Complexity of low-frequency blood oxygen level-dependent fluctuations covaries with local connectivity.

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Anderson, Jeffrey S; Zielinski, Brandon A; Nielsen, Jared A; Ferguson, Michael A

2014-04-01

Very low-frequency blood oxygen level-dependent (BOLD) fluctuations have emerged as a valuable tool for describing brain anatomy, neuropathology, and development. Such fluctuations exhibit power law frequency dynamics, with largest amplitude at lowest frequencies. The biophysical mechanisms generating such fluctuations are poorly understood. Using publicly available data from 1,019 subjects of age 7-30, we show that BOLD fluctuations exhibit temporal complexity that is linearly related to local connectivity (regional homogeneity), consistently and significantly covarying across subjects and across gray matter regions. This relationship persisted independently of covariance with gray matter density or standard deviation of BOLD signal. During late neurodevelopment, BOLD fluctuations were unchanged with age in association cortex while becoming more random throughout the rest of the brain. These data suggest that local interconnectivity may play a key role in establishing the complexity of low-frequency BOLD fluctuations underlying functional magnetic resonance imaging connectivity. Stable low-frequency power dynamics may emerge through segmentation and integration of connectivity during development of distributed large-scale brain networks. Copyright © 2013 Wiley Periodicals, Inc.

Correlations of noninvasive BOLD and TOLD MRI with pO2 and relevance to tumor radiation response.

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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.

Placental baseline conditions modulate the hyperoxic BOLD-MRI response.

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Sinding, Marianne; Peters, David A; Poulsen, Sofie S; Frøkjær, Jens B; Christiansen, Ole B; Petersen, Astrid; Uldbjerg, Niels; Sørensen, Anne

2018-01-01

Human pregnancies complicated by placental dysfunction may be characterized by a high hyperoxic Blood oxygen level-dependent (BOLD) MRI response. The pathophysiology behind this phenomenon remains to be established. The aim of this study was to evaluate whether it is associated with altered placental baseline conditions, including a lower oxygenation and altered tissue morphology, as estimated by the placental transverse relaxation time (T2*). We included 49 normal pregnancies (controls) and 13 pregnancies complicated by placental dysfunction (cases), defined by a birth weight baseline BOLD)/baseline BOLD) from a dynamic single-echo gradient-recalled echo (GRE) MRI sequence and the absolute ΔT2* (hyperoxic T2*- baseline T2*) from breath-hold multi-echo GRE sequences. In the control group, the relative ΔBOLD response increased during gestation from 5% in gestational week 20 to 20% in week 40. In the case group, the relative ΔBOLD response was significantly higher (mean Z-score 4.94; 95% CI 2.41, 7.47). The absolute ΔT2*, however, did not differ between controls and cases (p = 0.37), whereas the baseline T2* was lower among cases (mean Z-score -3.13; 95% CI -3.94, -2.32). Furthermore, we demonstrated a strong negative linear correlation between the Log 10 ΔBOLD response and the baseline T2* (r = -0.88, p baseline conditions, as the absolute increase in placental oxygenation (ΔT2*) does not differ between groups. Copyright © 2017 Elsevier Ltd. All rights reserved.

Wavelet entropy of BOLD time series : an application to Rolandic epilepsy

NARCIS (Netherlands)

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.

2017-01-01

Purpose: 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

Functional BOLD MRI: comparison of different field strengths in a motor task

International Nuclear Information System (INIS)

Meindl, T.; Born, C.; Britsch, S.; Reiser, M.; Schoenberg, S.

2008-01-01

The purpose was to evaluate the benefit of an increased field strength for functional magnetic resonance imaging in a motor task. Six right-handed volunteers were scanned at 1.5 T and 3.0 T using a motor task. Each experiment consisted of two runs with four activation blocks, each with right- and left-hand tapping. Analysis was done using BrainVoyagerQX registered . Differences between both field strengths concerning signal to noise (SNR), blood oxygen level-dependent (BOLD) signal change, functional sensitivity and BOLD contrast to noise (CNR) were tested using a paired t test. Delineation of activations and artifacts were graded by two independent readers. Results were further validated by means of a phantom study. The sensorimotor and premotor cortex, the supplementary motor area, subcortical and cerebellar structures were activated at each field strength. Additional activations of the right premotor cortex and right superior temporal gyrus were found at 3.0 T. Signal-to-noise, percentage of BOLD signal change, BOLD CNR and functional sensitivity improved at 3.0 T by a factor of up to 2.4. Functional imaging at 3.0 T results in detection of additional activated areas, increased SNR, BOLD signal change, functional sensitivity and BOLD CNR. (orig.)

To be so bold: boldness is repeatable and related to within individual behavioural variability in North Island robins.

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He, Ruchuan; Pagani-Núñez, Emilio; Chevallier, Clément; Barnett, Craig R A

2017-07-01

Behavioural research traditionally focusses on the mean responses of a group of individuals rather than variation in behaviour around the mean or among individuals. However, examining the variation in behaviour among and within individuals may also yield important insights into the evolution and maintenance of behaviour. Repeatability is the most commonly used measure of variability among individuals in behavioural research. However, there are other forms of variation within populations that have received less attention. One such measure is intraindividual variation in behaviour (IIV), which is a short-term fluctuation of within-individual behaviour. Such variation in behaviour might be important during interactions because it could decrease the ability of conspecific and heterospecific individuals to predict the behaviour of the subject, thus increasing the cost of the interaction. In this experiment, we made repeated measures of the latency of North Island robins to attack a prey in a novel situation (a form of boldness) and examined (i) repeatability of boldness (the propensity to take a risk), (ii) IIV of boldness, and (iii) whether there was a significant relationship between these two traits (a behavioural syndrome). We found that boldness was highly repeatable, that there were high levels of IIV in boldness, and that there was a negative relationship between boldness and IIV in boldness. This suggests that despite high levels of repeatability for this behaviour, there were also still significant differences in IIV among different individuals within the population. Moreover, bolder individuals had significantly less IIV in their boldness, which suggests that they were forming routines (which reduces behavioural variability) compared to shyer individuals. Our results definitively demonstrate that IIV itself varies across individuals and is linked with key behavioural traits, and we argue for the importance of future studies aimed at understanding its causes

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

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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

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

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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.

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

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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.

Volumetric BOLD fMRI simulation: from neurovascular coupling to multivoxel imaging

International Nuclear Information System (INIS)

Chen, Zikuan; Calhoun, Vince

2012-01-01

The blood oxygenation-level dependent (BOLD) functional magnetic resonance imaging (fMRI) modality has been numerically simulated by calculating single voxel signals. However, the observation on single voxel signals cannot provide information regarding the spatial distribution of the signals. Specifically, a single BOLD voxel signal simulation cannot answer the fundamental question: is the magnetic resonance (MR) image a replica of its underling magnetic susceptibility source? In this paper, we address this problem by proposing a multivoxel volumetric BOLD fMRI simulation model and a susceptibility expression formula for linear neurovascular coupling process, that allow us to examine the BOLD fMRI procedure from neurovascular coupling to MR image formation. Since MRI technology only senses the magnetism property, we represent a linear neurovascular-coupled BOLD state by a magnetic susceptibility expression formula, which accounts for the parameters of cortical vasculature, intravascular blood oxygenation level, and local neuroactivity. Upon the susceptibility expression of a BOLD state, we carry out volumetric BOLD fMRI simulation by calculating the fieldmap (established by susceptibility magnetization) and the complex multivoxel MR image (by intravoxel dephasing). Given the predefined susceptibility source and the calculated complex MR image, we compare the MR magnitude (phase, respectively) image with the predefined susceptibility source (the calculated fieldmap) by spatial correlation. The spatial correlation between the MR magnitude image and the magnetic susceptibility source is about 0.90 for the settings of T E = 30 ms, B 0 = 3 T, voxel size = 100 micron, vessel radius = 3 micron, and blood volume fraction = 2%. Using these parameters value, the spatial correlation between the MR phase image and the susceptibility-induced fieldmap is close to 1.00. Our simulation results show that the MR magnitude image is not an exact replica of the magnetic susceptibility

Blood oxygen level-dependent magnetic resonance imaging for detecting pathological patterns in patients with lupus nephritis: a preliminary study using gray-level co-occurrence matrix analysis.

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Shi, Huilan; Jia, Junya; Li, Dong; Wei, Li; Shang, Wenya; Zheng, Zhenfeng

2018-01-01

Objective Blood oxygen level-dependent magnetic resonance imaging (BOLD MRI) is a noninvasive technique useful in patients with renal disease. The current study was performed to determine whether BOLD MRI can contribute to the diagnosis of renal pathological patterns. Methods BOLD MRI was used to obtain functional magnetic resonance parameter R2* values. Gray-level co-occurrence matrixes (GLCMs) were generated for gray-scale maps. Several GLCM parameters were calculated and used to construct algorithmic models for renal pathological patterns. Results Histopathology and BOLD MRI were used to examine 12 patients. Two GLCM parameters, including correlation and energy, revealed differences among four groups of renal pathological patterns. Four Fisher's linear discriminant formulas were constructed using two variables, including the correlation at 45° and correlation at 90°. A cross-validation test showed that the formulas correctly predicted 28 of 36 samples, and the rate of correct prediction was 77.8%. Conclusions Differences in the texture characteristics of BOLD MRI in patients with lupus nephritis may be detected by GLCM analysis. Discriminant formulas constructed using GLCM parameters may facilitate prediction of renal pathological patterns.

Origins of intersubject variability of blood oxygenation level dependent and arterial spin labeling fMRI: implications for quantification of brain activity.

Science.gov (United States)

Gaxiola-Valdez, Ismael; Goodyear, Bradley G

2012-12-01

Accurate localization of brain activity using blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) has been challenged because of the large BOLD signal within distal veins. Arterial spin labeling (ASL) techniques offer greater sensitivity to the microvasculature but possess low temporal resolution and limited brain coverage. In this study, we show that the physiological origins of BOLD and ASL depend on whether percent change or statistical significance is being considered. For BOLD and ASL fMRI data collected during a simple unilateral hand movement task, we found that in the area of the contralateral motor cortex the centre of gravity (CoG) of the intersubject coefficient of variation (CV) of BOLD fMRI was near the brain surface for percent change in signal, whereas the CoG of the intersubject CV for Z-score was in close proximity of sites of brain activity for both BOLD and ASL. These findings suggest that intersubject variability of BOLD percent change is vascular in origin, whereas the origin of inter-subject variability of Z-score is neuronal for both BOLD and ASL. For longer duration tasks (12 s or greater), however, there was a significant correlation between BOLD and ASL percent change, which was not evident for short duration tasks (6 s). These findings suggest that analyses directly comparing percent change in BOLD signal between pre-defined regions of interest using short duration stimuli, as for example in event-related designs, may be heavily weighted by large-vessel responses rather than neuronal responses. Copyright © 2012 Elsevier Inc. All rights reserved.

BOLD magnetic resonance imaging in nephrology

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Hall ME

2018-03-01

Full Text Available Michael E Hall,1,2 Jennifer H Jordan,3 Luis A Juncos,1,2 W Gregory Hundley,3 John E Hall2 1Department of Medicine, University of Mississippi Medical Center, Jackson, MS, USA; 2Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS, USA; 3Department of Internal Medicine, Section on Cardiovascular Medicine, Wake Forest University School of Medicine, Winston-Salem, NC, USA Abstract: Magnetic resonance (MR imaging, a non-invasive modality that provides anatomic and physiologic information, is increasingly used for diagnosis of pathophysiologic conditions and for understanding renal physiology in humans. Although functional MR imaging methods were pioneered to investigate the brain, they also offer powerful techniques for investigation of other organ systems such as the kidneys. However, imaging the kidneys provides unique challenges due to potential complications from contrast agents. Therefore, development of non-contrast techniques to study kidney anatomy and physiology is important. Blood oxygen level-dependent (BOLD MR is a non-contrast imaging technique that provides functional information related to renal tissue oxygenation in various pathophysiologic conditions. Here we discuss technical considerations, clinical uses and future directions for use of BOLD MR as well as complementary MR techniques to better understand renal pathophysiology. Our intent is to summarize kidney BOLD MR applications for the clinician rather than focusing on the complex physical challenges that functional MR imaging encompasses; however, we briefly discuss some of those issues. Keywords: functional MRI, kidney, oxygenation, chronic kidney disease 

Quantifying the microvascular origin of BOLD-fMRI from first principles with two-photon microscopy and an oxygen-sensitive nanoprobe.

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Gagnon, Louis; Sakadžić, Sava; Lesage, Frédéric; Musacchia, Joseph J; Lefebvre, Joël; Fang, Qianqian; Yücel, Meryem A; Evans, Karleyton C; Mandeville, Emiri T; Cohen-Adad, Jülien; Polimeni, Jonathan R; Yaseen, Mohammad A; Lo, Eng H; Greve, Douglas N; Buxton, Richard B; Dale, Anders M; Devor, Anna; Boas, David A

2015-02-25

The blood oxygenation level-dependent (BOLD) contrast is widely used in functional magnetic resonance imaging (fMRI) studies aimed at investigating neuronal activity. However, the BOLD signal reflects changes in blood volume and oxygenation rather than neuronal activity per se. Therefore, understanding the transformation of microscopic vascular behavior into macroscopic BOLD signals is at the foundation of physiologically informed noninvasive neuroimaging. Here, we use oxygen-sensitive two-photon microscopy to measure the BOLD-relevant microvascular physiology occurring within a typical rodent fMRI voxel and predict the BOLD signal from first principles using those measurements. The predictive power of the approach is illustrated by quantifying variations in the BOLD signal induced by the morphological folding of the human cortex. This framework is then used to quantify the contribution of individual vascular compartments and other factors to the BOLD signal for different magnet strengths and pulse sequences. Copyright © 2015 the authors 0270-6474/15/353663-13$15.00/0.

Zolpidem reduces the blood oxygen level-dependent signal during visual system stimulation.

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Licata, Stephanie C; Lowen, Steven B; Trksak, George H; Maclean, Robert R; Lukas, Scott E

2011-08-15

Zolpidem is a short-acting imidazopyridine hypnotic that binds at the benzodiazepine binding site on specific GABA(A) receptors to enhance fast inhibitory neurotransmission. The behavioral and receptor pharmacology of zolpidem has been studied extensively, but little is known about its neuronal substrates in vivo. In the present within-subject, double-blind, and placebo-controlled study, blood oxygen level-dependent functional magnetic resonance imaging (BOLD fMRI) at 3 Tesla was used to assess the effects of zolpidem within the brain. Healthy participants (n=12) were scanned 60 min after acute oral administration of zolpidem (0, 5, 10, or 20mg), and changes in BOLD signal were measured in the visual cortex during presentation of a flashing checkerboard. Heart rate and oxygen saturation were monitored continuously throughout the session. Zolpidem (10 and 20mg) reduced the robust visual system activation produced by presentation of this stimulus, but had no effects on physiological activity during the fMRI scan. Zolpidem's modulation of the BOLD signal within the visual cortex is consistent with the abundant distribution of GABA(A) receptors localized in this region, as well as previous studies showing a relationship between increased GABA-mediated neuronal inhibition and a reduction in BOLD activation. Copyright © 2011 Elsevier Inc. All rights reserved.

Zolpidem reduces the blood oxygen level-dependent signal during visual system stimulation

Science.gov (United States)

Licata, Stephanie C.; Lowen, Steven B.; Trksak, George H.; MacLean, Robert R.; Lukas, Scott E.

2011-01-01

Zolpidem is a short-acting imidazopyridine hypnotic that binds at the benzodiazepine binding site on specific GABAA receptors to enhance fast inhibitory neurotransmission. The behavioral and receptor pharmacology of zolpidem has been studied extensively, but little is known about its neuronal substrates in vivo. In the present within-subject, double-blind, and placebo-controlled study, blood oxygen level-dependent functional magnetic resonance imaging (BOLD fMRI) at 3 Tesla was used to assess the effects of zolpidem within the brain. Healthy participants (n=12) were scanned 60 minutes after acute oral administration of zolpidem (0, 5, 10, or 20 mg), and changes in BOLD signal were measured in the visual cortex during presentation of a flashing checkerboard. Heart rate and oxygen saturation were monitored continuously throughout the session. Zolpidem (10 and 20 mg) reduced the robust visual system activation produced by presentation of this stimulus, but had no effects on physiological activity during the fMRI scan. Zolpidem’s modulation of the BOLD signal within the visual cortex is consistent with the abundant distribution of GABAA receptors localized in this region, as well as previous studies showing a relationship between increased GABA-mediated neuronal inhibition and a reduction in BOLD activation. PMID:21640782

BOLD cardiovascular magnetic resonance at 3.0 tesla in myocardial ischemia.

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Manka, Robert; Paetsch, Ingo; Schnackenburg, Bernhard; Gebker, Rolf; Fleck, Eckart; Jahnke, Cosima

2010-09-22

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). 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). 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 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.

