOLD response, the response was more systematic throughout the breast for the SSFSE (T2) sequence (% breast with response in the same direction: 51.2%±0.7% for T2* vs. 68.1%±16% for T2). In addition, the T2 sequence was less prone to magnetic susceptibility artifacts, especially in presence of seroma, and provided a more robust image with little distortion or artifacts. Conclusion: A T2 SSFSE sequence shows promise for measuring BOLD contrast in the context of breast radiotherapy utilizing a breath hold technique. Further study in a larger patient cohort is warranted to better refine this novel technique.

  12. Neural correlates of the psychedelic state as determined by fMRI studies with psilocybin

    Science.gov (United States)

    Carhart-Harris, Robin L.; Erritzoe, David; Williams, Tim; Stone, James M.; Reed, Laurence J.; Colasanti, Alessandro; Tyacke, Robin J.; Leech, Robert; Malizia, Andrea L.; Murphy, Kevin; Hobden, Peter; Evans, John; Feilding, Amanda; Wise, Richard G.; Nutt, David J.

    2012-01-01

    Psychedelic drugs have a long history of use in healing ceremonies, but despite renewed interest in their therapeutic potential, we continue to know very little about how they work in the brain. Here we used psilocybin, a classic psychedelic found in magic mushrooms, and a task-free functional MRI (fMRI) protocol designed to capture the transition from normal waking consciousness to the psychedelic state. Arterial spin labeling perfusion and blood-oxygen level-dependent (BOLD) fMRI were used to map cerebral blood flow and changes in venous oxygenation before and after intravenous infusions of placebo and psilocybin. Fifteen healthy volunteers were scanned with arterial spin labeling and a separate 15 with BOLD. As predicted, profound changes in consciousness were observed after psilocybin, but surprisingly, only decreases in cerebral blood flow and BOLD signal were seen, and these were maximal in hub regions, such as the thalamus and anterior and posterior cingulate cortex (ACC and PCC). Decreased activity in the ACC/medial prefrontal cortex (mPFC) was a consistent finding and the magnitude of this decrease predicted the intensity of the subjective effects. Based on these results, a seed-based pharmaco-physiological interaction/functional connectivity analysis was performed using a medial prefrontal seed. Psilocybin caused a significant decrease in the positive coupling between the mPFC and PCC. These results strongly imply that the subjective effects of psychedelic drugs are caused by decreased activity and connectivity in the brain's key connector hubs, enabling a state of unconstrained cognition. PMID:22308440

  13. Optimized design and analysis of sparse-sampling fMRI experiments

    Directory of Open Access Journals (Sweden)

    Tyler K Perrachione

    2013-04-01

    Full Text Available Sparse-sampling is an important methodological advance in functional magnetic resonance imaging (fMRI, in which silent delays are introduced between MR volume acquisitions, allowing for the presentation of auditory stimuli without contamination by acoustic scanner noise and for overt vocal responses without motion-induced artifacts in the functional timeseries. As such, the sparse-sampling technique has become a mainstay of principled fMRI research into the cognitive and systems neuroscience of speech, language, hearing, and music. Despite being in use for over a decade, there has been little systematic investigation of the acquisition parameters, experimental design considerations, and statistical analysis approaches that bear on the results and interpretation of sparse-sampling fMRI experiments. In this report, we examined how design and analysis choices related to the duration of repetition time (TR delay (an acquisition parameter, stimulation rate (an experimental design parameter and model basis function (an analysis parameter act independently and interactively to affect the neural activation profiles observed in fMRI. First, we conducted a series of computational simulations to explore the parameter space of sparse design and analysis with respect to these variables; second, we validated the results of these simulations in a series of sparse-sampling fMRI experiments. Overall, these experiments suggest three methodological approaches that can, in many situations, substantially improve the detection of neurophysiological response in sparse fMRI: (1 Sparse analyses should utilize a physiologically-informed model that incorporates hemodynamic response convolution to reduce model error. (2 The design of sparse fMRI experiments should maintain a high rate of stimulus presentation to maximize effect size. (3 TR delays of short to intermediate length can be used between acquisitions of sparse-sampled functional image volumes to improve

  14. Markov models for fMRI correlation structure: is brain functional connectivity small world, or decomposable into networks?

    OpenAIRE

    Varoquaux, Gaël; Gramfort, Alexandre; Poline, Jean Baptiste; Thirion, Bertrand

    2012-01-01

    International audience; Correlations in the signal observed via functional Magnetic Resonance Imaging (fMRI), are expected to reveal the interactions in the underlying neural populations through hemodynamic response. In particular, they highlight distributed set of mutually correlated regions that correspond to brain networks related to different cognitive functions. Yet graph-theoretical studies of neural connections give a different picture: that of a highly integrated system with small-wor...

  15. Hemodynamic response based mixture model to estimate micro- and macro-vasculature contributions in functional MRI

    CERN Document Server

    Singh, Manbir; Sungkarat, Witaya; Zhou, Yongxia

    2003-01-01

    A multi-componet model reflecting the temporal characteristics of micro- and macro-vasculature hemodynamic responses was used to fit the time-course of voxels in functional MRI (fMRI). The number of relevant components, the latency of the first component, the time- separation among the components, their relative amplitude and possible interpretation in terms of partial volume contributions of micro- and macro-components to the time-course data were investigated. Analysis of a reversing checkerboard experiment revealed that there was no improvement in the filing beyond two components. Using a two-component model, the fractional abundances of the micro- and macro-vasculature were estimated in individual voxels. These results suggest the potential of a mixture-model approach to mitigate partial volume effects and separate contributions of vascular components within a voxel in fMRI.

  16. Hemodynamic gestational adaptation in bitches

    OpenAIRE

    Almeida, Vívian Tavares de; Uscategui, Ricardo Andres Ramirez; Silva, Priscila Del Aguila da; Avante, Michele Lopes; Simões, Ana Paula Rodrigues; Vicente, Wilter Ricardo Russiano

    2017-01-01

    ABSTRACT: Throughout pregnancy, maternal hemodynamic adaptation is needed to ensure proper uterine perfusion and fetal development. When the uteroplacental vascular system is formed, starting with reduced resistance to uterine arterial flow, this results in decreased total vascular resistance, an activation of neuroendocrine vasoactive peptides, an increase in circulating blood and changes in the cardiovascular system morphophysiology to respond to the increasing demands of uterine perfusion....

  17. Hemodynamic Intervention of Cerebral Aneurysms

    Science.gov (United States)

    Meng, Hui

    2005-11-01

    Cerebral aneurysm is a pathological vascular response to hemodynamic stimuli. Endovascular treatment of cerebral aneurysms essentially alters the blood flow to stop them from continued growth and eventual rupture. Compared to surgical clipping, endovascular methods are minimally invasive and hence rapidly gaining popularity. However, they are not always effective with risks of aneurysm regrowth and various complications. We aim at developing a Virtual Intervention (VI) platform that allows: patient-specific flow calculation and risk prediction as well as recommendation of tailored intervention based on quantitative analysis. This is a lofty goal requiring advancement in three areas of research: (1). Advancement of image-based CFD; (2) Understanding the biological/pathological responses of tissue to hemodynamic factors in the context of cerebral aneurysms; and (3) Capability of designing and testing patient-specific endovascular devices. We have established CFD methodologies based on anatomical geometry obtained from 3D angiographic or CT images. To study the effect of hemodynamics on aneurysm development, we have created a canine model of a vascular bifurcation anastomosis to provide the hemodynamic environment similar to those in CA. Vascular remodeling was studied using histology and compared against the flow fields obtained from CFD. It was found that an intimal pad, similar to those frequently seen clinically, developed at the flow impingement site, bordering with an area of `groove' characteristic of an early stage of aneurysm, where the micro environment exhibits an elevated wall shear stresses. To further address the molecular mechanisms of the flow-mediated aneurysm pathology, we are also developing in vitro cell culture systems to complement the in vivo study. Our current effort in endovascular device development focuses on novel stents that alters the aneurysmal flow to promote thrombotic occlusion as well as favorable remodeling. Realization of an

  18. A predation cost to bold fish in the wild

    DEFF Research Database (Denmark)

    Hulthén, Kaj; Chapman, Ben; Nilsson, Anders P.

    2017-01-01

    Studies of predator-mediated selection on behaviour are critical for our understanding of the evolution and maintenance of behavioural diversity in natural populations. Consistent individual differences in prey behaviour, especially in the propensity to take risks ("boldness"), are widespread...... in the animal kingdom. Theory predicts that individual behavioural types differ in a cost-benefit trade-off where bolder individuals benefit from greater access to resources while paying higher predation-risk costs. However, explicitly linking predation events to individual behaviour under natural conditions...... evidence of behavioural type-dependent predation vulnerability in the wild, i.e. that there is a predation cost to boldness, which is critical for our understanding of the evolution and maintenance of behavioural diversity in natural populations....

  19. Different cerebral connectivity of obese and lean children studied with fMRI

    Science.gov (United States)

    Anaya Moreno, Maryan A.; Hernández López, Javier M.; Hidalgo Tobón, Silvia; Dies Suarez, Pilar; Barragán Pérez, Eduardo; De Celis Alonso, Benito

    2014-11-01

    In this work we studied the different fMRI brain activations and connections between normal weighted (NW) and obese (OB) infants for different types of food odours. A total of 30 right handed volunteers (infants 8.4±2 years) of both sexes were studied. Infants were divided in two group, one with BMI between 19 and 24 kg/m2 and the other with BMI over 30 kg/m2. The first part of this project consisted of a study in which fMRI BOLD activations to pleasant, neutral and healthy food was performed on both groups. Cerebellum regions were found to be more active in the NW group over the OB when presented with odour cues. OB volunteers in contrast showed larger activations in cingulate cortex structures than their NW counterparts when presented with food odours. The second part of this study performed connectivity studies (ROI to ROI) comparing both groups for each smell. The NW group presented for the onion smell a strong reward anticipation connection between the gustatory cortex and the cingulate cortex which the OB group did not have. In contrast the OB group presented strong orbitofrontal connections (decision making) with gustatory and somatosensory cortex when stimulated with the chocolate odour which the NW did not present. We can conclude that clear differences in fMRI BOLD activation as well as connectivity between the OB and NW groups were found. This points at a very different processing mechanisms of odour cues in infants. To our knowledge this study has never been performed before on infants.

  20. Age differences in the motor control of speech: An fMRI study of healthy aging.

    Science.gov (United States)

    Tremblay, Pascale; Sato, Marc; Deschamps, Isabelle

    2017-05-01

    Healthy aging is associated with a decline in cognitive, executive, and motor processes that are concomitant with changes in brain activation patterns, particularly at high complexity levels. While speech production relies on all these processes, and is known to decline with age, the mechanisms that underlie these changes remain poorly understood, despite the importance of communication on everyday life. In this cross-sectional group study, we investigated age differences in the neuromotor control of speech production by combining behavioral and functional magnetic resonance imaging (fMRI) data. Twenty-seven healthy adults underwent fMRI while performing a speech production task consisting in the articulation of nonwords of different sequential and motor complexity. Results demonstrate strong age differences in movement time (MT), with longer and more variable MT in older adults. The fMRI results revealed extensive age differences in the relationship between BOLD signal and MT, within and outside the sensorimotor system. Moreover, age differences were also found in relation to sequential complexity within the motor and attentional systems, reflecting both compensatory and de-differentiation mechanisms. At very high complexity level (high motor complexity and high sequence complexity), age differences were found in both MT data and BOLD response, which increased in several sensorimotor and executive control areas. Together, these results suggest that aging of motor and executive control mechanisms may contribute to age differences in speech production. These findings highlight the importance of studying functionally relevant behavior such as speech to understand the mechanisms of human brain aging. Hum Brain Mapp 38:2751-2771, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  1. Brain responses to mechanical rectal stimulation in patients with faecal incontinence: an fMRI study.

    Science.gov (United States)

    Mirbagheri, N; Hatton, S; Ng, K-S; Lagopoulos, J; Gladman, M A

    2017-10-01

    Continence is dependent on anorectal-brain interactions. Consequently, aberrations of the brain-gut axis may be important in the pathophysiology of faecal incontinence (FI) in certain patients. The aim of this study was to assess the feasibility of recording brain responses to rectal mechanical stimulation in patients with FI using functional magnetic resonance imaging (fMRI). A prospective, cohort pilot study was performed to assess brain responses during rectal stimulation in 14 patients [four men, mean (SD) age 62 (15) years]. Blood oxygen level dependent (BOLD) signals were measured by fMRI during rest and mechanical distension, involving random repetitions of isobaric phasic rectal distensions at fixed (15 and 45 mmHg) and variable (10% above sensory perception threshold) pressures. Increases in BOLD signals in response to high pressure rectal distension (45 mmHg) and maximum toleration were observed in the cingulate gyrus, thalamus, insular cortex, inferior frontal gyrus, cerebellum, caudate nucleus, supramarginal gyrus, putamen and amygdala. Additionally, activation of the supplementary motor cortex and caudate nucleus with inconsistent activity in the frontal lobe was observed. This study has demonstrated the feasibility of recording brain responses to rectal mechanical stimulation using fMRI in patients with FI, revealing activity in widespread areas of the brain involved in visceral sensory processing. The observed activity in the supplementary motor cortex and caudate nucleus, with relative paucity of activity in the frontal lobes, warrants investigation in future studies to determine whether aberrations in cerebral processing of rectal stimuli play a role in the pathogenesis of FI. Colorectal Disease © 2017 The Association of Coloproctology of Great Britain and Ireland.

  2. Controlling the false positive rate in fuzzy clustering using randomization: application to fMRI activation detection.

    Science.gov (United States)

    Jahanian, Hesamoddin; Hossein-Zadeh, Gholam-Ali; Soltanian-Zadeh, Hamid; Ardekani, Babak A

    2004-06-01

    Despite its potential advantages for fMRI analysis, fuzzy C-means (FCM) clustering suffers from limitations such as the need for a priori knowledge of the number of clusters, and unknown statistical significance and instability of the results. We propose a randomization-based method to control the false-positive rate and estimate statistical significance of the FCM results. Using this novel approach, we develop an fMRI activation detection method. The ability of the method in controlling the false-positive rate is shown by analysis of false positives in activation maps of resting-state fMRI data. Controlling the false-positive rate in FCM allows comparison of different fuzzy clustering methods, using different feature spaces, to other fMRI detection methods. In this article, using simulation and real fMRI data, we compare a novel feature space that takes the variability of the hemodynamic response function into account (HRF-based feature space) to the conventional cross-correlation analysis and FCM using the cross-correlation feature space. In both cases, the HRF-based feature space provides a greater sensitivity compared to the cross-correlation feature space and conventional cross-correlation analysis. Application of the proposed method to finger-tapping fMRI data, using HRF-based feature space, detected activation in sub-cortical regions, whereas both of the FCM with cross-correlation feature space and the conventional cross-correlation method failed to detect them.

  3. Pattern classification of fMRI data: applications for analysis of spatially distributed cortical networks.

    Science.gov (United States)

    Yourganov, Grigori; Schmah, Tanya; Churchill, Nathan W; Berman, Marc G; Grady, Cheryl L; Strother, Stephen C

    2014-08-01

    The field of fMRI data analysis is rapidly growing in sophistication, particularly in the domain of multivariate pattern classification. However, the interaction between the properties of the analytical model and the parameters of the BOLD signal (e.g. signal magnitude, temporal variance and functional connectivity) is still an open problem. We addressed this problem by evaluating a set of pattern classification algorithms on simulated and experimental block-design fMRI data. The set of classifiers consisted of linear and quadratic discriminants, linear support vector machine, and linear and nonlinear Gaussian naive Bayes classifiers. For linear discriminant, we used two methods of regularization: principal component analysis, and ridge regularization. The classifiers were used (1) to classify the volumes according to the behavioral task that was performed by the subject, and (2) to construct spatial maps that indicated the relative contribution of each voxel to classification. Our evaluation metrics were: (1) accuracy of out-of-sample classification and (2) reproducibility of spatial maps. In simulated data sets, we performed an additional evaluation of spatial maps with ROC analysis. We varied the magnitude, temporal variance and connectivity of simulated fMRI signal and identified the optimal classifier for each simulated environment. Overall, the best performers were linear and quadratic discriminants (operating on principal components of the data matrix) and, in some rare situations, a nonlinear Gaussian naïve Bayes classifier. The results from the simulated data were supported by within-subject analysis of experimental fMRI data, collected in a study of aging. This is the first study that systematically characterizes interactions between analysis model and signal parameters (such as magnitude, variance and correlation) on the performance of pattern classifiers for fMRI. Copyright © 2014 Elsevier Inc. All rights reserved.

  4. Spatially adaptive mixture modeling for analysis of FMRI time series.

    Science.gov (United States)

    Vincent, Thomas; Risser, Laurent; Ciuciu, Philippe

    2010-04-01

    Within-subject analysis in fMRI essentially addresses two problems, the detection of brain regions eliciting evoked activity and the estimation of the underlying dynamics. In Makni et aL, 2005 and Makni et aL, 2008, a detection-estimation framework has been proposed to tackle these problems jointly, since they are connected to one another. In the Bayesian formalism, detection is achieved by modeling activating and nonactivating voxels through independent mixture models (IMM) within each region while hemodynamic response estimation is performed at a regional scale in a nonparametric way. Instead of IMMs, in this paper we take advantage of spatial mixture models (SMM) for their nonlinear spatial regularizing properties. The proposed method is unsupervised and spatially adaptive in the sense that the amount of spatial correlation is automatically tuned from the data and this setting automatically varies across brain regions. In addition, the level of regularization is specific to each experimental condition since both the signal-to-noise ratio and the activation pattern may vary across stimulus types in a given brain region. These aspects require the precise estimation of multiple partition functions of underlying Ising fields. This is addressed efficiently using first path sampling for a small subset of fields and then using a recently developed fast extrapolation technique for the large remaining set. Simulation results emphasize that detection relying on supervised SMM outperforms its IMM counterpart and that unsupervised spatial mixture models achieve similar results without any hand-tuning of the correlation parameter. On real datasets, the gain is illustrated in a localizer fMRI experiment: brain activations appear more spatially resolved using SMM in comparison with classical general linear model (GLM)-based approaches, while estimating a specific parcel-based HRF shape. Our approach therefore validates the treatment of unsmoothed fMRI data without fixed GLM

  5. Good exemplars of natural scene categories elicit clearer patterns than bad exemplars but not greater BOLD activity.

    Directory of Open Access Journals (Sweden)

    Ana Torralbo

    Full Text Available Within the range of images that we might categorize as a "beach", for example, some will be more representative of that category than others. Here we first confirmed that humans could categorize "good" exemplars better than "bad" exemplars of six scene categories and then explored whether brain regions previously implicated in natural scene categorization showed a similar sensitivity to how well an image exemplifies a category. In a behavioral experiment participants were more accurate and faster at categorizing good than bad exemplars of natural scenes. In an fMRI experiment participants passively viewed blocks of good or bad exemplars from the same six categories. A multi-voxel pattern classifier trained to discriminate among category blocks showed higher decoding accuracy for good than bad exemplars in the PPA, RSC and V1. This difference in decoding accuracy cannot be explained by differences in overall BOLD signal, as average BOLD activity was either equivalent or higher for bad than good scenes in these areas. These results provide further evidence that V1, RSC and the PPA not only contain information relevant for natural scene categorization, but their activity patterns mirror the fundamentally graded nature of human categories. Analysis of the image statistics of our good and bad exemplars shows that variability in low-level features and image structure is higher among bad than good exemplars. A simulation of our neuroimaging experiment suggests that such a difference in variance could account for the observed differences in decoding accuracy. These results are consistent with both low-level models of scene categorization and models that build categories around a prototype.

  6. Complex motor task associated with non-linear BOLD responses in cerebro-cortical areas and cerebellum.

    Science.gov (United States)

    Alahmadi, Adnan A S; Samson, Rebecca S; Gasston, David; Pardini, Matteo; Friston, Karl J; D'Angelo, Egidio; Toosy, Ahmed T; Wheeler-Kingshott, Claudia A M

    2016-06-01

    Previous studies have used fMRI to address the relationship between grip force (GF) applied to an object and BOLD response. However, whilst the majority of these studies showed a linear relationship between GF and neural activity in the contralateral M1 and ipsilateral cerebellum, animal studies have suggested the presence of non-linear components in the GF-neural activity relationship. Here, we present a methodology for assessing non-linearities in the BOLD response to different GF levels, within primary motor as well as sensory and cognitive areas and the cerebellum. To be sensitive to complex forms, we designed a feasible grip task with five GF targets using an event-related visually guided paradigm and studied a cohort of 13 healthy volunteers. Polynomial functions of increasing order were fitted to the data. (1) activated motor areas irrespective of GF; (2) positive higher-order responses in and outside M1, involving premotor, sensory and visual areas and cerebellum; (3) negative correlations with GF, predominantly involving the visual domain. Overall, our results suggest that there are physiologically consistent behaviour patterns in cerebral and cerebellar cortices; for example, we observed the presence of a second-order effect in sensorimotor areas, consistent with an optimum metabolic response at intermediate GF levels, while higher-order behaviour was found in associative and cognitive areas. At higher GF levels, sensory-related cortical areas showed reduced activation, interpretable as a redistribution of the neural activity for more demanding tasks. These results have the potential of opening new avenues for investigating pathological mechanisms of neurological diseases.

  7. Optimal compressed sensing reconstructions of fMRI using 2D deterministic and stochastic sampling geometries

    Directory of Open Access Journals (Sweden)

    Jeromin Oliver

    2012-05-01

    Full Text Available Abstract Background Compressive sensing can provide a promising framework for accelerating fMRI image acquisition by allowing reconstructions from a limited number of frequency-domain samples. Unfortunately, the majority of compressive sensing studies are based on stochastic sampling geometries that cannot guarantee fast acquisitions that are needed for fMRI. The purpose of this study is to provide a comprehensive optimization framework that can be used to determine the optimal 2D stochastic or deterministic sampling geometry, as well as to provide optimal reconstruction parameter values for guaranteeing image quality in the reconstructed images. Methods We investigate the use of frequency-space (k-space sampling based on: (i 2D deterministic geometries of dyadic phase encoding (DPE and spiral low pass (SLP geometries, and (ii 2D stochastic geometries based on random phase encoding (RPE and random samples on a PDF (RSP. Overall, we consider over 36 frequency-sampling geometries at different sampling rates. For each geometry, we compute optimal reconstructions of single BOLD fMRI ON & OFF images, as well as BOLD fMRI activity maps based on the difference between the ON and OFF images. We also provide an optimization framework for determining the optimal parameters and sampling geometry prior to scanning. Results For each geometry, we show that reconstruction parameter optimization converged after just a few iterations. Parameter optimization led to significant image quality improvements. For activity detection, retaining only 20.3% of the samples using SLP gave a mean PSNR value of 57.58 dB. We also validated this result with the use of the Structural Similarity Index Matrix (SSIM image quality metric. SSIM gave an excellent mean value of 0.9747 (max = 1. This indicates that excellent reconstruction results can be achieved. Median parameter values also gave excellent reconstruction results for the ON/OFF images using the SLP sampling geometry

  8. An fMRI study

    Indian Academy of Sciences (India)

    fMRI data analysis revealed that while performing the task, the alcoholics showed enhanced activations in left supramarginal gyrus, precuneus bilaterally, left angular gyrus, and left middle temporal gyrus as compared to control subjects. The extensive activations observed in alcoholics as compared to controls suggest that ...

  9. Interhemispheric differences of fMRI responses to visual stimuli in patients with side-fixed migraine aura

    DEFF Research Database (Denmark)

    Hougaard, Anders; Amin, Faisal Mohammad; Hoffmann, Michael B

    2014-01-01

    Migraine sufferers with aura often report photosensitivity and visual discomfort outside of attacks and many consider bright or flickering light an attack-precipitating factor. The nature of this visual hypersensitivity and its relation to the underlying pathophysiology of the migraine aura...... is unknown. Using fMRI measurements during visual stimulation we examined the visual cortical responsiveness of patients with migraine with aura. We applied a within-patient design by assessing functional interhemispheric differences in patients consistently experiencing visual aura in the same visual...... hemifield. We recruited 20 patients with frequent side-fixed visual aura attacks (≥90% of auras occurring in the same visual hemifield) and 20 age and sex matched healthy controls and compared the fMRI blood oxygenation level dependent (BOLD) responses to visual stimulation between symptomatic...

  10. Limits of 2D-TCA in detecting BOLD responses to epileptic activity.

    Science.gov (United States)

    Khatamian, Yasha Borna; Fahoum, Firas; Gotman, Jean

    2011-05-01

    Two-dimensional temporal clustering analysis (2D-TCA) is a relatively new functional MRI (fMRI) based technique that breaks blood oxygen level dependent activity into separate components based on timing and has shown potential for localizing epileptic activity independently of electroencephalography (EEG). 2D-TCA has only been applied to detect epileptic activity in a few studies and its limits in detecting activity of various forms (i.e. activation size, amplitude, and frequency) have not been investigated. This study evaluated 2D-TCA's ability to detect various forms of both simulated epileptic activity and EEG-fMRI activity detected in patients. When applied to simulated data, 2D-TCA consistently detected activity in 6min runs containing 5 spikes/run, 10 spikes/run, and one 5s long event with hemodynamic response function amplitudes of at least 1.5%, 1.25%, and 1% above baseline respectively. When applied to patient data, while detection of interictal spikes was inconsistent, 2D-TCA consistently produced results similar to those obtained by EEG-fMRI when at least 2 prolonged interictal events (a few seconds each) occurred during the run. However, even for such cases it was determined that 2D-TCA can only be used to validate localization by other means or to create hypotheses as to where activity may occur, as it also detects changes not caused by epileptic activity. Copyright © 2011 Elsevier B.V. All rights reserved.

  11. PyMVPA: A python toolbox for multivariate pattern analysis of fMRI data.

    Science.gov (United States)

    Hanke, Michael; Halchenko, Yaroslav O; Sederberg, Per B; Hanson, Stephen José; Haxby, James V; Pollmann, Stefan

    2009-01-01

    Decoding patterns of neural activity onto cognitive states is one of the central goals of functional brain imaging. Standard univariate fMRI analysis methods, which correlate cognitive and perceptual function with the blood oxygenation-level dependent (BOLD) signal, have proven successful in identifying anatomical regions based on signal increases during cognitive and perceptual tasks. Recently, researchers have begun to explore new multivariate techniques that have proven to be more flexible, more reliable, and more sensitive than standard univariate analysis. Drawing on the field of statistical learning theory, these new classifier-based analysis techniques possess explanatory power that could provide new insights into the functional properties of the brain. However, unlike the wealth of software packages for univariate analyses, there are few packages that facilitate multivariate pattern classification analyses of fMRI data. Here we introduce a Python-based, cross-platform, and open-source software toolbox, called PyMVPA, for the application of classifier-based analysis techniques to fMRI datasets. PyMVPA makes use of Python's ability to access libraries written in a large variety of programming languages and computing environments to interface with the wealth of existing machine learning packages. We present the framework in this paper and provide illustrative examples on its usage, features, and programmability.

  12. Do we have a "mental syllabary" in the brain? An FMRI study.

    Science.gov (United States)

    Brendel, Bettina; Erb, Michael; Riecker, Axel; Grodd, Wolfgang; Ackermann, Hermann; Ziegler, Wolfram

    2011-01-01

    The present study combines functional magnetic resonance imaging (fMRI) and reaction time (RT) measurements to further elucidate the influence of syllable frequency and complexity on speech motor control processes, i.e., overt reading of pseudowords. Tying in with a recent fMRI-study of our group we focused on the concept of a mental syllabary housing syllable sized ready-made motor plans for high- (HF), but not low-frequency (LF) syllables. The RT-analysis disclosed a frequency effect weakened by a simultaneous complexity effect for HF-syllables. In contrast, the fMRI data revealed no effect of syllable frequency, but point to an impact of syllable structure: Compared with CV-items, syllables with a complex onset (CCV) yielded higher hemodynamic activation in motor "execution" areas (left sensorimotor cortex, right inferior cerebellum), which is at least partially compatible with our previous study. We discuss the role of the syllable in speech motor control.

  13. Assessment of sexual orientation using the hemodynamic brain response to visual sexual stimuli

    DEFF Research Database (Denmark)

    Ponseti, Jorge; Granert, Oliver; Jansen, Olav

    2009-01-01

    INTRODUCTION: The assessment of sexual orientation is of importance to the diagnosis and treatment of sex offenders and paraphilic disorders. Phallometry is considered gold standard in objectifying sexual orientation, yet this measurement has been criticized because of its intrusiveness and limited...... response patterns of the brain to sexual stimuli contained sufficient information to predict individual sexual orientation with high accuracy. These results suggest that fMRI-based classification methods hold promise for the diagnosis of paraphilic disorders (e.g., pedophilia)....... reliability. AIM: To evaluate whether the spatial response pattern to sexual stimuli as revealed by a change in blood oxygen level-dependent (BOLD) signal can be used for individual classification of sexual orientation. METHODS: We used a preexisting functional MRI (fMRI) data set that had been acquired...

  14. ROC-based determination of the number of clusters for fMRI activation detection

    Science.gov (United States)

    Jahanian, Hesamoddin; Soltanian-Zadeh, Hamid; Hossein-Zadeh, Gholam A.; Siadat, Mohammad-Reza

    2004-05-01

    Fuzzy C-means (FCM), in spite of its potent advantages in exploratory analyze of functional magnetic resonance imaging (fMRI), suffers from limitations such as a priori determination of number of clusters, unknown statistical significance for the results, and instability of the results when it is applied on raw fMRI time series. Choosing different number of clusters, or thresholding the membership degree at different levels, lead to considerably different activation maps. However, research work for finding a standard index to determine the number of clusters has not yet succeeded. Using randomization, we developed a method to control false positive rate in FCM, which gives a meaningful statistical significance to the results. Making use of this novel method and an ROC-based cluster validity measure, we determined the optimal number of clusters. In this study, we applied the FCM on a feature space that takes the variability of hemodynamic response function into account (HRF-based feature space). The proposed method found the accurate number of clusters in simulated fMRI data. In addition, the proposed method generated excellent results for experimental fMRI data and showed a good reproducibility for determining the number of clusters.

  15. Dual-TRACER: High resolution fMRI with constrained evolution reconstruction.

    Science.gov (United States)

    Li, Xuesong; Ma, Xiaodong; Li, Lyu; Zhang, Zhe; Zhang, Xue; Tong, Yan; Wang, Lihong; Sen Song; Guo, Hua

    2018-01-01

    fMRI with high spatial resolution is beneficial for studies in psychology and neuroscience, but is limited by various factors such as prolonged imaging time, low signal to noise ratio and scarcity of advanced facilities. Compressed Sensing (CS) based methods for accelerating fMRI data acquisition are promising. Other advanced algorithms like k-t FOCUSS or PICCS have been developed to improve performance. This study aims to investigate a new method, Dual-TRACER, based on Temporal Resolution Acceleration with Constrained Evolution Reconstruction (TRACER), for accelerating fMRI acquisitions using golden angle variable density spiral. Both numerical simulations and in vivo experiments at 3T were conducted to evaluate and characterize this method. Results show that Dual-TRACER can provide functional images with a high spatial resolution (1×1mm 2 ) under an acceleration factor of 20 while maintaining hemodynamic signals well. Compared with other investigated methods, dual-TRACER provides a better signal recovery, higher fMRI sensitivity and more reliable activation detection. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Nucleus accumbens deep brain stimulation results in insula and prefrontal activation: a large animal FMRI study.

    Directory of Open Access Journals (Sweden)

    Emily J Knight

    Full Text Available Deep Brain Stimulation (DBS of the nucleus accumbens (NAc has previously been investigated clinically for the treatment of several psychiatric conditions, including obsessive-compulsive disorder and treatment resistant depression. However, the mechanism underlying the therapeutic benefit of DBS, including the brain areas that are activated, remains largely unknown. Here, we utilized 3.0 T functional Magnetic Resonance Imaging (fMRI changes in Blood Oxygenation Level-Dependent (BOLD signal to test the hypothesis that NAc/internal capsule DBS results in global neural network activation in a large animal (porcine modelAnimals (n = 10 were implanted in the NAc/internal capsule with DBS electrodes and received stimulation (1, 3, and 5 V, 130 Hz, and pulse widths of 100 and 500 µsec. BOLD signal changes were evaluated using a gradient echo-echo planar imaging (GRE-EPI sequence in 3.0 T MRI. We used a normalized functional activation map for group analysis and applied general linear modeling across subjects (FDR<0.001. The anatomical location of the implanted DBS lead was confirmed with a CT scanWe observed stimulation-evoked activation in the ipsilateral prefrontal cortex, insula, cingulate and bilateral parahippocampal region along with decrease in BOLD signal in the ipsilateral dorsal region of the thalamus. Furthermore, as the stimulation voltage increased from 3 V to 5 V, the region of BOLD signal modulation increased in insula, thalamus, and parahippocampal cortex and decreased in the cingulate and prefrontal cortex. We also demonstrated that right and left NAc/internal capsule stimulation modulates identical areas ipsilateral to the side of the stimulationOur results suggest that NAc/internal capsule DBS results in modulation of psychiatrically important brain areas notably the prefrontal cortex, cingulate, and insular cortex, which may underlie the therapeutic effect of NAc DBS in psychiatric disorders. Finally, our fMRI setup in the large

  17. Robust Estimation of HDR in fMRI using H-infinity Filters

    DEFF Research Database (Denmark)

    Puthusserypady, Sadasivan; Jue, R.; Ratnarajah, T.

    2010-01-01

    Estimation and detection of the hemodynamic response (HDR) are of great importance in functional MRI (fMRI) data analysis. In this paper, we propose the use of three H-infinity adaptive filters (finite memory, exponentially weighted, and timevarying) for accurate estimation and detection of the H......-1487]. Performances of the proposed techniques are compared to the conventional t-test method as well as the well-known LMSs and recursive least squares algorithms. Extensive numerical simulations show that the proposed methods result in better HDR estimations and activation detections....

  18. Gamma rays induced bold seeded high yielding mutant in chickpea

    International Nuclear Information System (INIS)

    Wani, A.A.; Anis, M.

    2001-01-01

    In pulses especially in chickpea (Cicer arietinum L.), genetic variability has been exhausted due to natural selection and hence conventional breeding methods are not very fruitful. Mutation techniques are the best methods to enlarge the genetically conditioned variability of a species within a short time and have played a significant role in the development of many crop varieties. Investigations on the effects of ionizing radiations and chemical mutagens in induction of macro-mutations have received much attention owing to their utmost importance in plant breeding. The present study reports a bold seeded mutant in chickpea, the most dominating pulse crop on the Indian subcontinent. Fresh seeds of chickpea variety 'Pusa-212' were procured from IARI, New Delhi and treated with different doses/concentrations of gamma rays ( 60 Co source at NBRI, Lucknow) and ethyl methanesulphonate (EMS), individually as well as in combination, to raise the M1 generation. Seeds of M 1 plants were sown to raise M2 plant progenies. A bold seeded mutant was isolated from 400 Gy gamma ray treatments. The mutant was confirmed as true bred, all the mutant seeds gave rise to morphologically similar plants in M 3 , which were quite distinct from the control. The bold seeded mutant showed 'gigas' characteristics and vigorous growth. The plant remained initially straight but later on attained a trailing habit due to heavy secondary branching. The leaves, petioles, flowers, pods and seeds were almost double that of the parent variety, in size. The flowering occurred 10 days later than the parent and maturity was also delayed accordingly. Observations were recorded on various quantitative traits. Plant height and number of primary branches showed a significant improvement over the parent. It is interesting to note that the number of pods and number of seeds per pod significantly decreased. However, the hundred seed weight (31.73±0.59g) in the mutant plants was more than double in the parent

  19. Aging effects on the control of grip force magnitude: an fMRI study.

    Science.gov (United States)

    Noble, Jeremy W; Eng, Janice J; Kokotilo, Kristen J; Boyd, Lara A

    2011-06-01

    Functional neuroimaging techniques have allowed for investigations into the mechanisms of age-related deterioration in motor control. This study used functional Magnetic Resonance Imaging (fMRI) to investigate age related differences in the control of grip force magnitude. Using an event-related design, fMRI scans were completed on 13 older adults, and 13 gender matched younger adults, while using their dominant hand to squeeze a rubber bulb for 4s at 10%, 40% or 70% of their maximum voluntary contraction. Both groups were able to match the relative force targets, however the older adults produced significantly lower levels of absolute force. fMRI analysis consisted of a 1) region of interest (ROI) approach to detect differences in selected motor areas within brain and 2) a voxel-wise whole brain comparison to find areas of differential activation that were not defined a priori between the older and younger group. The ROI analysis revealed that despite producing lower levels of absolute force, the older adults showed higher levels of activity predominantly in subcortical structures (putamen, thalamus and cerebellum) when compared to the younger group. The older adults also showed higher levels of activity in the ipsilateral ventral premotor cortex. A total of 19 of the 22 ROIs analyzed showed a significant main effect of the required force-level. In the majority of the ROIs that showed a significant force effect there were no significant differences in the magnitude of the blood-oxygen-level-dependent (BOLD) signal between the 10% and 40% conditions but a significantly higher BOLD signal in the 70% condition, suggesting that the modulation of brain activation with grip force may not be controlled in a linear fashion. It was also found that the older adult group demonstrate higher levels of activation in 7 areas during a force production task at higher force levels using a voxel-wise analysis. The 7 clusters that showed significant differences tended to be areas

  20. FMRI evidence of 'mirror' responses to geometric shapes.

    Directory of Open Access Journals (Sweden)

    Clare Press

    Full Text Available Mirror neurons may be a genetic adaptation for social interaction. Alternatively, the associative hypothesis proposes that the development of mirror neurons is driven by sensorimotor learning, and that, given suitable experience, mirror neurons will respond to any stimulus. This hypothesis was tested using fMRI adaptation to index populations of cells with mirror properties. After sensorimotor training, where geometric shapes were paired with hand actions, BOLD response was measured while human participants experienced runs of events in which shape observation alternated with action execution or observation. Adaptation from shapes to action execution, and critically, observation, occurred in ventral premotor cortex (PMv and inferior parietal lobule (IPL. Adaptation from shapes to execution indicates that neuronal populations responding to the shapes had motor properties, while adaptation to observation demonstrates that these populations had mirror properties. These results indicate that sensorimotor training induced populations of cells with mirror properties in PMv and IPL to respond to the observation of arbitrary shapes. They suggest that the mirror system has not been shaped by evolution to respond in a mirror fashion to biological actions; instead, its development is mediated by stimulus-general processes of learning within a system adapted for visuomotor control.