Methods of Blood Oxygen Level-Dependent Magnetic Resonance Imaging Analysis for Evaluating Renal Oxygenation

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Fen Chen

2018-03-01

Full Text Available Blood oxygen level-dependent magnetic resonance imaging (BOLD MRI has recently been utilized as a noninvasive tool for evaluating renal oxygenation. Several methods have been proposed for analyzing BOLD images. Regional ROI selection is the earliest and most widely used method for BOLD analysis. In the last 20 years, many investigators have used this method to evaluate cortical and medullary oxygenation in patients with ischemic nephropathy, hypertensive nephropathy, diabetic nephropathy, chronic kidney disease (CKD, acute kidney injury and renal allograft rejection. However, clinical trials of BOLD MRI using regional ROI selection revealed that it was difficult to distinguish the renal cortico-medullary zones with this method, and that it was susceptible to observer variability. To overcome these deficiencies, several new methods were proposed for analyzing BOLD images, including the compartmental approach, fractional hypoxia method, concentric objects (CO method and twelve-layer concentric objects (TLCO method. The compartmental approach provides an algorithm to judge whether the pixel belongs to the cortex or medulla. Fractional kidney hypoxia, measured by using BOLD MRI, was negatively correlated with renal blood flow, tissue perfusion and glomerular filtration rate (GFR in patients with atherosclerotic renal artery stenosis. The CO method divides the renal parenchyma into six or twelve layers of thickness in each coronal slice of BOLD images and provides a R2* radial profile curve. The slope of the R2* curve associated positively with eGFR in CKD patients. Indeed, each method invariably has advantages and disadvantages, and there is generally no consensus method so far. Undoubtedly, analytic approaches for BOLD MRI with better reproducibility would assist clinicians in monitoring the degree of kidney hypoxia and thus facilitating timely reversal of tissue hypoxia.

PARTICLE FILTERING WITH SEQUENTIAL PARAMETER LEARNING FOR NONLINEAR BOLD fMRI SIGNALS.

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Xia, Jing; Wang, Michelle Yongmei

Analyzing the blood oxygenation level dependent (BOLD) effect in the functional magnetic resonance imaging (fMRI) is typically based on recent ground-breaking time series analysis techniques. This work represents a significant improvement over existing approaches to system identification using nonlinear hemodynamic models. It is important for three reasons. First, instead of using linearized approximations of the dynamics, we present a nonlinear filtering based on the sequential Monte Carlo method to capture the inherent nonlinearities in the physiological system. Second, we simultaneously estimate the hidden physiological states and the system parameters through particle filtering with sequential parameter learning to fully take advantage of the dynamic information of the BOLD signals. Third, during the unknown static parameter learning, we employ the low-dimensional sufficient statistics for efficiency and avoiding potential degeneration of the parameters. The performance of the proposed method is validated using both the simulated data and real BOLD fMRI data.

Arterial Spin Labeling and Blood Oxygen Level-Dependent MRI Cerebrovascular Reactivity in Cerebrovascular Disease

DEFF Research Database (Denmark)

Smeeing, Diederik P J; Hendrikse, Jeroen; Petersen, Esben T

2016-01-01

BACKGROUND: The cerebrovascular reactivity (CVR) results of blood oxygen level-dependent (BOLD) and arterial spin labeling (ASL) MRI studies performed in patients with cerebrovascular disease (steno-occlusive vascular disease or stroke) were systematically reviewed. SUMMARY: Thirty-one articles...... found a significant lower ASL CVR in the ipsilateral hemispheres of patients compared to controls. KEY MESSAGES: This review brings support for a reduced BOLD and ASL CVR in the ipsilateral hemisphere of patients with cerebrovascular disease. We suggest that future studies will be performed in a uniform...... way so reference values can be established and could be used to guide treatment decisions in patients with cerebrovascular disease....

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

Synthetic generation of myocardial blood-oxygen-level-dependent MRI time series via structural sparse decomposition modeling.

Science.gov (United States)

Rusu, Cristian; Morisi, Rita; Boschetto, Davide; Dharmakumar, Rohan; Tsaftaris, Sotirios A

2014-07-01

This paper aims to identify approaches that generate appropriate synthetic data (computer generated) for cardiac phase-resolved blood-oxygen-level-dependent (CP-BOLD) MRI. CP-BOLD MRI is a new contrast agent- and stress-free approach for examining changes in myocardial oxygenation in response to coronary artery disease. However, since signal intensity changes are subtle, rapid visualization is not possible with the naked eye. Quantifying and visualizing the extent of disease relies on myocardial segmentation and registration to isolate the myocardium and establish temporal correspondences and ischemia detection algorithms to identify temporal differences in BOLD signal intensity patterns. If transmurality of the defect is of interest pixel-level analysis is necessary and thus a higher precision in registration is required. Such precision is currently not available affecting the design and performance of the ischemia detection algorithms. In this work, to enable algorithmic developments of ischemia detection irrespective to registration accuracy, we propose an approach that generates synthetic pixel-level myocardial time series. We do this by 1) modeling the temporal changes in BOLD signal intensity based on sparse multi-component dictionary learning, whereby segmentally derived myocardial time series are extracted from canine experimental data to learn the model; and 2) demonstrating the resemblance between real and synthetic time series for validation purposes. We envision that the proposed approach has the capacity to accelerate development of tools for ischemia detection while markedly reducing experimental costs so that cardiac BOLD MRI can be rapidly translated into the clinical arena for the noninvasive assessment of ischemic heart disease.

The dependencies of fronto-parietal BOLD responses evoked by covert visual search suggest eye-centred coding.

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Atabaki, A; Dicke, P W; Karnath, H-O; Thier, P

2013-04-01

Visual scenes explored covertly are initially represented in a retinal frame of reference (FOR). On the other hand, 'later' stages of the cortical network allocating spatial attention most probably use non-retinal or non-eye-centred representations as they may ease the integration of different sensory modalities for the formation of supramodal representations of space. We tested if the cortical areas involved in shifting covert attention are based on eye-centred or non-eye-centred coding by using functional magnetic resonance imaging. Subjects were scanned while detecting a target item (a regularly oriented 'L') amidst a set of distractors (rotated 'L's). The array was centred either 5° right or left of the fixation point, independent of eye-gaze orientation, the latter varied in three steps: straight relative to the head, 10° left or 10° right. A quantitative comparison of the blood-oxygen-level-dependent (BOLD) responses for the three eye-gaze orientations revealed stronger BOLD responses in the right intraparietal sulcus (IPS) and the right frontal eye field (FEF) for search in the contralateral (i.e. left) eye-centred space, independent of whether the array was located in the right or left head-centred hemispace. The left IPS showed the reverse pattern, i.e. an activation by search in the right eye-centred hemispace. In other words, the IPS and the right FEF, members of the cortical network underlying covert search, operate in an eye-centred FOR. © 2013 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

Application of language blood oxygenation level dependent functional MRI in the navigating operation of neurosurgery

International Nuclear Information System (INIS)

Liu Shuyong; Li Min; Yao Chengjun; Geng Daoying

2011-01-01

Objective: To verify the accuracy of blood oxygenation level dependent (BOLD)-based activation using electrocortical stimulation mapping (ESM) and explore the value of language fMRI in the navigating operation of neurosurgery. Methods: In 8 cases with brain tumors, BOLD-fMRI examinations were done before the operations. Under the state of awake anesthesia,the patients were aroused and ESM was conducted. Point-to-point comparison between the BOLD signal activations and the ESM was carried out under the surveillance of the neuro-navigation technology. In order to observe the sensibility and specificity of BOLD activations, the location of BOLD activations and the point of ESM was compared to calculate the stimulating positive points inside the regions of BOLD signals (real positive), outside BOLD regions (pseudo- negative), the stimulating negative points inside the regions of BOLD signals (pseudo-positive), and outside BOLD region (real negative). Two kinds of criteria for assessment were used. One was that the positive stimulating points were located in BOLD regions, and the other was that the positive stimulating points were located within 1 cm around the range of BOLD regions. Removal of the lesions were conducted with the tissue 1 cm around the language region preserved, and the cortex inside 0.5-1.0 cm distance from the positive points were retained. Results: Of the 8 cases, only 6 finished the tasks. Among them, 3 cases were with astrocytoma of grade 2, 2 were with astrocytoma of grade 3, and one with glioblastoma. The total number of stimulating points was 48, among which the positive points were 11. When the first criteria was applied, the sensitivity was 72.7% (8/11), and the specificity was 81.8% (30/37). When the second criteria was applied, the sensitivity was 82.0% (9/11), and the specificity was 75.6% (28/37). Follow-up after operation showed no aphasia occurred. Conclusions: BOLD-fMRI had a high sensitivity and specificity in displaying the language

Calibrating the BOLD signal during a motor task using an extended fusion model incorporating DOT, BOLD and ASL data

Science.gov (United States)

Yücel, Meryem A.; Huppert, Theodore J.; Boas, David A.; Gagnon, Louis

2012-01-01

Multimodal imaging improves the accuracy of the localization and the quantification of brain activation when measuring different manifestations of the hemodynamic response associated with cerebral activity. In this study, we incorporated cerebral blood flow (CBF) changes measured with arterial spin labeling (ASL), Diffuse Optical Tomography (DOT) and blood oxygen level-dependent (BOLD) recordings to reconstruct changes in oxy- (ΔHbO2) and deoxyhemoglobin (ΔHbR). Using the Grubb relation between relative changes in CBF and cerebral blood volume (CBV), we incorporated the ASL measurement as a prior to the total hemoglobin concentration change (ΔHbT). We applied this ASL fusion model to both synthetic data and experimental multimodal recordings during a 2-sec finger-tapping task. Our results show that the new approach is very powerful in estimating ΔHbO2 and ΔHbR with high spatial and quantitative accuracy. Moreover, our approach allows the computation of baseline total hemoglobin concentration (HbT0) as well as of the BOLD calibration factor M on a single subject basis. We obtained an average HbT0 of 71 μM, an average M value of 0.18 and an average increase of 13 % in cerebral metabolic rate of oxygen (CMRO2), all of which are in agreement with values previously reported in the literature. Our method yields an independent measurement of M, which provides an alternative measurement to validate the hypercapnic calibration of the BOLD signal. PMID:22546318

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.

Determination of relative CMRO2 from CBF and BOLD changes: significant increase of oxygen consumption rate during visual stimulation

DEFF Research Database (Denmark)

Kim, S.G.; Rostrup, Egill; Larsson, H.B.

1999-01-01

signal changes were measured simultaneously using the flow-sensitive alternating inversion recovery (FAIR) technique. During hypercapnia established by an end-tidal CO2 increase of 1.46 kPa, CBF in the visual cortex increased by 47.3 +/- 17.3% (mean +/- SD; n = 9), and deltaR2* was -0.478 +/- 0.147 sec......The blood oxygenation level-dependent (BOLD) effect in functional magnetic resonance imaging depends on at least partial uncoupling between cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2) changes. By measuring CBF and BOLD simultaneously, the relative change in CMRO2 can...

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.

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

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Domsch, Sebastian; Mie, Moritz B.; Schad, Lothar R. [Heidelberg Univ., Medical Faculty Mannheim (Germany). Computer Assisted Clinical Medicine; Wenz, Frederik [Heidelberg Univ., Medical Faculty Mannheim (Germany). Dept. of Radiation Oncology

2014-10-01

Introduction: 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. Methods: The protocol consisted of a gradient-echo sampled spin-echo sequence (GESSE), a T{sub 2}-weighted Carr-Purcell-Meiboom-Gill (CPMG) sequence, and a T{sub 2}{sup *}-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. Results: 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. Conclusion: 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. (orig.)

Identifying and characterizing systematic temporally-lagged BOLD artifacts.

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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.

Cerebrovascular blood oxygenation level dependent pulsatility at baseline and following acute exercise among healthy adolescents.

Science.gov (United States)

Theyers, Athena E; Goldstein, Benjamin I; Metcalfe, Arron Ws; Robertson, Andrew D; MacIntosh, Bradley J

2018-01-01

Arterial stiffness is linked to cerebral small vessel damage and neurodegeneration, but barriers to accessing deep cerebrovascular anatomy limit our ability to assess the brain. This study describes an adaptation of a cardiac-related scrubbing method as a means of generating blood oxygenation level-dependent pulsatility maps based on the cardiac cycle. We examine BOLD pulsatility at rest, based on the non-parametric deviation from null metric, as well as changes following acute physiological stress from 20 min of moderate-intensity cycling in 45 healthy adolescents. We evaluate the influence of repetition time (TR) and echo time (TE) using simulated and multi-echo empirical data, respectively. There were tissue-specific and voxel-wise BOLD pulsatility decreases 20 min following exercise cessation. BOLD pulsatility detection was comparable over a range of TR and TE values when scan volumes were kept constant; however, short TRs (≤500 ms) and TEs (∼14 ms) acquisitions would yield the most efficient detection. Results suggest cardiac-related BOLD pulsatility may represent a robust and easily adopted method of mapping cerebrovascular pulsatility with voxel-wise resolution.

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

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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.)

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.

Zolpidem reduces the blood oxygen level-dependent signal during visual system stimulation

OpenAIRE

Licata, Stephanie C.; Lowen, Steven B.; Trksak, George H.; MacLean, Robert R.; Lukas, Scott E.

2011-01-01

Zolpidem is a short-acting imidazopyridine hypnotic that binds at the benzodiazepine binding site on specific GABAA receptors to enhance fast inhibitory neurotransmission. The behavioral and receptor pharmacology of zolpidem has been studied extensively, but little is known about its neuronal substrates in vivo. In the present within-subject, double-blind, and placebo-controlled study, blood oxygen level-dependent functional magnetic resonance imaging (BOLD fMRI) at 3 Tesla was used to assess...

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.

Correlative BOLD MR imaging of stages of synovitis in a rabbit model of antigen-induced arthritis

International Nuclear Information System (INIS)

Doria, Andrea S.; Crawley, Adrian; Gahunia, Harpal; Rayner, Tammy; Tassos, Vivian; Zhong, Anguo; Moineddin, Rahim; Pritzker, Kenneth; Mendes, Maria; Jong, Roland; Salter, Robert B.

2012-01-01

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.)

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.)

Simultaneous Imaging of CBF Change and BOLD with Saturation-Recovery-T1 Method.

Directory of Open Access Journals (Sweden)

Xiao Wang

Full Text Available A neuroimaging technique based on the saturation-recovery (SR-T1 MRI method was applied for simultaneously imaging blood oxygenation level dependence (BOLD contrast and cerebral blood flow change (ΔCBF, which is determined by CBF-sensitive T1 relaxation rate change (ΔR1CBF. This technique was validated by quantitatively examining the relationships among ΔR1CBF, ΔCBF, BOLD and relative CBF change (rCBF, which was simultaneously measured by laser Doppler flowmetry under global ischemia and hypercapnia conditions, respectively, in the rat brain. It was found that during ischemia, BOLD decreased 23.1±2.8% in the cortical area; ΔR1CBF decreased 0.020±0.004s-1 corresponding to a ΔCBF decrease of 1.07±0.24 ml/g/min and 89.5±1.8% CBF reduction (n=5, resulting in a baseline CBF value (=1.18 ml/g/min consistent with the literature reports. The CBF change quantification based on temperature corrected ΔR1CBF had a better accuracy than apparent R1 change (ΔR1app; nevertheless, ΔR1app without temperature correction still provides a good approximation for quantifying CBF change since perfusion dominates the evolution of the longitudinal relaxation rate (R1app. In contrast to the excellent consistency between ΔCBF and rCBF measured during and after ischemia, the BOLD change during the post-ischemia period was temporally disassociated with ΔCBF, indicating distinct CBF and BOLD responses. Similar results were also observed for the hypercapnia study. The overall results demonstrate that the SR-T1 MRI method is effective for noninvasive and quantitative imaging of both ΔCBF and BOLD associated with physiological and/or pathological changes.

Distinction between Neural and Vascular BOLD Oscillations and Intertwined Heart Rate Oscillations at 0.1 Hz in the Resting State and during Movement.

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Gert Pfurtscheller

Full Text Available In the resting state, blood oxygen level-dependent (BOLD oscillations with a frequency of about 0.1 Hz are conspicuous. Whether their origin is neural or vascular is not yet fully understood. Furthermore, it is not clear whether these BOLD oscillations interact with slow oscillations in heart rate (HR. To address these two questions, we estimated phase-locking (PL values between precentral gyrus (PCG and insula in 25 scanner-naïve individuals during rest and stimulus-paced finger movements in both hemispheres. PL was quantified in terms of time delay and duration in the frequency band 0.07 to 0.13 Hz. Results revealed both positive and negative time delays. Positive time delays characterize neural BOLD oscillations leading in the PCG, whereas negative time delays represent vascular BOLD oscillations leading in the insula. About 50% of the participants revealed positive time delays distinctive for neural BOLD oscillations, either with short or long unilateral or bilateral phase-locking episodes. An expected preponderance of neural BOLD oscillations was found in the left hemisphere during right-handed movement and unexpectedly in the right hemisphere during rest. Only neural BOLD oscillations were significantly associated with heart rate variability (HRV in the 0.1-Hz range in the first resting state. It is well known that participating in magnetic resonance imaging (MRI studies may be frightening and cause anxiety. In this respect it is important to note that the most significant hemispheric asymmetry (p<0.002 with a right-sided dominance of neural BOLD and a left-sided dominance of vascular BOLD oscillations was found in the first resting session in the scanner-naïve individuals. Whether the enhanced left-sided perfusion (dominance of vascular BOLD or the right-sided dominance of neural BOLD is related to the increased level of anxiety, attention or stress needs further research.

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

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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

Blood oxygen-level dependent functional assessment of cerebrovascular reactivity: Feasibility for intraoperative 3 Tesla MRI.

Science.gov (United States)

Fierstra, Jorn; Burkhardt, Jan-Karl; van Niftrik, Christiaan Hendrik Bas; Piccirelli, Marco; Pangalu, Athina; Kocian, Roman; Neidert, Marian Christoph; Valavanis, Antonios; Regli, Luca; Bozinov, Oliver

2017-02-01

To assess the feasibility of functional blood oxygen-level dependent (BOLD) MRI to evaluate intraoperative cerebrovascular reactivity (CVR) at 3 Tesla field strength. Ten consecutive neurosurgical subjects scheduled for a clinical intraoperative MRI examination were enrolled in this study. In addition to the clinical protocol a BOLD sequence was implemented with three cycles of 44 s apnea to calculate CVR values on a voxel-by-voxel basis throughout the brain. The CVR range was then color-coded and superimposed on an anatomical volume to create high spatial resolution CVR maps. Ten subjects (mean age 34.8 ± 13.4; 2 females) uneventfully underwent the intraoperative BOLD protocol, with no complications occurring. Whole-brain CVR for all subjects was (mean ± SD) 0.69 ± 0.42, whereas CVR was markedly higher for tumor subjects as compared to vascular subjects, 0.81 ± 0.44 versus 0.33 ± 0.10, respectively. Furthermore, color-coded functional maps could be robustly interpreted for a whole-brain assessment of CVR. We demonstrate that intraoperative BOLD MRI is feasible in creating functional maps to assess cerebrovascular reactivity throughout the brain in subjects undergoing a neurosurgical procedure. Magn Reson Med 77:806-813, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

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

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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.

Modulation of cognitive control levels via manipulation of saccade trial-type probability assessed with event-related BOLD fMRI.

Science.gov (United States)

Pierce, Jordan E; McDowell, Jennifer E

2016-02-01

Cognitive control supports flexible behavior adapted to meet current goals and can be modeled through investigation of saccade tasks with varying cognitive demands. Basic prosaccades (rapid glances toward a newly appearing stimulus) are supported by neural circuitry, including occipital and posterior parietal cortex, frontal and supplementary eye fields, and basal ganglia. These trials can be contrasted with complex antisaccades (glances toward the mirror image location of a stimulus), which are characterized by greater functional magnetic resonance imaging (MRI) blood oxygenation level-dependent (BOLD) signal in the aforementioned regions and recruitment of additional regions such as dorsolateral prefrontal cortex. The current study manipulated the cognitive demands of these saccade tasks by presenting three rapid event-related runs of mixed saccades with a varying probability of antisaccade vs. prosaccade trials (25, 50, or 75%). Behavioral results showed an effect of trial-type probability on reaction time, with slower responses in runs with a high antisaccade probability. Imaging results exhibited an effect of probability in bilateral pre- and postcentral gyrus, bilateral superior temporal gyrus, and medial frontal gyrus. Additionally, the interaction between saccade trial type and probability revealed a strong probability effect for prosaccade trials, showing a linear increase in activation parallel to antisaccade probability in bilateral temporal/occipital, posterior parietal, medial frontal, and lateral prefrontal cortex. In contrast, antisaccade trials showed elevated activation across all runs. Overall, this study demonstrated that improbable performance of a typically simple prosaccade task led to augmented BOLD signal to support changing cognitive control demands, resulting in activation levels similar to the more complex antisaccade task. Copyright © 2016 the American Physiological Society.

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...

Electrophysiological correlates of the BOLD signal for EEG-informed fMRI

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Murta, Teresa; Leite, Marco; Carmichael, David W; Figueiredo, Patrícia; Lemieux, Louis

2015-01-01

Electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) are important tools in cognitive and clinical neuroscience. Combined EEG–fMRI has been shown to help to characterise brain networks involved in epileptic activity, as well as in different sensory, motor and cognitive functions. A good understanding of the electrophysiological correlates of the blood oxygen level-dependent (BOLD) signal is necessary to interpret fMRI maps, particularly when obtained in combination with EEG. We review the current understanding of electrophysiological–haemodynamic correlates, during different types of brain activity. We start by describing the basic mechanisms underlying EEG and BOLD signals and proceed by reviewing EEG-informed fMRI studies using fMRI to map specific EEG phenomena over the entire brain (EEG–fMRI mapping), or exploring a range of EEG-derived quantities to determine which best explain colocalised BOLD fluctuations (local EEG–fMRI coupling). While reviewing studies of different forms of brain activity (epileptic and nonepileptic spontaneous activity; cognitive, sensory and motor functions), a significant attention is given to epilepsy because the investigation of its haemodynamic correlates is the most common application of EEG-informed fMRI. Our review is focused on EEG-informed fMRI, an asymmetric approach of data integration. We give special attention to the invasiveness of electrophysiological measurements and the simultaneity of multimodal acquisitions because these methodological aspects determine the nature of the conclusions that can be drawn from EEG-informed fMRI studies. We emphasise the advantages of, and need for, simultaneous intracranial EEG–fMRI studies in humans, which recently became available and hold great potential to improve our understanding of the electrophysiological correlates of BOLD fluctuations. PMID:25277370

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

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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...

When BOLD is thicker than water: processing social information about kin and friends at different levels of the social network.

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Wlodarski, Rafael; Dunbar, Robin I M

2016-12-01

The aim of this study was to examine differences in the neural processing of social information about kin and friends at different levels of closeness and social network level. Twenty-five female participants engaged in a cognitive social task involving different individuals in their social network while undergoing functional magnetic resonance imaging scanning to detect BOLD (Blood Oxygen Level Dependent) signals changes. Greater levels of activation occurred in several regions of the brain previously associated with social cognition when thinking about friends than when thinking about kin, including the posterior cingulate cortex (PCC) and the ventral medial prefrontal cortex (vMPFC). Linear parametric analyses across network layers further showed that, when it came to thinking about friends, activation increased in the vMPFC, lingual gyrus, and sensorimotor cortex as individuals thought about friends at closer layers of the network. These findings suggest that maintaining friendships may be more cognitively exacting than maintaining kin relationships. © The Author (2016). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

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

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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

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

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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.

Mapping Transient Hyperventilation Induced Alterations with Estimates of the Multi-Scale Dynamics of BOLD Signal.

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Kiviniemi, Vesa; Remes, Jukka; Starck, Tuomo; Nikkinen, Juha; Haapea, Marianne; Silven, Olli; Tervonen, Osmo

2009-01-01

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(alpha). 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 alpha, fractal dimension D(f), 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 alpha was able to differentiate also blood vessels from grey matter changes. D(f) 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.

Cortical Network Models of Firing Rates in the Resting and Active States Predict BOLD Responses.

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Maxwell R Bennett

Full Text Available Measurements of blood oxygenation level dependent (BOLD signals have produced some surprising observations. One is that their amplitude is proportional to the entire activity in a region of interest and not just the fluctuations in this activity. Another is that during sleep and anesthesia the average BOLD correlations between regions of interest decline as the activity declines. Mechanistic explanations of these phenomena are described here using a cortical network model consisting of modules with excitatory and inhibitory neurons, taken as regions of cortical interest, each receiving excitatory inputs from outside the network, taken as subcortical driving inputs in addition to extrinsic (intermodular connections, such as provided by associational fibers. The model shows that the standard deviation of the firing rate is proportional to the mean frequency of the firing when the extrinsic connections are decreased, so that the mean BOLD signal is proportional to both as is observed experimentally. The model also shows that if these extrinsic connections are decreased or the frequency of firing reaching the network from the subcortical driving inputs is decreased, or both decline, there is a decrease in the mean firing rate in the modules accompanied by decreases in the mean BOLD correlations between the modules, consistent with the observed changes during NREM sleep and under anesthesia. Finally, the model explains why a transient increase in the BOLD signal in a cortical area, due to a transient subcortical input, gives rises to responses throughout the cortex as observed, with these responses mediated by the extrinsic (intermodular connections.

Associations of resting-state fMRI functional connectivity with flow-BOLD coupling and regional vasculature.

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Tak, Sungho; Polimeni, Jonathan R; Wang, Danny J J; Yan, Lirong; Chen, J Jean

2015-04-01

There has been tremendous interest in applying functional magnetic resonance imaging-based resting-state functional connectivity (rs-fcMRI) measurements to the study of brain function. However, a lack of understanding of the physiological mechanisms of rs-fcMRI limits their ability to interpret rs-fcMRI findings. In this work, the authors examine the regional associations between rs-fcMRI estimates and dynamic coupling between the blood oxygenation level-dependent (BOLD) and cerebral blood flow (CBF), as well as resting macrovascular volume. Resting-state BOLD and CBF data were simultaneously acquired using a dual-echo pseudocontinuous arterial spin labeling (pCASL) technique, whereas macrovascular volume fraction was estimated using time-of-flight MR angiography. Functional connectivity within well-known functional networks—including the default mode, frontoparietal, and primary sensory-motor networks—was calculated using a conventional seed-based correlation approach. They found the functional connectivity strength to be significantly correlated with the regional increase in CBF-BOLD coupling strength and inversely proportional to macrovascular volume fraction. These relationships were consistently observed within all functional networks considered. Their findings suggest that highly connected networks observed using rs-fcMRI are not likely to be mediated by common vascular drainage linking distal cortical areas. Instead, high BOLD functional connectivity is more likely to reflect tighter neurovascular connections, attributable to neuronal pathways.

Spatiotopic coding of BOLD signal in human visual cortex depends on spatial attention.

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Sofia Crespi

Full Text Available The neural substrate of the phenomenological experience of a stable visual world remains obscure. One possible mechanism would be to construct spatiotopic neural maps where the response is selective to the position of the stimulus in external space, rather than to retinal eccentricities, but evidence for these maps has been inconsistent. Here we show, with fMRI, that when human subjects perform concomitantly a demanding attentive task on stimuli displayed at the fovea, BOLD responses evoked by moving stimuli irrelevant to the task were mostly tuned in retinotopic coordinates. However, under more unconstrained conditions, where subjects could attend easily to the motion stimuli, BOLD responses were tuned not in retinal but in external coordinates (spatiotopic selectivity in many visual areas, including MT, MST, LO and V6, agreeing with our previous fMRI study. These results indicate that spatial attention may play an important role in mediating spatiotopic selectivity.

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

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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.

Distinct BOLD Activation Profiles Following Central and Peripheral Oxytocin Administration in Awake Rats.

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Ferris, Craig F; Yee, Jason R; Kenkel, William M; Dumais, Kelly Marie; Moore, Kelsey; Veenema, Alexa H; Kulkarni, Praveen; Perkybile, Allison M; Carter, C Sue

2015-01-01

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 imaging (fMRI) in awake rats imaged at 7.0 T. These data were compared to OT (1 μg/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.

Navigator-gated 3D blood oxygen level-dependent CMR at 3.0-T for detection of stress-induced myocardial ischemic reactions.

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Jahnke, Cosima; Gebker, Rolf; Manka, Robert; Schnackenburg, Bernhard; Fleck, Eckart; Paetsch, Ingo

2010-04-01

This study determined the value of navigator-gated 3-dimensional blood oxygen level-dependent (BOLD) cardiac magnetic resonance (CMR) at 3.0-T for the detection of stress-induced myocardial ischemic reactions. Although BOLD CMR has been introduced for characterization of myocardial oxygenation status, previously reported CMR approaches suffered from a low signal-to-noise ratio and motion-related artifacts with impaired image quality and a limited diagnostic value in initial patient studies. Fifty patients with suspected or known coronary artery disease underwent CMR at 3.0-T followed by invasive X-ray angiography within 48 h. Three-dimensional BOLD images were acquired during free breathing with full coverage of the left ventricle in a short-axis orientation. The BOLD imaging was performed at rest and under adenosine stress, followed by stress and rest first-pass perfusion and delayed enhancement imaging. Quantitative coronary X-ray angiography (QCA) was used for coronary stenosis definition (diameter reduction > or =50%). The BOLD and first-pass perfusion images were semiquantitatively evaluated (for BOLD imaging, signal intensity differences between stress and rest [DeltaSI]; for perfusion imaging, myocardial perfusion reserve index [MPRI]). The image quality of BOLD CMR at rest and during adenosine stress was considered good to excellent in 90% and 84% of the patients, respectively. The DeltaSI measurements differed significantly between normal myocardium, myocardium supplied by a stenotic coronary artery, and infarcted myocardium (p exogenous contrast-enhancement studies. Copyright 2010 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

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

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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.

Using BOLD imaging to measure renal oxygenation dynamics in rats injected with diuretics

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Kusakabe, Yoshinori; Matsushita, Taro; Honda, Saori; Okada, Sakie; Murase, Kenya

2010-01-01

We used blood oxygenation level-dependent magnetic resonance imaging (BOLD MRI) to measure renal oxygenation dynamics in rats injected with diuretics and evaluated diuretic effect on renal oxygenation. We performed BOLD MRI studies in 32 rats using a 1.5-tesla MR imaging system for animal experiments. We intravenously injected rats with saline (n=7), furosemide (n=7), acetazolamide (n=6), or mannitol (n=6). For controls, 6 rats were not injected with drugs. We estimated the apparent transverse relaxation rate (R 2 *) from the apparent transverse relaxation time (T 2 *)-weighted images and measured the time course of R 2 * at 4-min intervals over approximately 30 min. Compared with preadministration values, the R 2 * value did not change significantly in either the cortex or medulla in the control and mannitol groups but decreased significantly in the saline group; the R 2 * value significantly decreased in the medulla but did not change significantly in the cortex in the furosemide group; and the R 2 * value significantly increased in the medulla and significantly decreased in the cortex in the acetazolamide group. Our study results suggest that BOLD MRI is useful for evaluating the dynamics of renal oxygenation in response to various diuretics in the renal cortex and in the medulla. (author)

BOLD quantified renal pO2 is sensitive to pharmacological challenges in rats.

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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.

Blood oxygenation level dependent signal and neuronal adaptation to optogenetic and sensory stimulation in somatosensory cortex in awake animals.

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Aksenov, Daniil P; Li, Limin; Miller, Michael J; Wyrwicz, Alice M

2016-11-01

The adaptation of neuronal responses to stimulation, in which a peak transient response is followed by a sustained plateau, has been well-studied. The blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) signal has also been shown to exhibit adaptation on a longer time scale. However, some regions such as the visual and auditory cortices exhibit significant BOLD adaptation, whereas other such as the whisker barrel cortex may not adapt. In the sensory cortex a combination of thalamic inputs and intracortical activity drives hemodynamic changes, although the relative contributions of these components are not entirely understood. The aim of this study is to assess the role of thalamic inputs vs. intracortical processing in shaping BOLD adaptation during stimulation in the somatosensory cortex. Using simultaneous fMRI and electrophysiology in awake rabbits, we measured BOLD, local field potentials (LFPs), single- and multi-unit activity in the cortex during whisker and optogenetic stimulation. This design allowed us to compare BOLD and haemodynamic responses during activation of the normal thalamocortical sensory pathway (i.e., both inputs and intracortical activity) vs. the direct optical activation of intracortical circuitry alone. Our findings show that whereas LFP and multi-unit (MUA) responses adapted, neither optogenetic nor sensory stimulation produced significant BOLD adaptation. We observed for both paradigms a variety of excitatory and inhibitory single unit responses. We conclude that sensory feed-forward thalamic inputs are not primarily responsible for shaping BOLD adaptation to stimuli; but the single-unit results point to a role in this behaviour for specific excitatory and inhibitory neuronal sub-populations, which may not correlate with aggregate neuronal activity. © 2016 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Abnormal Striatal BOLD Responses to Reward Anticipation and Reward Delivery in ADHD

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Furukawa, Emi; Bado, Patricia; Tripp, Gail; Mattos, Paulo; Wickens, Jeff R.; Bramati, Ivanei E.; Alsop, Brent; Ferreira, Fernanda Meireles; Lima, Debora; Tovar-Moll, Fernanda; Sergeant, Joseph A.; Moll, Jorge

2014-01-01

Altered reward processing has been proposed to contribute to the symptoms of attention deficit hyperactivity disorder (ADHD). The neurobiological mechanism underlying this alteration remains unclear. We hypothesize that the transfer of dopamine release from reward to reward-predicting cues, as normally observed in animal studies, may be deficient in ADHD. Functional magnetic resonance imaging (fMRI) was used to investigate striatal responses to reward-predicting cues and reward delivery in a classical conditioning paradigm. Data from 14 high-functioning and stimulant-naïve young adults with elevated lifetime symptoms of ADHD (8 males, 6 females) and 15 well-matched controls (8 males, 7 females) were included in the analyses. During reward anticipation, increased blood-oxygen-level-dependent (BOLD) responses in the right ventral and left dorsal striatum were observed in controls, but not in the ADHD group. The opposite pattern was observed in response to reward delivery; the ADHD group demonstrated significantly greater BOLD responses in the ventral striatum bilaterally and the left dorsal striatum relative to controls. In the ADHD group, the number of current hyperactivity/impulsivity symptoms was inversely related to ventral striatal responses during reward anticipation and positively associated with responses to reward. The BOLD response patterns observed in the striatum are consistent with impaired predictive dopamine signaling in ADHD, which may explain altered reward-contingent behaviors and symptoms of ADHD. PMID:24586543

Background MR gradient noise and non-auditory BOLD activations: a data-driven perspective.