  1. Normalized cut group clustering of resting-state FMRI data.

    Directory of Open Access Journals (Sweden)

    Martijn van den Heuvel

    Full Text Available BACKGROUND: Functional brain imaging studies have indicated that distinct anatomical brain regions can show coherent spontaneous neuronal activity during rest. Regions that show such correlated behavior are said to form resting-state networks (RSNs. RSNs have been investigated using seed-dependent functional connectivity maps and by using a number of model-free methods. However, examining RSNs across a group of subjects is still a complex task and often involves human input in selecting meaningful networks. METHODOLOGY/PRINCIPAL FINDINGS: We report on a voxel based model-free normalized cut graph clustering approach with whole brain coverage for group analysis of resting-state data, in which the number of RSNs is computed as an optimal clustering fit of the data. Inter-voxel correlations of time-series are grouped at the individual level and the consistency of the resulting networks across subjects is clustered at the group level, defining the group RSNs. We scanned a group of 26 subjects at rest with a fast BOLD sensitive fMRI scanning protocol on a 3 Tesla MR scanner. CONCLUSIONS/SIGNIFICANCE: An optimal group clustering fit revealed 7 RSNs. The 7 RSNs included motor/visual, auditory and attention networks and the frequently reported default mode network. The found RSNs showed large overlap with recently reported resting-state results and support the idea of the formation of spatially distinct RSNs during rest in the human brain.

  2. Assessment of sexual orientation using the hemodynamic brain response to visual sexual stimuli.

    Science.gov (United States)

    Ponseti, Jorge; Granert, Oliver; Jansen, Olav; Wolff, Stephan; Mehdorn, Hubertus; Bosinski, Hartmut; Siebner, Hartwig

    2009-06-01

    The assessment of sexual orientation is of importance to the diagnosis and treatment of sex offenders and paraphilic disorders. Phallometry is considered gold standard in objectifying sexual orientation, yet this measurement has been criticized because of its intrusiveness and limited reliability. To evaluate whether the spatial response pattern to sexual stimuli as revealed by a change in blood oxygen level-dependent (BOLD) signal can be used for individual classification of sexual orientation. We used a preexisting functional MRI (fMRI) data set that had been acquired in a nonclinical sample of 12 heterosexual men and 14 homosexual men. During fMRI, participants were briefly exposed to pictures of same-sex and opposite-sex genitals. Data analysis involved four steps: (i) differences in the BOLD response to female and male sexual stimuli were calculated for each subject; (ii) these contrast images were entered into a group analysis to calculate whole-brain difference maps between homosexual and heterosexual participants; (iii) a single expression value was computed for each subject expressing its correspondence to the group result; and (iv) based on these expression values, Fisher's linear discriminant analysis and the kappa-nearest neighbor classification method were used to predict the sexual orientation of each subject. Sensitivity and specificity of the two classification methods in predicting individual sexual orientation. Both classification methods performed well in predicting individual sexual orientation with a mean accuracy of >85% (Fisher's linear discriminant analysis: 92% sensitivity, 85% specificity; kappa-nearest neighbor classification: 88% sensitivity, 92% specificity). Despite the small sample size, the functional response patterns of the brain to sexual stimuli contained sufficient information to predict individual sexual orientation with high accuracy. These results suggest that fMRI-based classification methods hold promise for the diagnosis

  3. Decoding the encoding of functional brain networks: An fMRI classification comparison of non-negative matrix factorization (NMF), independent component analysis (ICA), and sparse coding algorithms.

    Science.gov (United States)

    Xie, Jianwen; Douglas, Pamela K; Wu, Ying Nian; Brody, Arthur L; Anderson, Ariana E

    2017-04-15

    Brain networks in fMRI are typically identified using spatial independent component analysis (ICA), yet other mathematical constraints provide alternate biologically-plausible frameworks for generating brain networks. Non-negative matrix factorization (NMF) would suppress negative BOLD signal by enforcing positivity. Spatial sparse coding algorithms (L1 Regularized Learning and K-SVD) would impose local specialization and a discouragement of multitasking, where the total observed activity in a single voxel originates from a restricted number of possible brain networks. The assumptions of independence, positivity, and sparsity to encode task-related brain networks are compared; the resulting brain networks within scan for different constraints are used as basis functions to encode observed functional activity. These encodings are then decoded using machine learning, by using the time series weights to predict within scan whether a subject is viewing a video, listening to an audio cue, or at rest, in 304 fMRI scans from 51 subjects. The sparse coding algorithm of L1 Regularized Learning outperformed 4 variations of ICA (pnegative BOLD signal, had the poorest accuracy compared to the ICA and sparse coding algorithms. Holding constant the effect of the extraction algorithm, encodings using sparser spatial networks (containing more zero-valued voxels) had higher classification accuracy (pNegative BOLD signal may capture task-related activations. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. The Temporal Lobes Differentiate between the Voices of Famous and Unknown People: An Event-Related fMRI Study on Speaker Recognition

    Science.gov (United States)

    Bethmann, Anja; Scheich, Henning; Brechmann, André

    2012-01-01

    It is widely accepted that the perception of human voices is supported by neural structures located along the superior temporal sulci. However, there is an ongoing discussion to what extent the activations found in fMRI studies are evoked by the vocal features themselves or are the result of phonetic processing. To show that the temporal lobes are indeed engaged in voice processing, short utterances spoken by famous and unknown people were presented to healthy young participants whose task it was to identify the familiar speakers. In two event-related fMRI experiments, the temporal lobes were found to differentiate between familiar and unfamiliar voices such that named voices elicited higher BOLD signal intensities than unfamiliar voices. Yet, the temporal cortices did not only discriminate between familiar and unfamiliar voices. Experiment 2, which required overtly spoken responses and allowed to distinguish between four familiarity grades, revealed that there was a fine-grained differentiation between all of these familiarity levels with higher familiarity being associated with larger BOLD signal amplitudes. Finally, we observed a gradual response change such that the BOLD signal differences between unfamiliar and highly familiar voices increased with the distance of an area from the transverse temporal gyri, especially towards the anterior temporal cortex and the middle temporal gyri. Therefore, the results suggest that (the anterior and non-superior portions of) the temporal lobes participate in voice-specific processing independent from phonetic components also involved in spoken speech material. PMID:23112826

  5. Improved sensitivity and specificity for resting state and task fMRI with multiband multi-echo EPI compared to multi-echo EPI at 7 T.

    Science.gov (United States)

    Boyacioğlu, Rasim; Schulz, Jenni; Koopmans, Peter J; Barth, Markus; Norris, David G

    2015-10-01

    A multiband multi-echo (MBME) sequence is implemented and compared to a matched standard multi-echo (ME) protocol to investigate the potential improvement in sensitivity and spatial specificity at 7 T for resting state and task fMRI. ME acquisition is attractive because BOLD sensitivity is less affected by variation in T2*, and because of the potential for separating BOLD and non-BOLD signal components. MBME further reduces TR thus increasing the potential reduction in physiological noise. In this study we used FSL-FIX to clean ME and MBME resting state and task fMRI data (both 3.5mm isotropic). After noise correction, the detection of resting state networks improves with more non-artifactual independent components being observed. Additional activation clusters for task data are discovered for MBME data (increased sensitivity) whereas existing clusters become more localized for resting state (improved spatial specificity). The results obtained indicate that MBME is superior to ME at high field strengths. Copyright © 2015 Elsevier Inc. All rights reserved.

  6. Foundations of layer-specific fMRI and investigations of neurophysiological activity in the laminarized neocortex and olfactory bulb of animal models.

    Science.gov (United States)

    Poplawsky, Alexander John; Fukuda, Mitsuhiro; Kim, Seong-Gi

    2017-05-12

    Laminar organization of neuronal circuits is a recurring feature of how the brain processes information. For instance, different layers compartmentalize different cell types, synaptic activities, and have unique intrinsic and extrinsic connections that serve as units for specialized signal processing. Functional MRI is an invaluable tool to investigate laminar processing in the in vivo human brain, but it measures neuronal activity indirectly by way of the hemodynamic response. Therefore, the accuracy of high-resolution laminar fMRI depends on how precisely it can measure localized microvascular changes nearest to the site of evoked activity. To determine the specificity of fMRI responses to the true neurophysiological responses across layers, the flexibility to invasive procedures in animal models has been necessary. In this review, we will examine different fMRI contrasts and their appropriate uses for layer-specific fMRI, and how localized laminar processing was examined in the neocortex and olfactory bulb. Through collective efforts, it was determined that microvessels, including capillaries, are regulated within single layers and that several endogenous and contrast-enhanced fMRI contrast mechanisms can separate these neural-specific vascular changes from the nonspecific, especially cerebral blood volume-weighted fMRI with intravenous contrast agent injection. We will also propose some open questions that are relevant for the successful implementation of layer-specific fMRI and its potential future directions to study laminar processing when combined with optogenetics. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. The Evaluation of Preprocessing Choices in Single-Subject BOLD fMRI Using NPAIRS Performance Metrics

    DEFF Research Database (Denmark)

    Stephen, LaConte; Rottenberg, David; Strother, Stephen

    2003-01-01

    signal-to-noise and our reproducibility estimates as derived previously. Second, we submit our model complexity curves in the prediction versus reproducibility space as reflecting classic bias-variance tradeoffs. Among the particular analysis chains considered, we found little impact in performance...... metrics with alignment, some benefit with temporal detrending, and greatest improvement with spatial smoothing....

  8. Fourier power, subjective distance, and object categories all provide plausible models of BOLD responses in scene-selective visual areas

    Science.gov (United States)

    Lescroart, Mark D.; Stansbury, Dustin E.; Gallant, Jack L.

    2015-01-01

    Perception of natural visual scenes activates several functional areas in the human brain, including the Parahippocampal Place Area (PPA), Retrosplenial Complex (RSC), and the Occipital Place Area (OPA). It is currently unclear what specific scene-related features are represented in these areas. Previous studies have suggested that PPA, RSC, and/or OPA might represent at least three qualitatively different classes of features: (1) 2D features related to Fourier power; (2) 3D spatial features such as the distance to objects in a scene; or (3) abstract features such as the categories of objects in a scene. To determine which of these hypotheses best describes the visual representation in scene-selective areas, we applied voxel-wise modeling (VM) to BOLD fMRI responses elicited by a set of 1386 images of natural scenes. VM provides an efficient method for testing competing hypotheses by comparing predictions of brain activity based on encoding models that instantiate each hypothesis. Here we evaluated three different encoding models that instantiate each of the three hypotheses listed above. We used linear regression to fit each encoding model to the fMRI data recorded from each voxel, and we evaluated each fit model by estimating the amount of variance it predicted in a withheld portion of the data set. We found that voxel-wise models based on Fourier power or the subjective distance to objects in each scene predicted much of the variance predicted by a model based on object categories. Furthermore, the response variance explained by these three models is largely shared, and the individual models explain little unique variance in responses. Based on an evaluation of previous studies and the data we present here, we conclude that there is currently no good basis to favor any one of the three alternative hypotheses about visual representation in scene-selective areas. We offer suggestions for further studies that may help resolve this issue. PMID:26594164

  9. Fourier power, subjective distance and object categories all provide plausible models of BOLD responses in scene-selective visual areas

    Directory of Open Access Journals (Sweden)

    Mark Daniel Lescroart

    2015-11-01

    Full Text Available Perception of natural visual scenes activates several functional areas in the human brain, including the Parahippocampal Place Area (PPA, Retrosplenial Complex (RSC, and the Occipital Place Area (OPA. It is currently unclear what specific scene-related features are represented in these areas. Previous studies have suggested that PPA, RSC, and/or OPA might represent at least three qualitatively different classes of features: (1 2D features related to Fourier power; (2 3D spatial features such as the distance to objects in a scene; or (3 abstract features such as the categories of objects in a scene. To determine which of these hypotheses best describes the visual representation in scene-selective areas, we applied voxel-wise modeling (VM to BOLD fMRI responses elicited by a set of 1,386 images of natural scenes. VM provides an efficient method for testing competing hypotheses by comparing predictions of brain activity based on encoding models that instantiate each hypothesis. Here we evaluated three different encoding models that instantiate each of the three hypotheses listed above. We used linear regression to fit each encoding model to the fMRI data recorded from each voxel, and we evaluated each fit model by estimating the amount of variance it predicted in a withheld portion of the data set. We found that voxel-wise models based on Fourier power or the subjective distance to objects in each scene predicted much of the variance predicted by a model based on object categories. Furthermore, the response variance explained by these three models is largely shared, and the individual models explain little unique variance in responses. Based on an evaluation of previous studies and the data we present here, we conclude that there is currently no good basis to favor any one of the three alternative hypotheses about visual representation in scene-selective areas. We offer suggestions for further studies that may help resolve this issue.

  10. Effect of luminance contrast on BOLD-fMRI response in deaf and normal occipital visual cortex

    International Nuclear Information System (INIS)

    Xue Yanping; Zhai Renyou; Jiang Tao; Cui Yong; Zhou Tiangang; Rao Hengyi; Zhuo Yan

    2002-01-01

    Objective: To examine the effect of luminance contrast stimulus by using blood oxygenation level dependent functional magnetic resonance imaging (BOLD-fMRI) within deaf occipital visual cortex, and to compare the distribution, extent, and intensity of activated areas between deaf subjects and normal hearing subjects. Methods: Twelve deaf subjects (average age 16.5) and 15 normal hearing subjects (average age 23.7) were stimulated by 4 kinds of luminance contrast (0.7, 2.2, 50.0, 180.0 lm). The fMRI data were collected on GE 1.5 T Signa Horizon LX MRI system and analyzed by AFNI to generate the activation map. Results: Responding to all 4 kinds of stimulus luminance contrast, all deaf and normal subjects showed significant activations in occipital visual cortex. For both deaf and normal subjects, the number of activated pixels increased significantly with increasing luminance contrast (F normal = 4.27, P deaf = 6.41, P 0.05). The local mean activation level for all activated pixels remained constant with increasing luminance contrast. However, there was an increase in the mean activation level for those activated pixels common to all trials as the stimulus luminance contrast was increased, but no significant difference was found within them (F normal = 0.79, P > 0.05; F deaf = 1.6, P > 0.05). Conclusion: The effect of luminance contrast on occipital visual cortex of deaf is similar to but somewhat higher than that of normal hearing subjects. In addition, it also proved that fMRI is a feasible method in the study of the deaf visual cortex

  11. Cortical response variation with different sound pressure levels: a combined event-related potentials and FMRI study.

    Directory of Open Access Journals (Sweden)

    Irene Neuner

    Full Text Available Simultaneous recording of electroencephalography (EEG and functional magnetic resonance imaging (fMRI provides high spatial and temporal resolution. In this study we combined EEG and fMRI to investigate the structures involved in the processing of different sound pressure levels (SPLs.EEG data were recorded simultaneously with fMRI from 16 healthy volunteers using MR compatible devices at 3 T. Tones with different SPLs were delivered to the volunteers and the N1/P2 amplitudes were included as covariates in the fMRI data analysis in order to compare the structures activated with high and low SPLs. Analysis of variance (ANOVA and ROI analysis were also performed. Additionally, source localisation analysis was performed on the EEG data.The integration of averaged ERP parameters into the fMRI analysis showed an extended map of areas exhibiting covariation with the BOLD signal related to the auditory stimuli. The ANOVA and ROI analyses also revealed additional brain areas other than the primary auditory cortex (PAC which were active with the auditory stimulation at different SPLs. The source localisation analyses showed additional sources apart from the PAC which were active with the high SPLs.The PAC and the insula play an important role in the processing of different SPLs. In the fMRI analysis, additional activation was found in the anterior cingulate cortex, opercular and orbito-frontal cortices with high SPLs. A strong response of the visual cortex was also found with the high SPLs, suggesting the presence of cross-modal effects.

  12. Hemodynamic effects of ventricular defibrillation

    Science.gov (United States)

    Pansegrau, Donald G.; Abboud, François M.

    1970-01-01

    Hemodynamic responses to ventricular defibrillation were studied in anesthetized dogs. Observations were made on arterial, right atrial and left ventricular end-diastolic pressures, on cardiac output (dye dilution), heart rate, and right atrial electrocardiogram. Ventricular fibrillation was induced electrically with a bipolar electrode catheter placed in the right ventricle. Fibrillation was maintained for 15 or 30 sec and terminated with a 400 w sec capacitor discharge across the thoracic cage. Responses lasted 1-10 min after conversion and included a cholinergic and an adrenergic component. The cholinergic component was characterized by sinus bradycardia, periods of sinus arrest, atrioventricular block, and ventricular premature beats. The adrenergic component included increases in arterial pressure, in cardiac output, and in left ventricular stroke work at a time when left ventricular end-diastolic pressure was normal; there was no change in total peripheral resistance. The pH of arterial blood decreased slightly and pCO2 increased but pO2 and the concentration of lactate were unchanged. Bilateral vagotomy and intravenous administration of atropine blocked the cholinergic component, unmasked a sinus tachycardia, and accentuated the adrenergic component of the response. The latter was blocked by intravenous administration of propranolol and phenoxybenzamine. These responses were related primarily to conversion of ventricular fibrillation rather than to the electrical discharge of countershock because countershock without ventricular fibrillation caused more transient and smaller responses than those observed with defibrillation: furthermore, the hemodynamic effects of defibrillation were augmented by prolongation of the duration of fibrillation. The results suggest that the cholinergic component of the response may be detrimental in that it favors spontaneous recurrence of fibrillation; on the other hand, the adrenergic component may be essential for conversion

  13. Topiramate and its effect on fMRI of language in patients with right or left temporal lobe epilepsy

    Science.gov (United States)

    Szaflarski, Jerzy P.; Allendorfer, Jane B.

    2013-01-01

    Topiramate (TPM) is well recognized for its negative effects oncognition, language performance and lateralization results on the intracarotid amobarbital procedure (IAP). But, the effects of TPM on functional MRI (fMRI) of language and the fMRI signals are less clear. Functional MRI is increasingly used for presurgical evaluation of epilepsy patients in place of IAP for language lateralization. Thus, the goal of this study was to assess the effects of TPM on fMRI signals. In this study, we included 8 patients with right temporal lobe epilepsy (RTLE) and 8 with left temporal lobe epilepsy (LTLE) taking TPM (+TPM). Matched to them for age, handedness and side of seizure onset were 8 patients with RTLE and 8 with LTLE not taking TPM (−TPM). Matched for age and handedness to the patients with TLE were 32 healthy controls. The fMRI paradigm involved semantic decision/tone decision task (in-scanner behavioral data were collected). All epilepsy patients received a standard neuropsychological language battery. One sample t-tests were performed within each group to assess task-specific activations. Functional MRI data random-effects analysis was performed to determine significant group activation differences and to assess the effect of TPM dose on task activation. Direct group comparisons of fMRI, language and demographic data between patients with R/L TLE +TPM vs. −TPM and the analysis of the effects of TPM on blood oxygenation level-dependent (BOLD) signal were performed. Groups were matched for age, handedness and, within the R/L TLE groups, for the age of epilepsy onset/duration and the number of AEDs/TPM dose. The in-scanner language performance of patients was worse when compared to healthy controls — all pTPM vs. −TPM showed significant fMRI signal differences between groups (increases in left cingulate gyrus and decreases in left superior temporal gyrus in the patients with LTLE +TPM; increases in the right BA 10 and left visual cortex and decreases in the

  14. Research progress of BOLD-functional MRI of hepatic encephalopathy

    International Nuclear Information System (INIS)

    Ni Ling; Zhang Longjiang; Lu Guangming

    2013-01-01

    Hepatic encephalopathy (HE), characterized by a wide spectrum of clinical manifestations, ranging from behavior abnormality, conscious disorder and even coma, is a consequence of liver dysfunction in both acute and chronic hepatic diseases. Minimal hepatic encephalopathy (MHE) refers to a subgroup of cirrhotic patients without clinical overt hepatic encephalopathy symptoms hut with abnormalities in neuro -cognitive functions. HE/MHE can have a far-reaching impact on quality of life and prognosis. The exact neuropathology mechanism was still unclear. Recently, functional MRI (fMRI) has been increasingly applied for investigating the neuro-pathophysiological mechanism of HE. This paper will review the fMRI research applied on uncovering the neuropathology mechanism of HE. (authors)

  15. The effect of letter-stroke boldness on reading speed in central and peripheral vision.

    Science.gov (United States)

    Bernard, Jean-Baptiste; Kumar, Girish; Junge, Jasmine; Chung, Susana T L

    2013-05-24

    People with central vision loss often prefer boldface print over normal print for reading. However, little is known about how reading speed is influenced by the letter-stroke boldness of font. In this study, we examined the reliance of reading speed on stroke boldness, and determined whether this reliance differs between the normal central and peripheral vision. Reading speed was measured using the rapid serial visual presentation paradigm, where observers with normal vision read aloud short single sentences presented on a computer monitor, one word at a time. Text was rendered in Courier at six levels of boldness, defined as the stroke-width normalized to that of the standard Courier font: 0.27, 0.72, 1, 1.48, 1.89 and 3.04× the standard. Testings were conducted at the fovea and 10° in the inferior visual field. Print sizes used were 0.8× and 1.4× the critical print size (smallest print size that can be read at the maximum reading speed). At the fovea, reading speed was invariant for the middle four levels of boldness, but dropped by 23.3% for the least and the most bold text. At 10° eccentricity, reading speed was virtually the same for all boldness reading speed does not benefit from bold text in the normal fovea and periphery. Excessive increase in stroke boldness may even impair reading speed, especially in the periphery. Copyright © 2013 Elsevier Ltd. All rights reserved.

  16. Hemodynamic Effects of Glucagon - A Literature Review.

    Science.gov (United States)

    Meidahl Petersen, Kasper; Bøgevig, Søren; Holst, Jens Juul; Knop, Filip Krag; Christensen, Mikkel Bring

    2018-03-13

    Glucagon's effects on hemodynamic parameters - most notably heart rate and cardiac contractility - are overlooked. The glucagon receptor is a central target in novel and anticipated type 2 diabetes therapies and hemodynamic consequences of glucagon signaling have therefore become increasingly important. In this review we summarize and evaluate published studies on glucagon pharmacology with focus on clinical hemodynamic effects in humans. PubMed, EMBASE and the Cochrane library were searched for clinical studies concerning hemodynamic effects of glucagon (no year restriction). Papers reporting effects of a defined glucagon dose on any hemodynamic parameter were included. Reference searches were conducted in retrieved articles. Hemodynamic effects of glucagon have been investigated mainly in cohort-studies of heart failure patients receiving large glucagon bolus injections. The identified studies had shortcomings related to restricted patient groups, lack of a control group, randomization or blinding. We identified no properly conducted randomized clinical trials. The majority of human studies report stimulating effects of pharmacological glucagon doses on heart rate, cardiac contractility and blood pressure. The effects were characterized by short duration, inter-individual variation and rapid desensitization. Some studies reported no measurable effects of glucagon. The level of evidence regarding hemodynamic effects of glucagon is low and observations in published studies are inconsistent. Actual effects, inter-individual variation, dose-response relationships and possible long-term effects of supra-physiological glucagon levels warrant further investigation.

  17. Is the self special in the dorsomedial prefrontal cortex? An fMRI study.

    Science.gov (United States)

    Yaoi, Ken; Osaka, Naoyuki; Osaka, Mariko

    2009-01-01

    In recent years, several neuroimaging studies have suggested that the neural basis of the self-referential process1 is special, especially in the medial prefrontal cortex (MPFC). However, it remains controversial whether activity of the MPFC (and other related brain regions) appears only during the self-referential process. We investigated the neural correlates during the processing of references to the self, close other (friend), and distant other (prime minister) using fMRI. In comparison with baseline findings, referential processing to the three kinds of persons defined above showed common activation patterns in the dorsomedial prefrontal cortex (DMPFC), left middle temporal gyrus, left angular gyrus, posterior cingulate cortex and right cerebellum. Additionally, percent changes in BOLD signal in five regions of interest demonstrated the same findings. The result indicated that DMPFC was not special for the self-referential process, while there are common neural bases for evaluating the personalities of the self and others.

  18. Functional cortical and subcortical abnormalities in pedophilia: a combined study using a choice reaction time task and fMRI.

    Science.gov (United States)

    Poeppl, Timm B; Nitschke, Joachim; Dombert, Beate; Santtila, Pekka; Greenlee, Mark W; Osterheider, Michael; Mokros, Andreas

    2011-06-01

    Pedophiles show sexual interest in prepubescent children but not in adults. Research into the neurofunctional mechanisms of paraphilias has gathered momentum over the last years. To elucidate the underlying neural processing of sexual interest among pedophiles and to highlight the differences in comparison with nonparaphilic sexual interest in adults. Nine pedophilic patients and 11 nonpedophilic control subjects underwent functional magnetic resonance imaging (fMRI) while viewing pictures of nude (prepubescents, pubescents, and adults) and neutral content, as well as performing a concomitant choice reaction time task (CRTT). Brain blood oxygen level-dependent (BOLD) signals and response latencies in the CRTT during exposure to each picture category. Analysis of behavioral data showed group differences in reaction times regarding prepubescent and adult but not pubescent stimuli. During stimulation with pictures displaying nude prepubescents, pedophiles showed increased BOLD response in brain areas known to be involved in processing of visual sexual stimuli. Comparison of pedophilic patients with the control group discovered differences in BOLD responses with respect to prepubescent and adult but not to pubescent stimuli. Differential effects in particular occurred in the cingulate gyrus and insular region. The brain response of pedophiles to visual sexual stimulation by images of nude prepubescents is comparable with previously described neural patterns of sexual processing in nonpedophilic human males evoked by visual stimuli depicting nude adults. Nevertheless, group differences found in the cingulate gyrus and the insular region suggest an important role of these brain areas in pedophilic sexual interest. Furthermore, combining attention-based methods like CRTT with fMRI may be a viable option for future diagnostic procedures regarding pedophilia. © 2011 International Society for Sexual Medicine.

  19. Role of mitochondrial calcium uptake homeostasis in resting state fMRI brain networks.

    Science.gov (United States)

    Kannurpatti, Sridhar S; Sanganahalli, Basavaraju G; Herman, Peter; Hyder, Fahmeed

    2015-11-01

    Mitochondrial Ca(2+) uptake influences both brain energy metabolism and neural signaling. Given that brain mitochondrial organelles are distributed in relation to vascular density, which varies considerably across brain regions, we hypothesized different physiological impacts of mitochondrial Ca(2+) uptake across brain regions. We tested the hypothesis by monitoring brain "intrinsic activity" derived from the resting state functional MRI (fMRI) blood oxygen level dependent (BOLD) fluctuations in different functional networks spanning the somatosensory cortex, caudate putamen, hippocampus and thalamus, in normal and perturbed mitochondrial Ca(2+) uptake states. In anesthetized rats at 11.7 T, mitochondrial Ca(2+) uptake was inhibited or enhanced respectively by treatments with Ru360 or kaempferol. Surprisingly, mitochondrial Ca(2+) uptake inhibition by Ru360 and enhancement by kaempferol led to similar dose-dependent decreases in brain-wide intrinsic activities in both the frequency domain (spectral amplitude) and temporal domain (resting state functional connectivity; RSFC). The fact that there were similar dose-dependent decreases in the frequency and temporal domains of the resting state fMRI-BOLD fluctuations during mitochondrial Ca(2+) uptake inhibition or enhancement indicated that mitochondrial Ca(2+) uptake and its homeostasis may strongly influence the brain's functional organization at rest. Interestingly, the resting state fMRI-derived intrinsic activities in the caudate putamen and thalamic regions saturated much faster with increasing dosage of either drug treatment than the drug-induced trends observed in cortical and hippocampal regions. Regional differences in how the spectral amplitude and RSFC changed with treatment indicate distinct mitochondrion-mediated spontaneous neuronal activity coupling within the various RSFC networks determined by resting state fMRI. Copyright © 2015 John Wiley & Sons, Ltd.

  20. Sensory-motor networks involved in speech production and motor control: an fMRI study.

    Science.gov (United States)

    Behroozmand, Roozbeh; Shebek, Rachel; Hansen, Daniel R; Oya, Hiroyuki; Robin, Donald A; Howard, Matthew A; Greenlee, Jeremy D W

    2015-04-01

    Speaking is one of the most complex motor behaviors developed to facilitate human communication. The underlying neural mechanisms of speech involve sensory-motor interactions that incorporate feedback information for online monitoring and control of produced speech sounds. In the present study, we adopted an auditory feedback pitch perturbation paradigm and combined it with functional magnetic resonance imaging (fMRI) recordings in order to identify brain areas involved in speech production and motor control. Subjects underwent fMRI scanning while they produced a steady vowel sound /a/ (speaking) or listened to the playback of their own vowel production (playback). During each condition, the auditory feedback from vowel production was either normal (no perturbation) or perturbed by an upward (+600 cents) pitch-shift stimulus randomly. Analysis of BOLD responses during speaking (with and without shift) vs. rest revealed activation of a complex network including bilateral superior temporal gyrus (STG), Heschl's gyrus, precentral gyrus, supplementary motor area (SMA), Rolandic operculum, postcentral gyrus and right inferior frontal gyrus (IFG). Performance correlation analysis showed that the subjects produced compensatory vocal responses that significantly correlated with BOLD response increases in bilateral STG and left precentral gyrus. However, during playback, the activation network was limited to cortical auditory areas including bilateral STG and Heschl's gyrus. Moreover, the contrast between speaking vs. playback highlighted a distinct functional network that included bilateral precentral gyrus, SMA, IFG, postcentral gyrus and insula. These findings suggest that speech motor control involves feedback error detection in sensory (e.g. auditory) cortices that subsequently activate motor-related areas for the adjustment of speech parameters during speaking. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. The BOLD cerebrovascular reactivity response to progressive hypercapnia in young and elderly.

    Science.gov (United States)

    Bhogal, Alex A; De Vis, Jill B; Siero, Jeroen C W; Petersen, Esben T; Luijten, Peter R; Hendrikse, Jeroen; Philippens, Marielle E P; Hoogduin, Hans

    2016-10-01

    Blood Oxygenation Level Dependent (BOLD) imaging in combination with vasoactive stimuli can be used to probe cerebrovascular reactivity (CVR). Characterizing the healthy, age-related changes in the BOLD-CVR response can provide a reference point from which to distinguish abnormal CVR from the otherwise normal effects of ageing. Using a computer controlled gas delivery system, we examine differences in BOLD-CVR response to progressive hypercapnia between 16 young (28±3years, 9 female) and 30 elderly subjects (66±4years, 13 female). Furthermore, we incorporate baseline T 2 * information to broaden our interpretation of the BOLD-CVR response. Significant age-related differences were observed. Grey matter CVR at 7mmHg above resting PetCO 2 was lower amongst elderly (0.19±0.06%ΔBOLD/mmHg) as compared to young subjects (0.26±0.07%ΔBOLD/mmHg). White matter CVR at 7mmHg above baseline PetCO 2 showed no significant difference between young (0.04±0.02%ΔBOLD/mmHg) and elderly subjects (0.05±0.03%ΔBOLD/mmHg). We saw no significant differences in the BOLD signal response to progressive hypercapnia between male and female subjects in either grey or white matter. The observed differences in the healthy BOLD-CVR response could be explained by age-related changes in vascular mechanical properties. Copyright © 2016 Elsevier Inc. All rights reserved.

  2. Altered fMRI connectivity dynamics in temporal lobe epilepsy might explain seizure semiology

    Directory of Open Access Journals (Sweden)

    Helmut eLaufs

    2014-09-01

    Full Text Available Abstract: Temporal lobe epilepsy (TLE can be conceptualized as a network disease. The network can be characterized by inter-regional functional connectivity, i.e. blood oxygen level-dependent (BOLD signal correlations between any two region pairs. However, functional connectivity is not constant over time, thus computing correlation at a given time and then at some later time could give different results (non-stationarity. We hypothesized (1 that non-stationarities can be induced by epilepsy (e.g. interictal epileptic activity increasing local signal variance and that (2 these transient events contribute to fluctuations in connectivity leading to pathological functioning, i.e. TLE semiology. We analyzed fMRI data from 27 patients with TLE and 22 healthy controls focusing on EEG-confirmed wake epochs only to protect against sleep-induced connectivity changes. Testing hypothesis (1, we identified brain regions where the BOLD signal variance was significantly greater in TLE than in controls: the temporal pole - including the hippocampus. Taking the latter as the seed region and testing hypothesis (2 we calculated the time-varying interregional correlation values (dynamic functional connectivity to other brain regions and found greater connectivity variance in the TLE than the control group mainly in the precuneus, the supplementary and sensori-motor and the frontal cortices.We conclude that the highest BOLD signal variance in the hippocampi is highly suggestive of a specific epilepsy-related effect. The altered connectivity dynamics in TLE patients might help to explain the hallmark semiological features of dyscognitive seizures including impaired consciousness (precuneus, frontal cortex, sensory disturbance and motor automatisms (sensorimotor cortices, supplementary motor cortex. Accounting for the non-stationarity and state-dependence of functional connectivity are a prerequisite in the search for potential connectivity-derived biomarkers in TLE.

  3. Altered FMRI connectivity dynamics in temporal lobe epilepsy might explain seizure semiology.

    Science.gov (United States)

    Laufs, Helmut; Rodionov, Roman; Thornton, Rachel; Duncan, John Sydney; Lemieux, Louis; Tagliazucchi, Enzo

    2014-01-01

    Temporal lobe epilepsy (TLE) can be conceptualized as a network disease. The network can be characterized by inter-regional functional connectivity, i.e., blood oxygen level-dependent (BOLD) signal correlations between any two regions. However, functional connectivity is not constant over time, thus computing correlation at a given time and then at some later time could give different results (non-stationarity). We hypothesized (1) that non-stationarities can be induced by epilepsy (e.g., interictal epileptic activity) increasing local signal variance and that (2) these transient events contribute to fluctuations in connectivity leading to pathological functioning, i.e., TLE semiology. We analyzed fMRI data from 27 patients with TLE and 22 healthy controls focusing on EEG-confirmed wake epochs only to protect against sleep-induced connectivity changes. Testing hypothesis (1), we identified brain regions where the BOLD signal variance was significantly greater in TLE than in controls: the temporal pole - including the hippocampus. Taking the latter as the seed region and testing hypothesis (2), we calculated the time-varying inter-regional correlation values (dynamic functional connectivity) to other brain regions and found greater connectivity variance in the TLE than the control group mainly in the precuneus, the supplementary and sensorimotor, and the frontal cortices. We conclude that the highest BOLD signal variance in the hippocampi is highly suggestive of a specific epilepsy-related effect. The altered connectivity dynamics in TLE patients might help to explain the hallmark semiological features of dyscognitive seizures including impaired consciousness (precuneus, frontal cortex), sensory disturbance, and motor automatisms (sensorimotor cortices, supplementary motor cortex). Accounting for the non-stationarity and state-dependence of functional connectivity are a prerequisite in the search for potential connectivity-derived biomarkers in TLE.

  4. fMRI data visualization with BrainBlend and Blender.

    Science.gov (United States)

    Pyka, Martin; Hertog, Matthias; Fernandez, Raul; Hauke, Sascha; Heider, Dominik; Dannlowski, Udo; Konrad, Carsten

    2010-03-01

    The visualization and exploration of neuroimaging data is important for the analysis of anatomical and functional magnetic resonance (MR) images and thresholded statistical parametric maps. While two-dimensional orthogonal views of neuroimaging data are used to display statistical analyses, real three-dimensional (3d) depictions are helpful for showing the spatial distribution of a functional network, as well as its temporal evolution. However, viewers that are freely available on the internet offer only limited rendering capabilities and depictions of temporal changes of the blood oxygen level-dependent (BOLD) response. In this article, we present BrainBlend, a toolbox for the software package Statistical Parametric Mapping (SPM), that generates voxeldata files to be used with the open-source 3d-software "Blender". Our interface between SPM and Blender permits the use of any Analyze- and Nifti-file for the creation of images and animations of transparent volumetric objects. Different kinds of anatomical, functional and statistical data can be rendered as volumetric objects in order to convey an immediate understanding of the three-dimensional shape. Representations of functional networks can be animated using a time course extracted from the general linear model or the independent component analysis. Relative BOLD activations of functional MR-images can be calculated for a time-resolved depiction of hemodynamic changes. The resulting animation can be displayed along with its corresponding paradigm matrix and the presented stimuli. BrainBlend is particularly suitable for the visual exploration of interactions between functional networks, for time-resolved animations of BOLD changes and meets high demands on visual quality in images and animations.

  5. Acetazolamide-augmented dynamic BOLD (aczBOLD imaging for assessing cerebrovascular reactivity in chronic steno-occlusive disease of the anterior circulation: An initial experience

    Directory of Open Access Journals (Sweden)

    Junjie Wu

    2017-01-01

    Full Text Available The purpose of this study was to measure cerebrovascular reactivity (CVR in chronic steno-occlusive disease using a novel approach that couples BOLD imaging with acetazolamide (ACZ vasoreactivity (aczBOLD, to evaluate dynamic effects of ACZ on BOLD and to establish the relationship between aczBOLD and dynamic susceptibility contrast (DSC perfusion MRI. Eighteen patients with unilateral chronic steno-occlusive disease of the anterior circulation underwent a 20-min aczBOLD imaging protocol, with ACZ infusion starting at 5 min of scan initiation. AczBOLD reactivity was calculated on a voxel-by-voxel basis to generate CVR maps for subsequent quantitative analyses. Reduced CVR was observed in the diseased vs. the normal hemisphere both by qualitative and quantitative assessment (gray matter (GM: 4.13% ± 1.16% vs. 4.90% ± 0.98%, P = 0.002; white matter (WM: 2.83% ± 1.23% vs. 3.50% ± 0.94%, P = 0.005. In all cases BOLD signal began increasing immediately following ACZ infusion, approaching a plateau at ~8.5 min after infusion, with the tissue volume of reduced augmentation increasing progressively with time, peaking at 2.60 min (time range above 95% of the maximum value: 0–4.43 min for the GM and 1.80 min (time range above 95% of the maximum value: 1.40–3.53 min for the WM. In the diseased hemisphere, aczBOLD CVR significantly correlated with baseline DSC time-to-maximum of the residue function (Tmax (P = 0.008 for the WM and normalized cerebral blood flow (P = 0.003 for the GM, and P = 0.001 for the WM. AczBOLD provides a novel, safe, easily implementable approach to CVR measurement in the routine clinical environments. Further studies can establish quantitative thresholds from aczBOLD towards identification of patients at heightened risk of recurrent ischemia and cognitive decline.

  6. Acetazolamide-augmented dynamic BOLD (aczBOLD) imaging for assessing cerebrovascular reactivity in chronic steno-occlusive disease of the anterior circulation: An initial experience.

    Science.gov (United States)

    Wu, Junjie; Dehkharghani, Seena; Nahab, Fadi; Qiu, Deqiang

    2017-01-01

    The purpose of this study was to measure cerebrovascular reactivity (CVR) in chronic steno-occlusive disease using a novel approach that couples BOLD imaging with acetazolamide (ACZ) vasoreactivity (aczBOLD), to evaluate dynamic effects of ACZ on BOLD and to establish the relationship between aczBOLD and dynamic susceptibility contrast (DSC) perfusion MRI. Eighteen patients with unilateral chronic steno-occlusive disease of the anterior circulation underwent a 20-min aczBOLD imaging protocol, with ACZ infusion starting at 5 min of scan initiation. AczBOLD reactivity was calculated on a voxel-by-voxel basis to generate CVR maps for subsequent quantitative analyses. Reduced CVR was observed in the diseased vs. the normal hemisphere both by qualitative and quantitative assessment (gray matter (GM): 4.13% ± 1.16% vs. 4.90% ± 0.98%, P  = 0.002; white matter (WM): 2.83% ± 1.23% vs. 3.50% ± 0.94%, P  = 0.005). In all cases BOLD signal began increasing immediately following ACZ infusion, approaching a plateau at ~ 8.5 min after infusion, with the tissue volume of reduced augmentation increasing progressively with time, peaking at 2.60 min (time range above 95% of the maximum value: 0-4.43 min) for the GM and 1.80 min (time range above 95% of the maximum value: 1.40-3.53 min) for the WM. In the diseased hemisphere, aczBOLD CVR significantly correlated with baseline DSC time-to-maximum of the residue function (T max ) ( P  = 0.008 for the WM) and normalized cerebral blood flow ( P  = 0.003 for the GM, and P  = 0.001 for the WM). AczBOLD provides a novel, safe, easily implementable approach to CVR measurement in the routine clinical environments. Further studies can establish quantitative thresholds from aczBOLD towards identification of patients at heightened risk of recurrent ischemia and cognitive decline.

  7. Pros and cons of using the informed basis set to account for hemodynamic response variability with developmental data

    Directory of Open Access Journals (Sweden)

    Fabien Cignetti

    2016-07-01

    Full Text Available Conventional analysis of functional magnetic resonance imaging (fMRI data using the general linear model (GLM employs a neural model convolved with a canonical hemodynamic response function (HRF peaking 5s after stimulation. Incorporation of a further basis function, namely the canonical HRF temporal derivative, accounts for delays in the hemodynamic response to neural activity. A population that may benefit from this flexible approach is children whose hemodynamic response is not yet mature. Here, we examined the effects of using the set based on the canonical HRF plus its temporal derivative on both first- and second-level GLM analyses, through simulations and using developmental data (an fMRI dataset on proprioceptive mapping in children and adults. Simulations of delayed fMRI first-level data emphasized the benefit of carrying forward to the second-level a derivative boost that combines derivative and nonderivative beta estimates. In the experimental data, second-level analysis using a paired t-test showed increased mean amplitude estimate (i.e., increased group contrast mean in several brain regions related to proprioceptive processing when using the derivative boost compared to using only the nonderivative term. This was true especially in children. However, carrying forward to the second-level the individual derivative boosts had adverse consequences on random-effects analysis that implemented one-sample t-test, yielding increased between-subject variance, thus affecting group-level statistic. Boosted data also presented a lower level of smoothness that had implication for the detection of group average activation. Imposing soft constraints on the derivative boost by limiting the time-to-peak range of the modelled response within a specified range (i.e., 4-6s mitigated these issues. These findings support the notion that there are pros and cons to using the informed basis set with developmental data.

  8. Larger Neural Responses Produce BOLD Signals That Begin Earlier in Time

    Directory of Open Access Journals (Sweden)

    Serena eThompson

    2014-06-01

    Full Text Available Functional MRI analyses commonly rely on the assumption that the temporal dynamics of hemodynamic response functions (HRFs are independent of the amplitude of the neural signals that give rise to them. The validity of this assumption is particularly important for techniques that use fMRI to resolve sub-second timing distinctions between responses, in order to make inferences about the ordering of neural processes. Whether or not the detailed shape of the HRF is independent of neural response amplitude remains an open question, however. We performed experiments in which we measured responses in primary visual cortex (V1 to large, contrast-reversing checkerboards at a range of contrast levels, which should produce varying amounts of neural activity. Ten subjects (ages 22-52 were studied in each of two experiments using 3 Tesla scanners. We used rapid, 250 msec, temporal sampling (repetition time, or TR and both short and long inter-stimulus interval (ISI stimulus presentations. We tested for a systematic relationship between the onset of the HRF and its amplitude across conditions, and found a strong negative correlation between the two measures when stimuli were separated in time (long- and medium-ISI experiments, but not the short-ISI experiment. Thus, stimuli that produce larger neural responses, as indexed by HRF amplitude, also produced HRFs with shorter onsets. The relationship between amplitude and latency was strongest in voxels with lowest mean-normalized variance (i.e., parenchymal voxels. The onset differences observed in the longer-ISI experiments are likely attributable to mechanisms of neurovascular coupling, since they are substantially larger than reported differences in the onset of action potentials in V1 as a function of response amplitude.

  9. Cerebral responses and role of the prefrontal cortex in conditioned pain modulation: an fMRI study in healthy subjects

    Science.gov (United States)

    Bogdanov, Volodymyr B.; Viganò, Alessandro; Noirhomme, Quentin; Bogdanova, Olena V.; Guy, Nathalie; Laureys, Steven; Renshaw, Perry F.; Dallel, Radhouane; Phillips, Christophe; Schoenen, Jean

    2017-01-01

    The mechanisms underlying conditioned pain modulation (CPM) are multifaceted. We searched for a link between individual differences in prefrontal cortex activity during multi-trial heterotopic noxious cold conditioning and modulation of the cerebral response to phasic heat pain. In 24 healthy female subjects, we conditioned laser heat stimuli to the left hand by applying alternatively ice-cold or lukewarm compresses to the right foot. We compared pain ratings with cerebral fMRI BOLD responses. We also analyzed the relation between CPM and BOLD changes produced by the heterotopic cold conditioning itself, as well as the impact of anxiety and habituation of cold-pain ratings. Specific cerebral activation was identified in precuneus and left posterior insula/SII, respectively, during early and sustained phases of cold application. During cold conditioning, laser pain decreased (n = 7), increased (n = 10) or stayed unchanged (n = 7). At the individual level, the psychophysical effect was directly proportional to the cold-induced modulation of the laser-induced BOLD response in left posterior insula/SII. The latter correlated with the BOLD response recorded 80 s earlier during the initial 10-s phase of cold application in anterior cingulate, orbitofrontal and lateral prefrontal cortices. High anxiety and habituation of cold pain were associated with greater laser heat-induced pain during heterotopic cold stimulation. The habituation was also linked to the early cold-induced orbitofrontal responses. We conclude that individual differences in conditioned pain modulation are related to different levels of prefrontal cortical activation by the early part of the conditioning stimulus, possibly due to different levels in trait anxiety. PMID:25461267

  10. Perceptual learning of motion direction discrimination with suppressed and unsuppressed MT in humans: an fMRI study.

    Directory of Open Access Journals (Sweden)

    Benjamin Thompson

    Full Text Available The middle temporal area of the extrastriate visual cortex (area MT is integral to motion perception and is thought to play a key role in the perceptual learning of motion tasks. We have previously found, however, that perceptual learning of a motion discrimination task is possible even when the training stimulus contains locally balanced, motion opponent signals that putatively suppress the response of MT. Assuming at least partial suppression of MT, possible explanations for this learning are that 1 training made MT more responsive by reducing motion opponency, 2 MT remained suppressed and alternative visual areas such as V1 enabled learning and/or 3 suppression of MT increased with training, possibly to reduce noise. Here we used fMRI to test these possibilities. We first confirmed that the motion opponent stimulus did indeed suppress the BOLD response within hMT+ compared to an almost identical stimulus without locally balanced motion signals. We then trained participants on motion opponent or non-opponent stimuli. Training with the motion opponent stimulus reduced the BOLD response within hMT+ and greater reductions in BOLD response were correlated with greater amounts of learning. The opposite relationship between BOLD and behaviour was found at V1 for the group trained on the motion-opponent stimulus and at both V1 and hMT+ for the group trained on the non-opponent motion stimulus. As the average response of many cells within MT to motion opponent stimuli is the same as their response to non-directional flickering noise, the reduced activation of hMT+ after training may reflect noise reduction.

  11. BOLD signal and functional connectivity associated with loving kindness meditation.

    Science.gov (United States)

    Garrison, Kathleen A; Scheinost, Dustin; Constable, R Todd; Brewer, Judson A

    2014-05-01

    Loving kindness is a form of meditation involving directed well-wishing, typically supported by the silent repetition of phrases such as "may all beings be happy," to foster a feeling of selfless love. Here we used functional magnetic resonance imaging to assess the neural substrate of loving kindness meditation in experienced meditators and novices. We first assessed group differences in blood oxygen level-dependent (BOLD) signal during loving kindness meditation. We next used a relatively novel approach, the intrinsic connectivity distribution of functional connectivity, to identify regions that differ in intrinsic connectivity between groups, and then used a data-driven approach to seed-based connectivity analysis to identify which connections differ between groups. Our findings suggest group differences in brain regions involved in self-related processing and mind wandering, emotional processing, inner speech, and memory. Meditators showed overall reduced BOLD signal and intrinsic connectivity during loving kindness as compared to novices, more specifically in the posterior cingulate cortex/precuneus (PCC/PCu), a finding that is consistent with our prior work and other recent neuroimaging studies of meditation. Furthermore, meditators showed greater functional connectivity during loving kindness between the PCC/PCu and the left inferior frontal gyrus, whereas novices showed greater functional connectivity during loving kindness between the PCC/PCu and other cortical midline regions of the default mode network, the bilateral posterior insula lobe, and the bilateral parahippocampus/hippocampus. These novel findings suggest that loving kindness meditation involves a present-centered, selfless focus for meditators as compared to novices.

  12. Hemodynamic Effects of Glucagon - A Literature Review

    DEFF Research Database (Denmark)

    Meidahl Petersen, Kasper; Bøgevig, Søren; Holst, Jens Juul

    2018-01-01

    Context: Glucagon's effects on hemodynamic parameters - most notably heart rate and cardiac contractility - are overlooked. The glucagon receptor is a central target in novel and anticipated type 2 diabetes therapies and hemodynamic consequences of glucagon signaling have therefore become increas...... is low and observations in published studies are inconsistent. Actual effects, inter-individual variation, dose-response relationships and possible long-term effects of supra-physiological glucagon levels warrant further investigation....

  13. Central Hemodynamics and Microcirculation in Critical Conditions

    Directory of Open Access Journals (Sweden)

    A. A. Kosovskikh

    2013-01-01

    Full Text Available Objective: to compare central hemodynamic and microcirculatory changes in critical conditions caused by different factors and to reveal their possible differences for a further differentiated approach to intensive therapy. Subjects and methods. The study covered 16 subjects with severe concomitant injury (mean age 41.96±2.83 years and 19 patients with general purulent peritonitis (mean age 45.34±2.16 years. Their follow-up was 7 days. The central hemodynamics was estimated by transpulmonary thermodilution using a Pulsion PiCCO Plus system (Pulsion Medical Systems, Germany. The microcirculatory bed was evaluated by cutaneous laser Doppler flowmetry using a LAKK-02 capillary blood flow laser analyzer (LAZMA Research-and-Production Association, Russian Federation. Results. The pattern of central hemodynamic and microcirculatory disorders varies with the trigger that has led to a critical condition. Central hemodynamics should be stabilized to ensure the average level of tissue perfusion in victims with severe concomitant injury. In general purulent peritonitis, microcirculatory disorders may persist even if the macrohemodynamic parameters are normal. Conclusion. The macrohemodynamic and microcirculatory differences obtained during the study suggest that a complex of intensive therapy should be differentiated and, if the latter is used, it is necessary not only to be based on the central hemodynamics, but also to take into consideration functional changes in microcirculation. Key words: severe concomitant injury, general purulent peritonitis, micro-circulation, central hemodynamics, type of circulation.

  14. Hemodynamics driven cardiac valve morphogenesis.

    Science.gov (United States)

    Steed, Emily; Boselli, Francesco; Vermot, Julien

    2016-07-01

    Mechanical forces are instrumental to cardiovascular development and physiology. The heart beats approximately 2.6 billion times in a human lifetime and heart valves ensure that these contractions result in an efficient, unidirectional flow of the blood. Composed of endocardial cells (EdCs) and extracellular matrix (ECM), cardiac valves are among the most mechanically challenged structures of the body both during and after their development. Understanding how hemodynamic forces modulate cardiovascular function and morphogenesis is key to unraveling the relationship between normal and pathological cardiovascular development and physiology. Most valve diseases have their origins in embryogenesis, either as signs of abnormal developmental processes or the aberrant re-expression of fetal gene programs normally quiescent in adulthood. Here we review recent discoveries in the mechanobiology of cardiac valve development and introduce the latest technologies being developed in the zebrafish, including live cell imaging and optical technologies, as well as modeling approaches that are currently transforming this field. This article is part of a Special Issue entitled: Cardiomyocyte Biology: Integration of Developmental and Environmental Cues in the Heart edited by Marcus Schaub and Hughes Abriel. Copyright © 2015. Published by Elsevier B.V.

  15. Separating neural and vascular effects of caffeine using simultaneous EEG–FMRI: Differential effects of caffeine on cognitive and sensorimotor brain responses

    Science.gov (United States)

    Diukova, Ana; Ware, Jennifer; Smith, Jessica E.; Evans, C. John; Murphy, Kevin; Rogers, Peter J.; Wise, Richard G.

    2012-01-01

    The effects of caffeine are mediated through its non-selective antagonistic effects on adenosine A1 and A2A adenosine receptors resulting in increased neuronal activity but also vasoconstriction in the brain. Caffeine, therefore, can modify BOLD FMRI signal responses through both its neural and its vascular effects depending on receptor distributions in different brain regions. In this study we aim to distinguish neural and vascular influences of a single dose of caffeine in measurements of task-related brain activity using simultaneous EEG–FMRI. We chose to compare low-level visual and motor (paced finger tapping) tasks with a cognitive (auditory oddball) task, with the expectation that caffeine would differentially affect brain responses in relation to these tasks. To avoid the influence of chronic caffeine intake, we examined the effect of 250 mg of oral caffeine on 14 non and infrequent caffeine consumers in a double-blind placebo-controlled cross-over study. Our results show that the task-related BOLD signal change in visual and primary motor cortex was significantly reduced by caffeine, while the amplitude and latency of visual evoked potentials over occipital cortex remained unaltered. However, during the auditory oddball task (target versus non-target stimuli) caffeine significantly increased the BOLD signal in frontal cortex. Correspondingly, there was also a significant effect of caffeine in reducing the target evoked response potential (P300) latency in the oddball task and this was associated with a positive potential over frontal cortex. Behavioural data showed that caffeine also improved performance in the oddball task with a significantly reduced number of missed responses. Our results are consistent with earlier studies demonstrating altered flow-metabolism coupling after caffeine administration in the context of our observation of a generalised caffeine-induced reduction in cerebral blood flow demonstrated by arterial spin labelling (19

  16. How motor, cognitive and musical expertise shapes the brain: Focus on fMRI and EEG resting-state functional connectivity

    DEFF Research Database (Denmark)

    Cantou, Pauline; Platel, Hervé; Desgranges, Béatrice

    2017-01-01

    Brain activity and structure are shaped by life experiences. This plasticity has often been demonstrated with different types of expertise by using functional magnetic resonance imaging (fMRI) and electroencephalography (EEG). Experts showed domain-specific functional neural changes during......-dependent (BOLD) and spontaneous neural activity fluctuations at rest. Since these correlations are thought to reflect a prior history co-activation of brain regions, we propose reviewing studies that focused on the effects of expertise in the motor, cognitive and musical domains on brain plasticity at rest...

  17. BOLD MRI in sheep fetuses: a non-invasive method for measuring changes in tissue oxygenation.

    Science.gov (United States)

    Sørensen, A; Pedersen, M; Tietze, A; Ottosen, L; Duus, L; Uldbjerg, N

    2009-12-01

    The purpose of this descriptive study was to correlate changes in the blood oxygen level-dependent (BOLD) magnetic resonance imaging (MRI) signal with direct measurements of fetal tissue oxygenation. Seven anesthetized ewes carrying singleton fetuses at 125 days' gestation (term 145 days) underwent BOLD MRI, covering the entire fetus in a multislice approach. The fetuses were subjected to normoxic, hypoxic and hyperoxic conditions by changing the O(2)/N(2)O ratio in the maternal ventilated gas supply. The partial pressure of oxygen (pO2) in the fetal liver was measured using an oxygen-sensitive optode. Maternal arterial blood samples were simultaneously withdrawn for blood gas analysis. These measurements were compared with BOLD MRI signals in the fetal liver, kidney, spleen and brain. We demonstrated a consistent increase in the BOLD MRI signal with increasing tissue pO(2). For the fetal liver, spleen and kidney we observed a clear association between changes in maternal arterial blood pO2 and changes in BOLD MRI signal. Interestingly, we found that the BOLD signal of the fetal brain remained unchanged during hypoxic, normoxic and hyperoxic conditions. This experimental study demonstrated that BOLD MRI is a reliable non-invasive method for measuring changes in tissue oxygenation in fetal sheep. The unchanged signal in the fetal brain during altered maternal oxygen conditions is probably explained by the brain-sparing mechanism. Copyright 2009 ISUOG. Published by John Wiley & Sons, Ltd.

  18. Prospective MR image alignment between breath-holds: Application to renal BOLD MRI.

    Science.gov (United States)

    Kalis, Inge M; Pilutti, David; Krafft, Axel J; Hennig, Jürgen; Bock, Michael

    2017-04-01

    To present an image registration method for renal blood oxygen level-dependent (BOLD) measurements that enables semiautomatic assessment of parenchymal and medullary R2* changes under a functional challenge. In a series of breath-hold acquisitions, three-dimensional data were acquired initially for prospective image registration of subsequent BOLD measurements. An algorithm for kidney alignment for BOLD renal imaging (KALIBRI) was implemented to detect the positions of the left and right kidney so that the kidneys were acquired in the subsequent BOLD measurement at consistent anatomical locations. Residual in-plane distortions were corrected retrospectively so that semiautomatic dynamic R2* measurements of the renal cortex and medulla become feasible. KALIBRI was tested in six healthy volunteers during a series of BOLD experiments, which included a 600- to 1000-mL water challenge. Prospective image registration and BOLD imaging of each kidney was achieved within a total measurement time of about 17 s, enabling its execution within a single breath-hold. KALIBRI improved the registration by up to 35% as found with mutual information measures. In four volunteers, a medullary R2* decrease of up to 40% was observed after water ingestion. KALIBRI improves the quality of two-dimensional time-resolved renal BOLD MRI by aligning local renal anatomy, which allows for consistent R2* measurements over many breath-holds. Magn Reson Med 77:1573-1582, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  19. The BOLD cerebrovascular reactivity response to progressive hypercapnia in young and elderly

    DEFF Research Database (Denmark)

    Bhogal, Alex A.; De Vis, Jill B.; Siero, Jeroen C.W.

    2016-01-01

    the otherwise normal effects of ageing. Using a computer controlled gas delivery system, we examine differences in BOLD-CVR response to progressive hypercapnia between 16 young (28 ± 3 years, 9 female) and 30 elderly subjects (66 ± 4 years, 13 female). Furthermore, we incorporate baseline T2* information...... to broaden our interpretation of the BOLD-CVR response. Significant age-related differences were observed. Grey matter CVR at 7 mm Hg above resting PetCO2 was lower amongst elderly (0.19 ± 0.06%ΔBOLD/mm Hg) as compared to young subjects (0.26 ± 0.07%ΔBOLD/mm Hg). White matter CVR at 7 mm Hg above baseline...... PetCO2 showed no significant difference between young (0.04 ± 0.02%ΔBOLD/mm Hg) and elderly subjects (0.05 ± 0.03%ΔBOLD/mm Hg). We saw no significant differences in the BOLD signal response to progressive hypercapnia between male and female subjects in either grey or white matter. The observed...

  20. Motor fMRI and cortical grey matter volume in adults born very preterm

    Directory of Open Access Journals (Sweden)

    E.J. Lawrence

    2014-10-01

    Full Text Available The primary aim of this study was to investigate the functional neuroanatomy of motor planning, initiation and execution in a cohort of young adults (mean age 20 years who were born very preterm (VPT; <33 weeks of gestation, as these individuals are at increased risk of experiencing neuromotor difficulties compared to controls. A cued motor task was presented to 20 right-handed VPT individuals and 20 controls within a functional magnetic resonance imaging (fMRI paradigm. Whole-brain grey matter volume was also quantified and associations with functional data were examined. Despite comparable task performance, fMRI results showed that the VPT group displayed greater brain activation compared to controls in a region comprising the right cerebellum and the lingual, parahippocampal and middle temporal gyri. The VPT group also displayed decreased grey matter volume in the right superior frontal/premotor cortex and left middle temporal gyri. Grey matter volume in the premotor and middle temporal clusters was significantly negatively correlated with BOLD activation in the cerebellum. Overall, these data suggest that preterm birth is associated with functional neuronal differences that persist into adulthood, which are likely to reflect neural reorganisation following early brain injury.

  1. Higher frequency network activity flow predicts lower frequency node activity in intrinsic low-frequency BOLD fluctuations.

    Science.gov (United States)

    Bajaj, Sahil; Adhikari, Bhim Mani; Dhamala, Mukesh

    2013-01-01

    The brain remains electrically and metabolically active during resting conditions. The low-frequency oscillations (LFO) of the blood oxygen level-dependent (BOLD) signal of functional magnetic resonance imaging (fMRI) coherent across distributed brain regions are known to exhibit features of this activity. However, these intrinsic oscillations may undergo dynamic changes in time scales of seconds to minutes during resting conditions. Here, using wavelet-transform based time-frequency analysis techniques, we investigated the dynamic nature of default-mode networks from intrinsic BOLD signals recorded from participants maintaining visual fixation during resting conditions. We focused on the default-mode network consisting of the posterior cingulate cortex (PCC), the medial prefrontal cortex (mPFC), left middle temporal cortex (LMTC) and left angular gyrus (LAG). The analysis of the spectral power and causal flow patterns revealed that the intrinsic LFO undergo significant dynamic changes over time. Dividing the frequency interval 0 to 0.25 Hz of LFO into four intervals slow-5 (0.01-0.027 Hz), slow-4 (0.027-0.073 Hz), slow-3 (0.073-0.198 Hz) and slow-2 (0.198-0.25 Hz), we further observed significant positive linear relationships of slow-4 in-out flow of network activity with slow-5 node activity, and slow-3 in-out flow of network activity with slow-4 node activity. The network activity associated with respiratory related frequency (slow-2) was found to have no relationship with the node activity in any of the frequency intervals. We found that the net causal flow towards a node in slow-3 band was correlated with the number of fibers, obtained from diffusion tensor imaging (DTI) data, from the other nodes connecting to that node. These findings imply that so-called resting state is not 'entirely' at rest, the higher frequency network activity flow can predict the lower frequency node activity, and the network activity flow can reflect underlying structural

  2. O7.10CORRELATION OF PRE-OPERATIVE LANGUAGE FMRI WITH INTRA-OPERATIVE DIRECT CORTICAL STIMULATION FINDINGS IN GLIOMA SURGERY IDENTIFIES POTENTIAL FALSE POSITIVE FMRI ACTIVATIONS WITH CONVENTIONAL ANALYSIS

    Science.gov (United States)

    Coope, D.J.; Karabatsou, K.; Green, S.; Wall, G.; Bambrough, J.

    2014-01-01

    BACKGROUND: Functional MRI (fMRI) has an increasingly established role in surgical planning for glioma patients. However, the presence of neuro-vascular decoupling in the vicinity of the tumor, along with other tumor specific phenomena, raises at least theoretical concerns of potential inaccuracies. Several studies have attempted to correlate fMRI findings with cortical mapping performed using direct cortical stimulation (DCS). Results with respect to language mapping in particular have not been consistent and have focused upon investigating the sensitivity of fMRI to detect eloquent tissue. The possibility of false positive activations that could lead to regions of tumor being incorrectly labeled as inoperable has not been fully explored, in part due to the challenge of accurately recording DCS findings. METHODS: Ten patients with suspected primary or recurrent low-grade gliomas underwent pre-operative fMRI including 3-4 language paradigms on a Phillips 3T Achieva scanner. Comprehensive neuropsychological assessment was also completed prior to awake craniotomy. fMRI data processed using Phillips proprietary IViewBOLD was made available using the BrainLab VectorVision neuro-navigation system for planning of the craniotomy. The surgeon was blinded to fMRI outcomes for the duration of cortical mapping to minimize bias. DCS was completed using a bipolar stimulator tracked continuously using the BrainLab system networked via the VVLink interface to a research system running 3D Slicer. DCS outcomes were recorded by the surgeon using a panel of footswitches to trigger a custom logging module. fMRI data was re-processed using Statistical Parametric Mapping (SPM) 8 to generate t-statistic maps with a simple threshold of 3 applied analogous to the standard clinical implementation. DCS outcomes within 10mm of a cluster of ≥10 voxels above the threshold were analyzed. RESULTS: A mean of 125.4 [range 64-178] unique DCS outcomes were recorded per subject with 60 [32

  3. Analysis of Neural-BOLD Coupling through Four Models of the Neural Metabolic Demand

    Directory of Open Access Journals (Sweden)

    Christopher W Tyler

    2015-12-01

    Full Text Available The coupling of the neuronal energetics to the blood-oxygen-level-dependent (BOLD response is still incompletely understood. To address this issue, we compared the fits of four plausible models of neurometabolic coupling dynamics to available data for simultaneous recordings of the local field potential (LFP and the local BOLD response recorded from monkey primary visual cortex over a wide range of stimulus durations. The four models of the metabolic demand driving the BOLD response were: direct coupling with the overall LFP; rectified coupling to the LFP; coupling with a slow adaptive component of the implied neural population response; and coupling with the non-adaptive intracellular input signal defined by the stimulus time course. Taking all stimulus durations into account, the results imply that the BOLD response is most closely coupled with metabolic demand derived from the intracellular input waveform, without significant influence from the adaptive transients and nonlinearities exhibited by the LFP waveform.

  4. Transverse patterning dissociates human EEG theta power and hippocampal BOLD activation.

    Science.gov (United States)

    Meltzer, Jed A; Fonzo, Greg A; Constable, R Todd

    2009-01-01

    Theta oscillations (4-8 Hz) are often modulated in human electroencephalogram (EEG) studies of memory, whereas overlapping frequencies dominate rodent hippocampal EEG. An emerging parallelism between theta reactivity and hippocampal functional magnetic resonance imaging activation has suggested a homology between theta activity in humans and rodents, representing a process of cortico-hippocampal interaction involved in memory. In the present study, we investigated EEG reactivity during performance of a relational memory task that induces a negative hippocampal blood oxygenation level dependent (BOLD) signal change, compared to a nonrelational control condition. Relational trials induced theta increases and alpha decreases. Low Resolution Electromagnetic Brain Tomography estimates localized theta and alpha modulation to frontal midline and parietal midline cortices, respectively, both of which exhibit negative BOLD responses in this task. Thus, theta and alpha dynamics are dissociable from positive BOLD activation, and may, in fact, colocalize with negative BOLD responses.

  5. A data-driven sparse GLM for fMRI analysis using sparse dictionary learning with MDL criterion.

    Science.gov (United States)

    Lee, Kangjoo; Tak, Sungho; Ye, Jong Chul

    2011-05-01

    We propose a novel statistical analysis method for functional magnetic resonance imaging (fMRI) to overcome the drawbacks of conventional data-driven methods such as the independent component analysis (ICA). Although ICA has been broadly applied to fMRI due to its capacity to separate spatially or temporally independent components, the assumption of independence has been challenged by recent studies showing that ICA does not guarantee independence of simultaneously occurring distinct activity patterns in the brain. Instead, sparsity of the signal has been shown to be more promising. This coincides with biological findings such as sparse coding in V1 simple cells, electrophysiological experiment results in the human medial temporal lobe, etc. The main contribution of this paper is, therefore, a new data driven fMRI analysis that is derived solely based upon the sparsity of the signals. A compressed sensing based data-driven sparse generalized linear model is proposed that enables estimation of spatially adaptive design matrix as well as sparse signal components that represent synchronous, functionally organized and integrated neural hemodynamics. Furthermore, a minimum description length (MDL)-based model order selection rule is shown to be essential in selecting unknown sparsity level for sparse dictionary learning. Using simulation and real fMRI experiments, we show that the proposed method can adapt individual variation better compared to the conventional ICA methods.

  6. fMRI and brain activation after sport concussion: a tale of two cases

    Directory of Open Access Journals (Sweden)

    Michael G Hutchison

    2014-04-01

    Full Text Available Sport-related concussions are now recognized as a major public health concern: The number of participants in sport and recreation is growing, possibly playing their games faster, and there is heightened public awareness of injuries to some high-profile athletes. However, many clinicians still rely on subjective symptom reports for the clinical determination of recovery. Relying on subjective symptom reports can be dangerous, as it has been shown that some concussed athletes may downplay their symptoms. The use of neuropsychological (NP testing tools has enabled clinicians to measure the effects and extent of impairment following concussion more precisely, providing more objective metrics for determining recovery after concussion. Nevertheless, there is a remaining concern that brain abnormalities may exist beyond the point at which individuals achieve recovery in self-reported symptoms and cognition measured by NP testing. Our understanding of brain recovery after concussion is important not only from a neuroscience perspective, but also from the perspective of clinical decision making for safe return-to-play (RTP. A number of advanced neuroimaging tools, including blood oxygen level dependent (BOLD functional magnetic resonance imaging (fMRI, have independently yielded early information on these abnormal brain functions. In the two cases presented in this article, we report contrasting brain activation patterns and recovery profiles using fMRI. Importantly, fMRI was conducted using adapted versions of the most sensitive computerized NP tests administered in current clinical practice to determine impairments and recovery after sport-related concussion. One of the cases is consistent with the concept of lagging brain recovery.

  7. Multilingualism and fMRI: Longitudinal Study of Second Language Acquisition

    Directory of Open Access Journals (Sweden)

    John Wright

    2013-05-01

    Full Text Available BOLD fMRI is often used for the study of human language. However, there are still very few attempts to conduct longitudinal fMRI studies in the study of language acquisition by measuring auditory comprehension and reading. The following paper is the first in a series concerning a unique longitudinal study devoted to the analysis of bi- and multilingual subjects who are: (1 already proficient in at least two languages; or (2 are acquiring Russian as a second/third language. The focus of the current analysis is to present data from the auditory sections of a set of three scans acquired from April, 2011 through April, 2012 on a five-person subject pool who are learning Russian during the study. All subjects were scanned using the same protocol for auditory comprehension on the same General Electric LX 3T Signa scanner in Duke University Hospital. Using a multivariate analysis of covariance (MANCOVA for statistical analysis, proficiency measurements are shown to correlate significantly with scan results in the Russian conditions over time. The importance of both the left and right hemispheres in language processing is discussed. Special attention is devoted to the importance of contextualizing imaging data with corresponding behavioral and empirical testing data using a multivariate analysis of variance. This is the only study to date that includes: (1 longitudinal fMRI data with subject-based proficiency and behavioral data acquired in the same time frame; and (2 statistical modeling that demonstrates the importance of covariate language proficiency data for understanding imaging results of language acquisition.

  8. Multilingualism and fMRI: Longitudinal Study of Second Language Acquisition

    Science.gov (United States)

    Andrews, Edna; Frigau, Luca; Voyvodic-Casabo, Clara; Voyvodic, James; Wright, John

    2013-01-01

    BOLD fMRI is often used for the study of human language. However, there are still very few attempts to conduct longitudinal fMRI studies in the study of language acquisition by measuring auditory comprehension and reading. The following paper is the first in a series concerning a unique longitudinal study devoted to the analysis of bi- and multilingual subjects who are: (1) already proficient in at least two languages; or (2) are acquiring Russian as a second/third language. The focus of the current analysis is to present data from the auditory sections of a set of three scans acquired from April, 2011 through April, 2012 on a five-person subject pool who are learning Russian during the study. All subjects were scanned using the same protocol for auditory comprehension on the same General Electric LX 3T Signa scanner in Duke University Hospital. Using a multivariate analysis of covariance (MANCOVA) for statistical analysis, proficiency measurements are shown to correlate significantly with scan results in the Russian conditions over time. The importance of both the left and right hemispheres in language processing is discussed. Special attention is devoted to the importance of contextualizing imaging data with corresponding behavioral and empirical testing data using a multivariate analysis of variance. This is the only study to date that includes: (1) longitudinal fMRI data with subject-based proficiency and behavioral data acquired in the same time frame; and (2) statistical modeling that demonstrates the importance of covariate language proficiency data for understanding imaging results of language acquisition. PMID:24961428

  9. Investigating Inhibitory Control in Children with Epilepsy: An fMRI Study

    Science.gov (United States)

    Triplett, Regina L.; Velanova, Katerina; Luna, Beatriz; Padmanabhan, Aarthi; Gaillard, William D.; Asato, Miya R.