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Haller, Sven; Homola, György A; Scheffler, Klaus; Beckmann, Christian F; Bartsch, Andreas J

2009-07-28

The effect of echoplanar imaging (EPI) acoustic background noise on blood oxygenation level dependent (BOLD) activations was investigated. Two EPI pulse sequences were compared: (i) conventional EPI with a pulsating sound component of typically 8-10 Hz, which is a potent physiological stimulus, and (ii) the more recently developed continuous-sound EPI, which is perceived as less distractive despite equivalent peak sound pressure levels. Sixteen healthy subjects performed an established demanding visual n-back working memory task. Using an exploratory data analysis technique (tensorial probabilistic independent component analysis; tensor-PICA), we studied the inter-session/within-subject response variability introduced by continuous-sound versus conventional EPI acoustic background noise in addition to temporal and spatial signal characteristics. The analysis revealed a task-related component associated with the established higher-level working memory and motor feedback response network, which exhibited a significant 19% increase in its average effect size for the continuous-sound as opposed to conventional EPI. Stimulus-related lower-level activations, such as primary visual areas, were not modified. EPI acoustic background noise influences much more than the auditory system per se. This analysis provides additional evidence for an enhancement of task-related, extra-auditory BOLD activations by continuous-sound EPI due to less distractive acoustic background gradient noise.

Implications of oxidative stress in the brain plasticity originated by fasting: a BOLD-fMRI study.

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Belaïch, Rachida; Boujraf, Saïd; Benzagmout, Mohammed; Magoul, Rabia; Maaroufi, Mustapha; Tizniti, Siham

2017-11-01

The goal of this study was assessing the intermittent fasting effect on brain plasticity and oxidative stress (OS) using blood-oxygenation-level dependent (BOLD)-functional magnetic resonance image (fMRI) approach. Evidences of physiological and molecular phenomena involved in this process are discussed and compared to reported literature. Six fully healthy male non-smokers volunteered in this study. All volunteers were right handed, and have an equilibrated, consistent and healthy daily nutritional habit, and a healthy lifestyle. Participants were allowed consuming food during evening and night time while fasting with self-prohibiting food and liquids during 14 hours/day from sunrise to sunset. All participants underwent identical brain BOLD-fMRI protocol. The images were acquired in the Department of Radiology and Clinical Imaging of the University Hospital of Fez, Fez, Morocco. The anatomical brain and BOLD-fMRIs were acquired using a 1.5-Tesla scanner (Signa, General Electric, Milwaukee, United States). BOLD-fMRI image acquisition was done using single-shot gradient echo echo-planer imaging sequence. BOLD-fMRI paradigm consisted of the motor task where volunteers were asked to perform finger taping of the right hand. Two BOLD-fMRI scan sessions were performed, the first one between the 5th and 10th days preceding the start of fasting and the second between days 25th and 28th of the fasting month. All sessions were performed between 3:30 PM and 5:30 PM. Although individual maps were originated from different individual participants, they cover the same anatomic area in each case. Image processing and statistical analysis were conducted with Statistical Parameter Mapping version 8 (2008, Welcome Department of Cognitive Neurology, London UK). The maximal BOLD signal changes were calculated for each subject in the motor area M1; Activation maps were calculated and overlaid on the anatomical images. Group analysis of the data was performed, and the average volume

Physiologic characterization of inflammatory arthritis in a rabbit model with BOLD and DCE MRI at 1.5 Tesla

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Nasui, Otilia C.; Chan, Michael W.; Nathanael, George; Rayner, Tammy; Weiss, Ruth; Detzler, Garry; Zhong, Anguo [The Hospital for Sick Children, Department of Diagnostic Imaging, Toronto, ON (Canada); Crawley, Adrian [University of Toronto, Department of Medical Imaging, Toronto, ON (Canada); Toronto Western Hospital, Department of Medical Imaging, Toronto, ON (Canada); Miller, Elka [Children' s Hospital of Eastern Ontario (CHEO), Department of Diagnostic Imaging, Ottawa, ON (Canada); Belik, Jaques [The Hospital for Sick Children, Department of Neonatology, Toronto, ON (Canada); Cheng, Hai-Ling; Kassner, Andrea; Doria, Andrea S. [The Hospital for Sick Children, Department of Diagnostic Imaging, Toronto, ON (Canada); University of Toronto, Department of Medical Imaging, Toronto, ON (Canada); Moineddin, Rahim [Department of Public Health, Family and Community Medicine, Toronto, ON (Canada); Jong, Roland; Rogers, Marianne [Mount Sinai Hospital, Department of Pathology, Toronto, ON (Canada)

2014-11-15

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 (PO{sub 2}) 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. (orig.)

Working memory in volunteers and schizophrenics using BOLD fMRI

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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

BOLD Imaging in Awake Wild-Type and Mu-Opioid Receptor Knock-Out Mice Reveals On-Target Activation Maps in Response to Oxycodone

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Kelsey Moore

2016-11-01

Full Text Available Blood oxygen level dependent (BOLD imaging in awake mice was used to identify differences in brain activity between wild-type, and Mu (µ opioid receptor knock-outs (MuKO in response to oxycodone (OXY. Using a segmented, annotated MRI mouse atlas and computational analysis, patterns of integrated positive and negative BOLD activity were identified across 122 brain areas. The pattern of positive BOLD showed enhanced activation across the brain in WT mice within 15 min of intraperitoneal administration of 2.5 mg of OXY. BOLD activation was detected in 72 regions out of 122, and was most prominent in areas of high µ opioid receptor density (thalamus, ventral tegmental area, substantia nigra, caudate putamen, basal amygdala and hypothalamus, and focus on pain circuits indicated strong activation in major pain processing centers (central amygdala, solitary tract, parabrachial area, insular cortex, gigantocellularis area, ventral thalamus primary sensory cortex and prelimbic cortex. Importantly, the OXY-induced positive BOLD was eliminated in MuKO mice in most regions, with few exceptions (some cerebellar nuclei, CA3 of the hippocampus, medial amygdala and preoptic areas. This result indicates that most effects of OXY on positive BOLD are mediated by the µ opioid receptor (on-target effects. OXY also caused an increase in negative BOLD in WT mice in few regions (16 out of 122 and, unlike the positive BOLD response the negative BOLD was only partially eliminated in the MuKO mice (cerebellum, and in some case intensified (hippocampus. Negative BOLD analysis therefore shows activation and deactivation events in the absence of the µ receptor for some areas where receptor expression is normally extremely low or absent (off-target effects. Together, our approach permits establishing opioid-induced BOLD activation maps in awake mice. In addition, comparison of WT and MuKO mutant mice reveals both on-target and off-target activation events, and set an OXY

Post-contractile BOLD contrast in skeletal muscle at 7 T reveals inter-individual heterogeneity in the physiological responses to muscle contraction.

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Towse, Theodore F; Elder, Christopher P; Bush, Emily C; Klockenkemper, Samuel W; Bullock, Jared T; Dortch, Richard D; Damon, Bruce M

2016-12-01

Muscle blood oxygenation-level dependent (BOLD) contrast is greater in magnitude and potentially more influenced by extravascular BOLD mechanisms at 7 T than it is at lower field strengths. Muscle BOLD imaging of muscle contractions at 7 T could, therefore, provide greater or different contrast than at 3 T. The purpose of this study was to evaluate the feasibility of using BOLD imaging at 7 T to assess the physiological responses to in vivo muscle contractions. Thirteen subjects (four females) performed a series of isometric contractions of the calf muscles while being scanned in a Philips Achieva 7 T human imager. Following 2 s maximal isometric plantarflexion contractions, BOLD signal transients ranging from 0.3 to 7.0% of the pre-contraction signal intensity were observed in the soleus muscle. We observed considerable inter-subject variability in both the magnitude and time course of the muscle BOLD signal. A subset of subjects (n = 7) repeated the contraction protocol at two different repetition times (T R : 1000 and 2500 ms) to determine the potential of T 1 -related inflow effects on the magnitude of the post-contractile BOLD response. Consistent with previous reports, there was no difference in the magnitude of the responses for the two T R values (3.8 ± 0.9 versus 4.0 ± 0.6% for T R  = 1000 and 2500 ms, respectively; mean ± standard error). These results demonstrate that studies of the muscle BOLD responses to contractions are feasible at 7 T. Compared with studies at lower field strengths, post-contractile 7 T muscle BOLD contrast may afford greater insight into microvascular function and dysfunction. Copyright © 2016 John Wiley & Sons, Ltd.

Vascular Steal Explains Early Paradoxical Blood Oxygen Level-Dependent Cerebrovascular Response in Brain Regions with Delayed Arterial Transit Times

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Julien Poublanc

2013-04-01

Full Text Available Introduction: Blood oxygen level-dependent (BOLD magnetic resonance imaging (MRI during manipulation of inhaled carbon dioxide (CO2 can be used to measure cerebrovascular reactivity (CVR and map regions of exhausted cerebrovascular reserve. These regions exhibit a reduced or negative BOLD response to inhaled CO2. In this study, we sought to clarify the mechanism behind the negative BOLD response by investigating its time delay (TD. Dynamic susceptibility contrast (DSC MRI with the injection of a contrast agent was used as the gold standard in order to provide measurement of the blood arrival time to which CVR TD could be compared. We hypothesize that if negative BOLD responses are the result of a steal phenomenon, they should be synchronized with positive BOLD responses from healthy brain tissue, even though the blood arrival time would be delayed. Methods: On a 3-tesla MRI system, BOLD CVR and DSC images were collected in a group of 19 patients with steno-occlusive cerebrovascular disease. For each patient, we generated a CVR magnitude map by regressing the BOLD signal with the end-tidal partial pressure of CO2 (PETCO2, and a CVR TD map by extracting the time of maximum cross-correlation between the BOLD signal and PETCO2. In addition, a blood arrival time map was generated by fitting the DSC signal with a gamma variate function. ROI masks corresponding to varying degrees of reactivity were constructed. Within these masks, the mean CVR magnitude, CVR TD and DSC blood arrival time were extracted and averaged over the 19 patients. CVR magnitude and CVR TD were then plotted against DSC blood arrival time. Results: The results show that CVR magnitude is highly correlated to DSC blood arrival time. As expected, the most compromised tissues with the longest blood arrival time have the lowest (most negative CVR magnitude. However, CVR TD shows a noncontinuous relationship with DSC blood arrival time. CVR TD is well correlated to DSC blood arrival time

Task effects on BOLD signal correlates of implicit syntactic processing

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Caplan, David

2010-01-01

BOLD signal was measured in sixteen participants who made timed font change detection judgments in visually presented sentences that varied in syntactic structure and the order of animate and inanimate nouns. Behavioral data indicated that sentences were processed to the level of syntactic structure. BOLD signal increased in visual association areas bilaterally and left supramarginal gyrus in the contrast of sentences with object- and subject-extracted relative clauses without font changes in which the animacy order of the nouns biased against the syntactically determined meaning of the sentence. This result differs from the findings in a non-word detection task (Caplan et al, 2008a), in which the same contrast led to increased BOLD signal in the left inferior frontal gyrus. The difference in areas of activation indicates that the sentences were processed differently in the two tasks. These differences were further explored in an eye tracking study using the materials in the two tasks. Issues pertaining to how parsing and interpretive operations are affected by a task that is being performed, and how this might affect BOLD signal correlates of syntactic contrasts, are discussed. PMID:20671983

Systematic protocol for assessment of the validity of BOLD MRI in a rabbit model of inflammatory arthritis at 1.5 tesla

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Chan, Michael W.; Nathanael, George; Kis, Antonella; Amirabadi, Afsaneh; Zhong, Anguo; Rayner, Tammy; Weiss, Ruth; Detzler, Garry; Gahunia, Harpal [The Hospital for Sick Children, Department of Diagnostic Imaging, Toronto (Canada); Jong, Roland [Mount Sinai Hospital, Department of Pathology and Laboratory Medicine, Toronto (Canada); Moineddin, Rahim [Family and Community Medicine, Department of Public Health, Toronto (Canada); Crawley, Adrian [University of Toronto, Department of Medical Imaging, Toronto (Canada); Toronto Western Hospital, Department of Medical Imaging, Toronto (Canada); Doria, Andrea S. [The Hospital for Sick Children, Department of Diagnostic Imaging, Toronto (Canada); University of Toronto, Department of Medical Imaging, Toronto (Canada)

2014-05-15

Blood-oxygen-level-dependent (BOLD) MRI has the potential to identify regions of early hypoxic and vascular joint changes in inflammatory arthritis. There is no standard protocol for analysis of BOLD MRI measurements in musculoskeletal disorders. To optimize the following BOLD MRI reading parameters: (1) statistical threshold values (low, r > 0.01 versus high, r > 0.2); (2) summary measures of BOLD contrast (percentage of activated voxels [PT%] versus percentage signal difference between on-and-off signal intensities [diff{sub o}n{sub o}ff]); and (3) direction of BOLD response (positive, negative and positive + negative). Using BOLD MRI protocols at 1.5 T, arthritic (n = 21) and contralateral (n = 21) knees of 21 juvenile rabbits were imaged at baseline and on days 1, 14 and 28 after a unilateral intra-articular injection of carrageenan. Nine non-injected rabbits served as external control knees (n = 18). By comparing arthritic to contralateral knees, receiver operating characteristic curves were used to determine diagnostic accuracy. Using diff{sub o}n{sub o}ff and positive + negative responses, a threshold of r > 0.01 was more accurate than r > 0.2 (P = 0.03 at day 28). Comparison of summary measures yielded no statistically significant difference (P > 0.05). Although positive + negative (AUC = 0.86 at day 28) and negative responses (AUC = 0.90 at day 28) for PT% were the most diagnostically accurate, positive + negative responses for diff{sub o}n{sub o}ff (AUC = 0.78 at day 28) also had acceptable accuracy. The most clinically relevant reading parameters included a lower threshold of r > 0.01 and a positive + negative BOLD response. We propose that diff{sub o}n{sub o}ff is a more clinically relevant summary measure of BOLD MRI, while PT% can be used as an ancillary measure. (orig.)

Nonlinear Bayesian Estimation of BOLD Signal under Non-Gaussian Noise

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Ali Fahim Khan

2015-01-01

Full Text Available Modeling the blood oxygenation level dependent (BOLD signal has been a subject of study for over a decade in the neuroimaging community. Inspired from fluid dynamics, the hemodynamic model provides a plausible yet convincing interpretation of the BOLD signal by amalgamating effects of dynamic physiological changes in blood oxygenation, cerebral blood flow and volume. The nonautonomous, nonlinear set of differential equations of the hemodynamic model constitutes the process model while the weighted nonlinear sum of the physiological variables forms the measurement model. Plagued by various noise sources, the time series fMRI measurement data is mostly assumed to be affected by additive Gaussian noise. Though more feasible, the assumption may cause the designed filter to perform poorly if made to work under non-Gaussian environment. In this paper, we present a data assimilation scheme that assumes additive non-Gaussian noise, namely, the e-mixture noise, affecting the measurements. The proposed filter MAGSF and the celebrated EKF are put to test by performing joint optimal Bayesian filtering to estimate both the states and parameters governing the hemodynamic model under non-Gaussian environment. Analyses using both the synthetic and real data reveal superior performance of the MAGSF as compared to EKF.

Spatiotemporal alignment of in utero BOLD-MRI series.

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Turk, Esra Abaci; Luo, Jie; Gagoski, Borjan; Pascau, Javier; Bibbo, Carolina; Robinson, Julian N; Grant, P Ellen; Adalsteinsson, Elfar; Golland, Polina; Malpica, Norberto

2017-08-01

To present a method for spatiotemporal alignment of in-utero magnetic resonance imaging (MRI) time series acquired during maternal hyperoxia for enabling improved quantitative tracking of blood oxygen level-dependent (BOLD) signal changes that characterize oxygen transport through the placenta to fetal organs. The proposed pipeline for spatiotemporal alignment of images acquired with a single-shot gradient echo echo-planar imaging includes 1) signal nonuniformity correction, 2) intravolume motion correction based on nonrigid registration, 3) correction of motion and nonrigid deformations across volumes, and 4) detection of the outlier volumes to be discarded from subsequent analysis. BOLD MRI time series collected from 10 pregnant women during 3T scans were analyzed using this pipeline. To assess pipeline performance, signal fluctuations between consecutive timepoints were examined. In addition, volume overlap and distance between manual region of interest (ROI) delineations in a subset of frames and the delineations obtained through propagation of the ROIs from the reference frame were used to quantify alignment accuracy. A previously demonstrated rigid registration approach was used for comparison. The proposed pipeline improved anatomical alignment of placenta and fetal organs over the state-of-the-art rigid motion correction methods. In particular, unexpected temporal signal fluctuations during the first normoxia period were significantly decreased (P quantitative studies of placental function by improving spatiotemporal alignment across placenta and fetal organs. 1 Technical Efficacy: Stage 1 J. MAGN. RESON. IMAGING 2017;46:403-412. © 2017 International Society for Magnetic Resonance in Medicine.

Dictionary-driven Ischemia Detection from Cardiac Phase-Resolved Myocardial BOLD MRI at Rest

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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

Beware of Boldness

National Research Council Canada - National Science Library

Crane, Conrad C

2006-01-01

... to be?"1 Army Field Manual 7.0, Training the Force, states that the goals of operational deployments and major training opportunities are to enhance unit readiness and "produce bold, innovative leaders...

Early anti-correlated BOLD signal changes of physiologic origin.

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Bright, Molly G; Bianciardi, Marta; de Zwart, Jacco A; Murphy, Kevin; Duyn, Jeff H

2014-02-15

Negative BOLD signals that are synchronous with resting state fluctuations have been observed in large vessels in the cortical sulci and surrounding the ventricles. In this study, we investigated the origin of these negative BOLD signals by applying a Cued Deep Breathing (CDB) task to create transient hypocapnia and a resultant global fMRI signal decrease. We hypothesized that a global stimulus would amplify the effect in large vessels and that using a global negative (vasoconstrictive) stimulus would test whether these voxels exhibit either inherently negative or simply anti-correlated BOLD responses. Significantly anti-correlated, but positive, BOLD signal changes during respiratory challenges were identified in voxels primarily located near edges of brain spaces containing CSF. These positive BOLD responses occurred earlier than the negative CDB response across most of gray matter voxels. These findings confirm earlier suggestions that in some brain regions, local, fractional changes in CSF volume may overwhelm BOLD-related signal changes, leading to signal anti-correlation. We show that regions with CDB anti-correlated signals coincide with most, but not all, of the regions with negative BOLD signal changes observed during a visual and motor stimulus task. Thus, the addition of a physiological challenge to fMRI experiments can help identify which negative BOLD signals are passive physiological anti-correlations and which may have a putative neuronal origin. Published by Elsevier Inc.

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

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Tom J Van Grootel

the visual pathways. Since fMRI BOLD reflects neural activity on a population level, our results indicate that, although individual neurons might be adult-like, a longer maturation process takes place on a population level.

"Extreme Bold" in the Faculty Ranks

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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…

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

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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

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

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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.

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

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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.

Increased BOLD activation to predator stressor in subiculum and midbrain of amphetamine-sensitized maternal rats.

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Febo, Marcelo; Pira, Ashley S

2011-03-25

Amphetamine, which is known to cause sensitization, potentiates the hormonal and neurobiological signatures of stress and may also increase sensitivity to stress-inducing stimuli in limbic areas. Trimethylthiazoline (5μL TMT) is a chemical constituent of fox feces that evokes innate fear and activates the neuronal and hormonal signatures of stress in rats. We used blood oxygen level dependent (BOLD) MRI to test whether amphetamine sensitization (1mg/kg, i.p. ×3days) in female rats has a lasting effect on the neural response to a stress-evoking stimulus, the scent of a predator, during the postpartum period. The subiculum and dopamine-enriched midbrain VTA/SN of amphetamine-sensitized but not control mothers showed a greater BOLD signal response to predator odor than a control putrid scent. The greater responsiveness of these two brain regions following stimulant sensitization might impact neural processing in response to stressors in the maternal brain. Copyright © 2010 Elsevier B.V. All rights reserved.

Blood oxygen level dependent magnetic resonance imaging for detecting pathological patterns in lupus nephritis patients: a preliminary study using a decision tree model.

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Shi, Huilan; Jia, Junya; Li, Dong; Wei, Li; Shang, Wenya; Zheng, Zhenfeng

2018-02-09

Precise renal histopathological diagnosis will guide therapy strategy in patients with lupus nephritis. Blood oxygen level dependent (BOLD) magnetic resonance imaging (MRI) has been applicable noninvasive technique in renal disease. This current study was performed to explore whether BOLD MRI could contribute to diagnose renal pathological pattern. Adult patients with lupus nephritis renal pathological diagnosis were recruited for this study. Renal biopsy tissues were assessed based on the lupus nephritis ISN/RPS 2003 classification. The Blood oxygen level dependent magnetic resonance imaging (BOLD-MRI) was used to obtain functional magnetic resonance parameter, R2* values. Several functions of R2* values were calculated and used to construct algorithmic models for renal pathological patterns. In addition, the algorithmic models were compared as to their diagnostic capability. Both Histopathology and BOLD MRI were used to examine a total of twelve patients. Renal pathological patterns included five classes III (including 3 as class III + V) and seven classes IV (including 4 as class IV + V). Three algorithmic models, including decision tree, line discriminant, and logistic regression, were constructed to distinguish the renal pathological pattern of class III and class IV. The sensitivity of the decision tree model was better than that of the line discriminant model (71.87% vs 59.48%, P decision tree model was equivalent to that of the line discriminant model (63.87% vs 63.73%, P = 0.939) and higher than that of the logistic regression model (63.87% vs 38.0%, P decision tree model was greater than that of the line discriminant model (0.765 vs 0.629, P Decision tree models constructed using functions of R2* values may facilitate the prediction of renal pathological patterns.

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

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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.

Computing moment to moment BOLD activation for real-time neurofeedback

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Hinds, Oliver; Ghosh, Satrajit; Thompson, Todd W.; Yoo, Julie J.; Whitfield-Gabrieli, Susan; Triantafyllou, Christina; Gabrieli, John D.E.

2013-01-01

Estimating moment to moment changes in blood oxygenation level dependent (BOLD) activation levels from functional magnetic resonance imaging (fMRI) data has applications for learned regulation of regional activation, brain state monitoring, and brain-machine interfaces. In each of these contexts, accurate estimation of the BOLD signal in as little time as possible is desired. This is a challenging problem due to the low signal-to-noise ratio of fMRI data. Previous methods for real-time fMRI analysis have either sacrificed the ability to compute moment to moment activation changes by averaging several acquisitions into a single activation estimate or have sacrificed accuracy by failing to account for prominent sources of noise in the fMRI signal. Here we present a new method for computing the amount of activation present in a single fMRI acquisition that separates moment to moment changes in the fMRI signal intensity attributable to neural sources from those due to noise, resulting in a feedback signal more reflective of neural activation. This method computes an incremental general linear model fit to the fMRI timeseries, which is used to calculate the expected signal intensity at each new acquisition. The difference between the measured intensity and the expected intensity is scaled by the variance of the estimator in order to transform this residual difference into a statistic. Both synthetic and real data were used to validate this method and compare it to the only other published real-time fMRI method. PMID:20682350

Fitness Consequences of Boldness in Juvenile and Adult Largemouth Bass.

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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.

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

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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

Differences in aggression, activity and boldness between native and introduced populations of an invasive crayfish

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Pintor, L.M.; Sih, A.; Bauer, M.L.

2008-01-01

Aggressiveness, along with foraging voracity and boldness, are key behavioral mechanisms underlying the competitive displacement and invasion success of exotic species. However, do aggressiveness, voracity and boldness of the invader depend on the presence of an ecologically similar native competitor in the invaded community? We conducted four behavioral assays to compare aggression, foraging voracity, threat response and boldness to forage under predation risk of multiple populations of exotic signal crayfish Pacifastacus leniusculus across its native and invaded range with and without a native congener, the Shasta crayfish P. fortis. We predicted that signal crayfish from the invaded range and sympatric with a native congener (IRS) should be more aggressive to outcompete a close competitor than populations from the native range (NR) or invaded range and allopatric to a native congener (IRA). Furthermore, we predicted that IRS populations of signal crayfish should be more voracious, but less bold to forage under predation risk since native predators and prey likely possess appropriate behavioral responses to the invader. Contrary to our predictions, results indicated that IRA signal crayfish were more aggressive towards conspecifics and more voracious and active foragers, yet also bolder to forage under predation risk in comparison to NR and IRS populations, which did not differ in behavior. Higher aggression/voracity/ boldness was positively correlated with prey consumption rates, and hence potential impacts on prey. We suggest that the positive correlations between aggression/voracity/boldness are the result of an overall aggression syndrome. Results of stream surveys indicated that IRA streams have significantly lower prey biomass than in IRS streams, which may drive invading signal crayfish to be more aggressive/voracious/bold to acquire resources to establish a population. ?? 2008 The Authors.

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

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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.

Task-Related Modulations of BOLD Low-Frequency Fluctuations within the Default Mode Network

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Tommasin, Silvia; Mascali, Daniele; Gili, Tommaso; Assan, Ibrahim Eid; Moraschi, Marta; Fratini, Michela; Wise, Richard G.; Macaluso, Emiliano; Mangia, Silvia; Giove, Federico

2017-01-01

Spontaneous low-frequency Blood-Oxygenation Level-Dependent (BOLD) signals acquired during resting state are characterized by spatial patterns of synchronous fluctuations, ultimately leading to the identification of robust brain networks. The resting-state brain networks, including the Default Mode Network (DMN), are demonstrated to persist during sustained task execution, but the exact features of task-related changes of network properties are still not well characterized. In this work we sought to examine in a group of 20 healthy volunteers (age 33 ± 6 years, 8 F/12 M) the relationship between changes of spectral and spatiotemporal features of one prominent resting-state network, namely the DMN, during the continuous execution of a working memory n-back task. We found that task execution impacted on both functional connectivity and amplitude of BOLD fluctuations within large parts of the DMN, but these changes correlated between each other only in a small area of the posterior cingulate. We conclude that combined analysis of multiple parameters related to connectivity, and their changes during the transition from resting state to continuous task execution, can contribute to a better understanding of how brain networks rearrange themselves in response to a task. PMID:28845420

Task-Related Modulations of BOLD Low-Frequency Fluctuations within the Default Mode Network

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Silvia Tommasin

2017-07-01

Full Text Available Spontaneous low-frequency Blood-Oxygenation Level-Dependent (BOLD signals acquired during resting state are characterized by spatial patterns of synchronous fluctuations, ultimately leading to the identification of robust brain networks. The resting-state brain networks, including the Default Mode Network (DMN, are demonstrated to persist during sustained task execution, but the exact features of task-related changes of network properties are still not well characterized. In this work we sought to examine in a group of 20 healthy volunteers (age 33 ± 6 years, 8 F/12 M the relationship between changes of spectral and spatiotemporal features of one prominent resting-state network, namely the DMN, during the continuous execution of a working memory n-back task. We found that task execution impacted on both functional connectivity and amplitude of BOLD fluctuations within large parts of the DMN, but these changes correlated between each other only in a small area of the posterior cingulate. We conclude that combined analysis of multiple parameters related to connectivity, and their changes during the transition from resting state to continuous task execution, can contribute to a better understanding of how brain networks rearrange themselves in response to a task.

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

Brain magnetic resonance imaging with contrast dependent on blood oxygenation

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Ogawa, S.; Lee, T.M.; Kay, A.R.; Tank, D.W.

1990-01-01

Paramagnetic deoxyhemoglobin in venous blood is a naturally occurring contrast agent for magnetic resonance imaging (MRI). By accentuating the effects of this agent through the use of gradient-echo techniques in high yields, the authors demonstrate in vivo images of brain microvasculature with image contrast reflecting the blood oxygen level. This blood oxygenation level-dependent (BOLD) contrast follows blood oxygen changes induced by anesthetics, by insulin-induced hypoglycemia, and by inhaled gas mixtures that alter metabolic demand or blood flow. The results suggest that BOLD contrast can be used to provide in vivo real-time maps of blood oxygenation in the brain under normal physiological conditions. BOLD contrast adds an additional feature to magnetic resonance imaging and complement other techniques that are attempting to provide position emission tomography-like measurements related to regional neural activity

Time courses of MRI BOLD signals in prolonged visual stimulation. Comparison between colors and orders

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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)

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

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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.

Hypoxia in Prostate Cancer: Correlation of BOLD-MRI With Pimonidazole Immunohistochemistry-Initial Observations

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Hoskin, Peter J.; Carnell, Dawn M.; Taylor, N. Jane; Smith, Rowena E.; Stirling, J. James; Daley, Frances M.; Saunders, Michele I.; Bentzen, Soren M.; Collins, David J.; D'Arcy, James A.; Padhani, Anwar P.

2007-01-01

Purpose: To investigate the ability of blood oxygen level-dependent (BOLD) MRI to depict clinically significant prostate tumor hypoxia. Methods and Materials: Thirty-three patients with prostate carcinoma undergoing radical prostatectomy were studied preoperatively, using gradient echo sequences without and with contrast medium enhancement, to map relative tissue oxygenation according to relaxivity rates and relative blood volume (rBV). Pimonidazole was administered preoperatively, and whole-mount sections of selected tumor-bearing slices were stained for pimonidazole fixation and tumor and nontumor localization. Histologic and imaging parameters were independently mapped onto patient prostate outlines. Using 5-mm grids, 861 nontumor grid locations were compared with 237 tumor grids (with >50% tumor per location) using contingency table analysis with respect to the ability of imaging to predict pimonidazole staining. Results: Twenty patients completed the imaging and histologic protocols. Pimonidazole staining was found in 33% of nontumor and in 70% of tumor grids. The sensitivity of the MR relaxivity parameter R 2 * in depicting tumor hypoxia was high (88%), improving with the addition of low rBV information (95%) without changing specificity (36% and 29%, respectively). High R 2 * increased the positive predictive value for hypoxia by 6% (70% to 76%); conversely, low R 2 * decreased the likelihood of hypoxia being present by 26% (70% to 44%) and by 41% (71% to 30%) when combined with rBV information. Conclusion: R 2 * maps from BOLD-MRI have high sensitivity but low specificity for defining intraprostatic tumor hypoxia. This together with the negative predictive value of 70% when combined with blood volume information makes BOLD-MRI a potential noninvasive technique for mapping prostatic tumor hypoxia

"Boldness" in the domestic dog differs among breeds and breed groups.

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Starling, Melissa J; Branson, Nicholas; Thomson, Peter C; McGreevy, Paul D

2013-07-01

"Boldness" in dogs is believed to be one end of the shy-bold axis, representing a super-trait. Several personality traits fall under the influence of this super-trait. Previous studies on boldness in dogs have found differences among breeds, but grouping breeds on the basis of behavioural similarities has been elusive. This study investigated differences in the expression of boldness among dog breeds, kennel club breed groups, and sub-groups of kennel club breed groups by way of a survey on dog personality circulated among Australian dog-training clubs and internet forums and lists. Breed had a significant effect on boldness (F=1.63, numDF=111, denDF=272, ppurpose. Retrievers were significantly bolder than flushing and pointing breeds (Reg. Coef.=2.148; S.E.=0.593; pdogs. Differences in boldness among groups and sub-groups suggest that behavioural tendencies may be influenced by historical purpose regardless of whether that purpose still factors in selective breeding. Copyright © 2013 Elsevier B.V. All rights reserved.

Resting State BOLD Variability in Alzheimer’s Disease: A Marker of Cognitive Decline or Cerebrovascular Status?