    2014-01-01

    SUMMARY Objective Deficits in executive function are increasingly noted in children with epilepsy and have been associated with poor academic and psychosocial outcomes. Impaired inhibitory control contributes to executive dysfunction in children with epilepsy; however, its neuroanatomic basis has not yet been investigated. We used functional Magnetic Resonance Imaging (fMRI) to probe the integrity of activation in brain regions underlying inhibitory control in children with epilepsy. Methods This cross-sectional study consisted of 34 children aged 8 to 17 years: 17 with well-controlled epilepsy and 17 age-and sex-matched controls. Participants performed the antisaccade (AS) task, representative of inhibitory control, during fMRI scanning. We compared AS performance during neutral and reward task conditions and evaluated task-related blood-oxygen level dependent (BOLD) activation. Results Children with epilepsy demonstrated impaired AS performance compared to controls during both neutral (non-reward) and reward trials, but exhibited significant task improvement during reward trials. Post-hoc analysis revealed that younger patients made more errors than older patients and all controls. fMRI results showed preserved activation in task-relevant regions in patients and controls, with the exception of increased activation in the left posterior cingulate gyrus in patients specifically with generalized epilepsy across neutral and reward trials. Significance Despite impaired inhibitory control, children with epilepsy accessed typical neural pathways as did their peers without epilepsy. Children with epilepsy showed improved behavioral performance in response to the reward condition, suggesting potential benefits of the use of incentives in cognitive remediation. PMID:25223606

  10. Multilingualism and fMRI: Longitudinal Study of Second Language Acquisition.

    Science.gov (United States)

    Andrews, Edna; Frigau, Luca; Voyvodic-Casabo, Clara; Voyvodic, James; Wright, John

    2013-05-28

    BOLD fMRI is often used for the study of human language. However, there are still very few attempts to conduct longitudinal fMRI studies in the study of language acquisition by measuring auditory comprehension and reading. The following paper is the first in a series concerning a unique longitudinal study devoted to the analysis of bi- and multilingual subjects who are: (1) already proficient in at least two languages; or (2) are acquiring Russian as a second/third language. The focus of the current analysis is to present data from the auditory sections of a set of three scans acquired from April, 2011 through April, 2012 on a five-person subject pool who are learning Russian during the study. All subjects were scanned using the same protocol for auditory comprehension on the same General Electric LX 3T Signa scanner in Duke University Hospital. Using a multivariate analysis of covariance (MANCOVA) for statistical analysis, proficiency measurements are shown to correlate significantly with scan results in the Russian conditions over time. The importance of both the left and right hemispheres in language processing is discussed. Special attention is devoted to the importance of contextualizing imaging data with corresponding behavioral and empirical testing data using a multivariate analysis of variance. This is the only study to date that includes: (1) longitudinal fMRI data with subject-based proficiency and behavioral data acquired in the same time frame; and (2) statistical modeling that demonstrates the importance of covariate language proficiency data for understanding imaging results of language acquisition.

  11. Non-invasive multiparametric qBOLD approach for robust mapping of the oxygen extraction fraction.

    Science.gov (United States)

    Domsch, Sebastian; Mie, Moritz B; Wenz, Frederik; Schad, Lothar R

    2014-09-01

    The quantitative blood oxygenation level-dependent (qBOLD) method has not become clinically established yet because long acquisition times are necessary to achieve an acceptable certainty of the parameter estimates. In this work, a non-invasive multiparametric (nimp) qBOLD approach based on a simple analytical model is proposed to facilitate robust oxygen extraction fraction (OEF) mapping within clinically acceptable acquisition times by using separate measurements. The protocol consisted of a gradient-echo sampled spin-echo sequence (GESSE), a T2-weighted Carr-Purcell-Meiboom-Gill (CPMG) sequence, and a T2(*)-weighted multi-slice multi-echo gradient echo (MMGE) sequence. The GESSE acquisition time was less than 5 minutes and the extra measurement time for CPMG/MMGE was below 2 minutes each. The proposed nimp-qBOLD approach was validated in healthy subjects (N = 5) and one patient. The proposed nimp-qBOLD approach facilitated more robust OEF mapping with significantly reduced inter- and intra-subject variability compared to the standard qBOLD method. Thereby, an average OEF in all subjects of 27±2% in white matter (WM) and 29±2% in gray matter (GM) using the nimp-qBOLD method was more stable compared to 41±10% (WM) and 46±10% (GM) with standard qBOLD. Moreover, the spatial variance in the image slice (i.e. standard deviation divided by mean) was on average reduced from 35% to 25%. In addition, the preliminary results of the patient are encouraging. The proposed nimp-qBOLD technique provides a promising tool for robust OEF mapping within clinically acceptable acquisition times and could therefore provide an important contribution for analyzing tumors or monitoring the success of radio and chemo therapies. Copyright © 2014. Published by Elsevier GmbH.

  12. Gamma-ray-induced bold seeded early maturing groundnut selections

    International Nuclear Information System (INIS)

    Manoharan, V.; Thangavelu, S.

    1990-01-01

    Full text: ''Chico'' is an early maturing (85-90 days) erect groundnut (Arachis hypogaea L.) genotype utilised in groundnut improvement to incorporate earliness in high yielding varieties. Though it has high shelling out-turn, its yield potential is low since it has small seeds. Mutation breeding was started with the objective of improving the seed size. In a preliminary experiment, dry seeds were treated with 20, 30, 40 or 50 kR of gamma rays. The M 1 generation was grown during the post rainy season of 1988-1989. The M 2 generation was planted as individual plant progeny rows during the rainy season of 1989. 105 progeny rows were studied, the total number of M 2 plants being 1,730. All the M 2 plants were harvested 90 days after sowing. Seven mutants with bold seed size were obtained. The mutants had 100 kernel weight ranging from 22.2 to 40.4 g compared to 21.1 g of control. The study is in progress. (author)

  13. Predictors of dyspnea prevalence: Results from the BOLD study

    Science.gov (United States)

    Grønseth, Rune; Vollmer, William M.; Hardie, Jon A.; Ólafsdóttir, Inga Sif; Lamprecht, Bernd; Buist, A. Sonia; Gnatiuc, Louisa; Gulsvik, Amund; Johannessen, Ane; Enright, Paul

    2014-01-01

    Dyspnea is a cardinal symptom for cardiorespiratory diseases. No study has assessed worldwide variation in dyspnea prevalence or predictors of dyspnea. We used cross-sectional data from population-based samples in 15 countries of the BOLD study to estimate prevalence of dyspnea in the full sample as well as in an a priori defined low-risk group (few risk factors or dyspnea-associated diseases). Dyspnea was defined by the modified Medical Research Council questions. We used ordered logistic regression analysis to study the association of dyspnea with site, sex, age, education, smoking habits, low/high BMI, self-reported disease, and spirometry results. Of the 9,484 participants, 27% reported any dyspnea. In the low-risk subsample (N=4,329), 16% reported some dyspnea. In multivariate analyses, all covariates were correlated to dyspnea, but only 13% of dyspnea variation was explained. Women reported more dyspnea than men (odds ratio ≈ 2.1). When forced vital capacity (FVC) fell below 60% of predicted, dyspnea was much more likely. There was considerable geographical variation in dyspnea, even when we adjusted for known risk factors and spirometry results. We were only able to explain 13% of dyspnea variation. PMID:24176991

  14. Cerebral hemodynamics: concepts of clinical importance

    Directory of Open Access Journals (Sweden)

    Edson Bor-Seng-Shu

    2012-05-01

    Full Text Available Cerebral hemodynamics and metabolism are frequently impaired in a wide range of neurological diseases, including traumatic brain injury and stroke, with several pathophysiological mechanisms of injury. The resultant uncoupling of cerebral blood flow and metabolism can trigger secondary brain lesions, particularly in early phases, consequently worsening the patient's outcome. Cerebral blood flow regulation is influenced by blood gas content, blood viscosity, body temperature, cardiac output, altitude, cerebrovascular autoregulation, and neurovascular coupling, mediated by chemical agents such as nitric oxide (NO, carbon monoxide (CO, eicosanoid products, oxygen-derived free radicals, endothelins, K+, H+, and adenosine. A better understanding of these factors is valuable for the management of neurocritical care patients. The assessment of both cerebral hemodynamics and metabolism in the acute phase of neurocritical care conditions may contribute to a more effective planning of therapeutic strategies for reducing secondary brain lesions. In this review, the authors have discussed concepts of cerebral hemodynamics, considering aspects of clinical importance.

  15. The quantitative genetic architecture of the bold-shy continuum in zebrafish, Danio rerio.

    Directory of Open Access Journals (Sweden)

    Mary E Oswald

    Full Text Available In studies of consistent individual differences (personality along the bold-shy continuum, a pattern of behavioral correlations frequently emerges: individuals towards the bold end of the continuum are more likely to utilize risky habitat, approach potential predators, and feed under risky conditions. Here, we address the hypothesis that observed phenotypic correlations among component behaviors of the bold-shy continuum are a result of underlying genetic correlations (quantitative genetic architecture. We used a replicated three-generation pedigree of zebrafish (Danio rerio to study three putative components of the bold-shy continuum: horizontal position, swim level, and feeding latency. We detected significant narrow-sense heritabilities as well as significant genetic and phenotypic correlations among all three behaviors, such that fish selected for swimming at the front of the tank swam closer to the observer, swam higher in the water column, and fed more quickly than fish selected for swimming at the back of the tank. Further, the lines varied in their initial open field behavior (swim level and activity level. The quantitative genetic architecture of the bold-shy continuum indicates that the multivariate behavioral phenotype characteristic of a "bold" personality type may be a result of correlated evolution via underlying genetic correlations.

  16. One pair of hands is not like another: caudate BOLD response in dogs depends on signal source and canine temperament.

    Science.gov (United States)

    Cook, Peter F; Spivak, Mark; Berns, Gregory S

    2014-01-01

    Having previously used functional MRI to map the response to a reward signal in the ventral caudate in awake unrestrained dogs, here we examined the importance of signal source to canine caudate activation. Hand signals representing either incipient reward or no reward were presented by a familiar human (each dog's respective handler), an unfamiliar human, and via illustrated images of hands on a computer screen to 13 dogs undergoing voluntary fMRI. All dogs had received extensive training with the reward and no-reward signals from their handlers and with the computer images and had minimal exposure to the signals from strangers. All dogs showed differentially higher BOLD response in the ventral caudate to the reward versus no reward signals, and there was a robust effect at the group level. Further, differential response to the signal source had a highly significant interaction with a dog's general aggressivity as measured by the C-BARQ canine personality assessment. Dogs with greater aggressivity showed a higher differential response to the reward signal versus no-reward signal presented by the unfamiliar human and computer, while dogs with lower aggressivity showed a higher differential response to the reward signal versus no-reward signal from their handler. This suggests that specific facets of canine temperament bear more strongly on the perceived reward value of relevant communication signals than does reinforcement history, as each of the dogs were reinforced similarly for each signal, regardless of the source (familiar human, unfamiliar human, or computer). A group-level psychophysiological interaction (PPI) connectivity analysis showed increased functional coupling between the caudate and a region of cortex associated with visual discrimination and learning on reward versus no-reward trials. Our findings emphasize the sensitivity of the domestic dog to human social interaction, and may have other implications and applications pertinent to the training and

  17. One pair of hands is not like another: caudate BOLD response in dogs depends on signal source and canine temperament

    Directory of Open Access Journals (Sweden)

    Peter F. Cook

    2014-09-01

    Full Text Available Having previously used functional MRI to map the response to a reward signal in the ventral caudate in awake unrestrained dogs, here we examined the importance of signal source to canine caudate activation. Hand signals representing either incipient reward or no reward were presented by a familiar human (each dog’s respective handler, an unfamiliar human, and via illustrated images of hands on a computer screen to 13 dogs undergoing voluntary fMRI. All dogs had received extensive training with the reward and no-reward signals from their handlers and with the computer images and had minimal exposure to the signals from strangers. All dogs showed differentially higher BOLD response in the ventral caudate to the reward versus no reward signals, and there was a robust effect at the group level. Further, differential response to the signal source had a highly significant interaction with a dog’s general aggressivity as measured by the C-BARQ canine personality assessment. Dogs with greater aggressivity showed a higher differential response to the reward signal versus no-reward signal presented by the unfamiliar human and computer, while dogs with lower aggressivity showed a higher differential response to the reward signal versus no-reward signal from their handler. This suggests that specific facets of canine temperament bear more strongly on the perceived reward value of relevant communication signals than does reinforcement history, as each of the dogs were reinforced similarly for each signal, regardless of the source (familiar human, unfamiliar human, or computer. A group-level psychophysiological interaction (PPI connectivity analysis showed increased functional coupling between the caudate and a region of cortex associated with visual discrimination and learning on reward versus no-reward trials. Our findings emphasize the sensitivity of the domestic dog to human social interaction, and may have other implications and applications

  18. Restructuring Reward Mechanisms in Nicotine Addiction: A Pilot fMRI Study of Mindfulness-Oriented Recovery Enhancement for Cigarette Smokers

    Directory of Open Access Journals (Sweden)

    B. Froeliger

    2017-01-01

    Full Text Available The primary goal of this pilot feasibility study was to examine the effects of Mindfulness-Oriented Recovery Enhancement (MORE, a behavioral treatment grounded in dual-process models derived from cognitive science, on frontostriatal reward processes among cigarette smokers. Healthy adult (N=13; mean (SD age 49 ± 12.2 smokers provided informed consent to participate in a 10-week study testing MORE versus a comparison group (CG. All participants underwent two fMRI scans: pre-tx and after 8-weeks of MORE. Emotion regulation (ER, smoking cue reactivity (CR, and resting-state functional connectivity (rsFC were assessed at each fMRI visit; smoking and mood were assessed throughout. As compared to the CG, MORE significantly reduced smoking (d=2.06 and increased positive affect (d=2.02. MORE participants evidenced decreased CR-BOLD response in ventral striatum (VS; d=1.57 and ventral prefrontal cortex (vPFC; d=1.7 and increased positive ER-BOLD in VS (dVS=2.13 and vPFC (dvmPFC=2.66. Importantly, ER was correlated with smoking reduction (r’s = .68 to .91 and increased positive affect (r’s = .52 to .61. These findings provide preliminary evidence that MORE may facilitate the restructuring of reward processes and play a role in treating the pathophysiology of nicotine addiction.

  19. Hemodynamic significance of internal carotid artery disease

    DEFF Research Database (Denmark)

    Schroeder, T

    1988-01-01

    a significant improvement in baseline flow occur. Flow reserve determined by cerebral vasodilation, however, will improve in most patients with hemodynamic failure. In addition, some patients in the low-pressure group develop marked, but temporary, hyperperfusion after reconstruction of very high grade carotid...

  20. Central Hemodynamics for Management of Arteriosclerotic Diseases.

    Science.gov (United States)

    Hashimoto, Junichiro

    2017-08-01

    Arteriosclerosis, particularly aortosclerosis, is the most critical risk factor associated with cardiovascular, cerebrovascular, and renal diseases. The pulsatile hemodynamics in the central aorta consists of blood pressure, flow, and stiffness and substantially differs from the peripheral hemodynamics in muscular arteries. Arteriosclerotic changes with age appear earlier in the elastic aorta, and age-dependent increases in central pulse pressure are more marked than those apparent from brachial pressure measurement. Central pressure can be affected by lifestyle habits, metabolic disorders, and endocrine and inflammatory diseases in a manner different from brachial pressure. Central pulse pressure widening due to aortic stiffening increases left ventricular afterload in systole and reduces coronary artery flow in diastole, predisposing aortosclerotic patients to myocardial hypertrophy and ischemia. The widened pulse pressure is also transmitted deep into low-impedance organs such as the brain and kidney, causing microvascular damage responsible for lacunar stroke and albuminuria. In addition, aortic stiffening increases aortic blood flow reversal, which can lead to retrograde embolic stroke and renal function deterioration. Central pressure has been shown to predict cardiovascular events in most previous studies and potentially serves as a surrogate marker for intervention. Quantitative and comprehensive evaluation of central hemodynamics is now available through various noninvasive pressure/flow measurement modalities. This review will focus on the clinical usefulness and mechanistic rationale of central hemodynamic measurements for cardiovascular risk management.

  1. Force plate monitoring of human hemodynamics

    Czech Academy of Sciences Publication Activity Database

    Kříž, J.; Šeba, Petr

    2008-01-01

    Roč. 2, č. 1 (2008), s. 1-9 ISSN 1753-4631 Grant - others:GA ČR(CZ) GP202/06/P130; GA MŠk(CZ) LC06002 Institutional research plan: CEZ:AV0Z10100521 Keywords : hemodynamics * balistocardiography * pulse wave velocity Subject RIV: BO - Biophysics www.nonlinearbiomedphys.com

  2. Brain hemodynamic activity during viewing and re-viewing of comedy movies explained by experienced humor.

    Science.gov (United States)

    Jääskeläinen, Iiro P; Pajula, Juha; Tohka, Jussi; Lee, Hsin-Ju; Kuo, Wen-Jui; Lin, Fa-Hsuan

    2016-06-21

    Humor is crucial in human social interactions. To study the underlying neural processes, three comedy clips were shown twice to 20 volunteers during functional magnetic resonance imaging (fMRI). Inter-subject similarities in humor ratings, obtained immediately after fMRI, explained inter-subject correlation of hemodynamic activity in right frontal pole and in a number of other brain regions. General linear model analysis also indicated activity in right frontal pole, as well as in additional cortical areas and subcortically in striatum, explained by humorousness. The association of the right frontal pole with experienced humorousness is a novel finding, which might be related to humor unfolding over longer time scales in the movie clips. Specifically, frontal pole has been shown to exhibit longer temporal receptive windows than, e.g., sensory areas, which might have enabled processing of humor in the clips based on holding information and reinterpreting that in light of new information several (even tens of) seconds later. As another novel finding, medial and lateral prefrontal areas, frontal pole, posterior-inferior temporal areas, posterior parietal areas, posterior cingulate, striatal structures and amygdala showed reduced activity upon re-viewing of the clips, suggesting involvement in processing of humor related to novelty of the comedic events.

  3. EEG correlates of time-varying BOLD functional connectivity

    Science.gov (United States)

    Chang, Catie; Liu, Zhongming; Chen, Michael C.; Liu, Xiao; Duyn, Jeff H.

    2013-01-01

    Recent resting-state fMRI studies have shown that the apparent functional connectivity (FC) between brain regions may undergo changes on time-scales of seconds to minutes, the basis and importance of which are largely unknown. Here, we examine the electrophysiological correlates of within-scan FC variations during a condition of eyes-closed rest. A sliding window analysis of simultaneous EEG-fMRI data was performed to examine whether temporal variations in coupling between three major networks (default mode; DMN, dorsal attention; DAN, and salience network; SN) are associated with temporal variations in mental state, as assessed from the amplitude of alpha and theta oscillations in the EEG. In our dataset, alpha power showed a significant inverse relationship with the strength of connectivity between DMN and DAN. In addition, alpha power covaried with the spatial extent of anticorrelation between DMN and DAN, with higher alpha power associated with larger anticorrelation extent. Results suggest an electrical signature of the time-varying FC between the DAN and DMN, potentially reflecting neural and state-dependent variations. PMID:23376790

  4. Monitoring Local Regional Hemodynamic Signal Changes during Motor Execution and Motor Imagery Using Near-Infrared Spectroscopy

    Directory of Open Access Journals (Sweden)

    Naoki eIso

    2016-01-01

    Full Text Available The aim of this study was to clarify the topographical localization of motor-related regional hemodynamic signal changes during motor execution (ME and motor imagery (MI by using near-infrared spectroscopy (NIRS, as this technique is more clinically expedient than established methods (e.g. fMRI. Twenty right-handed healthy subjects participated in this study. The experimental protocol was a blocked design consisting of 3 cycles of 20 s of task performance and 30 s of rest. The tapping sequence task was performed with their fingers under 4 conditions: ME and MI with the right or left hand. Hemodynamic brain activity was measured with NIRS to monitor changes in oxygenated hemoglobin (oxy-Hb concentration. Oxy-Hb in the somatosensory motor cortex (SMC increased significantly only during contralateral ME and showed a significant interaction between task and hand. There was a main effect of hand in the left SMC. Although there were no significant main effects or interactions in the supplemental motor area (SMA and premotor area (PMA, oxy-Hb increased substantially under all conditions. These results clarified the topographical localization by motor-related regional hemodynamic signal changes during ME and MI by using NIRS.

  5. How feedback, motor imagery, and reward influence brain self-regulation using real-time fMRI.

    Science.gov (United States)

    Sepulveda, Pradyumna; Sitaram, Ranganatha; Rana, Mohit; Montalba, Cristian; Tejos, Cristian; Ruiz, Sergio

    2016-09-01

    The learning process involved in achieving brain self-regulation is presumed to be related to several factors, such as type of feedback, reward, mental imagery, duration of training, among others. Explicitly instructing participants to use mental imagery and monetary reward are common practices in real-time fMRI (rtfMRI) neurofeedback (NF), under the assumption that they will enhance and accelerate the learning process. However, it is still not clear what the optimal strategy is for improving volitional control. We investigated the differential effect of feedback, explicit instructions and monetary reward while training healthy individuals to up-regulate the blood-oxygen-level dependent (BOLD) signal in the supplementary motor area (SMA). Four groups were trained in a two-day rtfMRI-NF protocol: GF with NF only, GF,I with NF + explicit instructions (motor imagery), GF,R with NF + monetary reward, and GF,I,R with NF + explicit instructions (motor imagery) + monetary reward. Our results showed that GF increased significantly their BOLD self-regulation from day-1 to day-2 and GF,R showed the highest BOLD signal amplitude in SMA during the training. The two groups who were instructed to use motor imagery did not show a significant learning effect over the 2 days. The additional factors, namely motor imagery and reward, tended to increase the intersubject variability in the SMA during the course of training. Whole brain univariate and functional connectivity analyses showed common as well as distinct patterns in the four groups, representing the varied influences of feedback, reward, and instructions on the brain. Hum Brain Mapp 37:3153-3171, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  6. An fMRI study on cortical responses during active self-touch and passive touch from others

    Directory of Open Access Journals (Sweden)

    Rochelle eAckerley

    2012-08-01

    Full Text Available Active, self-touch and the passive touch from an external source engage comparable afferent mechanoreceptors on the touched skin site. However, touch directed to glabrous skin compared to hairy skin will activate different types of afferent mechanoreceptors. Despite perceptual similarities between touch to different body sites, it is likely that the touch information is processed differently. In the present study, we used functional magnetic resonance imaging (fMRI to elucidate the cortical differences in the neural signal of touch representations during active, self-touch and passive touch from another, to both glabrous (palm and hairy (arm skin, where a soft brush was used as the stimulus. There were two active touch conditions, where the participant used the brush in their right hand to stroke either their left palm or arm. There were two similar passive, touch conditions where the experimenter used an identical brush to stroke the same palm and arm areas on the participant. Touch on the left palm elicited a large, significant, positive blood-oxygenation level dependence (BOLD signal in right sensorimotor areas. Less extensive activity was found for touch to the arm. Separate somatotopical palm and arm representations were found in Brodmann area 3 of the right primary somatosensory cortex (SI and in both these areas, active stroking gave significantly higher signals than passive stroking. Active, self-touch elicited a positive BOLD signal in a network of sensorimotor cortical areas in the left hemisphere, compared to the resting baseline. In contrast, during passive touch, a significant negative BOLD signal was found in the left SI. Thus, each of the four conditions had a unique cortical signature despite similarities in afferent signalling or evoked perception. It is hypothesized that attentional mechanisms play a role in the modulation of the touch signal in the right SI, accounting for the differences found between active and passive touch.

  7. An FMRI-compatible Symbol Search task.

    Science.gov (United States)

    Liebel, Spencer W; Clark, Uraina S; Xu, Xiaomeng; Riskin-Jones, Hannah H; Hawkshead, Brittany E; Schwarz, Nicolette F; Labbe, Donald; Jerskey, Beth A; Sweet, Lawrence H

    2015-03-01

    Our objective was to determine whether a Symbol Search paradigm developed for functional magnetic resonance imaging (FMRI) is a reliable and valid measure of cognitive processing speed (CPS) in healthy older adults. As all older adults are expected to experience cognitive declines due to aging, and CPS is one of the domains most affected by age, establishing a reliable and valid measure of CPS that can be administered inside an MR scanner may prove invaluable in future clinical and research settings. We evaluated the reliability and construct validity of a newly developed FMRI Symbol Search task by comparing participants' performance in and outside of the scanner and to the widely used and standardized Symbol Search subtest of the Wechsler Adult Intelligence Scale (WAIS). A brief battery of neuropsychological measures was also administered to assess the convergent and discriminant validity of the FMRI Symbol Search task. The FMRI Symbol Search task demonstrated high test-retest reliability when compared to performance on the same task administered out of the scanner (r=.791; pSymbol Search (r=.717; pSymbol Search task were also observed. The FMRI Symbol Search task is a reliable and valid measure of CPS in healthy older adults and exhibits expected sensitivity to the effects of age on CPS performance.

  8. Bi-Directional Tuning of Amygdala Sensitivity in Combat Veterans Investigated with fMRI

    Science.gov (United States)

    Brashers-Krug, Tom; Jorge, Ricardo

    2015-01-01

    Objectives Combat stress can be followed by persistent emotional consequences. It is thought that these emotional consequences are caused in part by increased amygdala reactivity. It is also thought that amygdala hyper-reactivity results from decreased inhibition from portions of the anterior cingulate cortex (ACC) in which activity is negatively correlated with activity in the amygdala. However, experimental support for these proposals has been inconsistent. Methods We showed movies of combat and civilian scenes during a functional magnetic resonance imaging (fMRI) session to 50 veterans of recent combat. We collected skin conductance responses (SCRs) as measures of emotional arousal. We examined the relation of blood oxygenation-level dependent (BOLD) signal in the amygdala and ACC to symptom measures and to SCRs. Results Emotional arousal, as measured with SCR, was greater during the combat movie than during the civilian movie and did not depend on symptom severity. As expected, amygdala signal during the less-arousing movie increased with increasing symptom severity. Surprisingly, during the more-arousing movie amygdala signal decreased with increasing symptom severity. These differences led to the unexpected result that amygdala signal in highly symptomatic subjects was lower during the more-arousing movie than during the less-arousing movie. Also unexpectedly, we found no significant inverse correlation between any portions of the amygdala and ACC. Rather, signal throughout more than 80% of the ACC showed a strong positive correlation with signal throughout more than 90% of the amygdala. Conclusions Amygdala reactivity can be tuned bi-directionally, either up or down, in the same person depending on the stimulus and the degree of post-traumatic symptoms. The exclusively positive correlations in BOLD activity between the amygdala and ACC contrast with findings that have been cited as evidence for inhibitory control of the amygdala by the ACC. The

  9. Language exposure induced neuroplasticity in the bilingual brain: a follow-up fMRI study.

    Science.gov (United States)

    Tu, Liu; Wang, Junjing; Abutalebi, Jubin; Jiang, Bo; Pan, Ximin; Li, Meng; Gao, Wei; Yang, Yuchen; Liang, Bishan; Lu, Zhi; Huang, Ruiwang

    2015-03-01

    Although several studies have shown that language exposure crucially influence the cerebral representation of bilinguals, the effects of short-term change of language exposure in daily life upon language control areas in bilinguals are less known. To explore this issue, we employed follow-up fMRI to investigate whether differential exposure induces neuroplastic changes in the language control network in high-proficient Cantonese (L1)-Mandarin (L2) early bilinguals. The same 10 subjects underwent twice BOLD-fMRI scans while performing a silent narration task which corresponded to two different language exposure conditions, CON-1 (L1/L2 usage percentage, 50%:50%) and CON-2 (L1/L2 usage percentage, 90%:10%). We report a strong effect of language exposure in areas related to language control for the less exposed language. Interestingly, these significant effects were present after only a 30-day period of differential language exposure. In detail, we reached the following results: (1) the interaction effect of language and language exposure condition was found significantly in the left pars opercularis (BA 44) and marginally in the left MFG (BA 9); (2) in CON-2, increases of activation values in L2 were found significantly in bilateral BA 46 and BA 9, in the left BA44, and marginally in the left caudate; and (3) in CON-2, we found a significant negative correlation between language exposure to L2 and the BOLD activation value specifically in the left ACC. These findings strongly support the hypothesis that even short periods of differential exposure to a given language may induce significant neuroplastic changes in areas responsible for language control. The language which a bilingual is less exposed to and is also less used will be in need of increased mental control as shown by the increased activity of language control areas. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. One-Class FMRI-Inspired EEG Model for Self-Regulation Training.

    Directory of Open Access Journals (Sweden)

    Yehudit Meir-Hasson

    Full Text Available Recent evidence suggests that learned self-regulation of localized brain activity in deep limbic areas such as the amygdala, may alleviate symptoms of affective disturbances. Thus far self-regulation of amygdala activity could be obtained only via fMRI guided neurofeedback, an expensive and immobile procedure. EEG on the other hand is relatively inexpensive and can be easily implemented in any location. However the clinical utility of EEG neurofeedback for affective disturbances remains limited due to low spatial resolution, which hampers the targeting of deep limbic areas such as the amygdala. We introduce an EEG prediction model of amygdala activity from a single electrode. The gold standard used for training is the fMRI-BOLD signal in the amygdala during simultaneous EEG/fMRI recording. The suggested model is based on a time/frequency representation of the EEG data with varying time-delay. Previous work has shown a strong inhomogeneity among subjects as is reflected by the models created to predict the amygdala BOLD response from EEG data. In that work, different models were constructed for different subjects. In this work, we carefully analyzed the inhomogeneity among subjects and were able to construct a single model for the majority of the subjects. We introduce a method for inhomogeneity assessment. This enables us to demonstrate a choice of subjects for which a single model could be derived. We further demonstrate the ability to modulate brain-activity in a neurofeedback setting using feedback generated by the model. We tested the effect of the neurofeedback training by showing that new subjects can learn to down-regulate the signal amplitude compared to a sham group, which received a feedback obtained by a different participant. This EEG based model can overcome substantial limitations of fMRI-NF. It can enable investigation of NF training using multiple sessions and large samples in various locations.

  11. Age-related functional changes in gustatory and reward processing regions: An fMRI study.

    Science.gov (United States)

    Jacobson, Aaron; Green, Erin; Murphy, Claire

    2010-11-01

    Changes in appetite in older adults may result in unhealthy weight change and negatively affect overall nutrition. Research examining gustatory processing in young adults has linked changes in patterns of the hemodynamic response of gustatory and motivation related brain regions to the physiological states of hunger and satiety. Whether the same brain regions are involved in taste processing in older adults is unknown. The current study used functional magnetic resonance imaging (fMRI) to examine age-related changes in gustatory processing during hedonic assessment. Caffeine, citric acid, sucrose, and NaCl were administered orally during two event-related fMRI sessions, one during hunger and one after a pre-load. Participants assessed the pleasantness of the solutions in each session. Increased activity of the insula was seen in both age groups during hunger. Activity of secondary and higher order taste processing and reward regions such as the orbitofrontal cortex, amygdala, hippocampus, thalamus, and caudate nucleus was also observed. Hunger and satiety differentially affected the hemodynamic response, resulting in positive global activation during hunger and negative during satiety in both age groups. While in a state of hunger, the frequency and consistency of positive activation in gustatory and reward processing regions was greater in older adults. Additional regions not commonly associated with taste processing were also activated in older adults. Investigating the neurological response of older adults to taste stimuli under conditions of hunger and satiety may aid in understanding appetite, health, and functional changes in this population. Copyright 2010 Elsevier Inc. All rights reserved.

  12. A Non-Parametric Approach for the Activation Detection of Block Design fMRI Simulated Data Using Self-Organizing Maps and Support Vector Machine.

    Science.gov (United States)

    Bahrami, Sheyda; Shamsi, Mousa

    2017-01-01

    Functional magnetic resonance imaging (fMRI) is a popular method to probe the functional organization of the brain using hemodynamic responses. In this method, volume images of the entire brain are obtained with a very good spatial resolution and low temporal resolution. However, they always suffer from high dimensionality in the face of classification algorithms. In this work, we combine a support vector machine (SVM) with a self-organizing map (SOM) for having a feature-based classification by using SVM. Then, a linear kernel SVM is used for detecting the active areas. Here, we use SOM for feature extracting and labeling the datasets. SOM has two major advances: (i) it reduces dimension of data sets for having less computational complexity and (ii) it is useful for identifying brain regions with small onset differences in hemodynamic responses. Our non-parametric model is compared with parametric and non-parametric methods. We use simulated fMRI data sets and block design inputs in this paper and consider the contrast to noise ratio (CNR) value equal to 0.6 for simulated datasets. fMRI simulated dataset has contrast 1-4% in active areas. The accuracy of our proposed method is 93.63% and the error rate is 6.37%.

  13. Using fMRI to Detect Activation of the Cortical and Subcortical Auditory Centers: Development of a Standard Protocol for a Conventional 1.5-T MRI Scanner

    International Nuclear Information System (INIS)

    Tae, Woo Suk; Kim, Sam Soo; Lee, Kang Uk; Lee, Seung Hwan; Nam, Eui Cheol; Choi, Hyun Kyung

    2009-01-01

    We wanted to develop a standard protocol for auditory functional magnetic resonance imaging (fMRI) for detecting blood oxygenation level-dependent (BOLD) responses at the cortical and subcortical auditory centers with using a 1.5-T MRI scanner. Fourteen normal volunteers were enrolled in the study. The subjects were stimulated by four repetitions of 32 sec each with broadband white noise and silent period blocks as a run (34 echo planar images [EPIs]). Multiple regression analysis for the individual analysis and one-sample t-tests for the group analysis were applied (FDR, p <0.05). The auditory cortex was activated in most of the volunteers (left 100% and right 92.9% at an uncorrected p value <0.05, and left 92.9% and right 92.9% at an uncorreced p value <0.01). The cochlear nuclei (100%, 85.7%), inferior colliculi (71.4%, 64.3%), medial geniculate bodies (64.3%, 35.7%) and superior olivary complexes (35.7%, 35.7%) showed significant BOLD responses at uncorrected p values of <0.05 and p <0.01, respectively. On the group analysis, the cortical and subcortical auditory centers showed significant BOLD responses (FDR, p <0.05), except for the superior olivary complex. The signal intensity time courses of the auditory centers showed biphasic wave forms. We successfully visualized BOLD responses at the cortical and subcortical auditory centers using appropriate sound stimuli and an image acquisition method with a 1.5-T MRI scanner

  14. Biology and hemodynamics of aneurismal vasculopathies

    International Nuclear Information System (INIS)

    Pereira, Vitor Mendes; Brina, Olivier; Gonzalez, Ana Marcos; Narata, Ana Paula; Ouared, Rafik; Karl-Olof, Lovblad

    2013-01-01

    Aneurysm vasculopathies represents a group of vascular disorders that share a common morphological diagnosis: a vascular dilation, the aneurysm. They can have a same etiology and a different clinical presentation or morphology, or have different etiology and very similar anatomical geometry. The biology of the aneurysm formation is a complex process that will be a result of an endogenous predisposition and epigenetic factors later on including the intracranial hemodynamics. We describe the biology of saccular aneurysms, its growth and rupture, as well as, current concepts of hemodynamics derived from application of computational flow dynamics on patient specific vascular models. Furthermore, we describe different aneurysm phenotypes and its extremely variability on morphological and etiological presentation

  15. Hemodynamic significance of internal carotid artery disease

    DEFF Research Database (Denmark)

    Schroeder, T

    1988-01-01

    Neurologic symptoms in the region of an internal carotid artery stenosis are considered to be embolic in most instances. Only in a subgroup has carotid occlusive disease with impairment of the collateral supply, caused a state of hemodynamic failure with marked reduction of perfusion pressure....... Though unproven, it is reasonable to assume that without surgical intervention, the risk is higher than average for patients with hemodynamic failure. Equally, should there be any postoperative improvement of cerebral blood flow or neurologic deficits, it should be looked for in this group. Thus......, it is necessary to distinguish those with low perfusion pressure from the population of patients with carotid artery disease. Preoperative clinical evaluation and direct visualization of the carotid bifurcation should be supplemented by indirect physiological tests which allow assessment of collateral perfusion...