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Vanessa Scarapicchia

2018-02-01

Full Text Available Background: Alzheimer’s disease (AD is a neurodegenerative disorder that may benefit from early diagnosis and intervention. Therefore, there is a need to identify early biomarkers of AD using non-invasive techniques such as functional magnetic resonance imaging (fMRI. Recently, novel approaches to the analysis of resting-state fMRI data have been developed that focus on the moment-to-moment variability in the blood oxygen level dependent (BOLD signal. The objective of the current study was to investigate BOLD variability as a novel early biomarker of AD and its associated psychophysiological correlates.Method: Data were obtained from the Alzheimer’s Disease Neuroimaging Initiative (ADNI 2 database from 19 participants with AD and 19 similarly aged controls. For each participant, a map of BOLD signal variability (SDBOLD was computed as the standard deviation of the BOLD timeseries at each voxel. Group comparisons were performed to examine global differences in resting state SDBOLD in AD versus healthy controls. Correlations were then examined between participant SDBOLD maps and (1 ADNI-derived composite scores of memory and executive function and (2 neuroimaging markers of cerebrovascular status.Results: Between-group comparisons revealed significant (p < 0.05 increases in SDBOLD in patients with AD relative to healthy controls in right-lateralized frontal regions. Lower memory scores and higher WMH burden were associated with greater SDBOLD in the healthy control group (p < 0.1, but not individuals with AD.Conclusion: The current study provides proof of concept of a novel resting state fMRI analysis technique that is non-invasive, easily accessible, and clinically compatible. To further explore the potential of SDBOLD as a biomarker of AD, additional studies in larger, longitudinal samples are needed to better understand the changes in SDBOLD that characterize earlier stages of disease progression and their underlying psychophysiological

Assessment of cerebral blood flow reserve using blood oxygen level-dependent echo planar imaging after acetazolamide administration in patients post-STA-MCA anastomosis surgery

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Zenke, Kiichiro; Kusunoki, Katsusuke; Saito, Masahiro; Sadamoto, Kazuhiko; Ohta, Shinsuke; Kumon, Yoshiaki; Sakaki, Saburo; Nagasawa, Kiyoshi

1998-01-01

Recently, blood oxygen level-dependent (BOLD) echo planar imaging (EPI) has been used to estimate blood flow changes. Theoretically, a relative decrement of deoxyhemoglobin in cerebral blood supply induces a MR signal change after neuronal stimulation. In the present study, we have attempted to evaluate CBF reserve capacity by the BOLD EPI in patients who had undergone STA-MCA anastomosis surgery. Then, we compared with the signal intensity changes obtained by this procedure with the CBF changes by Xe-SPECT after acetazolamide administration. Six patients, post-STA-MCA anastomosis surgery, were studied. Pre-operatively, MR signal intensity and CBF, by Xe-SPECT, were increased in the intact side after acetazolamide administration in all patients, and MR signal intensities were decreased in low flow regions after acetazolamide administration in all four patients in whom so-called steal phenomenon was demonstrated by Xe-SPECT study. Post-operatively, poor response was shown after acetazolamide administration with both Xe-SPECT and BOLD EPI in the two patients who had unsuccessful anastomoses. In the successfully anastomosed patients, improved vascular reactivity was demonstrated on BOLD EPI after acetazolamide administration in 3 of 4 patients in whom an improvement of vascular reactivity was demonstrated on Xe-SPECT. In one patient, MRI studies were considered to have technical artifacts, because the MR signal intensity did not increase, even in the intact side after acetazolamide administration. In conclusion, BOLD EPI after acetazolamide administration is an useful procedure for the pre- and post-operative of vascular reserve in patients with ischemic stroke. (author)

Task-related modulations of BOLD low-frequency fluctuations within the default mode network

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Tommasin, Silvia; Mascali, Daniele; Gili, Tommaso; Eid Assan, Ibrahim; Moraschi, Marta; Fratini, Michela; Wise, Richard G.; Macaluso, Emiliano; Mangia, Silvia; Giove, Federico

2017-07-01

Spontaneous low-frequency Blood-Oxygenation Level-Dependent (BOLD) signals acquired during resting state are characterized by spatial patterns of synchronous fluctuations, ultimately leading to the identification of robust brain networks. The resting-state brain networks, including the Default Mode Network (DMN), are demonstrated to persist during sustained task execution, but the exact features of task-related changes of network properties are still not well characterized. In this work we sought to examine in a group of 20 healthy volunteers (age 33±6 years, 8F/12M) the relationship between changes of spectral and spatiotemporal features of one prominent resting-state network, namely the DMN, during the steady-state execution of a sustained working memory n-back task. We found that the steady state execution of such a task impacted on both functional connectivity and amplitude of BOLD fluctuations within large parts of the DMN, but these changes correlated between each other only in a small area of the posterior cingulate. We conclude that combined analysis of multiple parameters related to connectivity, and their changes during the transition from resting state to steady-state task execution, can contribute to a better understanding of how brain networks rearrange themselves in response of a task.

A preliminary study of murine walker-256 tumor hypoxia detected by blood oxygen level dependent-MR

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Zhang Shengjian; Mao Jian; Wu Bin; Peng Weijun

2013-01-01

Objective: To establish Walker-256 transplantation tumor model in SD Rats. To study of R_2"* signal changes on murine Walker-256 tumor after inhaling Carbogen by blood oxygen level dependent (BOLD)-MR, and to explore the feasibility of BOLD-MRI on detecting tumor hypoxia. Methods: Walker-256 tumor cell implanted subcutaneously in right lower abdomen of 95 female SD rats. MR was performed on the tumor-forming rats when the maximum diameter of tumor reached 1-3 cm, using a 3.0 T MR scanner equipped with a 3 inch animal surface coil. BOLD-MRI was done by using a multiecho SPGR sequence during inhaling air and at 10 minute after inhaling Carbogen, respectively. All images were transferred to GE ADW 4.3 workstation, then a baseline R_2"* (R_2"* a) and R_2"* (R_2"* b) after inhaling Carbogen of tumor was calculated using R_2 Star analysis software and ΔR_2"* was calculated through ΔR_2"* = R_2"* b -R_2"* a", meanwhile the volume of tumor were calculated as well. The difference of R_2"* signal pre and post-inhaling of Carbogen was compared with a paired t test, Pearson correlation was calculated between R_2"* a, ΔR_2"* and the volume of tumor, respectively. The correlation between ΔR_2"* and R_2"* a was also assessed by Pearson correlation. Results: Sixty-eight of ninety-five female SD rats formed the tumor (71.6%). The volume of tumor was from 352 to 13 173 mm"3. Mean ΔR_2"* decreased significantly (-2.26 ± 3.90) s"-"1 from (41.18 ± 22.29) s"-"1 during breathing air to (38.91 ± 21.35) s"-"1 10 min after inhaling Carbogen (t = 4.01, P 0.05). Conclusions: BOLD-MRI can detect the R_2"* signal change of murine Walker-256 tumor pre-and post-inhaling of Carbogen. The R_2"* signal showed significant decrease after inhaling Carbogen, however, the individual variation was remarkable. (authors)

Brain functional BOLD perturbation modelling for forward fMRI and inverse mapping

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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

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

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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.

The effect of renal denervation on kidney oxygenation as determined by BOLD MRI in patients with hypertension

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Vink, E.E.; Boer, A.; Blankestijn, P.J. [University Medical Center Utrecht, Department of Nephrology, P.O. Box 85500, GA, Utrecht (Netherlands); Verloop, W.L.; Voskuil, M. [University Medical Center Utrecht, Department of Cardiology, Utrecht (Netherlands); Spiering, W.; Leiner, T. [University Medical Center Utrecht, Department of Vascular Medicine, Utrecht (Netherlands); Vonken, E.; Hoogduin, J.M. [University Medical Center Utrecht, Department of Radiology, Utrecht (Netherlands); Bots, M.L. [University Medical Center Utrecht, Julius Center for Health Sciences and Primary Care, Utrecht (Netherlands)

2015-07-15

Renal denervation (RDN) is a promising therapy for resistant hypertension. RDN is assumed to decrease sympathetic activity. Consequently, RDN can potentially increase renal oxygenation. Blood oxygen level-dependent MRI (BOLD-MRI) provides a non-invasive tool to determine renal oxygenation in humans. The aim of the current study was to investigate the effect of RDN on renal oxygenation as determined by BOLD-MRI. Patients with resistant hypertension or the inability to follow a stable drug regimen due to unacceptable side effects were included. BOLD-MRI was performed before and 12 months after RDN. Twenty-seven patients were imaged on 3 T and 19 on 1.5 T clinical MRI systems. Fifty-four patients were included, 46 patients (23 men, mean age 57 years) completed the study. Mean 24-h BP changed from 163(±20)/98(±14) mmHg to 154(±22)/92(±13) mmHg (p = 0.001 and p < 0.001). eGFR did not change after RDN [77(±18) vs. 79(±20) mL/min/1.73 m{sup 2}; p = 0.13]. RDN did not affect renal oxygenation [1.5 T: cortical R2*: 12.5(±0.9) vs. 12.5(±0.9), p = 0.94; medullary R2*: 19.6(±1.7) vs. 19.3(1.4), p = 0.40; 3 T: cortical R2*: 18.1(±0.8) vs. 17.8(±1.2), p = 0.47; medullary R2*: 27.4(±1.9) vs. 26.7(±1.8), p = 0.19]. The current study shows that RDN does not lead to changes in renal oxygenation 1 year after RDN as determined by BOLD-MRI. (orig.)

Nalmefene Reduces Reward Anticipation in Alcohol Dependence: An Experimental Functional Magnetic Resonance Imaging Study.

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Quelch, Darren R; Mick, Inge; McGonigle, John; Ramos, Anna C; Flechais, Remy S A; Bolstridge, Mark; Rabiner, Eugenii; Wall, Matthew B; Newbould, Rexford D; Steiniger-Brach, Björn; van den Berg, Franz; Boyce, Malcolm; Østergaard Nilausen, Dorrit; Breuning Sluth, Lasse; Meulien, Didier; von der Goltz, Christoph; Nutt, David; Lingford-Hughes, Anne

2017-06-01

Nalmefene is a µ and δ opioid receptor antagonist, κ opioid receptor partial agonist that has recently been approved in Europe for treating alcohol dependence. It offers a treatment approach for alcohol-dependent individuals with "high-risk drinking levels" to reduce their alcohol consumption. However, the neurobiological mechanism underpinning its effects on alcohol consumption remains to be determined. Using a randomized, double-blind, placebo-controlled, within-subject crossover design we aimed to determine the effect of a single dose of nalmefene on striatal blood oxygen level-dependent (BOLD) signal change during anticipation of monetary reward using the monetary incentive delay task following alcohol challenge. Twenty-two currently heavy-drinking, non-treatment-seeking alcohol-dependent males were recruited. The effect of single dose nalmefene (18 mg) on changes in a priori defined striatal region of interest BOLD signal change during reward anticipation compared with placebo was investigated using functional magnetic resonance imaging. Both conditions were performed under intravenous alcohol administration (6% vol/vol infusion to achieve a target level of 80 mg/dL). Datasets from 18 participants were available and showed that in the presence of the alcohol infusion, nalmefene significantly reduced the BOLD response in the striatal region of interest compared with placebo. Nalmefene did not alter brain perfusion. Nalmefene blunts BOLD response in the mesolimbic system during anticipation of monetary reward and an alcohol infusion. This is consistent with nalmefene's actions on opioid receptors, which modulate the mesolimbic dopaminergic system, and provides a neurobiological basis for its efficacy. Copyright © 2017 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

Sustained negative BOLD response in human fMRI finger tapping task.

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Liu, Yadong; Shen, Hui; Zhou, Zongtan; Hu, Dewen

2011-01-01

In this work, we investigated the sustained negative blood oxygen level-dependent (BOLD) response (sNBR) using functional magnetic resonance imaging during a finger tapping task. We observed that the sNBR for this task was more extensive than has previously been reported. The cortical regions involved in sNBR are divided into the following three groups: frontal, somatosensory and occipital. By investigating the spatial structure, area, amplitude, and dynamics of the sNBR in comparison with those of its positive BOLD response (PBR) counterpart, we made the following observations. First, among the three groups, the somatosensory group contained the greatest number of activated voxels and the fewest deactivated voxels. In addition, the amplitude of the sNBR in this group was the smallest among the three groups. Second, the onset and peak time of the sNBR are both larger than those of the PBR, whereas the falling edge time of the sNBR is less than that of the PBR. Third, the long distance between most sNBR foci and their corresponding PBR foci makes it unlikely that they share the same blood supply artery. Fourth, the couplings between the sNBR and its PBR counterpart are distinct among different regions and thus should be investigated separately. These findings imply that the origin of most sNBR foci in the finger-tapping task is much more likely to be neuronal activity suppression rather than "blood steal."

Sustained negative BOLD response in human fMRI finger tapping task.

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Yadong Liu

Full Text Available In this work, we investigated the sustained negative blood oxygen level-dependent (BOLD response (sNBR using functional magnetic resonance imaging during a finger tapping task. We observed that the sNBR for this task was more extensive than has previously been reported. The cortical regions involved in sNBR are divided into the following three groups: frontal, somatosensory and occipital. By investigating the spatial structure, area, amplitude, and dynamics of the sNBR in comparison with those of its positive BOLD response (PBR counterpart, we made the following observations. First, among the three groups, the somatosensory group contained the greatest number of activated voxels and the fewest deactivated voxels. In addition, the amplitude of the sNBR in this group was the smallest among the three groups. Second, the onset and peak time of the sNBR are both larger than those of the PBR, whereas the falling edge time of the sNBR is less than that of the PBR. Third, the long distance between most sNBR foci and their corresponding PBR foci makes it unlikely that they share the same blood supply artery. Fourth, the couplings between the sNBR and its PBR counterpart are distinct among different regions and thus should be investigated separately. These findings imply that the origin of most sNBR foci in the finger-tapping task is much more likely to be neuronal activity suppression rather than "blood steal."

Exploring BOLD changes during spatial attention in non-stimulated visual cortex.

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Linda Heinemann

Full Text Available Blood oxygen level-dependent (BOLD responses were measured in parts of primary visual cortex that represented unstimulated visual field regions at different distances from a stimulated central target location. The composition of the visual scene varied by the presence or absence of additional peripheral distracter stimuli. Bottom-up effects were assessed by comparing peripheral activity during central stimulation vs. no stimulation. Top-down effects were assessed by comparing active vs. passive conditions. In passive conditions subjects simply watched the central letter stimuli and in active conditions they had to report occurrence of pre-defined targets in a rapid serial letter stream. Onset of the central letter stream enhanced activity in V1 representations of the stimulated region. Within representations of the periphery activation decreased and finally turned into deactivation with increasing distance from the stimulated location. This pattern was most pronounced in the active conditions and during the presence of peripheral stimuli. Active search for a target did not lead to additional enhancement at areas representing the attentional focus but to a stronger deactivation in the vicinity. Suppressed neuronal activity was also found in the non distracter condition suggesting a top-down attention driven effect. Our observations suggest that BOLD signal decreases in primary visual cortex are modulated by bottom-up sensory-driven factors such as the presence of distracters in the visual field as well as by top-down attentional processes.

BOLD signal and functional connectivity associated with loving kindness meditation

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

2014-01-01

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. PMID:24944863

Socially bold personality in the real communication and Internet communication: the analysis of representations of people of the different age

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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.

Assessment of early renal allograft dysfunction with blood oxygenation level-dependent MRI and diffusion-weighted imaging

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Park, Sung Yoon [Department of Radiology and Research Institute of Radiological Science, Severance Hospital, Yonsei University College of Medicine, Seoul (Korea, Republic of); Kim, Chan Kyo, E-mail: chankyokim@skku.edu [Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of); Park, Byung Kwan [Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of); Kim, Sung Ju; Lee, Sanghoon [Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of); Huh, Wooseong [Department of Nephrology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of)

2014-12-15

Highlights: • R2* and ADC in renal allografts are moderately correlated with eGFR. • R2* and ADC are lower in early allograft dysfunction than normal allograft function. • No significant difference between AR and ATN was found in both R2* and ADC. - Abstract: Purpose: To investigate blood oxygenation level-dependent (BOLD) MRI and diffusion-weighted imaging (DWI) at 3 T for assessment of early renal allograft dysfunction. Materials and methods: 34 patients with a renal allograft (early dysfunction, 24; normal, 10) were prospectively enrolled. BOLD MRI and DWI were performed at 3 T. R2* and apparent diffusion coefficient (ADC) values were measured in cortex and medulla of the allografts. Correlation between R2* or ADC values and estimated glomerular filtration rate (eGFR) was investigated. R2* or ADC values were compared among acute rejection (AR), acute tubular necrosis (ATN) and normal function. Results: In all renal allografts, cortical or medullary R2* and ADC values were moderately correlated with eGFR (P < 0.05). Early dysfunction group showed lower R2* and ADC values than normal function group (P < 0.05). AR or ATN had lower R2* values than normal allografts (P < 0.05), and ARs had lower cortical ADC values than normal allografts (P < 0.05). No significant difference of R2* or ADC values was found between AR and ATN (P > 0.05). Conclusion: BOLD MRI and DWI at 3 T may demonstrate early functional state of renal allografts, but may be limited in characterizing a cause of early renal allograft dysfunction. Further studies are needed.

Towards prognostic biomarkers from BOLD fluctuations to differentiate a first epileptic seizure from new-onset epilepsy.

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Gupta, Lalit; Janssens, Rick; Vlooswijk, Mariëlle C G; Rouhl, Rob P W; de Louw, Anton; Aldenkamp, Albert P; Ulman, Shrutin; Besseling, René M H; Hofman, Paul A M; van Kranen-Mastenbroek, Vivianne H; Hilkman, Danny M; Jansen, Jacobus F A; Backes, Walter H

2017-03-01

The diagnosis of epilepsy cannot be reliably made prior to a patient's second seizure in most cases. Therefore, adequate diagnostic tools are needed to differentiate subjects with a first seizure from those with a seizure preceding the onset of epilepsy. The objective was to explore spontaneous blood oxygen level-dependent (BOLD) fluctuations in subjects with a first-ever seizure and patients with new-onset epilepsy (NOE), and to find characteristic biomarkers for seizure recurrence after the first seizure. We examined 17 first-seizure subjects, 19 patients with new-onset epilepsy (NOE), and 18 healthy controls. All subjects underwent clinical investigation and received electroencephalography and resting-state functional magnetic resonance imaging (MRI). The BOLD time series were analyzed in terms of regional homogeneity (ReHo) and fractional amplitude of low-frequency fluctuations (fALFFs). We found significantly stronger amplitudes (higher fALFFs) in patients with NOE relative to first-seizure subjects and healthy controls. The frequency range of 73-198 mHz (slow-3 subband) appeared most useful for discriminating patients with NOE from first-seizure subjects. The ReHo measure did not show any significant differences. The fALFF appears to be a noninvasive measure that characterizes spontaneous BOLD fluctuations and shows stronger amplitudes in the slow-3 subband of patients with NOE relative first-seizure subjects and healthy controls. A larger study population with follow-up is required to determine whether fALFF holds promise as a potential biomarker for identifying subjects at increased risk to develop epilepsy. Wiley Periodicals, Inc. © 2017 International League Against Epilepsy.

Approaches to brain stress testing: BOLD magnetic resonance imaging with computer-controlled delivery of carbon dioxide.

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W Alan C Mutch

Full Text Available BACKGROUND: An impaired vascular response in the brain regionally may indicate reduced vascular reserve and vulnerability to ischemic injury. Changing the carbon dioxide (CO(2 tension in arterial blood is commonly used as a cerebral vasoactive stimulus to assess the cerebral vascular response, changing cerebral blood flow (CBF by up to 5-11 percent/mmHg in normal adults. Here we describe two approaches to generating the CO(2 challenge using a computer-controlled gas blender to administer: i a square wave change in CO(2 and, ii a ramp stimulus, consisting of a continuously graded change in CO(2 over a range. Responses were assessed regionally by blood oxygen level dependent (BOLD magnetic resonance imaging (MRI. METHODOLOGY/PRINCIPAL FINDINGS: We studied 8 patients with known cerebrovascular disease (carotid stenosis or occlusion and 2 healthy subjects. The square wave stimulus was used to study the dynamics of the vascular response, while the ramp stimulus assessed the steady-state response to CO(2. Cerebrovascular reactivity (CVR maps were registered by color coding and overlaid on the anatomical scans generated with 3 Tesla MRI to assess the corresponding BOLD signal change/mmHg change in CO(2, voxel-by-voxel. Using a fractal temporal approach, detrended fluctuation analysis (DFA maps of the processed raw BOLD signal per voxel over the same CO(2 range were generated. Regions of BOLD signal decrease with increased CO(2 (coded blue were seen in all of these high-risk patients, indicating regions of impaired CVR. All patients also demonstrated regions of altered signal structure on DFA maps (Hurst exponents less than 0.5; coded blue indicative of anti-persistent noise. While 'blue' CVR maps remained essentially stable over the time of analysis, 'blue' DFA maps improved. CONCLUSIONS/SIGNIFICANCE: This combined dual stimulus and dual analysis approach may be complementary in identifying vulnerable brain regions and thus constitute a regional as

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

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...

Spatial–temporal signature of resting-state BOLD signals in classic trigeminal neuralgia

Directory of Open Access Journals (Sweden)

Wang Y

2017-12-01

Full Text Available Yanping Wang,1 Congying Xu,1 Liping Zhai,1 Xudong Lu,1 Xiaoqiang Wu,1 Yahui Yi,2 Ziyun Liu,1 Qiaobing Guan,1 Xiaoling Zhang1 1Department of Neurology, the Second Hospital of Jiaxing City, Jiaxing, Zhejiang, 2Department of Radiology, the Second Hospital of Jiaxing City, Jiaxing, Zhejiang, China Abstract: Resting-state functional magnetic resonance imaging (R-fMRI signals are spatiotemporally organized. R-fMRI studies in patients with classic trigeminal neuralgia (CTN have suggested alterations in functional connectivity. However, far less attention has been given to investigations of the local oscillations and their frequency-specific changes in these patients. The objective of this study was to address this issue in patients with CTN. R-fMRI data from 17 patients with CTN and 19 age- and gender-matched healthy controls (HCs were analyzed using amplitude of low-frequency fluctuation (ALFF. The ALFF was computed across different frequencies (slow-4: 0.027–0.073 Hz; slow-5: 0.01–0.027 Hz; and typical band: 0.01–0.08 Hz in patients with CTN compared to HCs. In the typical band, patients with CTN showed increases of ALFF in bilateral temporal, occipital, and left middle frontal regions and in the left middle cingulate gyrus, as well as decreases of ALFF in the right inferior temporal region and in regions (medial prefrontal regions of default mode network. These significant group differences were identified in different sub-bands, with greater brainstem findings in higher frequencies (slow-4 and extensive default mode network and right postparietal results in lower frequencies (slow-5. Furthermore, significant relationships were found between subjective pain ratings and both amplitudes of higher frequency (slow-4 blood oxygen level-dependent (BOLD signals in pain localization brain regions and lower frequencies (slow-5 in pain signaling/modulating brain regions in the patients, and decreased ALFF within the prefrontal regions was significantly

Ultrafast bold fMRI using single-shot spin-echo echo planar imaging

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Boujraf Said

2009-01-01

Full Text Available The choice of imaging parameters for functional MRI can have an impact on the accuracy of functional localization by affecting the image quality and the degree of blood oxygenation-dependent (BOLD contrast achieved. By improving sampling efficiency, parallel acquisition techniques such as sensitivity encoding (SENSE have been used to shorten readout trains in single-shot (SS echo planar imaging (EPI. This has been applied to susceptibility artifact reduction and improving spatial resolution. SENSE together with single-shot spin-echo (SS-SE imaging may also reduce off-resonance artifacts. The goal of this work was to investigate the BOLD response of a SENSE-adapted SE-EPI on a three Tesla scanner. Whole-brain fMRI studies of seven healthy right hand-dominant volunteers were carried out in a three Tesla scanner. fMRI was performed using an SS-SE EPI sequence with SENSE. The data was processed using statistical parametric mapping. Both, group and individual subject data analyses were performed. Individual average percentage and maximal percentage signal changes attributed to the BOLD effect in M1 were calculated for all the subjects as a function of echo time. Corresponding activation maps and the sizes of the activated clusters were also calculated. Our results show that susceptibility artifacts were reduced with the use of SENSE; and the acquired BOLD images were free of the typical quadrature artifacts of SS-EPI. Such measures are crucial at high field strengths. SS SE-EPI with SENSE offers further benefits in this regard and is more specific for oxygenation changes in the microvasculature bed. Functional brain activity can be investigated with the help of single-shot spin echo EPI using SENSE at high magnetic fields.

Altered auditory BOLD response to conspecific birdsong in zebra finches with stuttered syllables.

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Henning U Voss

2010-12-01

Full Text Available How well a songbird learns a song appears to depend on the formation of a robust auditory template of its tutor's song. Using functional magnetic resonance neuroimaging we examine auditory responses in two groups of zebra finches that differ in the type of song they sing after being tutored by birds producing stuttering-like syllable repetitions in their songs. We find that birds that learn to produce the stuttered syntax show attenuated blood oxygenation level-dependent (BOLD responses to tutor's song, and more pronounced responses to conspecific song primarily in the auditory area field L of the avian forebrain, when compared to birds that produce normal song. These findings are consistent with the presence of a sensory song template critical for song learning in auditory areas of the zebra finch forebrain. In addition, they suggest a relationship between an altered response related to familiarity and/or saliency of song stimuli and the production of variant songs with stuttered syllables.

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.

Crossing the implementation chasm: a proposal for bold action.

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Lorenzi, Nancy M; Novak, Laurie L; Weiss, Jacob B; Gadd, Cynthia S; Unertl, Kim M

2008-01-01

As health care organizations dramatically increase investment in information technology (IT) and the scope of their IT projects, implementation failures become critical events. Implementation failures cause stress on clinical units, increase risk to patients, and result in massive costs that are often not recoverable. At an estimated 28% success rate, the current level of investment defies management logic. This paper asserts that there are "chasms" in IT implementations that represent risky stages in the process. Contributors to the chasms are classified into four categories: design, management, organization, and assessment. The American College of Medical Informatics symposium participants recommend bold action to better understand problems and challenges in implementation and to improve the ability of organizations to bridge these implementation chasms. The bold action includes the creation of a Team Science for Implementation strategy that allows for participation from multiple institutions to address the long standing and costly implementation issues. The outcomes of this endeavor will include a new focus on interdisciplinary research and an inter-organizational knowledge base of strategies and methods to optimize implementations and subsequent achievement of organizational objectives.

Visual cortex and auditory cortex activation in early binocularly blind macaques: A BOLD-fMRI study using auditory stimuli.

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Wang, Rong; Wu, Lingjie; Tang, Zuohua; Sun, Xinghuai; Feng, Xiaoyuan; Tang, Weijun; Qian, Wen; Wang, Jie; Jin, Lixin; Zhong, Yufeng; Xiao, Zebin

2017-04-15

Cross-modal plasticity within the visual and auditory cortices of early binocularly blind macaques is not well studied. In this study, four healthy neonatal macaques were assigned to group A (control group) or group B (binocularly blind group). Sixteen months later, blood oxygenation level-dependent functional imaging (BOLD-fMRI) was conducted to examine the activation in the visual and auditory cortices of each macaque while being tested using pure tones as auditory stimuli. The changes in the BOLD response in the visual and auditory cortices of all macaques were compared with immunofluorescence staining findings. Compared with group A, greater BOLD activity was observed in the bilateral visual cortices of group B, and this effect was particularly obvious in the right visual cortex. In addition, more activated volumes were found in the bilateral auditory cortices of group B than of group A, especially in the right auditory cortex. These findings were consistent with the fact that there were more c-Fos-positive cells in the bilateral visual and auditory cortices of group B compared with group A (p visual cortices of binocularly blind macaques can be reorganized to process auditory stimuli after visual deprivation, and this effect is more obvious in the right than the left visual cortex. These results indicate the establishment of cross-modal plasticity within the visual and auditory cortices. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

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

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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.

Metabolic Changes Underlying Bold Signal Variations after Administration of Zolpidem

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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)

Monaural and binaural contributions to interaural-level-difference sensitivity in human auditory cortex.

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Stecker, G Christopher; McLaughlin, Susan A; Higgins, Nathan C

2015-10-15

Whole-brain functional magnetic resonance imaging was used to measure blood-oxygenation-level-dependent (BOLD) responses in human auditory cortex (AC) to sounds with intensity varying independently in the left and right ears. Echoplanar images were acquired at 3 Tesla with sparse image acquisition once per 12-second block of sound stimulation. Combinations of binaural intensity and stimulus presentation rate were varied between blocks, and selected to allow measurement of response-intensity functions in three configurations: monaural 55-85 dB SPL, binaural 55-85 dB SPL with intensity equal in both ears, and binaural with average binaural level of 70 dB SPL and interaural level differences (ILD) ranging ±30 dB (i.e., favoring the left or right ear). Comparison of response functions equated for contralateral intensity revealed that BOLD-response magnitudes (1) generally increased with contralateral intensity, consistent with positive drive of the BOLD response by the contralateral ear, (2) were larger for contralateral monaural stimulation than for binaural stimulation, consistent with negative effects (e.g., inhibition) of ipsilateral input, which were strongest in the left hemisphere, and (3) also increased with ipsilateral intensity when contralateral input was weak, consistent with additional, positive, effects of ipsilateral stimulation. Hemispheric asymmetries in the spatial extent and overall magnitude of BOLD responses were generally consistent with previous studies demonstrating greater bilaterality of responses in the right hemisphere and stricter contralaterality in the left hemisphere. Finally, comparison of responses to fast (40/s) and slow (5/s) stimulus presentation rates revealed significant rate-dependent adaptation of the BOLD response that varied across ILD values. Copyright © 2015. Published by Elsevier Inc.

Consistency in boldness, activity and exploration at different stages of life

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2013-01-01

Background Animals show consistent individual behavioural patterns over time and over situations. This phenomenon has been referred to as animal personality or behavioural syndromes. Little is known about consistency of animal personalities over entire life times. We investigated the repeatability of behaviour in common voles (Microtus arvalis) at different life stages, with different time intervals, and in different situations. Animals were tested using four behavioural tests in three experimental groups: 1. before and after maturation over three months, 2. twice as adults during one week, and 3. twice as adult animals over three months, which resembles a substantial part of their entire adult life span of several months. Results Different behaviours were correlated within and between tests and a cluster analysis showed three possible behavioural syndrome-axes, which we name boldness, exploration and activity. Activity and exploration behaviour in all tests was highly repeatable in adult animals tested over one week. In animals tested over maturation, exploration behaviour was consistent whereas activity was not. Voles that were tested as adults with a three-month interval showed the opposite pattern with stable activity but unstable exploration behaviour. Conclusions The consistency in behaviour over time suggests that common voles do express stable personality over short time. Over longer periods however, behaviour is more flexible and depending on life stage (i.e. tested before/after maturation or as adults) of the tested individual. Level of boldness or activity does not differ between tested groups and maintenance of variation in behavioural traits can therefore not be explained by expected future assets as reported in other studies. PMID:24314274

Combined diffusion-weighted, blood oxygen level-dependent, and dynamic contrast-enhanced MRI for characterization and differentiation of renal cell carcinoma.

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Notohamiprodjo, Mike; Staehler, Michael; Steiner, Nicole; Schwab, Felix; Sourbron, Steven P; Michaely, Henrik J; Helck, Andreas D; Reiser, Maximilian F; Nikolaou, Konstantin

2013-06-01

To investigate a multiparametric magnetic resonance imaging (MRI) approach comprising diffusion-weighted imaging (DWI), blood oxygen-dependent (BOLD), and dynamic contrast-enhanced (DCE) MRI for characterization and differentiation of primary renal cell carcinoma (RCC). Fourteen patients with clear-cell carcinoma and four patients with papillary RCC were examined with DWI, BOLD MRI, and DCE MRI at 1.5T. The apparent diffusion coefficient (ADC) was calculated with a monoexponential decay. The spin-dephasing rate R2* was derived from parametric R2* maps. DCE-MRI was analyzed using a two-compartment exchange model allowing separation of perfusion (plasma flow [FP] and plasma volume [VP]), permeability (permeability surface area product [PS]), and extravascular extracellular volume (VE). Statistical analysis was performed with Wilcoxon signed-rank test, Pearson's correlation coefficient, and receiver operating characteristic curve analysis. Clear-cell RCC showed higher ADC and lower R2* compared to papillary subtypes, but differences were not significant. FP of clear-cell subtypes was significantly higher than in papillary RCC. Perfusion parameters showed moderate but significant inverse correlation with R2*. VE showed moderate inverse correlation with ADC. Fp and Vp showed best sensitivity for histological differentiation. Multiparametric MRI comprising DWI, BOLD, and DCE MRI is feasible for assessment of primary RCC. BOLD moderately correlates to DCE MRI-derived perfusion. ADC shows moderate correlation to the extracellular volume, but does not correlate to tumor oxygenation or perfusion. In this preliminary study DCE-MRI appeared superior to BOLD and DWI for histological differentiation. Copyright © 2013 AUR. Published by Elsevier Inc. All rights reserved.

Staging Hemodynamic Failure With Blood Oxygen-Level-Dependent Functional Magnetic Resonance Imaging Cerebrovascular Reactivity: A Comparison Versus Gold Standard (15O-)H2O-Positron Emission Tomography.

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Fierstra, Jorn; van Niftrik, Christiaan; Warnock, Geoffrey; Wegener, Susanne; Piccirelli, Marco; Pangalu, Athina; Esposito, Giuseppe; Valavanis, Antonios; Buck, Alfred; Luft, Andreas; Bozinov, Oliver; Regli, Luca

2018-03-01

Increased stroke risk correlates with hemodynamic failure, which can be assessed with ( 15 O-)H 2 O positron emission tomography (PET) cerebral blood flow (CBF) measurements. This gold standard technique, however, is not established for routine clinical imaging. Standardized blood oxygen-level-dependent (BOLD) functional magnetic resonance imaging+CO 2 is a noninvasive and potentially widely applicable tool to assess whole-brain quantitative cerebrovascular reactivity (CVR). We examined the agreement between the 2 imaging modalities and hypothesized that quantitative CVR can be a surrogate imaging marker to assess hemodynamic failure. Nineteen data sets of subjects with chronic cerebrovascular steno-occlusive disease (age, 60±11 years; 4 women) and unilaterally impaired perfusion reserve on Diamox-challenged ( 15 O-)H 2 O PET were studied and compared with a standardized BOLD functional magnetic resonance imaging+CO 2 examination within 6 weeks (8±19 days). Agreement between quantitative CBF- and CVR-based perfusion reserve was assessed. Hemodynamic failure was staged according to PET findings: stage 0: normal CBF, normal perfusion reserve; stage I: normal CBF, decreased perfusion reserve; and stage II: decreased CBF, decreased perfusion reserve. The BOLD CVR data set of the same subjects was then matched to the corresponding stage of hemodynamic failure. PET-based stage I versus stage II could also be clearly separated with BOLD CVR measurements (CVR for stage I 0.11 versus CVR for stage II -0.03; P the affected hemisphere and middle cerebral artery territory ( P the affected hemisphere and middle cerebral artery territory and for identifying hemodynamic failure stage II. BOLD CVR may, therefore, be considered for prospective studies assessing stroke risk in patients with chronic cerebrovascular steno-occlusive disease, in particular because it can potentially be implemented in routine clinical imaging. © 2018 American Heart Association, Inc.