  16. Time courses of MRI BOLD signals in prolonged visual stimulation. Comparison between colors and orders

    International Nuclear Information System (INIS)

    Kashikura, Kenichi; Fujita, Hideaki; Kershaw, J.B.; Matsuura, Tetsuya; Seki, Chie; Kashikura, Akemi; Ardekani, B.A.; Kanno, Iwao

    1998-01-01

    We investigated: the BOLD signal response during 270 second photic stimulation using an EPI pulse sequence; the BOLD signal response for two different color checkerboards; and the BOLD signal response during six consecutive stimulation series. Ten healthy human subjects (age 25±5.5 years) were studied with a 1.5 T MRI system (Siemens Vision, Erlangen, Germany). Black and white (BW) and red and white (RW) checkerboards alternating at 8 Hz were applied in turns for a total series of six. Stimulation timing was: 30 sec. off, 15 sec. on, 15 sec. off, 270 sec. on, 15 sec. off, 15 sec. on, 15 sec. off. Acquired data were analyzed according to color and/or order: color (without considering the order); color and order (1st BW vs. 1st RW, 2nd BW vs. 2nd RW, 3rd BW vs. 3rd RW); and order (without considering the color). A t-test (p<0.001) was used for obtaining the activated areas, and simple regression and two-way repeated-measures ANOVA were used for testing the statistical significance of the BOLD response. Results were: the BOLD signal responses during sustained photic stimulation maintained a constant level for the full duration and all series, suggesting stable levels of oxygen extraction and metabolism during cortical activation; the BOLD signal responses in two colors showed no significant difference in time response, suggesting that the neuronal populations perceiving black and red give a similar time response; and the effect of habituation or fatigue as observed by a signal decrease was not obtained, although the S.D. for each subject greatly increased with time and might be an indicator for evaluation fatigue or attention. (author)

  17. Importance of Collateralization in Patients With Large Artery Intracranial Occlusive Disease: Long-Term Longitudinal Assessment of Cerebral Hemodynamic Function

    Directory of Open Access Journals (Sweden)

    Larissa McKetton

    2018-04-01

    Full Text Available Patients with large artery intracranial occlusive disease (LAICOD are at risk for both acute ischemia and chronic hypoperfusion. Collateral circulation plays an important role in prognosis, and imaging plays an essential role in diagnosis, treatment planning, and prognosis of patients with LAICOD. In addition to standard structural imaging, assessment of cerebral hemodynamic function is important to determine the adequacy of collateral supply. Among the currently available methods of assessment of cerebral hemodynamic function, measurement of cerebrovascular reactivity (CVR using blood oxygen level-dependent (BOLD MRI and precisely controlled CO2 has shown to be a safe, reliable, reproducible, and clinically useful method for long-term assessment of patients. Here, we report a case of long-term follow-up in a 28-year-old Caucasian female presented to the neurology clinic with a history of TIAs and LAICOD of the right middle cerebral artery (MCA. Initial structural MRI showed a right MCA stenosis and a small right coronal radiate lacunar infarct. Her CVR study showed a large area of impaired CVR with a paradoxical decrease in BOLD signal with hypercapnia involving the right MCA territory indicating intracerebral steal. The patient was managed medically with anticoagulant and antiplatelet therapy and was followed-up for over 9 years with both structural and functional imaging. Cortical thickness (CT measures were longitudinally assessed from a region of interest that was applied to subsequent time points in the cortical region exhibiting steal physiology and in the same region of the contralateral healthy hemisphere. In the long-term follow-up, the patient exhibited improvement in her CVR as demonstrated by the development of collaterals with negligible changes to CT. Management of patients with LAICOD remains challenging since no revascularization strategies have shown efficacy except in patients with moyamoya disease. Management is well

  18. HEMODYNAMIC EFFECTS OF XENON ANESTHESIA IN CHILDREN

    Directory of Open Access Journals (Sweden)

    M. V. Bykov

    2014-01-01

    Full Text Available The study was aimed at hemodynamic effects of xenon on operative interventions in children. Patients and methods: the study involved 30 5-17-year-old children – 10 (33.3% girls and 20 (66.7% boys with ASA score 1-3 admitted for surgical treatment. The children underwent endotracheal anesthesia with xenon-oxygen mixture (Xe:O2 = 60-65:30% and fentanyl (2.5‑3.5  mcg/kg per hour for the following operations: appendectomy – 10 (33.3% patients, herniotomy – 8 (26.7% patients, Ivanissevich procedure – 6 (20.0% patients, plastic surgery of posttraumatic defects of skin and soft tissues – 4 (13.3% patients, abdominal adhesiotomy – 2 (6.7% patients. Central hemodynamics was studied echocardiographically (Philips HD 11, the Netherlands using the Teichholz technique along the cephalocaudal axis (parasternal access. Results: the anesthesia was notable for hemodynamic stability during the operation: as a result, a statistically significant (p < 0.05 increase in systolic, diastolic and mean arterial pressure by 10, 18 and 17%, respectively, was observed. Conclusion: the analysis demonstrated that xenon anesthesia improves lusitropic myocardial function statistically significantly increasing cardiac output by 12% by way of increasing stroke volume by 30%. 

  19. A robust method for suppressing motion-induced coil sensitivity variations during prospective correction of head motion in fMRI.

    Science.gov (United States)

    Faraji-Dana, Zahra; Tam, Fred; Chen, J Jean; Graham, Simon J

    2016-10-01

    Prospective motion correction is a promising candidate solution to suppress the effects of head motion during fMRI, ideally allowing the imaging plane to remain fixed with respect to the moving head. Residual signal artifacts may remain, however, because head motion in relation to a fixed multi-channel receiver coil (with non-uniform sensitivity maps) can potentially introduce unwanted signal variations comparable to the weak fMRI BOLD signal (~1%-4% at 1.5-3.0T). The present work aimed to investigate the magnitude of these residual artifacts, and characterize the regime over which prospective motion correction benefits from adjusting sensitivity maps to reflect relative positional change between the head and the coil. Numerical simulations were used to inform human fMRI experiments. The simulations indicated that for axial imaging within a commonly used 12-channel head coil, 5° of head rotation in-plane produced artifact signal changes of ~3%. Subsequently, six young adults were imaged with and without overt head motions of approximately this extent, with and without prospective motion correction using the Prospective Acquisition CorrEction (PACE) method, and with and without sensitivity map adjustments. Sensitivity map adjustments combined with PACE strongly protected against the artifacts of interest, as indicated by comparing three metrics of data quality (number of activated voxels, Dice coefficient of activation overlap, temporal standard deviation of baseline fMRI timeseries data) across the different experimental conditions. It is concluded that head motion in relation to a fixed multi-channel coil can adversely affect fMRI with prospective motion correction, and that sensitivity map adjustment can mitigate this effect at 3.0T. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. Caffeine differentially alters cortical hemodynamic activity during working memory: a near infrared spectroscopy study.

    Science.gov (United States)

    Heilbronner, Urs; Hinrichs, Hermann; Heinze, Hans-Jochen; Zaehle, Tino

    2015-10-01

    Caffeine is a widely used stimulant with potentially beneficial effects on cognition as well as vasoconstrictive properties. In functional magnetic imaging research, caffeine has gained attention as a potential enhancer of the blood oxygenation level-dependent (BOLD) response. In order to clarify changes of oxy- and deoxyhemoglobin (HbO and HbR) induced by caffeine during a cognitive task, we investigated a working memory (WM) paradigm (visual 2-back) using near-infrared spectroscopy (NIRS). Behaviorally, caffeine had no effect on the WM performance but influenced reaction times in the 0-back condition. NIRS data demonstrate caffeine-dependent alterations of the course of the hemodynamic response. The intake of 200 mg caffeine caused a significant decrease of the HbO response between 20 and 40 s after the onset of a 2-back task in the bilateral inferior frontal cortex (IFC). In parallel, the HbR response of the left IFC was significantly increased due to caffeine intake. In line with previous results, we did not detect an effect of caffeine on most aspects of behavior. Effects of caffeine on brain vasculature were detected as general reduction of HbO. Neuronal effects of caffeine are reflected in an increased concentration of HbR in the left hemisphere when performing a verbal memory task and suggest influences on metabolism.

  1. Sparse representation of higher-order functional interaction patterns in task-based FMRI data.

    Science.gov (United States)

    Zhang, Shu; Li, Xiang; Lv, Jinglei; Jiang, Xi; Zhu, Dajiang; Chen, Hanbo; Zhang, Tuo; Guo, Lei; Liu, Tianming

    2013-01-01

    Traditional task-based fMRI activation detection methods, e.g., the widely used general linear model (GLM), assume that the brain's hemodynamic responses follow the block-based or event-related stimulus paradigm. Typically, these activation detections are performed voxel-wise independently, and then are usually followed by statistical corrections. Despite remarkable successes and wide adoption of these methods, it remains largely unknown how functional brain regions interact with each other within specific networks during task performance blocks and in the baseline. In this paper, we present a novel algorithmic pipeline to statistically infer and sparsely represent higher-order functional interaction patterns within the working memory network during task performance and in the baseline. Specifically, a collection of higher-order interactions are inferred via the greedy equivalence search (GES) algorithm for both task and baseline blocks. In the next stage, an effective online dictionary learning algorithm is utilized for sparse representation of the inferred higher-order interaction patterns. Application of this framework on a working memory task-based fMRI data reveals interesting and meaningful distributions of the learned sparse dictionary atoms in task and baseline blocks. In comparison with traditional voxel-wise activation detection and recent pair-wise functional connectivity analysis, our framework offers a new methodology for representation and exploration of higher-order functional activities in the brain.

  2. Cerebral Blood Flow Measurement Using fMRI and PET: A Cross-Validation Study

    Directory of Open Access Journals (Sweden)

    Jean J. Chen

    2008-01-01

    Full Text Available An important aspect of functional magnetic resonance imaging (fMRI is the study of brain hemodynamics, and MR arterial spin labeling (ASL perfusion imaging has gained wide acceptance as a robust and noninvasive technique. However, the cerebral blood flow (CBF measurements obtained with ASL fMRI have not been fully validated, particularly during global CBF modulations. We present a comparison of cerebral blood flow changes (ΔCBF measured using a flow-sensitive alternating inversion recovery (FAIR ASL perfusion method to those obtained using H2O15 PET, which is the current gold standard for in vivo imaging of CBF. To study regional and global CBF changes, a group of 10 healthy volunteers were imaged under identical experimental conditions during presentation of 5 levels of visual stimulation and one level of hypercapnia. The CBF changes were compared using 3 types of region-of-interest (ROI masks. FAIR measurements of CBF changes were found to be slightly lower than those measured with PET (average ΔCBF of 21.5±8.2% for FAIR versus 28.2±12.8% for PET at maximum stimulation intensity. Nonetheless, there was a strong correlation between measurements of the two modalities. Finally, a t-test comparison of the slopes of the linear fits of PET versus ASL ΔCBF for all 3 ROI types indicated no significant difference from unity (P>.05.

  3. Performance quantification of clustering algorithms for false positive removal in fMRI by ROC curves

    Directory of Open Access Journals (Sweden)

    André Salles Cunha Peres

    Full Text Available Abstract Introduction Functional magnetic resonance imaging (fMRI is a non-invasive technique that allows the detection of specific cerebral functions in humans based on hemodynamic changes. The contrast changes are about 5%, making visual inspection impossible. Thus, statistic strategies are applied to infer which brain region is engaged in a task. However, the traditional methods like general linear model and cross-correlation utilize voxel-wise calculation, introducing a lot of false-positive data. So, in this work we tested post-processing cluster algorithms to diminish the false-positives. Methods In this study, three clustering algorithms (the hierarchical cluster, k-means and self-organizing maps were tested and compared for false-positive removal in the post-processing of cross-correlation analyses. Results Our results showed that the hierarchical cluster presented the best performance to remove the false positives in fMRI, being 2.3 times more accurate than k-means, and 1.9 times more accurate than self-organizing maps. Conclusion The hierarchical cluster presented the best performance in false-positive removal because it uses the inconsistency coefficient threshold, while k-means and self-organizing maps utilize a priori cluster number (centroids and neurons number; thus, the hierarchical cluster avoids clustering scattered voxels, as the inconsistency coefficient threshold allows only the voxels to be clustered that are at a minimum distance to some cluster.

  4. Dynamic modeling of neuronal responses in fMRI using cubature Kalman filtering.

    Science.gov (United States)

    Havlicek, Martin; Friston, Karl J; Jan, Jiri; Brazdil, Milan; Calhoun, Vince D

    2011-06-15

    This paper presents a new approach to inverting (fitting) models of coupled dynamical systems based on state-of-the-art (cubature) Kalman filtering. Crucially, this inversion furnishes posterior estimates of both the hidden states and parameters of a system, including any unknown exogenous input. Because the underlying generative model is formulated in continuous time (with a discrete observation process) it can be applied to a wide variety of models specified with either ordinary or stochastic differential equations. These are an important class of models that are particularly appropriate for biological time-series, where the underlying system is specified in terms of kinetics or dynamics (i.e., dynamic causal models). We provide comparative evaluations with generalized Bayesian filtering (dynamic expectation maximization) and demonstrate marked improvements in accuracy and computational efficiency. We compare the schemes using a series of difficult (nonlinear) toy examples and conclude with a special focus on hemodynamic models of evoked brain responses in fMRI. Our scheme promises to provide a significant advance in characterizing the functional architectures of distributed neuronal systems, even in the absence of known exogenous (experimental) input; e.g., resting state fMRI studies and spontaneous fluctuations in electrophysiological studies. Importantly, unlike current Bayesian filters (e.g. DEM), our scheme provides estimates of time-varying parameters, which we will exploit in future work on the adaptation and enabling of connections in the brain. Copyright © 2011 Elsevier Inc. All rights reserved.

  5. The neural correlates of problem states: testing FMRI predictions of a computational model of multitasking.

    Directory of Open Access Journals (Sweden)

    Jelmer P Borst

    Full Text Available BACKGROUND: It has been shown that people can only maintain one problem state, or intermediate mental representation, at a time. When more than one problem state is required, for example in multitasking, performance decreases considerably. This effect has been explained in terms of a problem state bottleneck. METHODOLOGY: In the current study we use the complimentary methodologies of computational cognitive modeling and neuroimaging to investigate the neural correlates of this problem state bottleneck. In particular, an existing computational cognitive model was used to generate a priori fMRI predictions for a multitasking experiment in which the problem state bottleneck plays a major role. Hemodynamic responses were predicted for five brain regions, corresponding to five cognitive resources in the model. Most importantly, we predicted the intraparietal sulcus to show a strong effect of the problem state manipulations. CONCLUSIONS: Some of the predictions were confirmed by a subsequent fMRI experiment, while others were not matched by the data. The experiment supported the hypothesis that the problem state bottleneck is a plausible cause of the interference in the experiment and that it could be located in the intraparietal sulcus.

  6. To boldly gulp: standard metabolic rate and boldness have context-dependent influences on risk-taking to breathe air in a catfish.

    Science.gov (United States)

    McKenzie, David J; Belão, Thiago C; Killen, Shaun S; Rantin, F Tadeu

    2015-12-01

    The African sharptooth catfish Clarias gariepinus has bimodal respiration, it has a suprabranchial air-breathing organ alongside substantial gills. We used automated bimodal respirometry to reveal that undisturbed juvenile catfish (N=29) breathed air continuously in normoxia, with a marked diurnal cycle. Air breathing and routine metabolic rate (RMR) increased in darkness when, in the wild, this nocturnal predator forages. Aquatic hypoxia (20% air saturation) greatly increased overall reliance on air breathing. We investigated whether two measures of risk taking to breathe air, namely absolute rates of aerial O2 uptake (ṀO2,air) and the percentage of RMR obtained from air (%ṀO2,air), were influenced by individual standard metabolic rate (SMR) and boldness. In particular, whether any influence varied with resource availability (normoxia versus hypoxia) or relative fear of predation (day versus night). Individual SMR, derived from respirometry, had an overall positive influence on ṀO2,air across all contexts but a positive influence on %ṀO2,air only in hypoxia. Thus, a pervasive effect of SMR on air breathing became most acute in hypoxia, when individuals with higher O2 demand took proportionally more risks. Boldness was estimated as time required to resume air breathing after a fearful stimulus in daylight normoxia (Tres). Although Tres had no overall influence on ṀO2,air or %ṀO2,air, there was a negative relationship between Tres and %ṀO2,air in daylight, in normoxia and hypoxia. There were two Tres response groups, 'bold' phenotypes with Tres below 75 min (N=13) which, in daylight, breathed proportionally more air than 'shy' phenotypes with Tres above 115 min (N=16). Therefore, individual boldness influenced air breathing when fear of predation was high. Thus, individual energy demand and personality did not have parallel influences on the emergent tendency to take risks to obtain a resource; their influences varied in strength with context. © 2015

  7. Abnormal regional homogeneity in Parkinson's disease: a resting state fMRI study

    International Nuclear Information System (INIS)

    Li, Y.; Liang, P.; Jia, X.; Li, K.

    2016-01-01

    Aim: To examine the functional brain alterations in Parkinson's disease (PD) by measuring blood oxygenation level dependent (BOLD) functional MRI (fMRI) signals at rest while controlling for the structural atrophy. Materials and methods: Twenty-three PD patients and 20 age, gender, and education level matched normal controls (NC) were included in this study. Resting state fMRI and structural MRI data were acquired. The resting state brain activity was measured by the regional homogeneity (ReHo) method and the grey matter (GM) volume was attained by the voxel-based morphology (VBM) analysis. Two-sample t-test was then performed to detect the group differences with structural atrophy as a covariate. Results: VBM analysis showed GM volume reductions in the left superior frontal gyrus, left paracentral lobule, and left middle frontal gyrus in PD patients as compared to NC. There were widespread ReHo differences between NC and PD patients. Compared to NC, PD patients showed significant alterations in the motor network, including decreased ReHo in the right primary sensory cortex (S1), while increased ReHo in the left premotor area (PMA) and left dorsolateral prefrontal cortex (DLPFC). In addition, a cluster in the left superior occipital gyrus (SOG) also showed increased ReHo in PD patients. Conclusion: The current findings indicate that significant changes of ReHo in the motor and non-motor cortices have been detected in PD patients, independent of age, gender, education level, and structural atrophy. The present study thus suggests ReHo abnormalities as a potential biomarker for the diagnosis of PD and further provides insights into the biological mechanism of the disease. - Highlights: • Functional changes were found in PD patients independent of structural atrophy. • Both increased and decreased ReHo were observed in motor network regions in PD. • Increased ReHo was detected in visual association cortex for PD patients.

  8. FMRI of spinal and supra-spinal correlates of temporal pain summation in fibromyalgia patients.

    Science.gov (United States)

    Bosma, Rachael L; Mojarad, Elham Ameli; Leung, Lawrence; Pukall, Caroline; Staud, Roland; Stroman, Patrick W

    2016-04-01

    Fibromyalgia syndrome (FM) is a debilitating chronic pain condition, which afflicts primarily females. Although the etiology of this illness is not completely understood, FM pain is thought to rely on enhanced pain sensitivity maintained by central mechanisms. One of these mechanisms is central pain amplification, which is characterized by altered temporal summation of second pain (TSSP). Here we use a TSSP paradigm and functional MRI (fMRI) of the spinal cord, brainstem, and brain to noninvasively examine the central nervous system contributions to TSSP in FM patients and normal controls (NC). Functional MRI of pain-free female adults (N = 15) and FM patients (N = 14) was conducted while brief, repetitive heat pain stimuli (0.33 Hz) were applied to the thenar eminence of the hand (C6 dermatome). The stimulus intensity was adjusted to each participant's heat pain sensitivity to achieve moderate pain. Data were analyzed by means of a General Linear Model and region-of-interest analyses. All participants demonstrated significant pain summation in the TSSP condition. FM subjects, however, required significantly lower stimulus intensities than NC to achieve similar TSSP. fMRI analyses of perceptually equal TSSP identified similar brain activity in NC and FM subjects; however, multiple areas in the brainstem (rostral ventromedial medulla and periaqueductal grey region) and spinal cord (dorsal horn) exhibited greater activity in NC subjects. Finally, increased after-sensations and enhanced dorsal horn activity was demonstrated in FM patients. In conclusion, the spinal and brainstem BOLD responses to TSSP are different between NC and FM patients, which may indicate alterations to descending pain control mechanisms suggesting contributions of these mechanisms to central sensitization and pain of FM patients. © 2016 Wiley Periodicals, Inc.

  9. The brain effects of laser acupuncture in healthy individuals: an FMRI investigation.

    Directory of Open Access Journals (Sweden)

    Im Quah-Smith

    2010-09-01

    Full Text Available As laser acupuncture is being increasingly used to treat mental disorders, we sought to determine whether it has a biologically plausible effect by using functional magnetic resonance imaging (fMRI to investigate the cerebral activation patterns from laser stimulation of relevant acupoints.Ten healthy subjects were randomly stimulated with a fibreoptic infrared laser on 4 acupoints (LR14, CV14, LR8 and HT7 used for depression following the principles of Traditional Chinese Medicine (TCM, and 1 control non-acupoint (sham point in a blocked design (alternating verum laser and placebo laser/rest blocks, while the blood oxygenation level-dependent (BOLD fMRI response was recorded from the whole brain on a 3T scanner. Many of the acupoint laser stimulation conditions resulted in different patterns of neural activity. Regions with significantly increased activation included the limbic cortex (cingulate and the frontal lobe (middle and superior frontal gyrus. Laser acupuncture tended to be associated with ipsilateral brain activation and contralateral deactivation that therefore cannot be simply attributed to somatosensory stimulation.We found that laser stimulation of acupoints lead to activation of frontal-limbic-striatal brain regions, with the pattern of neural activity somewhat different for each acupuncture point. This is the first study to investigate laser acupuncture on a group of acupoints useful in the management of depression. Differing activity patterns depending on the acupoint site were demonstrated, suggesting that neurological effects vary with the site of stimulation. The mechanisms of activation and deactivation and their effects on depression warrant further investigation.

  10. The supraspinal neural correlate of bladder cold sensation--an fMRI study.

    Science.gov (United States)

    Mehnert, Ulrich; Michels, Lars; Zempleni, Monika-Zita; Schurch, Brigitte; Kollias, Spyros

    2011-06-01

    In recent years, functional imaging studies have revealed a supraspinal network, which is involved in perception and processing of bladder distention. Very little information exists on the cortical representation of C-fiber transmitted temperature sensation of the human bladder, although C-fibers seem to be involved in the pathomechanisms of bladder dysfunctions. Our aim was, therefore, to evaluate the outcome of bladder cold stimulation on supraspinal activity using functional magnetic resonance imaging (fMRI). A block design fMRI study was performed in 14 healthy females at the MR-center of the University of Zurich. After catheterization, all subjects were investigated in a 3.0-Tesla Scanner. The scanning consisted of 10 repetitive cycles. Each cycle consisted of five conditions: REST, INFUSION, SENSATION, DRAIN 1, and DRAIN 2. Cold saline was passively infused at 4-8°C during scanning. Not more than 100 ml were infused per cycle. Blood-oxygen-level-dependent (BOLD) signal analysis of the different conditions was compared to REST. All activations were evaluated on a random effects level at P = 0.001. Activation of brain regions for bladder cold stimulation (DRAIN 1 period) was found bilaterally in the inferior parietal lobe [Brodmann area (BA) 40], the right insula (BA 13), the right cerebellar posterior lobe, the right middle temporal gyrus (BA 20), and the right postcentral gyrus (BA 3). In conclusion, bladder cooling caused a different supraspinal activation pattern compared to what is known to occur during bladder distention. This supports our hypothesis that cold sensation is processed differently from bladder distension at the supraspinal level. Copyright © 2010 Wiley-Liss, Inc.

  11. Global Functional Connectivity Differences between Sleep-Like States in Urethane Anesthetized Rats Measured by fMRI.

    Directory of Open Access Journals (Sweden)

    Ekaterina Zhurakovskaya

    Full Text Available Sleep is essential for nervous system functioning and sleep disorders are associated with several neurodegenerative diseases. However, the macroscale connectivity changes in brain networking during different sleep states are poorly understood. One of the hindering factors is the difficulty to combine functional connectivity investigation methods with spontaneously sleeping animals, which prevents the use of numerous preclinical animal models. Recent studies, however, have implicated that urethane anesthesia can uniquely induce different sleep-like brain states, resembling rapid eye movement (REM and non-REM (NREM sleep, in rodents. Therefore, the aim of this study was to assess changes in global connectivity and topology between sleep-like states in urethane anesthetized rats, using blood oxygenation level dependent (BOLD functional magnetic resonance imaging. We detected significant changes in corticocortical (increased in NREM-like state and corticothalamic connectivity (increased in REM-like state. Additionally, in graph analysis the modularity, the measure of functional integration in the brain, was higher in NREM-like state than in REM-like state, indicating a decrease in arousal level, as in normal sleep. The fMRI findings were supported by the supplementary electrophysiological measurements. Taken together, our results show that macroscale functional connectivity changes between sleep states can be detected robustly with resting-state fMRI in urethane anesthetized rats. Our findings pave the way for studies in animal models of neurodegenerative diseases where sleep abnormalities are often one of the first markers for the disorder development.

  12. Action video gaming and the brain: fMRI effects without behavioral effects in visual and verbal cognitive tasks.

    Science.gov (United States)

    Richlan, Fabio; Schubert, Juliane; Mayer, Rebecca; Hutzler, Florian; Kronbichler, Martin

    2018-01-01

    In this functional magnetic resonance imaging (fMRI) study, we compared task performance together with brain activation in a visuospatial task (VST) and a letter detection task (LDT) between longtime action video gamers ( N  =   14) and nongamers ( N  =   14) in order to investigate possible effects of gaming on cognitive and brain abilities. Based on previous research, we expected advantages in performance for experienced action video gamers accompanied by less activation (due to higher efficiency) as measured by fMRI in the frontoparietal attention network. Contrary to these expectations, we did not find differences in overall task performance, nor in brain activation during the VST. We identified, however, a significantly different increase in the BOLD signal from a baseline task to the LDT in action video gamers compared with nongamers. This increased activation was evident in a number of frontoparietal regions including the left middle paracingulate cortex, the left superior frontal sulcus, the opercular part of the left inferior frontal gyrus, and the left and right posterior parietal cortex. Furthermore, we found increased activation in the triangular part of the left inferior frontal gyrus in gamers relative to nongamers when activation during the LDT was compared with activation during the VST. In sum, the expected positive relation between action video game experience and cognitive performance could not be confirmed. Despite their comparable task performance, however, gamers and nongamers exhibited clear-cut differences in brain activation patterns presumably reflecting differences in neural engagement, especially during verbal cognitive tasks.

  13. The fMRI study on the front-parietal activation in abacus mental calculation trained children

    International Nuclear Information System (INIS)

    Zhao Kunyuan; Wang Bin; Long Jinfeng; Li Lixin; Shen Xiaojun

    2010-01-01

    Objective: To investigate the difference in front-parietal activation between the trained and untrained children engaged in addition and multiplication with functional magnetic resonance imaging (fMRI), and to explore the role of abacus mental calculation in brain development. Methods: Twenty-four children trained with abacus mental calculation and twelve untrained children performed mental calculation tasks including addition, multiplication and number-object control judging tasks. Blood oxygenation level dependence (BOLD) fMRI was performed when they were calculating. All data were analyzed by SPM2 (statistical parametric mapping 2) to generate the brain activation map. Results: The performance of the trained group had better correctness and shorter reaction time than that of the untrained group. The front-parietal activation between two groups had obvious difference. The activation involved less prefrontal cortex in the trained group than in the untrained group (P<0.05). The parietal activation in the trained group was mainly in the posterior superior parietal lobe/ precuneus, whereas the activation areas focused on the inferior parietal lobule in the untrained group. Conclusion: Abacus mental calculation involves multiple functional areas. and these areas may work together as a whole in processing arithmetic problems. Abacus mental calculation not only enhances the information processing in some brain areas and improves the utilization efficiency of neural resources, but also plays an important role in developing brain. (authors)

  14. On clustering fMRI time series

    DEFF Research Database (Denmark)

    Goutte, Cyril; Toft, Peter Aundal; Rostrup, E.

    1999-01-01

    Analysis of fMRI time series is often performed by extracting one or more parameters for the individual voxels. Methods based, e.g., on various statistical tests are then used to yield parameters corresponding to probability of activation or activation strength. However, these methods do not indi...

  15. Functional Laterality of Task-Evoked Activation in Sensorimotor Cortex of Preterm Infants: An Optimized 3 T fMRI Study Employing a Customized Neonatal Head Coil.

    Science.gov (United States)

    Scheef, Lukas; Nordmeyer-Massner, Jurek A; Smith-Collins, Adam Pr; Müller, Nicole; Stegmann-Woessner, Gaby; Jankowski, Jacob; Gieseke, Jürgen; Born, Mark; Seitz, Hermann; Bartmann, Peter; Schild, Hans H; Pruessmann, Klaas P; Heep, Axel; Boecker, Henning

    2017-01-01

    Functional magnetic resonance imaging (fMRI) in neonates has been introduced as a non-invasive method for studying sensorimotor processing in the developing brain. However, previous neonatal studies have delivered conflicting results regarding localization, lateralization, and directionality of blood oxygenation level dependent (BOLD) responses in sensorimotor cortex (SMC). Amongst the confounding factors in interpreting neonatal fMRI studies include the use of standard adult MR-coils providing insufficient signal to noise, and liberal statistical thresholds, compromising clinical interpretation at the single subject level. Here, we employed a custom-designed neonatal MR-coil adapted and optimized to the head size of a newborn in order to improve robustness, reliability and validity of neonatal sensorimotor fMRI. Thirteen preterm infants with a median gestational age of 26 weeks were scanned at term-corrected age using a prototype 8-channel neonatal head coil at 3T (Achieva, Philips, Best, NL). Sensorimotor stimulation was elicited by passive extension/flexion of the elbow at 1 Hz in a block design. Analysis of temporal signal to noise ratio (tSNR) was performed on the whole brain and the SMC, and was compared to data acquired with an 'adult' 8 channel head coil published previously. Task-evoked activation was determined by single-subject SPM8 analyses, thresholded at p lateralization of SMC activation, as found in children and adults, is already present in the newborn period.

  16. Occupational exposure in hemodynamic; Exposicao ocupacional em hemodinamica

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Amanda J.; Fernandes, Ivani M.; Silva, Paula P. Nou; Sordi, Gian Maria A.A.; Carneiro, Janete C.G.G., E-mail: ajsilva@ipen.b, E-mail: imfernandes@ipen.b, E-mail: ppsilva@ipen.b, E-mail: gmsordi@ipen.b, E-mail: janetegc@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-10-26

    This paper has an objective to perform a radiometric survey at a hemodynamic service. Besides, it was intended to evaluate the effective dose of health professionals and to provide data which can contribute with minimization of exposures during the realization of hemodynamic procedure. The radiometric survey was realized in the real environment of work simulating the conditions of a hemodynamic study with a ionization chamber

  17. Examining the regional and cerebral depth-dependent BOLD cerebrovascular reactivity response at 7T.

    Science.gov (United States)

    Bhogal, Alex A; Philippens, Marielle E P; Siero, Jeroen C W; Fisher, Joseph A; Petersen, Esben Thade; Luijten, Peter R; Hoogduin, Hans

    2015-07-01

    Changes in cerebral blood flow (CBF) in response to hypercapnia induced changes in vascular tone, known as cerebrovascular reactivity (CVR), can be measured using the Blood Oxygenation Level Dependent (BOLD) MR contrast. We examine regional differences in the BOLD-CVR response to a progressively increasing hypercapnic stimulus as well as regional BOLD characteristics for the return to baseline normocapnia. CVR across 9 subjects was highest in the cerebral lobes and deep gray matter. Peak CVR in these regions was measured at 3.6±1.6mmHg above baseline end-tidal CO2. White matter CVR was generally reduced compared to that of the gray matter (peak white matter CVR was ~48% lower). A positive relationship between the end-tidal CO2 value at which peak CVR was measured and white matter depth is observed. Furthermore, the time required for the BOLD signal to return to baseline after cessation of the hypercapnic stimulus, was also related to white matter depth; the return, expressed as a time constant, was ~25% longer in white matter. To explain the observed differences in regional CVR response, a model is proposed that takes into account the local architecture of the cerebrovascular, which can result in changes in regional blood flow distribution as a function of end-tidal CO2. Copyright © 2015. Published by Elsevier Inc.

  18. 76 FR 66283 - Notice of Intent To Grant Partially Exclusive Patent License; BOLD Industries, Inc.

    Science.gov (United States)

    2011-10-26

    ... license to practice in the United States, the Government- owned inventions described in U.S. Patent... System.//U.S. Patent Application Serial No. 12/778,892 filed on May 12, 2010: Scene Illuminator. DATES... Department of the Navy Notice of Intent To Grant Partially Exclusive Patent License; BOLD Industries, Inc...

  19. BOLD effect on calf muscle groups in elderly females with different bone mineral density.

    Science.gov (United States)

    Ma, Heather T; Griffith, James F; Ye, Chenfei; Yeung, David K; Xing, Xu; Leung, Ping-Chung; Yuan, Jing

    2014-01-01

    This study examined the BOLD effect on calf muscles in elderly subjects with different bone mineral density. The purpose was to investigate the oxygenation characteristics in different calf muscle groups for the elderly females and compare the muscle oxygenation among groups with different bone mineral density. Temporary vascular occlusion was induced with air-cuff compression of the thigh and BOLD-MRI data curve was fitted to derive quantitative parameters. Three muscle groups, gastrocnemius muscle (lateral head), soleus muscle, and tibialis anterior muscle, were investigated individually. Quantitative CT measurement was conducted on each subject, based on which subjects were classified into normal, osteopenia, and osteoporosis groups. The BOLD signal in soleus muscle showed the lowest minimum ischemic value during ischemia and the steepest slope during hyperemia. As soleus muscle is mainly composed by slow-twitch oxidative muscle fibers, current results may be due to a higher vascular bed density and better endothelial function in such muscle. By t-test, the half-life of the BOLD signal decay during ischemia in both gastrocnemius and soleus muscles was significantly prolonged in osteoporosis group, indicating a degenerated muscular oxygen metabolic capacity in osteoporotic patients.

  20. Using pulse oximetry to account for high and low frequency physiological artifacts in the BOLD signal.

    Science.gov (United States)

    Verstynen, Timothy D; Deshpande, Vibhas

    2011-04-15

    The BOLD signal not only reflects changes in local neural activity, but also exhibits variability from physiological processes like cardiac rhythms and breathing. We investigated how both of these physiological sources are reflected in the pulse oximetry (PO) signal, a direct measure of blood oxygenation, and how this information can be used to account for different types of noise in the BOLD response. Measures of heart rate, respiration and PO were simultaneously recorded while neurologically healthy participants performed an eye-movement task in a 3T MRI. PO exhibited power in frequencies that matched those found in the independently recorded cardiac and respiration signals. Using the phasic and aphasic properties of these signals as nuisance regressors, we found that the different frequency components of the PO signal could be used to identify different types of physiological artifacts in the BOLD response. A comparison of different physiological noise models found that a simple, down-sampled version of the PO signal improves the estimation of task-relevant statistics nearly as well as more established noise models that may run the risk of over-parameterization. These findings suggest that the PO signal captures multiple sources of physiological noise in the BOLD response and provides a simple and efficient way of modeling these noise sources in subsequent analysis. Copyright © 2011 Elsevier Inc. All rights reserved.

  1. Efecto del tamaño kernel en el suavizado de señal BOLD en paradigmas funcionales (RMf (Effect of kernel size for BOLD signal smoothing in functional paradigms (fMRI

    Directory of Open Access Journals (Sweden)

    Laia Farràs-Permanyer

    2015-04-01

    Full Text Available Smoothing is a filtering technique that is essential for brain signal analysis and consists in calculating and comparing the average activation of a voxel to that of its neighbours. Several authors have proposed alternatives or modifications to this process; nonetheless, articles that compare the effect of different sizes of smoothing remain scarce. Thus, the aim of this study was to investigate the effect of applying different smoothing sizes and to highlight the importance of choosing the correct smoothing size. Five smoothing criteria were applied to brain images obtained during an easy motor task performed by five adult participants. Significant differences were found between different smoothing sizes, mainly between the non-smoothing application and the smallest smoothing size versus the two largest smoothing sizes. The signals from the most activated brain areas did not disappear with increased smoothing, whereas signals from less active or smaller areas disappeared. Despite the study sample size, the results suggest that smoothing is relevant in functional magnetic resonance image processing and that the optimum smoothing size is 2.5 and 3.

  2. BOLD cardiovascular magnetic resonance at 3.0 tesla in myocardial ischemia

    Directory of Open Access Journals (Sweden)

    Gebker Rolf

    2010-09-01

    Full Text Available Abstract Background The purpose of this study was to determine the ability of Blood Oxygen Level Dependent (BOLD cardiovascular magnetic resonance (CMR to detect stress-inducible myocardial ischemic reactions in the presence of angiographically significant coronary artery disease (CAD. Methods Forty-six patients (34 men; age 65 ± 9 years, with suspected or known coronary artery disease underwent CMR at 3Tesla prior to clinically indicated invasive coronary angiography. BOLD CMR was performed in 3 short axis slices of the heart at rest and during adenosine stress (140 μg/kg/min followed by late gadolinium enhancement (LGE imaging. In all 16 standard myocardial segments, T2* values were derived at rest and under adenosine stress. Quantitative coronary angiography served as the standard of reference and defined normal myocardial segments (i.e. all 16 segments in patients without any CAD, ischemic segments (i.e. supplied by a coronary artery with ≥50% luminal narrowing and non-ischemic segments (i.e. supplied by a non-significantly stenosed coronary artery in patients with significant CAD. Results Coronary angiography demonstrated significant CAD in 23 patients. BOLD CMR at rest revealed significantly lower T2* values for ischemic segments (26.7 ± 11.6 ms compared to normal (31.9 ± 11.9 ms; p Conclusions Rest and stress BOLD CMR at 3Tesla proved feasible and differentiated between ischemic, non-ischemic, and normal myocardial segments in a clinical patient population. BOLD CMR during vasodilator stress identified patients with significant CAD.

  3. Multishot versus single-shot pulse sequences in very high field fMRI: a comparison using retinotopic mapping.

    Directory of Open Access Journals (Sweden)

    Jascha D Swisher

    Full Text Available High-resolution functional MRI is a leading application for very high field (7 Tesla human MR imaging. Though higher field strengths promise improvements in signal-to-noise ratios (SNR and BOLD contrast relative to fMRI at 3 Tesla, these benefits may be partially offset by accompanying increases in geometric distortion and other off-resonance effects. Such effects may be especially pronounced with the single-shot EPI pulse sequences typically used for fMRI at standard field strengths. As an alternative, one might consider multishot pulse sequences, which may lead to somewhat lower temporal SNR than standard EPI, but which are also often substantially less susceptible to off-resonance effects. Here we consider retinotopic mapping of human visual cortex as a practical test case by which to compare examples of these sequence types for high-resolution fMRI at 7 Tesla. We performed polar angle retinotopic mapping at each of 3 isotropic resolutions (2.0, 1.7, and 1.1 mm using both accelerated single-shot 2D EPI and accelerated multishot 3D gradient-echo pulse sequences. We found that single-shot EPI indeed led to greater temporal SNR and contrast-to-noise ratios (CNR than the multishot sequences. However, additional distortion correction in postprocessing was required in order to fully realize these advantages, particularly at higher resolutions. The retinotopic maps produced by both sequence types were qualitatively comparable, and showed equivalent test/retest reliability. Thus, when surface-based analyses are planned, or in other circumstances where geometric distortion is of particular concern, multishot pulse sequences could provide a viable alternative to single-shot EPI.

  4. Language changes coincide with motor and fMRI changes following upper extremity motor therapy for hemiparesis: a brief report.

    Science.gov (United States)

    Harnish, Stacy; Meinzer, Marcus; Trinastic, Jonathan; Fitzgerald, David; Page, Stephen

    2014-09-01

    To formally assess changes in language, affected UE movement, and motor functional activation changes via functional magnetic resonance imaging (fMRI) following participation in motor therapy without any accompanying language intervention. Pre-post case series. Five subjects with stroke exhibiting chronic, stable UE hemiparesis. The upper extremity section of the Fugl-Meyer (FM), the Western Aphasia Battery (WAB), and functional magnetic resonance imaging (fMRI), administered during performance of an affected UE motor task. All subjects were administered six weeks of repetitive task specific training (RTP), performed for approximately 2.5 hours per day, split into two sessions. For the first four weeks of the intervention period, RTP was administered every weekday, whereas, for the subsequent two weeks, RTP was administered 3 days/week. Epidural cortical stimulation was co-administered with the RTP via an electrode array and implanted pulse generator. For all sessions, one subject worked with a single therapist. Four weeks before and four weeks after the intervention period, all subjects were administered the FM, WAB, and fMRI. Three of the subjects exhibited clinically significant language changes on the WAB. These individuals exhibited the largest motor changes as measured by the FM. Functional MRI revealed distinct motor activation patterns in these subjects, characterized by more strongly right lateralized focal BOLD activity or a shift in activation toward the right hemisphere. Language changes appear to co-occur with motor changes after UE RTP. Understanding the underlying mechanisms of these findings may lead to more efficient and synergistic rehabilitative therapy delivery.

  5. Real-time fMRI pattern decoding and neurofeedback using FRIEND: an FSL-integrated BCI toolbox.

    Science.gov (United States)

    Sato, João R; Basilio, Rodrigo; Paiva, Fernando F; Garrido, Griselda J; Bramati, Ivanei E; Bado, Patricia; Tovar-Moll, Fernanda; Zahn, Roland; Moll, Jorge

    2013-01-01

    The demonstration that humans can learn to modulate their own brain activity based on feedback of neurophysiological signals opened up exciting opportunities for fundamental and applied neuroscience. Although EEG-based neurofeedback has been long employed both in experimental and clinical investigation, functional MRI (fMRI)-based neurofeedback emerged as a promising method, given its superior spatial resolution and ability to gauge deep cortical and subcortical brain regions. In combination with improved computational approaches, such as pattern recognition analysis (e.g., Support Vector Machines, SVM), fMRI neurofeedback and brain decoding represent key innovations in the field of neuromodulation and functional plasticity. Expansion in this field and its applications critically depend on the existence of freely available, integrated and user-friendly tools for the neuroimaging research community. Here, we introduce FRIEND, a graphic-oriented user-friendly interface package for fMRI neurofeedback and real-time multivoxel pattern decoding. The package integrates routines for image preprocessing in real-time, ROI-based feedback (single-ROI BOLD level and functional connectivity) and brain decoding-based feedback using SVM. FRIEND delivers an intuitive graphic interface with flexible processing pipelines involving optimized procedures embedding widely validated packages, such as FSL and libSVM. In addition, a user-defined visual neurofeedback module allows users to easily design and run fMRI neurofeedback experiments using ROI-based or multivariate classification approaches. FRIEND is open-source and free for non-commercial use. Processing tutorials and extensive documentation are available.

  6. Real-time fMRI pattern decoding and neurofeedback using FRIEND: an FSL-integrated BCI toolbox.

    Directory of Open Access Journals (Sweden)

    João R Sato

    Full Text Available The demonstration that humans can learn to modulate their own brain activity based on feedback of neurophysiological signals opened up exciting opportunities for fundamental and applied neuroscience. Although EEG-based neurofeedback has been long employed both in experimental and clinical investigation, functional MRI (fMRI-based neurofeedback emerged as a promising method, given its superior spatial resolution and ability to gauge deep cortical and subcortical brain regions. In combination with improved computational approaches, such as pattern recognition analysis (e.g., Support Vector Machines, SVM, fMRI neurofeedback and brain decoding represent key innovations in the field of neuromodulation and functional plasticity. Expansion in this field and its applications critically depend on the existence of freely available, integrated and user-friendly tools for the neuroimaging research community. Here, we introduce FRIEND, a graphic-oriented user-friendly interface package for fMRI neurofeedback and real-time multivoxel pattern decoding. The package integrates routines for image preprocessing in real-time, ROI-based feedback (single-ROI BOLD level and functional connectivity and brain decoding-based feedback using SVM. FRIEND delivers an intuitive graphic interface with flexible processing pipelines involving optimized procedures embedding widely validated packages, such as FSL and libSVM. In addition, a user-defined visual neurofeedback module allows users to easily design and run fMRI neurofeedback experiments using ROI-based or multivariate classification approaches. FRIEND is open-source and free for non-commercial use. Processing tutorials and extensive documentation are available.

  7. On neural correlates of individual differences in novel grammar learning: An fMRI study.

    Science.gov (United States)

    Kepinska, Olga; de Rover, Mischa; Caspers, Johanneke; Schiller, Niels O

    2017-04-01

    We examine the role of language analytical ability, one of the components of language aptitude - a specific ability for learning languages - during acquisition of a novel grammar. We investigated whether the neural basis of Artificial Grammar Learning (AGL) differs between populations of highly and moderately skilled learners. Participants performed an AGL task during an fMRI scan and data from task's test phases were analysed. Highly skilled learners performed better than moderately skilled ones and engaged during the task more neural resources in the right hemisphere, i.e. in the right angular/supramarginal gyrus and superior frontal and middle frontal gyrus and in the posterior cingulate gyrus. Additional analyses investigating the temporal dynamics of brain activity during learning revealed lateralisation differences in the modulation of activity in the parietal and temporal cortex. In particular, the left angular gyrus BOLD activity was coupled with high performance on the AGL task and with a steep learning curve. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Decoding semantics across fMRI sessions with different stimulus modalities: a practical MVPA study.

    Science.gov (United States)

    Akama, Hiroyuki; Murphy, Brian; Na, Li; Shimizu, Yumiko; Poesio, Massimo

    2012-01-01

    Both embodied and symbolic accounts of conceptual organization would predict partial sharing and partial differentiation between the neural activations seen for concepts activated via different stimulus modalities. But cross-participant and cross-session variability in BOLD activity patterns makes analyses of such patterns with MVPA methods challenging. Here, we examine the effect of cross-modal and individual variation on the machine learning analysis of fMRI data recorded during a word property generation task. We present the same set of living and non-living concepts (land-mammals, or work tools) to a cohort of Japanese participants in two sessions: the first using auditory presentation of spoken words; the second using visual presentation of words written in Japanese characters. Classification accuracies confirmed that these semantic categories could be detected in single trials, with within-session predictive accuracies of 80-90%. However cross-session prediction (learning from auditory-task data to classify data from the written-word-task, or vice versa) suffered from a performance penalty, achieving 65-75% (still individually significant at p « 0.05). We carried out several follow-on analyses to investigate the reason for this shortfall, concluding that distributional differences in neither time nor space alone could account for it. Rather, combined spatio-temporal patterns of activity need to be identified for successful cross-session learning, and this suggests that feature selection strategies could be modified to take advantage of this.

  9. Decoding Semantics across fMRI sessions with Different Stimulus Modalities: A practical MVPA Study

    Directory of Open Access Journals (Sweden)

    Hiroyuki eAkama

    2012-08-01

    Full Text Available Both embodied and symbolic accounts of conceptual organization would predict partial sharing and partial differentiation between the neural activations seen for concepts activated via different stimulus modalities. But cross-participant and cross-session variability in BOLD activity patterns makes analyses of such patterns with MVPA methods challenging. Here we examine the effect of cross-modal and individual variation on the machine learning analysis of fMRI data recorded during a word property generation task. We present the same set of living and non-living concepts (land-mammals, or work tools to a cohort of Japanese participants in two sessions: the first using auditory presentation of spoken words; the second using visual presentation of words written in Japanese characters. Classification accuracies confirmed that these semantic categories could be detected in single trials, with within-session predictive accuracies of 80-90%. However cross-session prediction (learning from auditory-task data to classify data from the written-word-task, or vice-versa suffered from a performance penalty, achieving 65-75% (still individually significant at p<<0.05. We carried out several follow-on analyses to investigate the reason for this shortfall, concluding that distributional differences in neither time nor space alone could account for it. Rather, combined spatio-temporal patterns of activity need to be identified for successful cross-session learning, and this suggests that feature selection strategies could be modified to take advantage of this.

  10. Neural Encoding of Acupuncture Needling Sensations: Evidence from a fMRI Study

    Directory of Open Access Journals (Sweden)

    Xiaoling Wang

    2013-01-01

    Full Text Available Deqi response, a psychophysical response characterized by a spectrum of different needling sensations, is essential for Chinese acupuncture clinical efficacy. Previous neuroimaging research works have investigated the neural correlates of an overall deqi response by summating the scores of different needling sensations. However, the roles of individual sensations in brain activity and how they interact with each other remain to be clarified. In this study, we applied fMRI to investigate the neural correlates of individual components of deqi during acupuncture on the right LV3 (Taichong acupoint. We selected a subset of deqi responses, namely, pressure, heaviness, fullness, numbness, and tingling. Using the individual components of deqi of different subjects as covariates in the analysis of percentage change of bold signal, pressure was found to be a striking sensation, contributing to most of negative activation of a limbic-paralimbic-neocortical network (LPNN. The similar or opposite neural activity in the heavily overlapping regions is found to be responding to different needling sensations, including bilateral LPNN, right orbitofrontal cortex, and bilateral posterior parietal cortex. These findings provide the neuroimaging evidence of how the individual needle sensations interact in the brain, showing that the modulatory effects of different needling sensations contribute to acupuncture modulations of LPNN network.

  11. Is fMRI "noise" really noise? Resting state nuisance regressors remove variance with network structure.

    Science.gov (United States)

    Bright, Molly G; Murphy, Kevin

    2015-07-01

    Noise correction is a critical step towards accurate mapping of resting state BOLD fMRI connectivity. Noise sources related to head motion or physiology are typically modelled by nuisance regressors, and a generalised linear model is applied to regress out the associated signal variance. In this study, we use independent component analysis (ICA) to characterise the data variance typically discarded in this pre-processing stage in a cohort of 12 healthy volunteers. The signal variance removed by 24, 12, 6, or only 3 head motion parameters demonstrated network structure typically associated with functional connectivity, and certain networks were discernable in the variance extracted by as few as 2 physiologic regressors. Simulated nuisance regressors, unrelated to the true data noise, also removed variance with network structure, indicating that any group of regressors that randomly sample variance may remove highly structured "signal" as well as "noise." Furthermore, to support this we demonstrate that random sampling of the original data variance continues to exhibit robust network structure, even when as few as 10% of the original volumes are considered. Finally, we examine the diminishing returns of increasing the number of nuisance regressors used in pre-processing, showing that excessive use of motion regressors may do little better than chance in removing variance within a functional network. It remains an open challenge to understand the balance between the benefits and confounds of noise correction using nuisance regressors. Copyright © 2015. Published by Elsevier Inc.

  12. Extinction of Conditioned Fear in Adolescents and Adults: A Human fMRI Study

    Directory of Open Access Journals (Sweden)

    Despina E. Ganella

    2018-01-01

    Full Text Available Little is known about the neural correlates of fear learning in adolescents, a population at increased risk for anxiety disorders. Healthy adolescents (mean age 16.26 and adults (mean age 29.85 completed a fear learning paradigm across two stages during functional magnetic resonance imaging (fMRI. Stage 1 involved conditioning and extinction, and stage 2 involved extinction recall, re-conditioning, followed by re-extinction. During extinction recall, we observed a higher skin conductance response to the CS+ relative to CS− in adolescents compared to adults, which was accompanied by a reduction in dorsolateral prefrontal cortex (dlPFC activity. Relative to adults, adolescents also had significantly reduced activation in the ventromedial PFC, dlPFC, posterior cingulate cortex (PCC, and temporoparietal junction (TPJ during extinction recall compared to late extinction. Age differences in PCC activation between late extinction and late conditioning were also observed. These results show for the first time that healthy adolescent humans show different behavioral responses, and dampened PFC activity during short-term extinction recall compared to healthy adults. We also identify the PCC and TPJ as novel regions that may be associated with impaired extinction in adolescents. Also, while adults showed significant correlations between differential SCR and BOLD activity in some brain regions during late extinction and recall, adolescents did not show any significant correlations. This study highlights adolescent-specific neural correlates of extinction, which may explain the peak in prevalence of anxiety disorders during adolescence.

  13. Brain activation profiles during kinesthetic and visual imagery: An fMRI study.

    Science.gov (United States)

    Kilintari, Marina; Narayana, Shalini; Babajani-Feremi, Abbas; Rezaie, Roozbeh; Papanicolaou, Andrew C

    2016-09-01

    The aim of this study was to identify brain regions involved in motor imagery and differentiate two alternative strategies in its implementation: imagining a motor act using kinesthetic or visual imagery. Fourteen adults were precisely instructed and trained on how to imagine themselves or others perform a movement sequence, with the aim of promoting kinesthetic and visual imagery, respectively, in the context of an fMRI experiment using block design. We found that neither modality of motor imagery elicits activation of the primary motor cortex and that each of the two modalities involves activation of the premotor area which is also activated during action execution and action observation conditions, as well as of the supplementary motor area. Interestingly, the visual and the posterior cingulate cortices show reduced BOLD signal during both imagery conditions. Our results indicate that the networks of regions activated in kinesthetic and visual imagery of motor sequences show a substantial, while not complete overlap, and that the two forms of motor imagery lead to a differential suppression of visual areas. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. fMRI Evidence of ‘Mirror’ Responses to Geometric Shapes

    Science.gov (United States)

    Press, Clare; Catmur, Caroline; Cook, Richard; Widmann, Hannah; Heyes, Cecilia; Bird, Geoffrey

    2012-01-01

    Mirror neurons may be a genetic adaptation for social interaction [1]. Alternatively, the associative hypothesis [2], [3] proposes that the development of mirror neurons is driven by sensorimotor learning, and that, given suitable experience, mirror neurons will respond to any stimulus. This hypothesis was tested using fMRI adaptation to index populations of cells with mirror properties. After sensorimotor training, where geometric shapes were paired with hand actions, BOLD response was measured while human participants experienced runs of events in which shape observation alternated with action execution or observation. Adaptation from shapes to action execution, and critically, observation, occurred in ventral premotor cortex (PMv) and inferior parietal lobule (IPL). Adaptation from shapes to execution indicates that neuronal populations responding to the shapes had motor properties, while adaptation to observation demonstrates that these populations had mirror properties. These results indicate that sensorimotor training induced populations of cells with mirror properties in PMv and IPL to respond to the observation of arbitrary shapes. They suggest that the mirror system has not been shaped by evolution to respond in a mirror fashion to biological actions; instead, its development is mediated by stimulus-general processes of learning within a system adapted for visuomotor control. PMID:23251653

  15. Anatomy and time course of discrimination and categorization processes in vision: an fMRI study.

    Science.gov (United States)

    Pernet, C; Franceries, X; Basan, S; Cassol, E; Démonet, J F; Celsis, P

    2004-08-01

    Studies investigating the cerebral areas involved in visual processes generally oppose either different tasks or different stimulus types. This work addresses, by fMRI, the interaction between the type of task (discrimination vs. categorization) and the type of stimulus (Latin letters, well-known geometrical figures, and Korean letters). Behavioral data revealed that the two tasks did not differ in term of percentage of errors or correct responses, but a delay of 185 ms was observed for the categorization task in comparison with the discrimination task. All conditions activated a common neural network that includes both striate and extrastriate areas, especially the fusiform gyri, the precunei, the insulae, and the dorsolateral frontal cortex. In addition, interaction analysis revealed that the right insula was sensitive to both tasks and stimuli, and that stimulus type induced several significant signal variations for the categorization task in right frontal cortex, the right middle occipital gyrus, the right cuneus, and the left and right fusiform gyri, whereas for the discrimination task, significant signal variations were observed in the right occipito-parietal junction only. Finally, analyzing the latency of the BOLD signal also revealed a differential neural dynamics according to tasks but not to stimulus type. These temporal differences suggest a parallel hemisphere processing in the discrimination task vs. a cooperative interhemisphere processing in the categorization task that may reflect the observed differences in reaction time.

  16. Visioning in the brain: an fMRI study of inspirational coaching and mentoring.

    Science.gov (United States)

    Jack, Anthony I; Boyatzis, Richard E; Khawaja, Masud S; Passarelli, Angela M; Leckie, Regina L

    2013-01-01

    Effective coaching and mentoring is crucial to the success of individuals and organizations, yet relatively little is known about its neural underpinnings. Coaching and mentoring to the Positive Emotional Attractor (PEA) emphasizes compassion for the individual's hopes and dreams and has been shown to enhance a behavioral change. In contrast, coaching to the Negative Emotional Attractor (NEA), by focusing on externally defined criteria for success and the individual's weaknesses in relation to them, does not show sustained change. We used fMRI to measure BOLD responses associated with these two coaching styles. We hypothesized that PEA coaching would be associated with increased global visual processing and with engagement of the parasympathetic nervous system (PNS), while the NEA coaching would involve greater engagement of the sympathetic nervous system (SNS). Regions showing more activity in PEA conditions included the lateral occipital cortex, superior temporal cortex, medial parietal, subgenual cingulate, nucleus accumbens, and left lateral prefrontal cortex. We relate these activations to visioning, PNS activity, and positive affect. Regions showing more activity in NEA conditions included medial prefrontal regions and right lateral prefrontal cortex. We relate these activations to SNS activity, self-trait attribution and negative affect.

  17. Changes in fMRI magnitude data and phase data observed in block-design and event-related tasks.

    Science.gov (United States)

    Arja, Sunil Kumar; Feng, Zhaomei; Chen, Zikuan; Caprihan, Arvind; Kiehl, Kent A; Adali, Tülay; Calhoun, Vince D

    2010-02-15

    Functional magnetic resonance imaging (fMRI) data are acquired as a complex image pair including magnitude and phase information. The vast majority of fMRI experiments do not attempt to take advantage of the time varying phase information. The phase of the MRI signal is related to the local magnetic field changes, suggesting it may contain useful information about the source of hemodynamic activity. Analysis of phase data acquired from different fMRI experiments has shown the presence of activity in response to various stimuli. However, there have been no studies that have examined phase data in a larger group of subjects for multiple types of fMRI tasks nor have studies examined phase changes due to event-related stimuli. In this paper, we evaluate the correspondence between the magnitude and phase changes at a group level in a block-design motor tapping task and in an event-related auditory oddball task. The results for both block-design and event-related tasks indicate the presence of task-related information in the phase data with phase-only and magnitude-only approaches showing signal changes in the expected brain regions. Although there is more overall activity detected with magnitude data, the phase-only analysis also reveals activity in regions expected to be involved in the task, some of which were not significantly activated in the magnitude-only analysis, suggesting that the phase might provide some unique information. In addition, the phase can potentially increase sensitivity within regions also showing magnitude changes. Future work should focus on additional methods for combining the magnitude and phase data. Copyright 2009 Elsevier Inc. All rights reserved.

  18. A wavelet-based estimator of the degrees of freedom in denoised fMRI time series for probabilistic testing of functional connectivity and brain graphs.

    Science.gov (United States)

    Patel, Ameera X; Bullmore, Edward T

    2016-11-15

    Connectome mapping using techniques such as functional magnetic resonance imaging (fMRI) has become a focus of systems neuroscience. There remain many statistical challenges in analysis of functional connectivity and network architecture from BOLD fMRI multivariate time series. One key statistic for any time series is its (effective) degrees of freedom, df, which will generally be less than the number of time points (or nominal degrees of freedom, N). If we know the df, then probabilistic inference on other fMRI statistics, such as the correlation between two voxel or regional time series, is feasible. However, we currently lack good estimators of df in fMRI time series, especially after the degrees of freedom of the "raw" data have been modified substantially by denoising algorithms for head movement. Here, we used a wavelet-based method both to denoise fMRI data and to estimate the (effective) df of the denoised process. We show that seed voxel correlations corrected for locally variable df could be tested for false positive connectivity with better control over Type I error and greater specificity of anatomical mapping than probabilistic connectivity maps using the nominal degrees of freedom. We also show that wavelet despiked statistics can be used to estimate all pairwise correlations between a set of regional nodes, assign a P value to each edge, and then iteratively add edges to the graph in order of increasing P. These probabilistically thresholded graphs are likely more robust to regional variation in head movement effects than comparable graphs constructed by thresholding correlations. Finally, we show that time-windowed estimates of df can be used for probabilistic connectivity testing or dynamic network analysis so that apparent changes in the functional connectome are appropriately corrected for the effects of transient noise bursts. Wavelet despiking is both an algorithm for fMRI time series denoising and an estimator of the (effective) df of denoised

  19. Review: hemodynamic response to carbon monoxide

    Energy Technology Data Exchange (ETDEWEB)

    Penney, D.G.

    1988-04-01

    Historically, and at present, carbon monoxide is a major gaseous poison responsible for widespread morbidity and mortality. From threshold to maximal nonlethal levels, a variety of cardiovascular changes occur, both immediately and in the long term, whose homeostatic function it is to renormalize tissue oxygen delivery. However, notwithstanding numerous studies over the past century, the literature remains equivocal regarding the hemodynamic responses in animals and humans, although CO hypoxia is clearly different in several respects from hypoxic hypoxia. Factors complicating interpretation of experimental findings include species, CO dose level and rate, route of CO delivery, duration, level of exertion, state of consciousness, and anesthetic agent used. Augmented cardiac output usually observed with moderate COHb may be compromised in more sever poisoning for the same reasons, such that regional or global ischemia result. The hypotension usually seen in most animal studies is thought to be a primary cause of CNS damage resulting from acute CO poisoning, yet the exact mechanism(s) remains unproven in both animals and humans, as does the way in which CO produces hypotension. This review briefly summarizes the literature relevant to the short- and long-term hemodynamic responses reported in animals and humans. It concludes by presenting an overview using data from a single species in which the most complete work has been done to date.

  20. Cerebral hemodynamics and functional prognosis in hydrocephalus

    International Nuclear Information System (INIS)

    Hirai, Osamu; Nishikawa, Michio; Watanabe, Shu; Yamakawa, Hiroyasu; Kinoshita, Yoshimasa; Uno, Akira; Handa, Hajime

    1989-01-01

    The functional outcome of cerebral hemodynamics in the chronic stage of juvenile hydrocephalus was determined using single photon emission computed tomography (SPECT). Five patients including three with aqueductal stenosis, one with post-meningitic hydrocephalus, and one case with hydrocephalus having developed after repair of a huge occipital encephalocele. Early images of cerebral blood flow (CBF) were obtained 25 minutes after intravenous injection of 123-I-iodoamphetamine (IMP), and late images were scanned 3 hours later. Cerebral blood volume (CBV) was also measured using 99m Tc in three patients. Twenty cases with adult communicating hydrocephalus were also investigated from the point of view of shunt effectiveness. Although there was no remarkable change in the cerebrovascular bed in the juvenile cases, CBF of the remnant brain parenchyma was good irrespective of the degree of ventricular dilatation. There was a periventricular-related IMP uptake in each case; however, it somehow matched the ventricular span. Functional outcome one to 23 years after the initial shunt operation was good in every case, despite multiple shunt revisions. Redistribution on late images had no bearing on clinical states. In adult cases, 8 patients with effective shunting demonstrated a relatively localized periventricular low perfusion, with preoperative increased cerebrospinal fluid (CSF) pressure. On the contrary, 12 patients with no improvement with or without ventricular-reduced IMP uptake, despite low CSF pressure. The present study indicates that periventricular hemodynamics may play an important role in cerebral function compromised by hydrocephalus. (J.P.N.)

  1. Cerebral hemodynamics and functional prognosis in hydrocephalus

    Energy Technology Data Exchange (ETDEWEB)

    Hirai, Osamu; Nishikawa, Michio; Watanabe, Shu; Yamakawa, Hiroyasu; Kinoshita, Yoshimasa; Uno, Akira; Handa, Hajime (Hamamatsu Rosai Hospital, Shizuoka (Japan))

    1989-11-01

    The functional outcome of cerebral hemodynamics in the chronic stage of juvenile hydrocephalus was determined using single photon emission computed tomography (SPECT). Five patients including three with aqueductal stenosis, one with post-meningitic hydrocephalus, and one case with hydrocephalus having developed after repair of a huge occipital encephalocele. Early images of cerebral blood flow (CBF) were obtained 25 minutes after intravenous injection of 123-I-iodoamphetamine (IMP), and late images were scanned 3 hours later. Cerebral blood volume (CBV) was also measured using {sup 99m}Tc in three patients. Twenty cases with adult communicating hydrocephalus were also investigated from the point of view of shunt effectiveness. Although there was no remarkable change in the cerebrovascular bed in the juvenile cases, CBF of the remnant brain parenchyma was good irrespective of the degree of ventricular dilatation. There was a periventricular-related IMP uptake in each case; however, it somehow matched the ventricular span. Functional outcome one to 23 years after the initial shunt operation was good in every case, despite multiple shunt revisions. Redistribution on late images had no bearing on clinical states. In adult cases, 8 patients with effective shunting demonstrated a relatively localized periventricular low perfusion, with preoperative increased cerebrospinal fluid (CSF) pressure. On the contrary, 12 patients with no improvement with or without ventricular-reduced IMP uptake, despite low CSF pressure. The present study indicates that periventricular hemodynamics may play an important role in cerebral function compromised by hydrocephalus. (J.P.N.).

  2. Hemodynamic Simulations in Dialysis Access Fistulae

    Science.gov (United States)

    McGah, Patrick; Leotta, Daniel; Beach, Kirk; Riley, James; Aliseda, Alberto

    2010-11-01

    Arteriovenous fistulae are created surgically to provide adequate access for dialysis in patients with End-Stage Renal Disease. It has long been hypothesized that the hemodynamic and mechanical forces (such as wall shear stress, wall stretch, or flow- induced wall vibrations) constitute the primary external influence on the remodeling process. Given that nearly 50% of fistulae fail after one year, understanding fistulae hemodynamics is an important step toward improving patency in the clinic. We perform numerical simulations of the flow in patient-specific models of AV fistulae reconstructed from 3D ultrasound scans with physiologically-realistic boundary conditions also obtained from Doppler ultrasound. Comparison of the flow features in different geometries and configurations e.g. end-to-side vs. side-to-side, with the in vivo longitudinal outcomes will allow us to hypothesize which flow conditions are conducive to fistulae success or failure. The flow inertia and pulsatility in the simulations (mean Re 700, max Re 2000, Wo 4) give rise to complex secondary flows and coherent vortices, further complicating the spatio- temporal variability of the wall pressure and shear stresses. Even in mature fistulae, the anastomotic regions are subjected to non-physiological shear stresses (>10.12pcPa) which may potentially lead to complications.

  3. Patient-Specific Modeling of Intraventricular Hemodynamics

    Science.gov (United States)

    Vedula, Vijay; Marsden, Alison

    2017-11-01

    Heart disease is the one of the leading causes of death in the world. Apart from malfunctions in electrophysiology and myocardial mechanics, abnormal hemodynamics is a major factor attributed to heart disease across all ages. Computer simulations offer an efficient means to accurately reproduce in vivo flow conditions and also make predictions of post-operative outcomes and disease progression. We present an experimentally validated computational framework for performing patient-specific modeling of intraventricular hemodynamics. Our modeling framework employs the SimVascular open source software to build an anatomic model and employs robust image registration methods to extract ventricular motion from the image data. We then employ a stabilized finite element solver to simulate blood flow in the ventricles, solving the Navier-Stokes equations in arbitrary Lagrangian-Eulerian (ALE) coordinates by prescribing the wall motion extracted during registration. We model the fluid-structure interaction effects of the cardiac valves using an immersed boundary method and discuss the potential application of this methodology in single ventricle physiology and trans-catheter aortic valve replacement (TAVR). This research is supported in part by the Stanford Child Health Research Institute and the Stanford NIH-NCATS-CTSA through Grant UL1 TR001085 and partly through NIH NHLBI R01 Grant 5R01HL129727-02.

  4. The Effect of Neuraxial Anesthesia on Maternal Cerebral Hemodynamics

    NARCIS (Netherlands)

    Postma, Ineke R.; van Veen, Teelkien R.; Mears, Scott L.; Zeeman, Gerda G.; Haeri, Sina; Belfort, Michael A.

    2014-01-01

    Objective Neuraxial anesthesia is known to reduce sympathetic tone and mean arterial pressure. Effects on cerebral hemodynamics in pregnancy are not well known. We hypothesize that cerebral hemodynamic parameters will change with respect to baseline following regional analgesia/anesthesia. Study

  5. Advanced Hemodynamic Management in Patients with Septic Shock.

    Science.gov (United States)

    Saugel, Bernd; Huber, Wolfgang; Nierhaus, Axel; Kluge, Stefan; Reuter, Daniel A; Wagner, Julia Y

    2016-01-01

    In patients with sepsis and septic shock, the hemodynamic management in both early and later phases of these "organ dysfunction syndromes" is a key therapeutic component. It needs, however, to be differentiated between "early goal-directed therapy" (EGDT) as proposed for the first 6 hours of emergency department treatment by Rivers et al. in 2001 and "hemodynamic management" using advanced hemodynamic monitoring in the intensive care unit (ICU). Recent large trials demonstrated that nowadays protocolized EGDT does not seem to be superior to "usual care" in terms of a reduction in mortality in emergency department patients with early identified septic shock who promptly receive antibiotic therapy and fluid resuscitation. "Hemodynamic management" comprises (a) making the diagnosis of septic shock as one differential diagnosis of circulatory shock, (b) assessing the hemodynamic status including the identification of therapeutic conflicts, and (c) guiding therapeutic interventions. We propose two algorithms for hemodynamic management using transpulmonary thermodilution-derived variables aiming to optimize the cardiocirculatory and pulmonary status in adult ICU patients with septic shock. The complexity and heterogeneity of patients with septic shock implies that individualized approaches for hemodynamic management are mandatory. Defining individual hemodynamic target values for patients with septic shock in different phases of the disease must be the focus of future studies.

  6. Hemodynamic effects of sevoflurane versus propofol anesthesia for ...

    African Journals Online (AJOL)

    Adele

    cryotherapy, radiofrequency does not induce hemodynamic instability. In an animal study, hepatic artery blood flow and peripheral blood pressure did not change significantly during peritoneal insufflation for radiofrequency ablation surgery.8. We did not intend to investigate the effects of LRFA itself on the hemodynamics.

  7. New approach to intracardiac hemodynamic measurements in small animals

    DEFF Research Database (Denmark)

    Eskesen, Kristian; Olsen, Niels T; Dimaano, Veronica L

    2012-01-01

    Invasive measurements of intracardiac hemodynamics in animal models have allowed important advances in the understanding of cardiac disease. Currently they are performed either through a carotid arteriotomy or via a thoracotomy and apical insertion. Both of these techniques have disadvantages...... and are not conducive to repeated measurements. Therefore, the purpose of this study was to develop a new technique for measuring intracardiac hemodynamics....

  8. Invasive hemodynamic characterization of heart failure with preserved ejection fraction

    DEFF Research Database (Denmark)

    Andersen, Mads Jønsson; Borlaug, Barry A

    2014-01-01

    Recent hemodynamic studies have advanced our understanding of heart failure with preserved ejection fraction (HFpEF). Despite improved pathophysiologic insight, clinical trials have failed to identify an effective treatment for HFpEF. Invasive hemodynamic assessment can diagnose or exclude HFp...... of pathophysiological differences and inform the design and entry criteria for future trials....

  9. Hemodynamic Stability during Induction of Anesthesia in Elderly Patients: Propofol + Ketamine versus Propofol + Etomidate

    Directory of Open Access Journals (Sweden)

    Hamzeh Hosseinzadeh

    2013-07-01

    Conclusion: Both methods of induction -ketamine + propofol and etomidate + propofol- are effective in maintaining hemodynamic stability and preventing hemodynamic changes due to propofol administration.

  10. Imaging speech production using fMRI.

    Science.gov (United States)

    Gracco, Vincent L; Tremblay, Pascale; Pike, Bruce

    2005-05-15

    Human speech is a well-learned, sensorimotor, and ecological behavior ideal for the study of neural processes and brain-behavior relations. With the advent of modern neuroimaging techniques such as positron emission tomography (PET) and functional magnetic resonance imaging (fMRI), the potential for investigating neural mechanisms of speech motor control, speech motor disorders, and speech motor development has increased. However, a practical issue has limited the application of fMRI to issues in spoken language production and other related behaviors (singing, swallowing). Producing these behaviors during volume acquisition introduces motion-induced signal changes that confound the activation signals of interest. A number of approaches, ranging from signal processing to using silent or covert speech, have attempted to remove or prevent the effects of motion-induced artefact. However, these approaches are flawed for a variety of reasons. An alternative approach, that has only recently been applied to study single-word production, uses pauses in volume acquisition during the production of natural speech motion. Here we present some representative data illustrating the problems associated with motion artefacts and some qualitative results acquired from subjects producing short sentences and orofacial nonspeech movements in the scanner. Using pauses or silent intervals in volume acquisition and block designs, results from individual subjects result in robust activation without motion-induced signal artefact. This approach is an efficient method for studying the neural basis of spoken language production and the effects of speech and language disorders using fMRI.

  11. Behavior, neuropsychology and fMRI.

    Science.gov (United States)

    Bennett, Maxwell R; Hatton, Sean; Hermens, Daniel F; Lagopoulos, Jim

    Cognitive neuroscientists in the late 20th century began the task of identifying the part(s) of the brain concerned with normal behavior as manifest in the psychological capacities as affective powers, reasoning, behaving purposively and the pursuit of goals, following introduction of the 'functional magnetic resonance imaging' (fMRI) method for identifying brain activity. For this research program to be successful two questions require satisfactory answers. First, as the fMRI method can currently only be used on stationary subjects, to what extent can neuropsychological tests applicable to such stationary subjects be correlated with normal behavior. Second, to what extent can correlations between the various neuropsychological tests on the one hand, and sites of brain activity determined with fMRI on the other, be regarded as established. The extent to which these questions have yet received satisfactory answers is reviewed, and suggestions made both for improving correlations of neuropsychological tests with behavior as well as with the results of fMRI-based observations. Copyright © 2016. Published by Elsevier Ltd.

  12. The Effect of Task-Irrelevant Fearful-Face Distractor on Working Memory Processing in Mild Cognitive Impairment versus Healthy Controls: An Exploratory fMRI Study in Female Participants

    Directory of Open Access Journals (Sweden)

    Amer M. Burhan

    2016-01-01

    Full Text Available In mild cognitive impairment (MCI, a risk state for Alzheimer’s disease, patients have objective cognitive deficits with relatively preserved functioning. fMRI studies have identified anomalies during working memory (WM processing in individuals with MCI. The effect of task-irrelevant emotional face distractor on WM processing in MCI remains unclear. We aim to explore the impact of fearful-face task-irrelevant distractor on WM processing in MCI using fMRI. Hypothesis. Compared to healthy controls (HC, MCI patients will show significantly higher BOLD signal in a priori identified regions of interest (ROIs during a WM task with a task-irrelevant emotional face distractor. Methods. 9 right-handed female participants with MCI and 12 matched HC performed a WM task with standardized task-irrelevant fearful versus neutral face distractors randomized and counterbalanced across WM trials. MRI images were acquired during the WM task and BOLD signal was analyzed using statistical parametric mapping (SPM to identify signal patterns during the task response phase. Results. Task-irrelevant fearful-face distractor resulted in higher activation in the amygdala, anterior cingulate, and frontal areas, in MCI participants compared to HC. Conclusions. This exploratory study suggests altered WM processing as a result of fearful-face distractor in MCI.

  13. Functional Laterality of Task-Evoked Activation in Sensorimotor Cortex of Preterm Infants: An Optimized 3 T fMRI Study Employing a Customized Neonatal Head Coil.

    Directory of Open Access Journals (Sweden)

    Lukas Scheef

    Full Text Available Functional magnetic resonance imaging (fMRI in neonates has been introduced as a non-invasive method for studying sensorimotor processing in the developing brain. However, previous neonatal studies have delivered conflicting results regarding localization, lateralization, and directionality of blood oxygenation level dependent (BOLD responses in sensorimotor cortex (SMC. Amongst the confounding factors in interpreting neonatal fMRI studies include the use of standard adult MR-coils providing insufficient signal to noise, and liberal statistical thresholds, compromising clinical interpretation at the single subject level.Here, we employed a custom-designed neonatal MR-coil adapted and optimized to the head size of a newborn in order to improve robustness, reliability and validity of neonatal sensorimotor fMRI. Thirteen preterm infants with a median gestational age of 26 weeks were scanned at term-corrected age using a prototype 8-channel neonatal head coil at 3T (Achieva, Philips, Best, NL. Sensorimotor stimulation was elicited by passive extension/flexion of the elbow at 1 Hz in a block design. Analysis of temporal signal to noise ratio (tSNR was performed on the whole brain and the SMC, and was compared to data acquired with an 'adult' 8 channel head coil published previously. Task-evoked activation was determined by single-subject SPM8 analyses, thresholded at p < 0.05, whole-brain FWE-corrected.Using a custom-designed neonatal MR-coil, we found significant positive BOLD responses in contralateral SMC after unilateral passive sensorimotor stimulation in all neonates (analyses restricted to artifact-free data sets = 8/13. Improved imaging characteristics of the neonatal MR-coil were evidenced by additional phantom and in vivo tSNR measurements: phantom studies revealed a 240% global increase in tSNR; in vivo studies revealed a 73% global and a 55% local (SMC increase in tSNR, as compared to the 'adult' MR-coil.Our findings strengthen the

  14. Effect of confounding variables on hemodynamic response function estimation using averaging and deconvolution analysis: An event-related NIRS study.

    Science.gov (United States)

    Aarabi, Ardalan; Osharina, Victoria; Wallois, Fabrice

    2017-07-15

    Slow and rapid event-related designs are used in fMRI and functional near-infrared spectroscopy (fNIRS) experiments to temporally characterize the brain hemodynamic response to discrete events. Conventional averaging (CA) and the deconvolution method (DM) are the two techniques commonly used to estimate the Hemodynamic Response Function (HRF) profile in event-related designs. In this study, we conducted a series of simulations using synthetic and real NIRS data to examine the effect of the main confounding factors, including event sequence timing parameters, different types of noise, signal-to-noise ratio (SNR), temporal autocorrelation and temporal filtering on the performance of these techniques in slow and rapid event-related designs. We also compared systematic errors in the estimates of the fitted HRF amplitude, latency and duration for both techniques. We further compared the performance of deconvolution methods based on Finite Impulse Response (FIR) basis functions and gamma basis sets. Our results demonstrate that DM was much less sensitive to confounding factors than CA. Event timing was the main parameter largely affecting the accuracy of CA. In slow event-related designs, deconvolution methods provided similar results to those obtained by CA. In rapid event-related designs, our results showed that DM outperformed CA for all SNR, especially above -5 dB regardless of the event sequence timing and the dynamics of background NIRS activity. Our results also show that periodic low-frequency systemic hemodynamic fluctuations as well as phase-locked noise can markedly obscure hemodynamic evoked responses. Temporal autocorrelation also affected the performance of both techniques by inducing distortions in the time profile of the estimated hemodynamic response with inflated t-statistics, especially at low SNRs. We also found that high-pass temporal filtering could substantially affect the performance of both techniques by removing the low-frequency components of

  15. Inter-subject correlation of brain hemodynamic responses during watching a movie: localization in space and frequency

    Directory of Open Access Journals (Sweden)

    Jukka-Pekka Kauppi

    2010-03-01

    Full Text Available Cinema is a promising naturalistic stimulus that enables, for instance, elicitation of robust emotions during functional magnetic resonance imaging (fMRI. Inter-subject correlation (ISC has been used as a model-free analysis method to map the highly complex hemodynamic responses that are evoked during watching a movie. Here, we extended the ISC analysis to frequency domain using wavelet analysis combined with non-parametric permutation methods for making voxel-wise statistical inferences about frequency-band specific ISC. We applied these novel analysis methods to a dataset collected in our previous study where 12 subjects watched an emotionally engaging movie “Crash” during fMRI scanning. Our results suggest that several regions within the frontal and temporal lobes show ISC predominantly at low frequency bands, whereas visual cortical areas exhibit ISC also at higher frequencies. It is possible that these findings relate to recent observations of a cortical hierarchy of temporal receptive windows, or that the types of events processed in temporal and prefrontal cortical areas (e.g., social interactions occur over longer time periods than the stimulus features processed in the visual areas. Software tools to perform frequency-specific ISC analysis, together with a visualization application, are available as open source Matlab code.

  16. How motor, cognitive and musical expertise shapes the brain: Focus on fMRI and EEG resting-state functional connectivity

    DEFF Research Database (Denmark)

    Cantou, Pauline; Platel, Hervé; Desgranges, Béatrice

    2017-01-01

    Brain activity and structure are shaped by life experiences. This plasticity has often been demonstrated with different types of expertise by using functional magnetic resonance imaging (fMRI) and electroencephalography (EEG). Experts showed domain-specific functional neural changes during......-dependent (BOLD) and spontaneous neural activity fluctuations at rest. Since these correlations are thought to reflect a prior history co-activation of brain regions, we propose reviewing studies that focused on the effects of expertise in the motor, cognitive and musical domains on brain plasticity at rest......, to determine whether there is a domain-specific neural signature of expertise. After highlighting expertise-related changes within resting-state networks for each domain, we discuss their specificity to the trained activity and the methodological considerations concerning different conditions and analyses used...

  17. AIRMEN AS BOLD RISK TAKERS REDEFINING RISK TO ACHIEVE OPERATIONAL AGILITY

    Science.gov (United States)

    2017-04-15

    AIR WAR COLLEGE AIR UNIVERSITY AIRMEN AS BOLD RISK TAKERS REDEFINING RISK TO ACHIEVE OPERATIONAL AGILITY by Jonathan E. Zall...academic research paper are those of the author and do not reflect the official policy or position of the US government , the Department of Defense...or Air University. In accordance with Air Force Instruction 51-303, it is not copyrighted, but is the property of the United States government

  18. Detection of Acute Tubular Necrosis Using Blood Oxygenation Level-Dependent (BOLD MRI

    Directory of Open Access Journals (Sweden)

    Frederic Bauer

    2017-12-01

    Full Text Available Background/Aims: To date, there is no imaging technique to assess tubular function in vivo. Blood oxygen level-dependent magnetic resonance imaging (BOLD MRI measures tissue oxygenation based on the transverse relaxation rate (R2*. The present study investigates whether BOLD MRI can assess tubular function using a tubule-specific pharmacological maneuver. Methods: Cross sectional study with 28 participants including 9 subjects with ATN-induced acute kidney injury (AKI, 9 healthy controls, and 10 subjects with nephron sparing tumor resection (NSS with clamping of the renal artery serving as a model of ischemia/reperfusion (I/R-induced subclinical ATN (median clamping time 15 min, no significant decrease of eGFR, p=0.14. BOLD MRI was performed before and 5, 7, and 10 min after intravenous administration of 40 mg furosemide. Results: Urinary neutrophil gelatinase-associated lipocalin was significantly higher in ATN-induced AKI and NSS subjects than in healthy controls (p=0.03 and p=0.01, respectively. Before administration of furosemide, absolute medullary R2*, cortical R2*, and medullary/cortical R2* ratio did not significantly differ between ATN-induced AKI vs. healthy controls and between NSS-I/R vs. contralateral healthy kidneys (p>0.05 each. Furosemide led to a significant decrease in the medullary and cortical R2* of healthy subjects and NSS contralateral kidneys (p<0.05 each, whereas there was no significant change of R2* in ATN-induced AKI and the NSS-I/R kidneys (p>0.05 each. Conclusion: BOLD-MRI is able to detect even mild tubular injury but necessitates a tubule-specific pharmacological maneuver, e.g. blocking the Na+-K+-2Cl- transporter by furosemide.

  19. Hemodynamic characteristics of early stage hepatocellular carcinoma

    International Nuclear Information System (INIS)

    Kudo, Masatoshi; Tomita, Shusuke; Tochio, Hitoshi

    1992-01-01

    Hemodynamic characteristics were studied by using in vivo vascular imaging techniques in 17 resected early stage hepatocellular carcinoma (e-HCC) by comparing them with 49 resected advanced HCCs (ad-HCC) less than 3 cm in diameter. In this study, e-HCC was defined as the nodule being uniformly composed of well-differentiated HCC or adenomatous hyperplastic nodule containing well-differentiated HCC foci within the nodule. In vivo vascular imaging techniques are as follows; US angiography with intraarterial CO 2 microbubbles were performed to assess the tumor arterial vascularity, and CT during arterial portography (CTAP) was performed to assess the portal perfusion within the nodule. Of 17 e-HCC nodules 5 were hypervascular, 5 were isovascular, 4 were hypovascular, and 3 were vascular spot in hypovascular pattern in contrast to 49 ad-HCC nodules, 43 of which were hypervascular and 6 were isovascular. Of 14 e-HCCs, 9 nodules showed perfusion defect and 5 did not on CTAP, whereas all 37 ad-HCCs on which CTAP was performed, showed perfusion defect. Forty-one percent (7/17) of e-HCC showed fatty metamorphosis in contrast to 8% (4/49) of ad-HCC. In conclusion, hemodynamic characteristics of e-HCC are summarized as follows. (1) Arterial tumor neovascularization is relatively low. (2) Portal perfusion is present in some of e-HCC cases. (3) Hypoperfusion state both from arterial and portal supply is present in some of e-HCC cases. (4) Vascular spot in hypovascular pattern is characteristic arterial pattern in AH containing HCC foci. (5) Fatty metamorphosis may be related with hypoperfusion state of the nodule in e-HCC. (author)

  20. Left-right difference in fetal liver oxygenation during hypoxia estimated by BOLD MRI in a fetal sheep model.

    Science.gov (United States)

    Sørensen, A; Holm, D; Pedersen, M; Tietze, A; Stausbøl-Grøn, B; Duus, L; Uldbjerg, N

    2011-12-01

    The purpose of this study was to measure differences in oxygenation between the left and right sides of the fetal liver during varying oxygenation levels. Eight ewes carrying singleton fetuses at gestational age 125 days (term, 145 days) were included in the study. Under anesthesia the ewes were ventilated with gas containing different levels of oxygen, thereby subjecting the fetuses to hyperoxia (mean ± SD maternal arterial partial pressure of oxygen (pO2), 23.2 ± 8.2 kPa) and hypoxia (mean maternal arterial pO2, 7.1 ± 0.5 kPa). Changes in oxygenation within the fetal liver were assessed by blood oxygen level-dependent (BOLD) magnetic resonance imaging (MRI). During hyperoxia there was no difference between the BOLD signal in the left and right sides of the fetal liver; mean change in BOLDBOLD)(hyperox), -0.9 ± 3.7%. During hypoxia, however, the decrease in the BOLD signal was more pronounced in the right side as compared with the left side, thereby creating a significant increase in the left-right difference in the BOLD signal; mean ΔBOLD(hypox), 5.2 ± 2.2% (P = 0.002, paired t-test). The left-right difference was directly proportional to the degree of hypoxia (R2 = 0.86, P = 0.007). To our knowledge, this is the first study demonstrating differences in oxygenation between the left and right sides of the fetal liver during hypoxia, a difference that can be explained by increased ductus venosus shunting. Thus, the BOLD MRI technique is a promising non-invasive tool that might be useful for the future monitoring of the human fetus. Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.

  1. Socially bold personality in the real communication and Internet communication: the analysis of representations of people of the different age

    Directory of Open Access Journals (Sweden)

    Pogodina A. V.

    2017-03-01

    Full Text Available The article is concerned with the results of the study, subject of which is the submis- sion of the respondents of the different age groups about the social and bold personality. Required property of the respondents was the presence in the Internet environment and participation in various social networks. They assessed social and bold personal- ity in such contexts of communication, as real communication and Internet communication. Analyses were undertaken to determine the structural and content features of emotional and semantic representations of the phenomenon of the social and bold personality, depending on the context of communication, but also the detection of age-sensitive representations of the young respondents (19—35 years, middle-aged respondents (36-55 years and older respondents (from 56 to 70 years. The concept of the “social and bold personality in real communion” is shown to have a high semantic relevance, strongly marked positive emotional coloration and a similar factor structure for respondents of all age groups. The concept of the “social and bold personality in online communication” with a high semantic significance in the perception of the young respondents moves into a zone of moderate and semantic importance in representations of the middle-aged and older respondents. In representations of the respondents of all age groups, the attractiveness of the "social and bold personality in Internet communication" is less than in comparison with the "social and bold personality in the real communication". The age-specific of the social representations about social and bold personality in the real and virtual communication has been analysed in detail.

  2. Adult wheel access interaction with activity and boldness personality in Siberian dwarf hamsters (Phodopus sungorus).

    Science.gov (United States)

    Kanda, L Leann; Abdulhay, Amir; Erickson, Caitlin

    2017-05-01

    Individual animal personalities interact with environmental conditions to generate differences in behavior, a phenomenon of growing interest for understanding the effects of environmental enrichment on captive animals. Wheels are common environmental enrichment for laboratory rodents, but studies conflict on how this influences behavior, and interaction of wheels with individual personalities has rarely been examined. We examined whether wheel access altered personality profiles in adult Siberian dwarf hamsters. We assayed animals in a tunnel maze twice for baseline personality, then again at two and at seven weeks after the experimental group was provisioned with wheels in their home cages. Linear mixed model selection was used to assess changes in behavior over time and across environmental gradient of wheel exposure. While animals showed consistent inter-individual differences in activity, activity personality did not change upon exposure to a wheel. Boldness also varies among individuals, and there is evidence for female boldness scores converging after wheel exposure, that is, opposite shifts in behavior by high and low boldness individuals, although sample size is too small for the mixed model results to be robust. In general, Siberian dwarf hamsters appear to show low behavioral plasticity, particularly in general activity, in response to running wheels. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Present and future costs of COPD in Iceland and Norway: results from the BOLD study

    Science.gov (United States)

    Nielsen, R.; Johannessen, A.; Benediktsdottir, B.; Gislason, T.; Buist, A.S.; Gulsvik, A.; Sullivan, S.D.; Lee, T.A.

    2011-01-01

    The Burden of Obstructive Lung Disease (BOLD) initiative provides standardised estimates of the burden of chronic obstructive pulmonary disease (COPD) worldwide. We estimate the current and future economic burden of COPD in Reykjavik, Iceland and Bergen, Norway using data from the BOLD initiative. Data on utilisation of healthcare resources were gathered from the BOLD survey, existing literature and unit costs from national sources. Economic data were applied to a Markov model using transition probabilities derived from Framingham data. Sensitivity analyses were conducted varying unit costs, utilisation and prevalence of disease. The cost of COPD was €478 per patient per yr in Iceland and €284 per patient per yr in Norway. The estimated cumulative costs of COPD for the population aged ≥40 yrs, were €130 million and €1,539 million for the following 10 yrs in Iceland and Norway, respectively. Costs of COPD accounted for 1.2 and 0.7% of healthcare budgets in Iceland and Norway, respectively. Sensitivity analyses showed estimates were most sensitive to changes in exacerbation frequency. COPD has a significant economic burden in both Iceland and Norway and will grow in the future. Interventions aimed at avoiding exacerbations will have the most impact on costs of COPD over the next 20 yrs. PMID:19357148

  4. Identifying Childhood Characteristics that Underlie Pre-Morbid Risk for Substance Use Disorders: Socialization and Boldness

    Science.gov (United States)

    Hicks, Brian M.; Iacono, William G.; McGue, Matt

    2013-01-01

    Utilizing a longitudinal twin study (N = 2510), we identified the child characteristics present prior to initiation of substance use that best predicted later substance use disorders. Two independent traits accounted for the majority of pre-morbid risk: socialization (conformity to rules and conventional values) and boldness (sociability and social assurance, stress resilience, and thrill seeking). Low socialization was associated with disruptive behavior disorders, parental externalizing disorders, and environmental adversity, and exhibited moderate genetic (.45) and shared environmental influences (.30). Boldness was highly heritable (.71) and associated with less internalizing distress and environmental adversity. Together, these traits exhibited robust associations with adolescent and young adult substance use disorders (R = .48 and .50, respectively), and incremental prediction over disruptive behavior disorders, parental externalizing disorders, and environmental adversity. Results were replicated in an independent sample. Socialization and boldness offer a novel conceptualization of underlying risk for substance use disorders that has the potential to improve prediction and theory with implications for basic research, prevention, and intervention. PMID:24280373

  5. Ionizing radiation occupational exposure in the hemodynamics services

    International Nuclear Information System (INIS)

    Gronchi, Claudia Carla

    2004-01-01

    The purpose of this research is to study the ionizing radiation occupational exposure in the hemodynamic services of two large scale hospitals (Hospital A and Hospital B) of the Sao Paulo city. The research looked into annual doses that 279 professionals of the hemodynamic services were exposed to between 1991 and 2002. The data analyzed was collected from the database of the Instituto de Pesquisas Energeticas e Nucleares (IPEN) for Hospital A, and from the Radiological Protection Department of Hospital B. Besides this, measures of hands and crystalline lens equivalent doses were performed during hemodynamic procedures of the physicians, assistant physicians and nursing assistants with TL dosimeters (CaSO 4 :Dy + Teflon R) produced at IPEN. The safety procedures adopted by the hospitals were verified with the aid of a specific questionnaire for the hemodynamic services. Finally, a profile of the professionals that work in cardiac catheterism laboratories of the hemodynamic services was delineated, considering the variables of individual monitoring time, age and sex. This study allowed for observation of the behavior of the professionals' annual doses of these hemodynamic services in relation to the Comissao Nacional de Energia Nuclear and the Secretaria de Vigilancia Sanitaria limits. It showed that the annual doses of the same specialized occupations would vary from one hospital to another. It further showed the need of individual monitoring of the physicians' unprotected body parts (hands and crystalline lens) during the hemodynamic procedures. (author)

  6. Correlations of noninvasive BOLD and TOLD MRI with pO2 and relevance to tumor radiation response.

    Science.gov (United States)

    Hallac, Rami R; Zhou, Heling; Pidikiti, Rajesh; Song, Kwang; Stojadinovic, Strahinja; Zhao, Dawen; Solberg, Timothy; Peschke, Peter; Mason, Ralph P

    2014-05-01

    To examine the potential use of blood oxygenation level dependent (BOLD) and tissue oxygenation level dependent (TOLD) contrast MRI to assess tumor oxygenation and predict radiation response. BOLD and TOLD MRI were performed on Dunning R3327-AT1 rat prostate tumors during hyperoxic gas breathing challenge at 4.7 T. Animals were divided into two groups. In Group 1 (n = 9), subsequent (19) F MRI based on spin lattice relaxation of hexafluorobenzene reporter molecule provided quantitative oximetry for comparison. For Group 2 rats (n = 13) growth delay following a single dose of 30 Gy was compared with preirradiation BOLD and TOLD assessments. Oxygen (100%O2 ) and carbogen (95%O2 /5%CO2 ) challenge elicited similar BOLD, TOLD and pO2 responses. Strong correlations were observed between BOLD or R2* response and quantitative (19) F pO2 measurements. TOLD response showed a general trend with weaker correlation. Irradiation caused a significant tumor growth delay and tumors with larger changes in TOLD and R1 values upon oxygen breathing exhibited significantly increased tumor growth delay. These results provide further insight into the relationships between oxygen sensitive (BOLD/TOLD) MRI and tumor pO2 . Moreover, a larger increase in R1 response to hyperoxic gas challenge coincided with greater tumor growth delay following irradiation. Copyright © 2013 Wiley Periodicals, Inc.

  7. Sub-Millimeter T2 Weighted fMRI at 7 T: Comparison of 3D-GRASE and 2D SE-EPI

    Directory of Open Access Journals (Sweden)

    Valentin G. Kemper

    2015-05-01

    Full Text Available Functional magnetic resonance imaging (fMRI allows studying human brain function non-invasively up to the spatial resolution of cortical columns and layers. Most fMRI acquisitions rely on the blood oxygenation level dependent (BOLD contrast employing T2* weighted 2D multi-slice echo-planar imaging (EPI. At ultra-high magnetic field (i.e. 7 T and above, it has been shown experimentally and by simulation, that T2 weighted acquisitions yield a signal that is spatially more specific to the site of neuronal activity at the cost of functional sensitivity. This study compared two T2 weighted imaging sequences, inner-volume 3D Gradient-and-Spin-Echo (3D-GRASE and 2D Spin-Echo EPI (SE-EPI, with evaluation of their imaging point-spread function, functional specificity, and functional sensitivity at sub-millimeter resolution. Simulations and measurements of the imaging point-spread function revealed that the strongest anisotropic blurring in 3D-GRASE (along the second phase-encoding direction was about 60 % higher than the strongest anisotropic blurring in 2D SE-EPI (along the phase-encoding direction In a visual paradigm, the BOLD sensitivity of 3D-GRASE was found to be superior due to its higher temporal signal-to-noise ratio. High resolution cortical depth profiles suggested that the contrast mechanisms are similar between the two sequences, however, 2D SE-EPI had a higher surface bias owing to the higher T2* contribution of the longer in-plane EPI echo-train for full field of view compared to the reduced field of view of zoomed 3D-GRASE.

  8. Mapping cell-specific functional connections in the mouse brain using ChR2-evoked hemodynamics (Conference Presentation)

    Science.gov (United States)

    Bauer, Adam Q.; Kraft, Andrew; Baxter, Grant A.; Bruchas, Michael; Lee, Jin-Moo; Culver, Joseph P.

    2017-02-01

    Functional magnetic resonance imaging (fMRI) has transformed our understanding of the brain's functional organization. However, mapping subunits of a functional network using hemoglobin alone presents several disadvantages. Evoked and spontaneous hemodynamic fluctuations reflect ensemble activity from several populations of neurons making it difficult to discern excitatory vs inhibitory network activity. Still, blood-based methods of brain mapping remain powerful because hemoglobin provides endogenous contrast in all mammalian brains. To add greater specificity to hemoglobin assays, we integrated optical intrinsic signal(OIS) imaging with optogenetic stimulation to create an Opto-OIS mapping tool that combines the cell-specificity of optogenetics with label-free, hemoglobin imaging. Before mapping, titrated photostimuli determined which stimulus parameters elicited linear hemodynamic responses in the cortex. Optimized stimuli were then scanned over the left hemisphere to create a set of optogenetically-defined effective connectivity (Opto-EC) maps. For many sites investigated, Opto-EC maps exhibited higher spatial specificity than those determined using spontaneous hemodynamic fluctuations. For example, resting-state functional connectivity (RS-FC) patterns exhibited widespread ipsilateral connectivity while Opto-EC maps contained distinct short- and long-range constellations of ipsilateral connectivity. Further, RS-FC maps were usually symmetric about midline while Opto-EC maps displayed more heterogeneous contralateral homotopic connectivity. Both Opto-EC and RS-FC patterns were compared to mouse connectivity data from the Allen Institute. Unlike RS-FC maps, Thy1-based maps collected in awake, behaving mice closely recapitulated the connectivity structure derived using ex vivo anatomical tracer methods. Opto-OIS mapping could be a powerful tool for understanding cellular and molecular contributions to network dynamics and processing in the mouse brain.

  9. New coil positioning method for interleaved transcranial magnetic stimulation (TMS)/functional MRI (fMRI) and its validation in a motor cortex study.

    Science.gov (United States)

    Moisa, Marius; Pohmann, Rolf; Ewald, Lars; Thielscher, Axel

    2009-01-01

    To develop and test a novel method for coil placement in interleaved transcranial magnetic stimulation (TMS)/functional MRI (fMRI) studies. Initially, a desired TMS coil position at the subject's head is recorded using a neuronavigation system. Subsequently, a custom-made holding device is used for coil placement inside the MR scanner. The parameters of the device corresponding to the prerecorded position are automatically determined from a fast structural image acquired directly before the experiment. The spatial accuracy of our method was verified on a phantom. Finally, in a study on five subjects, the coil was placed above the cortical representation of a hand muscle in M1 and the blood oxygenation level-dependent (BOLD) responses to short repetitive TMS (rTMS) trains were assessed using echo-planar imaging (EPI) recordings. The spatial accuracy of our method is in the range of 2.9 +/- 1.3 (SD) mm. Motor cortex stimulation resulted in robust BOLD activations in motor- and auditory related brain areas, with the activation in M1 being localized in the hand knob. We present a user-friendly method for TMS coil positioning in the MR scanner that exhibits good spatial accuracy and speeds up the setup of the experiment. The motor-cortex study proves the viability of the approach and validates our interleaved TMS/fMRI setup.

  10. fMRI Adaptation between Action Observation and Action Execution Reveals Cortical Areas with Mirror Neuron Properties in Human BA 44/45.

    Science.gov (United States)

    de la Rosa, Stephan; Schillinger, Frieder L; Bülthoff, Heinrich H; Schultz, Johannes; Uludag, Kamil

    2016-01-01

    Mirror neurons (MNs) are considered to be the supporting neural mechanism for action understanding. MNs have been identified in monkey's area F5. The identification of MNs in the human homolog of monkeys' area F5 Broadmann Area 44/45 (BA 44/45) has been proven methodologically difficult. Cross-modal functional MRI (fMRI) adaptation studies supporting the existence of MNs restricted their analysis to a priori candidate regions, whereas studies that failed to find evidence used non-object-directed (NDA) actions. We tackled these limitations by using object-directed actions (ODAs) differing only in terms of their object directedness in combination with a cross-modal adaptation paradigm and a whole-brain analysis. Additionally, we tested voxels' blood oxygenation level-dependent (BOLD) response patterns for several properties previously reported as typical MN response properties. Our results revealed 52 voxels in left inferior frontal gyrus (IFG; particularly BA 44/45), which respond to both motor and visual stimulation and exhibit cross-modal adaptation between the execution and observation of the same action. These results demonstrate that part of human IFG, specifically BA 44/45, has BOLD response characteristics very similar to monkey's area F5.

  11. Permanent education that approaches radiation protection in hemodynamic service

    International Nuclear Information System (INIS)

    Flor, Rita de Cassia; Anjos, Djeniffer Valdirene dos

    2011-01-01

    In the hemodynamic services that apply ionizing radiation yet exist the necessity of capacitation of workers for actuation in those areas. So, this qualitative study performed in a hemodynamic service at Sao Jose, Santa Catarina, Brazil, had the objective to analyse how are developed the permanent education programs and the real necessity of workers. The results have shown that the workers are longing for their qualification and formation, as generally they are admitted with not any qualification for those services. So, the workers that realize the on duty hemodynamic service praxis must do it in a conscious manner and the E P is a way for to adopt good practice in radiological protection

  12. Weed or wheel! FMRI, behavioural, and toxicological investigations of how cannabis smoking affects skills necessary for driving.

    Science.gov (United States)

    Battistella, Giovanni; Fornari, Eleonora; Thomas, Aurélien; Mall, Jean-Frédéric; Chtioui, Haithem; Appenzeller, Monique; Annoni, Jean-Marie; Favrat, Bernard; Maeder, Philippe; Giroud, Christian

    2013-01-01

    Marijuana is the most widely used illicit drug, however its effects on cognitive functions underlying safe driving remain mostly unexplored. Our goal was to evaluate the impact of cannabis on the driving ability of occasional smokers, by investigating changes in the brain network involved in a tracking task. The subject characteristics, the percentage of Δ(9)-Tetrahydrocannabinol in the joint, and the inhaled dose were in accordance with real-life conditions. Thirty-one male volunteers were enrolled in this study that includes clinical and toxicological aspects together with functional magnetic resonance imaging of the brain and measurements of psychomotor skills. The fMRI paradigm was based on a visuo-motor tracking task, alternating active tracking blocks with passive tracking viewing and rest condition. We show that cannabis smoking, even at low Δ(9)-Tetrahydrocannabinol blood concentrations, decreases psychomotor skills and alters the activity of the brain networks involved in cognition. The relative decrease of Blood Oxygen Level Dependent response (BOLD) after cannabis smoking in the anterior insula, dorsomedial thalamus, and striatum compared to placebo smoking suggests an alteration of the network involved in saliency detection. In addition, the decrease of BOLD response in the right superior parietal cortex and in the dorsolateral prefrontal cortex indicates the involvement of the Control Executive network known to operate once the saliencies are identified. Furthermore, cannabis increases activity in the rostral anterior cingulate cortex and ventromedial prefrontal cortices, suggesting an increase in self-oriented mental activity. Subjects are more attracted by intrapersonal stimuli ("self") and fail to attend to task performance, leading to an insufficient allocation of task-oriented resources and to sub-optimal performance. These effects correlate with the subjective feeling of confusion rather than with the blood level of Δ(9)-Tetrahydrocannabinol

  13. Weed or Wheel! fMRI, Behavioural, and Toxicological Investigations of How Cannabis Smoking Affects Skills Necessary for Driving

    Science.gov (United States)

    Thomas, Aurélien; Mall, Jean-Frédéric; Chtioui, Haithem; Appenzeller, Monique; Annoni, Jean-Marie; Favrat, Bernard

    2013-01-01

    Marijuana is the most widely used illicit drug, however its effects on cognitive functions underling safe driving remain mostly unexplored. Our goal was to evaluate the impact of cannabis on the driving ability of occasional smokers, by investigating changes in the brain network involved in a tracking task. The subject characteristics, the percentage of Δ9-Tetrahydrocannabinol in the joint, and the inhaled dose were in accordance with real-life conditions. Thirty-one male volunteers were enrolled in this study that includes clinical and toxicological aspects together with functional magnetic resonance imaging of the brain and measurements of psychomotor skills. The fMRI paradigm was based on a visuo-motor tracking task, alternating active tracking blocks with passive tracking viewing and rest condition. We show that cannabis smoking, even at low Δ9-Tetrahydrocannabinol blood concentrations, decreases psychomotor skills and alters the activity of the brain networks involved in cognition. The relative decrease of Blood Oxygen Level Dependent response (BOLD) after cannabis smoking in the anterior insula, dorsomedial thalamus, and striatum compared to placebo smoking suggests an alteration of the network involved in saliency detection. In addition, the decrease of BOLD response in the right superior parietal cortex and in the dorsolateral prefrontal cortex indicates the involvement of the Control Executive network known to operate once the saliencies are identified. Furthermore, cannabis increases activity in the rostral anterior cingulate cortex and ventromedial prefrontal cortices, suggesting an increase in self-oriented mental activity. Subjects are more attracted by intrapersonal stimuli (“self”) and fail to attend to task performance, leading to an insufficient allocation of task-oriented resources and to sub-optimal performance. These effects correlate with the subjective feeling of confusion rather than with the blood level of Δ9-Tetrahydrocannabinol

  14. Weed or wheel! FMRI, behavioural, and toxicological investigations of how cannabis smoking affects skills necessary for driving.

    Directory of Open Access Journals (Sweden)

    Giovanni Battistella

    Full Text Available Marijuana is the most widely used illicit drug, however its effects on cognitive functions underlying safe driving remain mostly unexplored. Our goal was to evaluate the impact of cannabis on the driving ability of occasional smokers, by investigating changes in the brain network involved in a tracking task. The subject characteristics, the percentage of Δ(9-Tetrahydrocannabinol in the joint, and the inhaled dose were in accordance with real-life conditions. Thirty-one male volunteers were enrolled in this study that includes clinical and toxicological aspects together with functional magnetic resonance imaging of the brain and measurements of psychomotor skills. The fMRI paradigm was based on a visuo-motor tracking task, alternating active tracking blocks with passive tracking viewing and rest condition. We show that cannabis smoking, even at low Δ(9-Tetrahydrocannabinol blood concentrations, decreases psychomotor skills and alters the activity of the brain networks involved in cognition. The relative decrease of Blood Oxygen Level Dependent response (BOLD after cannabis smoking in the anterior insula, dorsomedial thalamus, and striatum compared to placebo smoking suggests an alteration of the network involved in saliency detection. In addition, the decrease of BOLD response in the right superior parietal cortex and in the dorsolateral prefrontal cortex indicates the involvement of the Control Executive network known to operate once the saliencies are identified. Furthermore, cannabis increases activity in the rostral anterior cingulate cortex and ventromedial prefrontal cortices, suggesting an increase in self-oriented mental activity. Subjects are more attracted by intrapersonal stimuli ("self" and fail to attend to task performance, leading to an insufficient allocation of task-oriented resources and to sub-optimal performance. These effects correlate with the subjective feeling of confusion rather than with the blood level of Δ(9

  15. Action processing and mirror neuron function in patients with amyotrophic lateral sclerosis: an fMRI study.

    Directory of Open Access Journals (Sweden)

    Laura Jelsone-Swain

    Full Text Available Amyotrophic lateral sclerosis (ALS is a highly debilitating and rapidly fatal neurodegenerative disease. It has been suggested that social cognition may be affected, such as impairment in theory of mind (ToM ability. Despite these findings, research in this area is scarce and the investigation of neural mechanisms behind such impairment is absent. Nineteen patients with ALS and eighteen healthy controls participated in this study. Because the mirror neuron system (MNS is thought to be involved in theory of mind, we first implemented a straightforward action-execution and observation task to assess basic MNS function. Second, we examined the social-cognitive ability to understand actions of others, which is a component of ToM. We used fMRI to assess BOLD activity differences between groups during both experiments. Theory of mind was also measured behaviorally using the Reading the Mind in the Eyes test (RME. ALS patients displayed greater BOLD activity during the action-execution and observation task, especially throughout right anterior cortical regions. These areas included the right inferior operculum, premotor and primary motor regions, and left inferior parietal lobe. A conjunction analysis showed significantly more co-activated voxels during both the observation and action-execution conditions in the patient group throughout MNS regions. These results support a compensatory response in the MNS during action processing. In the action understanding experiment, healthy controls performed better behaviorally and subsequently recruited greater regions of activity throughout the prefrontal cortex and middle temporal gyrus. Lastly, action understanding performance was able to cluster patients with ALS into high and lower performing groups, which then differentiated RME performance. Collectively, these data suggest that social cognition, particularly theory of mind, may be affected in a subset of patients with ALS. This impairment may be related to

  16. Action processing and mirror neuron function in patients with amyotrophic lateral sclerosis: an fMRI study.

    Science.gov (United States)

    Jelsone-Swain, Laura; Persad, Carol; Burkard, David; Welsh, Robert C

    2015-01-01

    Amyotrophic lateral sclerosis (ALS) is a highly debilitating and rapidly fatal neurodegenerative disease. It has been suggested that social cognition may be affected, such as impairment in theory of mind (ToM) ability. Despite these findings, research in this area is scarce and the investigation of neural mechanisms behind such impairment is absent. Nineteen patients with ALS and eighteen healthy controls participated in this study. Because the mirror neuron system (MNS) is thought to be involved in theory of mind, we first implemented a straightforward action-execution and observation task to assess basic MNS function. Second, we examined the social-cognitive ability to understand actions of others, which is a component of ToM. We used fMRI to assess BOLD activity differences between groups during both experiments. Theory of mind was also measured behaviorally using the Reading the Mind in the Eyes test (RME). ALS patients displayed greater BOLD activity during the action-execution and observation task, especially throughout right anterior cortical regions. These areas included the right inferior operculum, premotor and primary motor regions, and left inferior parietal lobe. A conjunction analysis showed significantly more co-activated voxels during both the observation and action-execution conditions in the patient group throughout MNS regions. These results support a compensatory response in the MNS during action processing. In the action understanding experiment, healthy controls performed better behaviorally and subsequently recruited greater regions of activity throughout the prefrontal cortex and middle temporal gyrus. Lastly, action understanding performance was able to cluster patients with ALS into high and lower performing groups, which then differentiated RME performance. Collectively, these data suggest that social cognition, particularly theory of mind, may be affected in a subset of patients with ALS. This impairment may be related to functioning of

  17. Hemodynamic response to Interictal Epileptiform Discharges addressed by personalized EEG-fNIRS recordings

    Directory of Open Access Journals (Sweden)

    Giovanni ePellegrino

    2016-03-01

    Full Text Available Objective: We aimed at studying the hemodynamic response (HR to Interictal Epileptic Discharges (IEDs using patient-specific and prolonged simultaneous ElectroEncephaloGraphy (EEG and functional Near InfraRed Spectroscopy (fNIRS recordings. Methods: The epileptic generator was localized using Magnetoencephalography source imaging. fNIRS montage was tailored for each patient, using an algorithm to optimize the sensitivity to the epileptic generator. Optodes were glued using collodion to achieve prolonged acquisition with high quality signal. fNIRS data analysis was handled with no a priori constraint on HR time course, averaging fNIRS signals to similar IEDs. Cluster-permutation analysis was performed on 3D reconstructed fNIRS data to identify significant spatio-temporal HR clusters. Standard (GLM with fixed HRF and cluster-permutation EEG-fMRI analyses were performed for comparison purposes. Results: fNIRS detected HR to IEDs for 8/9 patients. It mainly consisted oxy-hemoglobin increases (7 patients, followed by oxy-hemoglobin decreases (6 patients. HR was lateralized in 6 patients and lasted from 8.5 to 30s. Standard EEG-fMRI analysis detected an HR in 4/9 patients (4/9 without enough IEDs, 1/9 unreliable result. The cluster-permutation EEG-fMRI analysis restricted to the region investigated by fNIRS showed additional strong and non-canonical BOLD responses starting earlier than the IEDs and lasting up to 30s. Conclusions: i EEG-fNIRS is suitable to detect the HR to IEDs and can outperform EEG-fMRI because of prolonged recordings and greater chance to detect IEDs; ii cluster-permutation analysis unveils additional HR features underestimated when imposing a canonical HR function iii the HR is often bilateral and lasts up to 30s.

  18. A neuronal MCT2 knockdown in the rat somatosensory cortex reduces both the NMR lactate signal and the BOLD response during whisker stimulation.

    Science.gov (United States)

    Mazuel, Leslie; Blanc, Jordy; Repond, Cendrine; Bouchaud, Véronique; Raffard, Gérard; Déglon, Nicole; Bonvento, Gilles; Pellerin, Luc; Bouzier-Sore, Anne-Karine

    2017-01-01

    Although several in vitro and ex vivo evidence support the existence of lactate exchange between astrocytes and neurons, a direct demonstration in vivo is still lacking. In the present study, a lentiviral vector carrying a short hairpin RNA (shRNA) was used to downregulate the expression of the monocarboxylate transporter type 2 (MCT2) in neurons of the rat somatosensory cortex (called S1BF) by ~ 25%. After one hour of whisker stimulation, HRMAS 1H-NMR spectroscopy analysis of S1BF perchloric acid extracts showed that while an increase in lactate content is observed in both uninjected and shRNA-control injected extracts, such an effect was abrogated in shMCT2 injected rats. A 13C-incorporation analysis following [1-13C]glucose infusion during the stimulation confirmed that the elevated lactate observed during activation originates from newly synthesized [3-13C]lactate, with blood-derived [1-13C]glucose being the precursor. Moreover, the analysis of the 13C-labeling of glutamate in position C3 and C4 indicates that upon activation, there is an increase in TCA cycle velocity for control rats while a decrease is observed for MCT2 knockdown animals. Using in vivo localized 1H-NMR spectroscopy, an increase in lactate levels is observed in the S1BF area upon whisker stimulation for shRNA-control injected rats but not for MCT2 knockdown animals. Finally, while a robust BOLD fMRI response was evidenced in control rats, it was absent in MCT2 knockdown rats. These data not only demonstrate that glucose-derived lactate is locally produced following neuronal activation but also suggest that its use by neurons via MCT2 is probably essential to maintain synaptic activity within the barrel cortex.

  19. An fMRI study of Agency

    DEFF Research Database (Denmark)

    Charalampaki, Angeliki

    2017-01-01

    Sense of Agency comprises the experience of authorship over voluntarily executed movements. Research related to this phenomenon is substantial, considering altered Sense of Agency has been linked with neurological disorders like Cerebral palsy, Apraxia and Anosognosia for hemiplegia. Previous...... displays. For the purposes of our study twenty participants were recruited. The experimental procedure we considered appropriate to study the Sense of Agency, involved participants laying inside the fMRI scanner and while they had no visual feedback of their hand, they were instructed to draw straight...

  20. Journal of Clinical Monitoring and Computing 2017 end of year summary: cardiovascular and hemodynamic monitoring.

    Science.gov (United States)

    Saugel, Bernd; Bendjelid, Karim; Critchley, Lester A H; Scheeren, Thomas W L

    2018-02-26

    Hemodynamic monitoring provides the basis for the optimization of cardiovascular dynamics in intensive care medicine and anesthesiology. The Journal of Clinical Monitoring and Computing (JCMC) is an ideal platform to publish research related to hemodynamic monitoring technologies, cardiovascular (patho)physiology, and hemodynamic treatment strategies. In this review, we discuss selected papers published on cardiovascular and hemodynamic monitoring in the JCMC in 2017.

  1. Hemodynamic changes during robotic radical prostatectomy

    Directory of Open Access Journals (Sweden)

    Vanlal Darlong

    2012-01-01

    Full Text Available Background: Effect on hemodynamic changes and experience of robot-assisted laparoscopic radical prostatectomy (RALRP in steep Trendelenburg position (45° with high-pressure CO 2 pneumoperitoneum is very limited. Therefore, we planned this prospective clinical trial to study the effect of steep Tredelenburg position with high-pressure CO 2 pneumoperitoneum on hemodynamic parameters in a patient undergoing RALRP using FloTrac/Vigileo™1.10. Methods: After ethical approval and informed consent, 15 patients scheduled for RALRP were included in the study. In the operation room, after attaching standard monitors, the radial artery was cannulated. Anesthesia was induced with fentanyl (2 μg/kg and thiopentone (4-7 mg/kg, and tracheal intubation was facilitated by vecuronium bromide (0.1 mg/kg. The patient′s right internal jugular vein was cannulated and the Pre Sep™ central venous oximetry catheter was connected to it. Anesthesia was maintained with isoflurane in oxygen and nitrous oxide and intermittent boluses of vecuronium. Intermittent positive-pressure ventilation was provided to maintain normocapnea. After CO 2 pneumoperitoneum, position of the patient was gradually changed to 45° Trendelenburg over 5 min. The robot was then docked and the robot-assisted surgery started. Intraoperative monitoring included central venous pressure (CVP, stroke volume (SV, stroke volume variation (SVV, cardiac output (CO, cardiac index (CI and central venous oxygen saturation (ScvO 2 . Results: After induction of anesthesia, heart rate (HR, SV, CO and CI were decreased significantly from the baseline value (P>0.05. SV, CO and CI further decreased significantly after creating pneumoperitoneum (P>0.05. At the 45° Trendelenburg position, HR, SV, CO and CI were significantly decreased compared with baseline. Thereafter, CO and CI were persistently low throughout the 45° Trendelenburg position (P=0.001. HR at 20 min and 1 h, SV and mean arterial blood pressure

  2. Hemodynamic coherence and the rationale for monitoring the microcirculation

    NARCIS (Netherlands)

    Ince, Can

    2015-01-01

    This article presents a personal viewpoint of the shortcoming of conventional hemodynamic resuscitation procedures in achieving organ perfusion and tissue oxygenation following conditions of shock and cardiovascular compromise, and why it is important to monitor the microcirculation in such

  3. Central Hemodynamic Function in Miners with Thermal Injury

    Directory of Open Access Journals (Sweden)

    V. V. Moroz

    2008-01-01

    Full Text Available Objective: to study the specific features of central hemodynamic function in the acute phase of severe thermal injury (STI in miners who had a length of service of 10 years or more. Subjects and methods. A noninvasive study of central hemodynamics was conducted in 33 miners with severe thermal injury (a study group and 34 patients without a length of underground work who had the same condition (a control group. Both groups were matched by age and the nature and severity of thermal injuries. Central hemodynamics was evaluated by the following parameters: mean arterial blood, heart rate, stroke index (SI, cardiac index (CI, cardiac output (CO, specific vascular peripheral resistance (SVPR determined by Cubichek tetrapolar rheography. Results. The study indicated that on posttraumatic days 3—7, as compared with victims without a length of underground service, the miners had more pronounced central hemodynamic changes: decreases in CI, SI, and CO and an increase in SVPR. In the control group, from day 3, the hemodynamic changes were the following: increases in SI, SI, and CO and a decrease in SVPR. In the miners, the above features were attributable to the baseline central hemodynamic function. Conclusion. Thus, unlike the victims without a length of underground service, the miners with severe thermal injury develop more significant and prolonged central hemodynamic disorders. The detected differences during thermal injury are determined by the lowered reserve capacities of the cardiovascular system in miners due to the long-term exposure to poor working conditions, i. e. an underground service length of 10 years or more. Key words: thermal injury, miner, hemodynamics, type of circulation.

  4. Correlative BOLD MR imaging of stages of synovitis in a rabbit model of antigen-induced arthritis

    Energy Technology Data Exchange (ETDEWEB)

    Doria, Andrea S. [Hospital for Sick Children, Department of Diagnostic Imaging, Toronto (Canada); University of Toronto, Department of Medical Imaging, Toronto (Canada); Crawley, Adrian [University of Toronto, Department of Medical Imaging, Toronto (Canada); Toronto Western Hospital, Department of Medical Imaging, Toronto (Canada); Gahunia, Harpal; Rayner, Tammy; Tassos, Vivian; Zhong, Anguo [Hospital for Sick Children, Department of Diagnostic Imaging, Toronto (Canada); Moineddin, Rahim [Family and Community Medicine, Department of Public Health, Toronto (Canada); Pritzker, Kenneth; Mendes, Maria; Jong, Roland [Mount Sinai Hospital, Department of Pathology and Laboratory Medicine, Toronto (Canada); Salter, Robert B. [Hospital for Sick Children, Department of Orthopedic Surgery, Toronto (Canada)

    2012-01-15

    Because of the ability of blood-oxygen-level-dependent (BOLD) MRI to assess blood oxygenation changes within the microvasculature, this technique holds potential for evaluating early perisynovial changes in inflammatory arthritis. To evaluate the feasibility of BOLD MRI to detect interval perisynovial changes in knees of rabbits with inflammatory arthritis. Rabbit knees were injected with albumin (n=9) or saline (n=6) intra-articularly, or were not injected (control knees, n=9). Except for two rabbits (albumin-injected, n=2 knees; saline-injected, n=2 knees) that unexpectedly died on days 7 and 21 of the experiment, respectively, all other animals were scanned with BOLD MRI on days 0, 1, 7, 14, 21 and 28 after induction of arthritis. T2*-weighted gradient-echo MRI was performed during alternate 30 s of normoxia/hyperoxia. BOLD MRI measurements were compared with clinical, laboratory and histological markers. Percentage of activated voxels was significantly greater in albumin-injected knees than in contralateral saline-injected knees (P=0.04). For albumin-injected knees (P < 0.05) and among different categories of knees (P=0.009), the percentage of activated BOLD voxels varied over time. A quadratic curve for on-and-off BOLD difference was delineated for albumin- and saline-injected knees over time (albumin-injected, P=0.047; saline-injected, P=0.009). A trend toward a significant difference in synovial histological scores between albumin-injected and saline-injected knees was noted only for acute scores (P=0.07). As a proof of concept, BOLD MRI can depict perisynovial changes during progression of experimental arthritis. (orig.)

  5. Nonparametric trend estimation in the presence of fractal noise: application to fMRI time-series analysis.

    Science.gov (United States)

    Afshinpour, Babak; Hossein-Zadeh, Gholam-Ali; Soltanian-Zadeh, Hamid

    2008-06-30

    Unknown low frequency fluctuations called "trend" are observed in noisy time-series measured for different applications. In some disciplines, they carry primary information while in other fields such as functional magnetic resonance imaging (fMRI) they carry nuisance effects. In all cases, however, it is necessary to estimate them accurately. In this paper, a method for estimating trend in the presence of fractal noise is proposed and applied to fMRI time-series. To this end, a partly linear model (PLM) is fitted to each time-series. The parametric and nonparametric parts of PLM are considered as contributions of hemodynamic response and trend, respectively. Using the whitening property of wavelet transform, the unknown components of the model are estimated in the wavelet domain. The results of the proposed method are compared to those of other parametric trend-removal approaches such as spline and polynomial models. It is shown that the proposed method improves activation detection and decreases variance of the estimated parameters relative to the other methods.

  6. Self-regulation of brain activity in patients with postherpetic neuralgia: a double-blind randomized study using real-time FMRI neurofeedback.

    Science.gov (United States)

    Guan, Min; Ma, Lijia; Li, Li; Yan, Bin; Zhao, Lu; Tong, Li; Dou, Shewei; Xia, Linjie; Wang, Meiyun; Shi, Dapeng

    2015-01-01

    A pilot study has shown that real-time fMRI (rtfMRI) neurofeedback could be an alternative approach for chronic pain treatment. Considering the relative small sample of patients recruited and not strictly controlled condition, it is desirable to perform a replication as well as a double-blinded randomized study with a different control condition in chronic pain patients. Here we conducted a rtfMRI neurofeedback study in a subgroup of pain patients - patients with postherpetic neuralgia (PHN) and used a different sham neurofeedback control. We explored the feasibility of self-regulation of the rostral anterior cingulate cortex (rACC) activation in patients with PHN through rtfMRI neurofeedback and regulation of pain perception. Sixteen patients (46-71 years) with PHN were randomly allocated to a experimental group (n = 8) or a control group (n = 8). 2 patients in the control group were excluded for large head motion. The experimental group was given true feedback information from their rACC whereas the control group was given sham feedback information from their posterior cingulate cortex (PCC). All subjects were instructed to perform an imagery task to increase and decrease activation within the target region using rtfMRI neurofeedback. Online analysis showed 6/8 patients in the experimental group were able to increase and decrease the blood oxygen level dependent (BOLD) fMRI signal magnitude during intermittent feedback training. However, this modulation effect was not observed in the control group. Offline analysis showed that the percentage of BOLD signal change of the target region between the last and first training in the experimental group was significantly different from the control group's and was also significantly different than 0. The changes of pain perception reflected by numerical rating scale (NRS) in the experimental group were significantly different from the control group. However, there existed no significant correlations between BOLD signal

  7. A spatio-temporal nonparametric Bayesian variable selection model of fMRI data for clustering correlated time courses.

    Science.gov (United States)

    Zhang, Linlin; Guindani, Michele; Versace, Francesco; Vannucci, Marina

    2014-07-15

    In this paper we present a novel wavelet-based Bayesian nonparametric regression model for the analysis of functional magnetic resonance imaging (fMRI) data. Our goal is to provide a joint analytical framework that allows to detect regions of the brain which exhibit neuronal activity in response to a stimulus and, simultaneously, infer the association, or clustering, of spatially remote voxels that exhibit fMRI time series with similar characteristics. We start by modeling the data with a hemodynamic response function (HRF) with a voxel-dependent shape parameter. We detect regions of the brain activated in response to a given stimulus by using mixture priors with a spike at zero on the coefficients of the regression model. We account for the complex spatial correlation structure of the brain by using a Markov random field (MRF) prior on the parameters guiding the selection of the activated voxels, therefore capturing correlation among nearby voxels. In order to infer association of the voxel time courses, we assume correlated errors, in particular long memory, and exploit the whitening properties of discrete wavelet transforms. Furthermore, we achieve clustering of the voxels by imposing a Dirichlet process (DP) prior on the parameters of the long memory process. For inference, we use Markov Chain Monte Carlo (MCMC) sampling techniques that combine Metropolis-Hastings schemes employed in Bayesian variable selection with sampling algorithms for nonparametric DP models. We explore the performance of the proposed model on simulated data, with both block- and event-related design, and on real fMRI data. Copyright © 2014 Elsevier Inc. All rights reserved.

  8. The role of ecological context and predation risk-stimuli in revealing the true picture about the genetic basis of boldness evolution in fish

    DEFF Research Database (Denmark)

    Klefoth, Thomas; Skov, Christian; Krause, Jens

    2011-01-01

    To showcase the importance of genotype × environment interactions and the presence of predation risk in the experimental assessment of boldness in fish, we investigated boldness in terms of feeding behavior and refuge use in two genetically different populations of juvenile carp (Cyprinus carpio......) in two replicated experimental conditions in ponds and laboratory tanks. The populations were expected to exhibit genetic differences in boldness due to differential evolutionary adaptation to low-predation-risk pond aquaculture conditions. Boldness was measured in variants of open-field trials...

  9. Perceptual Characterization of the Macronutrient Picture System (MaPS for Food Image fMRI

    Directory of Open Access Journals (Sweden)

    Jill L. King

    2018-01-01

    Full Text Available Food image fMRI paradigms are used widely for investigating the neural basis of ingestive behavior. However, these paradigms have not been validated in terms of ingestive behavior constructs, engagement of food-relevant neural systems, or test-retest reliability, making the generalizability of study findings unclear. Therefore, we validated the Macronutrient Picture System (MaPS (McClernon et al., 2013, which includes food images from the six categories represented in the Geiselman Food Preference Questionnaire (FPQ (Geiselman et al., 1998. Twenty-five healthy young adults (n = 21 female, mean age = 20.6 ± 1.1 years, mean BMI = 22.1 ± 1.9 kg/m2 rated the MaPS images in terms of visual interest, appetitive quality, nutrition, emotional valence, liking, and frequency of consumption, and completed the FPQ. In a second study, 12 individuals (n=8 female, mean age = 25.0 ± 6.5 years, mean BMI = 28.2 ± 8.7 kg/m2 viewed MaPS and control images (vegetables and non-food during two separate 3T BOLD fMRI scans after fasting overnight. Intuitively, high fat/high sugar (HF/HS and high fat/high complex carbohydrate (HF/HCCHO images achieved higher liking and appetitive ratings, and lower nutrition ratings, than low fat/low complex carbohydrate/high protein (LF/LCHO/HP images on average. Within each food category, FPQ scores correlated strongly with MaPS image liking ratings (p < 0.001. Brain activation differences between viewing images of HF/HS and vegetables, and between HF/HCCHO and vegetables, were seen in several reward-related brain regions (e.g., putamen, insula, and medial frontal gyrus. Intra-individual, inter-scan agreement in a summary measure of brain activation differences in seven reward network regions of interest was high (ICC = 0.61, and was even higher when two distinct sets of food images with matching visual ratings were shown in the two scans (ICC = 0.74. These results suggest that the MaPS provides valid representation of food

  10. The cerebral correlates of set-shifting: an fMRI study of the trail making test

    Directory of Open Access Journals (Sweden)

    Moll Jorge

    2002-01-01

    Full Text Available The trail making test (TMT pertains to a family of tests that tap the ability to alternate between cognitive categories. However, the value of the TMT as a localizing instrument remains elusive. Here we report the results of a functional magnetic resonance imaging (fMRI study of a verbal adaptation of the TMT (vTMT. The vTMT takes advantage of the set-shifting properties of the TMT and, at the same time, minimizes the visuospatial and visuomotor components of the written TMT. Whole brain BOLD fMRI was performed during the alternating execution of vTMTA and vTMTB in seven normal adults with more than 12 years of formal education. Brain activation related to the set-shifting component of vTMTB was investigated by comparing performance on vTMTB with vTMTA, a simple counting task. There was a marked asymmetry of activation in favor of the left hemisphere, most notably in dorsolateral prefrontal cortex (BA 6 lateral, 44 and 46 and supplementary motor area/cingulate sulcus (BA 6 medial and 32. The intraparietal sulcus (BA 7 and 39 was bilaterally activated. These findings are in line with clinico-anatomic and functional neuroimaging data that point to a critical role of the dorsolateral and medial prefrontal cortices as well as the intraparietal sulci in the regulation of cognitive flexibility, intention, and the covert execution of saccades/anti-saccades. Many commonly used neuropsychological paradigms, such as the Stroop, Wisconsin Card Sorting, and go - no go tasks, share some patterns of cerebral activation with the TMT.

  11. The Difference between Aesthetic Appreciation of Artistic and Popular Music: Evidence from an fMRI Study

    Science.gov (United States)

    Luo, Qiuling; Mo, Lei

    2016-01-01

    To test the hypothesis that pleasure from artistic music is intellectual while that from popular music is physiological, this study investigated the different functional mechanisms between aesthetic appreciation of artistic and popular music using fMRI. 18 male non-musicians were scanned while they performed an aesthetic rating task for excerpts of artistic music, popular music and musical notes playing and singing (control). The rating scores of artistic and popular music excerpts were both significantly higher than that of control materials while the scores of them were not different. The fMRI results showed both artistic and popular conditions activated the VS and vmPFC, compared with control condition. When contrasted popular and artistic condition directly, we found popular music activated right putamen, while artistic music activated right mPFC. By parametric analysis, we found the activation of right putamen tracked the aesthetic ratings of popular music, whereas the BOLD signal in right mPFC tracked the aesthetic ratings of artistic music. These results indicate the reward induced by popular music is closer to a primary reward while that induced by artistic music is closer to a secondary reward. We also found artistic music activated ToM areas, including PCC/PC, arMFC and TPJ, when compared with popular music. And these areas also tracked aesthetic ratings of artistic music but not those of popular music. These results imply that the pleasure from former comes from cognitive empathy. In conclusion, this study gives clear neuronal evidences supporting the view that artistic music is of intelligence and social cognition involved while the popular music is of physiology. PMID:27814379

  12. Increase or Decrease of fMRI Activity in Adult Attention Deficit/ Hyperactivity Disorder: Does It Depend on Task Difficulty?

    Science.gov (United States)

    Biehl, Stefanie C; Merz, Christian J; Dresler, Thomas; Heupel, Julia; Reichert, Susanne; Jacob, Christian P; Deckert, Jürgen; Herrmann, Martin J

    2016-05-27

    Attention deficit/hyperactivity disorder has been shown to affect working memory, and fMRI studies in children and adolescents with attention deficit/hyperactivity disorder report hypoactivation in task-related attentional networks. However, studies with adult attention deficit/hyperactivity disorder patients addressing this issue as well as the effects of clinically valid methylphenidate treatment are scarce. This study contributes to closing this gap. Thirty-five adult patients were randomized to 6 weeks of double-blind placebo or methylphenidate treatment. Patients completed an fMRI n-back working memory task both before and after the assigned treatment, and matched healthy controls were tested and compared to the untreated patients. There were no whole-brain differences between any of the groups. However, when specified regions of interest were investigated, the patient group showed enhanced BOLD responses in dorsal and ventral areas before treatment. This increase was correlated with performance across all participants and with attention deficit/hyperactivity disorder symptoms in the patient group. Furthermore, we found an effect of treatment in the right superior frontal gyrus, with methylphenidate-treated patients exhibiting increased activation, which was absent in the placebo-treated patients. Our results indicate distinct activation differences between untreated adult attention deficit/hyperactivity disorder patients and matched healthy controls during a working memory task. These differences might reflect compensatory efforts by the patients, who are performing at the same level as the healthy controls. We furthermore found a positive effect of methylphenidate on the activation of a frontal region of interest. These observations contribute to a more thorough understanding of adult attention deficit/hyperactivity disorder and provide impulses for the evaluation of therapy-related changes. © The Author 2016. Published by Oxford University Press on behalf

  13. The Difference between Aesthetic Appreciation of Artistic and Popular Music: Evidence from an fMRI Study.

    Science.gov (United States)

    Huang, Ping; Huang, Hanhua; Luo, Qiuling; Mo, Lei

    2016-01-01

    To test the hypothesis that pleasure from artistic music is intellectual while that from popular music is physiological, this study investigated the different functional mechanisms between aesthetic appreciation of artistic and popular music using fMRI. 18 male non-musicians were scanned while they performed an aesthetic rating task for excerpts of artistic music, popular music and musical notes playing and singing (control). The rating scores of artistic and popular music excerpts were both significantly higher than that of control materials while the scores of them were not different. The fMRI results showed both artistic and popular conditions activated the VS and vmPFC, compared with control condition. When contrasted popular and artistic condition directly, we found popular music activated right putamen, while artistic music activated right mPFC. By parametric analysis, we found the activation of right putamen tracked the aesthetic ratings of popular music, whereas the BOLD signal in right mPFC tracked the aesthetic ratings of artistic music. These results indicate the reward induced by popular music is closer to a primary reward while that induced by artistic music is closer to a secondary reward. We also found artistic music activated ToM areas, including PCC/PC, arMFC and TPJ, when compared with popular music. And these areas also tracked aesthetic ratings of artistic music but not those of popular music. These results imply that the pleasure from former comes from cognitive empathy. In conclusion, this study gives clear neuronal evidences supporting the view that artistic music is of intelligence and social cognition involved while the popular music is of physiology.

  14. Physiologic characterization of inflammatory arthritis in a rabbit model with BOLD and DCE MRI at 1.5 Tesla.

    Science.gov (United States)

    Nasui, Otilia C; Chan, Michael W; Nathanael, George; Crawley, Adrian; Miller, Elka; Belik, Jaques; Cheng, Hai-Ling; Kassner, Andrea; Rayner, Tammy; Weiss, Ruth; Detzler, Garry; Zhong, Anguo; Moineddin, Rahim; Jong, Roland; Rogers, Marianne; Doria, Andrea S

    2014-11-01

    Our aim was to test the feasibility of blood oxygen level dependent magnetic resonance imaging (BOLD MRI) and dynamic contrast-enhanced (DCE) MRI to monitor periarticular hypoxic/inflammatory changes over time in a juvenile rabbit model of arthritis. We examined arthritic and contralateral nonarthritic knees of 21 juvenile rabbits at baseline and days 1,14, and 28 after induction of arthritis by unilateral intra-articular injection of carrageenin with BOLD and DCE MRI at 1.5 Tesla (T). Nine noninjected rabbits served as controls. Associations between BOLD and DCE-MRI and corresponding intra-articular oxygen pressure (PO2) and blood flow [blood perfusion units (BPU)] (polarographic probes, reference standards) or clinical-histological data were measured by correlation coefficients. Percentage BOLD MRI change obtained in contralateral knees correlated moderately with BPU on day 0 (r = -0.51, p = 0.02) and excellently on day 28 (r = -0.84, p = 0.03). A moderate correlation was observed between peak enhancement DCE MRI (day 1) and BPU measurements in arthritic knees (r = 0.49, p = 0.04). In acute arthritis, BOLD and DCE MRI highly correlated (r = 0.89, p = 0.04; r = 1.0, p < 0.0001) with histological scores in arthritic knees. The proposed techniques are feasible to perform at 1.5 T, and they hold potential as surrogate measures to monitor hypoxic and inflammatory changes over time in arthritis at higher-strength MRI fields. • BOLD and DCE MRI detect interval perisynovial changes in a rabbit knee • BOLD and DCE MRI act as surrogate markers of physiologic changes in arthritis • BOLD MRI signal represents oxygen extraction compared with intra-articular PO 2 • DCE MRI measurements estimate physiologic periarticular vascular properties • In rabbit knees with acute arthritis, BOLD/DCE MRI highly correlated with histological scores.

  15. Changes of right-hemispheric activation after constraint-induced, intensive language action therapy in chronic aphasia: fMRI evidence from auditory semantic processing1

    Science.gov (United States)

    Mohr, Bettina; Difrancesco, Stephanie; Harrington, Karen; Evans, Samuel; Pulvermüller, Friedemann

    2014-01-01

    The role of the two hemispheres in the neurorehabilitation of language is still under dispute. This study explored the changes in language-evoked brain activation over a 2-week treatment interval with intensive constraint induced aphasia therapy (CIAT), which is also called intensive language action therapy (ILAT). Functional magnetic resonance imaging (fMRI) was used to assess brain activation in perilesional left hemispheric and in homotopic right hemispheric areas during passive listening to high and low-ambiguity sentences and non-speech control stimuli in chronic non-fluent aphasia patients. All patients demonstrated significant clinical improvements of language functions after therapy. In an event-related fMRI experiment, a significant increase of BOLD signal was manifest in right inferior frontal and temporal areas. This activation increase was stronger for highly ambiguous sentences than for unambiguous ones. These results suggest that the known language improvements brought about by intensive constraint-induced language action therapy at least in part relies on circuits within the right-hemispheric homologs of left-perisylvian language areas, which are most strongly activated in the processing of semantically complex language. PMID:25452721

  16. Combination of DTI and fMRI reveals the white matter changes correlating with the decline of default-mode network activity in Alzheimer's disease

    Science.gov (United States)

    Wu, Xianjun; Di, Qian; Li, Yao; Zhao, Xiaojie

    2009-02-01

    Recently, evidences from fMRI studies have shown that there was decreased activity among the default-mode network in Alzheimer's disease (AD), and DTI researches also demonstrated that demyelinations exist in white matter of AD patients. Therefore, combining these two MRI methods may help to reveal the relationship between white matter damages and alterations of the resting state functional connectivity network. In the present study, we tried to address this issue by means of correlation analysis between DTI and resting state fMRI images. The default-mode networks of AD and normal control groups were compared to find the areas with significantly declined activity firstly. Then, the white matter regions whose fractional anisotropy (FA) value correlated with this decline were located through multiple regressions between the FA values and the BOLD response of the default networks. Among these correlating white matter regions, those whose FA values also declined were found by a group comparison between AD patients and healthy elderly control subjects. Our results showed that the areas with decreased activity among default-mode network included left posterior cingulated cortex (PCC), left medial temporal gyrus et al. And the damaged white matter areas correlated with the default-mode network alterations were located around left sub-gyral temporal lobe. These changes may relate to the decreased connectivity between PCC and medial temporal lobe (MTL), and thus correlate with the deficiency of default-mode network activity.

  17. Dictionary-driven Ischemia Detection from Cardiac Phase-Resolved Myocardial BOLD MRI at Rest

    Science.gov (United States)

    Bevilacqua, Marco; Dharmakumar, Rohan; Tsaftaris, Sotirios A.

    2016-01-01

    Cardiac Phase-resolved Blood-Oxygen-Level Dependent (CP–BOLD) MRI provides a unique opportunity to image an ongoing ischemia at rest. However, it requires post-processing to evaluate the extent of ischemia. To address this, here we propose an unsupervised ischemia detection (UID) method which relies on the inherent spatio-temporal correlation between oxygenation and wall motion to formalize a joint learning and detection problem based on dictionary decomposition. Considering input data of a single subject, it treats ischemia as an anomaly and iteratively learns dictionaries to represent only normal observations (corresponding to myocardial territories remote to ischemia). Anomaly detection is based on a modified version of One-class Support Vector Machines (OCSVM) to regulate directly the margins by incorporating the dictionary-based representation errors. A measure of ischemic extent (IE) is estimated, reflecting the relative portion of the myocardium affected by ischemia. For visualization purposes an ischemia likelihood map is created by estimating posterior probabilities from the OCSVM outputs, thus obtaining how likely the classification is correct. UID is evaluated on synthetic data and in a 2D CP–BOLD data set from a canine experimental model emulating acute coronary syndromes. Comparing early ischemic territories identified with UID against infarct territories (after several hours of ischemia), we find that IE, as measured by UID, is highly correlated (Pearson’s r = 0.84) w.r.t. infarct size. When advances in automated registration and segmentation of CP–BOLD images and full coverage 3D acquisitions become available, we hope that this method can enable pixel-level assessment of ischemia with this truly non-invasive imaging technique. PMID:26292338

  18. BOLD quantified renal pO2 is sensitive to pharmacological challenges in rats.

    Science.gov (United States)

    Thacker, Jon; Zhang, Jeff L; Franklin, Tammy; Prasad, Pottumarthi

    2017-07-01

    Blood oxygen level-dependent (BOLD) MRI has been effectively used to monitor changes in renal oxygenation. However, R2* (or T2*) is not specific to blood oxygenation and is dependent on other factors. This study investigates the use of a statistical model that takes these factors into account and maps BOLD MRI measurements to blood pO2. Spin echo and gradient echo images were obtained in six Sprague-Dawley rats and R2 and R2* maps were computed. Measurements were made at baseline, post-nitric oxide synthase inhibitor (L-NAME), and post-furosemide administration. A simulation of each region was performed to map R2' (computed as R2*-R2) to blood pO2. At baseline, blood pO2 in the outer medulla was 30.5 ± 1.2 mmHg and 51.9 ± 5.2 mmHg in the cortex, in agreement with previous invasive studies. Blood pO2 was found to decrease within the outer medulla following L-NAME (P pO2 in the cortex increased following furosemide (P pO2 is sensitive to pharmacological challenges, and baseline pO2 is comparable to literature values. Reporting pO2 instead of R2* could lead to a greater clinical impact of renal BOLD MRI and facilitate the identification of hypoxic regions. Magn Reson Med 78:297-302, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  19. Variational structure of Luttinger-Ward formalism and bold diagrammatic expansion for Euclidean lattice field theory.

    Science.gov (United States)

    Lin, Lin; Lindsey, Michael

    2018-03-06

    The Luttinger-Ward functional was proposed more than five decades ago and has been used to formally justify most practically used Green's function methods for quantum many-body systems. Nonetheless, the very existence of the Luttinger-Ward functional has been challenged by recent theoretical and numerical evidence. We provide a rigorously justified Luttinger-Ward formalism, in the context of Euclidean lattice field theory. Using the Luttinger-Ward functional, the free energy can be variationally minimized with respect to Green's functions in its domain. We then derive the widely used bold diagrammatic expansion rigorously, without relying on formal arguments such as partial resummation of bare diagrams to infinite order.

  20. The Rule of Three for Prizes in Science and the Bold Triptychs of Francis Bacon.

    Science.gov (United States)

    Goldstein, Joseph L

    2016-09-22

    For many scientific awards, such as Nobels and Laskers, the maximum number of recipients is three. This Rule of Three forces selection committees to make difficult decisions that increase the likelihood of singling out those individuals who open a new field and continue to lead it. The Rule of Three is reminiscent of art's three-panel triptych, a form that the modern master Francis Bacon used to distill complex stories in a bold way. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. BOLD VENTURE COMPUTATION SYSTEM for nuclear reactor core analysis, Version III

    Energy Technology Data Exchange (ETDEWEB)

    Vondy, D.R.; Fowler, T.B.; Cunningham, G.W. III.

    1981-06-01

    This report is a condensed documentation for VERSION III of the BOLD VENTURE COMPUTATION SYSTEM for nuclear reactor core analysis. An experienced analyst should be able to use this system routinely for solving problems by referring to this document. Individual reports must be referenced for details. This report covers basic input instructions and describes recent extensions to the modules as well as to the interface data file specifications. Some application considerations are discussed and an elaborate sample problem is used as an instruction aid. Instructions for creating the system on IBM computers are also given.

  2. BOLD VENTURE COMPUTATION SYSTEM for nuclear reactor core analysis, Version III

    International Nuclear Information System (INIS)

    Vondy, D.R.; Fowler, T.B.; Cunningham, G.W. III.

    1981-06-01

    This report is a condensed documentation for VERSION III of the BOLD VENTURE COMPUTATION SYSTEM for nuclear reactor core analysis. An experienced analyst should be able to use this system routinely for solving problems by referring to this document. Individual reports must be referenced for details. This report covers basic input instructions and describes recent extensions to the modules as well as to the interface data file specifications. Some application considerations are discussed and an elaborate sample problem is used as an instruction aid. Instructions for creating the system on IBM computers are also given

  3. Hemispheric asymmetry for affective stimulus processing in healthy subjects--a fMRI study.

    Directory of Open Access Journals (Sweden)

    Esther Beraha

    Full Text Available BACKGROUND: While hemispheric specialization of language processing is well established, lateralization of emotion processing is still under debate. Several conflicting hypotheses have been proposed, including right hemisphere hypothesis, valence asymmetry hypothesis and region-specific lateralization hypothesis. However, experimental evidence for these hypotheses remains inconclusive, partly because direct comparisons between hemispheres are scarce. METHODS: The present fMRI study systematically investigated functional lateralization during affective sti