Decreased BOLD responses in audiovisual processing

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Wiersinga-Post, Esther; Tomaskovic, Sonja; Slabu, Lavinia; Renken, Remco; de Smit, Femke; Duifhuis, Hendrikus

2010-01-01

Audiovisual processing was studied in a functional magnetic resonance imaging study using the McGurk effect. Perceptual responses and the brain activity patterns were measured as a function of audiovisual delay. In several cortical and subcortical brain areas, BOLD responses correlated negatively

When the Brain Takes 'BOLD' Steps: Real-Time fMRI Neurofeedback Can Further Enhance the Ability to Gradually Self-regulate Regional Brain Activation.

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Sorger, Bettina; Kamp, Tabea; Weiskopf, Nikolaus; Peters, Judith Caroline; Goebel, Rainer

2018-05-15

Brain-computer interfaces (BCIs) based on real-time functional magnetic resonance imaging (rtfMRI) are currently explored in the context of developing alternative (motor-independent) communication and control means for the severely disabled. In such BCI systems, the user encodes a particular intention (e.g., an answer to a question or an intended action) by evoking specific mental activity resulting in a distinct brain state that can be decoded from fMRI activation. One goal in this context is to increase the degrees of freedom in encoding different intentions, i.e., to allow the BCI user to choose from as many options as possible. Recently, the ability to voluntarily modulate spatial and/or temporal blood oxygenation level-dependent (BOLD)-signal features has been explored implementing different mental tasks and/or different encoding time intervals, respectively. Our two-session fMRI feasibility study systematically investigated for the first time the possibility of using magnitudinal BOLD-signal features for intention encoding. Particularly, in our novel paradigm, participants (n=10) were asked to alternately self-regulate their regional brain-activation level to 30%, 60% or 90% of their maximal capacity by applying a selected activation strategy (i.e., performing a mental task, e.g., inner speech) and modulation strategies (e.g., using different speech rates) suggested by the experimenters. In a second step, we tested the hypothesis that the additional availability of feedback information on the current BOLD-signal level within a region of interest improves the gradual-self regulation performance. Therefore, participants were provided with neurofeedback in one of the two fMRI sessions. Our results show that the majority of the participants were able to gradually self-regulate regional brain activation to at least two different target levels even in the absence of neurofeedback. When provided with continuous feedback on their current BOLD-signal level, most

Integration of BOLD-fMRI and DTI into radiation treatment planning for high-grade gliomas located near the primary motor cortexes and corticospinal tracts

International Nuclear Information System (INIS)

Wang, Minglei; Ma, Hui; Wang, Xiaodong; Guo, Yanhong; Xia, Xinshe; Xia, Hechun; Guo, Yulin; Huang, Xueying; He, Hong; Jia, Xiaoxiong; Xie, Yan

2015-01-01

The main objective of this study was to evaluate the efficacy of integrating the blood oxygen level dependent functional magnetic resonance imaging (BOLD-fMRI) and diffusion tensor imaging (DTI) data into radiation treatment planning for high-grade gliomas located near the primary motor cortexes (PMCs) and corticospinal tracts (CSTs). A total of 20 patients with high-grade gliomas adjacent to PMCs and CSTs between 2012 and 2014 were recruited. The bilateral PMCs and CSTs were located in the normal regions without any overlapping with target volume of the lesions. BOLD-fMRI, DTI and conventional MRI were performed on patients (Karnofsky performance score ≥ 70) before radical radiotherapy treatment. Four different imaging studies were conducted in each patient: a planning computed tomography (CT), an anatomical MRI, a DTI and a BOLD-fMRI. For each case, three treatment plans (3DCRT, IMRT and IMRT-PMC&CST) were developed by 3 different physicists using the Pinnacle planning system. Our study has shown that there was no significant difference between the 3DCRT and IMRT plans in terms of dose homogeneity, but IMRT displayed better planning target volume (PTV) dose conformity. In addition, we have found that the Dmax and Dmean to the ipsilateral and contralateral PMC and CST regions were considerably decreased in IMRT-PMC&CST group (p < 0.001). In conclusion, integration of BOLD-fMRI and DTI into radiation treatment planning is feasible and beneficial. With the assistance of the above-described techniques, the bilateral PMCs and CSTs adjacent to the target volume could be clearly marked as OARs and spared during treatment

A Big Five facet analysis of sub-clinical narcissism: understanding boldness in terms of well-known personality traits.

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Furnham, Adrian; Crump, John

2014-08-01

This study aimed to examine a Big Five 'bright-side' analysis of a sub-clinical personality disorder, i.e. narcissism. A total of 6957 British adults completed the NEO-PI-R, which measures the Big Five Personality factors at the domain and the facet level, as well as the Hogan Development Survey (HDS), which has a measure of Narcissism called Bold as one of its dysfunctional interpersonal tendencies. Correlation and regression results confirmed many of the associations between the Big Five domains and facets (NEO-PI-R) and sub-clinical narcissism. The Bold (Narcissism) scale from the HDS was the criterion variable in all analyses. Bold individuals are disagreeable extraverts with very low scores on facet Modesty but moderately high scores on Assertiveness, Competence and Achievement Striving. The study confirmed work using different population groups and different measures. Copyright © 2014 John Wiley & Sons, Ltd.

Real-time fMRI neurofeedback of the mediodorsal and anterior thalamus enhances correlation between thalamic BOLD activity and alpha EEG rhythm.

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Zotev, Vadim; Misaki, Masaya; Phillips, Raquel; Wong, Chung Ki; Bodurka, Jerzy

2018-02-01

Real-time fMRI neurofeedback (rtfMRI-nf) with simultaneous EEG allows volitional modulation of BOLD activity of target brain regions and investigation of related electrophysiological activity. We applied this approach to study correlations between thalamic BOLD activity and alpha EEG rhythm. Healthy volunteers in the experimental group (EG, n = 15) learned to upregulate BOLD activity of the target region consisting of the mediodorsal (MD) and anterior (AN) thalamic nuclei using rtfMRI-nf during retrieval of happy autobiographical memories. Healthy subjects in the control group (CG, n = 14) were provided with a sham feedback. The EG participants were able to significantly increase BOLD activities of the MD and AN. Functional connectivity between the MD and the inferior precuneus was significantly enhanced during the rtfMRI-nf task. Average individual changes in the occipital alpha EEG power significantly correlated with the average MD BOLD activity levels for the EG. Temporal correlations between the occipital alpha EEG power and BOLD activities of the MD and AN were significantly enhanced, during the rtfMRI-nf task, for the EG compared to the CG. Temporal correlations with the alpha power were also significantly enhanced for the posterior nodes of the default mode network, including the precuneus/posterior cingulate, and for the dorsal striatum. Our findings suggest that the temporal correlation between the MD BOLD activity and posterior alpha EEG power is modulated by the interaction between the MD and the inferior precuneus, reflected in their functional connectivity. Our results demonstrate the potential of the rtfMRI-nf with simultaneous EEG for noninvasive neuromodulation studies of human brain function. © 2017 Wiley Periodicals, Inc.

Relationship between BOLD amplitude and pattern classification of orientation-selective activity in the human visual cortex

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Tong, Frank; Harrison, Stephenie A.; Dewey, John A.; Kamitani, Yukiyasu

2012-01-01

Orientation-selective responses can be decoded from fMRI activity patterns in the human visual cortex, using multivariate pattern analysis (MVPA). To what extent do these feature-selective activity patterns depend on the strength and quality of the sensory input, and might the reliability of these activity patterns be predicted by the gross amplitude of the stimulus-driven BOLD response? Observers viewed oriented gratings that varied in luminance contrast (4, 20 or 100%) or spatial frequency (0.25, 1.0 or 4.0 cpd). As predicted, activity patterns in early visual areas led to better discrimination of orientations presented at high than low contrast, with greater effects of contrast found in area V1 than in V3. A second experiment revealed generally better decoding of orientations at low or moderate as compared to high spatial frequencies. Interestingly however, V1 exhibited a relative advantage at discriminating high spatial frequency orientations, consistent with the finer scale of representation in the primary visual cortex. In both experiments, the reliability of these orientation-selective activity patterns was well predicted by the average BOLD amplitude in each region of interest, as indicated by correlation analyses, as well as decoding applied to a simple model of voxel responses to simulated orientation columns. Moreover, individual differences in decoding accuracy could be predicted by the signal-to-noise ratio of an individual's BOLD response. Our results indicate that decoding accuracy can be well predicted by incorporating the amplitude of the BOLD response into simple simulation models of cortical selectivity; such models could prove useful in future applications of fMRI pattern classification. PMID:22917989

Evolution of boldness and life-history in response to selective harvesting

DEFF Research Database (Denmark)

Andersen, Ken Haste; Marty, Lise; Arlinghaus, Robert

2018-01-01

Whether intensive harvesting alters the behavioral repertoire of exploited fishes is currently unknown, but plausible. We extend a fish life-history model to account for boldness as a personality trait that affects foraging intensity, which affects energy intake and risk from predation and fishing...... gear. We systematically investigate life-history and behavioral trait evolution along the boldness–timidity axis in response to the full range of common selectivity and exploitation patterns in fisheries. In agreement with previous studies, we find that any type of harvesting selects for fast life...... histories and that merely elevated, yet unselective, fishing mortality favors boldness. We also find that timid-selective fishing (which can be expected in species targeted by active gear types) selects for increased boldness. By contrast, increased timidity is predicted when fishing targets bolder...

Increased BOLD Signals Elicited by High Gamma Auditory Stimulation of the Left Auditory Cortex in Acute State Schizophrenia

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Hironori Kuga, M.D.

2016-10-01

We acquired BOLD responses elicited by click trains of 20, 30, 40 and 80-Hz frequencies from 15 patients with acute episode schizophrenia (AESZ, 14 symptom-severity-matched patients with non-acute episode schizophrenia (NASZ, and 24 healthy controls (HC, assessed via a standard general linear-model-based analysis. The AESZ group showed significantly increased ASSR-BOLD signals to 80-Hz stimuli in the left auditory cortex compared with the HC and NASZ groups. In addition, enhanced 80-Hz ASSR-BOLD signals were associated with more severe auditory hallucination experiences in AESZ participants. The present results indicate that neural over activation occurs during 80-Hz auditory stimulation of the left auditory cortex in individuals with acute state schizophrenia. Given the possible association between abnormal gamma activity and increased glutamate levels, our data may reflect glutamate toxicity in the auditory cortex in the acute state of schizophrenia, which might lead to progressive changes in the left transverse temporal gyrus.

BOLD Granger causality reflects vascular anatomy.

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J Taylor Webb

Full Text Available A number of studies have tried to exploit subtle phase differences in BOLD time series to resolve the order of sequential activation of brain regions, or more generally the ability of signal in one region to predict subsequent signal in another region. More recently, such lag-based measures have been applied to investigate directed functional connectivity, although this application has been controversial. We attempted to use large publicly available datasets (FCON 1000, ADHD 200, Human Connectome Project to determine whether consistent spatial patterns of Granger Causality are observed in typical fMRI data. For BOLD datasets from 1,240 typically developing subjects ages 7-40, we measured Granger causality between time series for every pair of 7,266 spherical ROIs covering the gray matter and 264 seed ROIs at hubs of the brain's functional network architecture. Granger causality estimates were strongly reproducible for connections in a test and replication sample (n=620 subjects for each group, as well as in data from a single subject scanned repeatedly, both during resting and passive video viewing. The same effect was even stronger in high temporal resolution fMRI data from the Human Connectome Project, and was observed independently in data collected during performance of 7 task paradigms. The spatial distribution of Granger causality reflected vascular anatomy with a progression from Granger causality sources, in Circle of Willis arterial inflow distributions, to sinks, near large venous vascular structures such as dural venous sinuses and at the periphery of the brain. Attempts to resolve BOLD phase differences with Granger causality should consider the possibility of reproducible vascular confounds, a problem that is independent of the known regional variability of the hemodynamic response.

Correlation between MEG and BOLD fMRI signals induced by visual flicker stimuli

Institute of Scientific and Technical Information of China (English)

Chu Renxin; Holroyd Tom; Duyn Jeff

2007-01-01

The goal of this work was to investigate how the MEG signal amplitude correlates with that of BOLD fMRI.To investigate the correlation between fMRI and macroscopic electrical activity, BOLD fMRI and MEG was performed on the same subjects (n =5). A visual flicker stimulus of varying temporal frequency was used to elicit neural responses in early visual areas. A strong similarity was observed in frequency tuning curves between both modalities.Although, averaged over subjects, the BOLD tuning curve was somewhat broader than MEG, both BOLD and MEG had maxima at a flicker frequency of 10 Hz. Also, we measured the first and second harmonic components as the stimuli frequency by MEG. In the low stimuli frequency (less than 6 Hz), the second harmonic has comparable amplitude with the first harmonic, which implies that neural frequency response is nonlinear and has more nonlinear components in low frequency than in high frequency.

Resting bold fMRI differentiates dementia with Lewy bodies vs Alzheimer disease

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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

Cerebral Asymmetry of fMRI-BOLD Responses to Visual Stimulation.

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Anders Hougaard

Full Text Available Hemispheric asymmetry of a wide range of functions is a hallmark of the human brain. The visual system has traditionally been thought of as symmetrically distributed in the brain, but a growing body of evidence has challenged this view. Some highly specific visual tasks have been shown to depend on hemispheric specialization. However, the possible lateralization of cerebral responses to a simple checkerboard visual stimulation has not been a focus of previous studies. To investigate this, we performed two sessions of blood-oxygenation level dependent (BOLD functional magnetic resonance imaging (fMRI in 54 healthy subjects during stimulation with a black and white checkerboard visual stimulus. While carefully excluding possible non-physiological causes of left-to-right bias, we compared the activation of the left and the right cerebral hemispheres and related this to grey matter volume, handedness, age, gender, ocular dominance, interocular difference in visual acuity, as well as line-bisection performance. We found a general lateralization of cerebral activation towards the right hemisphere of early visual cortical areas and areas of higher-level visual processing, involved in visuospatial attention, especially in top-down (i.e., goal-oriented attentional processing. This right hemisphere lateralization was partly, but not completely, explained by an increased grey matter volume in the right hemisphere of the early visual areas. Difference in activation of the superior parietal lobule was correlated with subject age, suggesting a shift towards the left hemisphere with increasing age. Our findings suggest a right-hemispheric dominance of these areas, which could lend support to the generally observed leftward visual attentional bias and to the left hemifield advantage for some visual perception tasks.

SU-D-207A-03: Potential Role of BOLD MRI in Discrimination of Aggressive Tumor Habitat in Prostate Cancer

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Ford, J; Lopez, C; Tschudi, Y; Breto, A; Padgett, K; Pollack, A; Stoyanova, R [University of Miami Miller School of Medicine, Miami, FL (United States)

2016-06-15

Purpose: To determine whether blood oxygenation level dependent (BOLD) MRI signal measured in prostate cancer patients, in addition to quantitative diffusion and perfusion parameters from multiparametric (mp)MRI exams, can help discriminate aggressive and/or radioresistant lesions. Methods: Several ongoing clinical trials in our institution require mpMRI exam to determine eligibility (presence of identifiable tumor lesion on mpMRI) and prostate volumes for dose escalation. Upon consent, patients undergo fiducial markers placement and a T2*-weighted imaging at the time of CT sim to facilitate the fusion. In a retrospective analysis eleven clinical trial patients were identified who had undergone mpMRI on GE 3T magnet, followed by T2*-weighted imaging (time-period mean±SD = 48±20 days) using a consistent protocol (gradient echo, TR/TE=30/11.8ms, flip angle=12, matrix=256×256×75, voxel size=1.25×1.25×2.5mm). ROIs for prostate tumor lesions were automatically determined using ADC threshold ≤1200 µm2/s. Although the MR protocol was not intended for BOLD analysis, we utilized the T2*-weighted signal normalized to that in nearby muscle; likewise, T2-weighted lesion signal was normalized to muscle, following rigid registration of the T2 to T2* images. The ratio of these normalized signals, T2*/T2, is a measure of BOLD effect in the prostate tumors. Perfusion parameters (Ktrans, ve, kep) were also calculated. Results: T2*/T2 (mean±SE) was found to be substantially lower for Gleason score (GS) 8&9 (0.82±0.04) compared to GS 7 (1.08±0.07). A k-means cluster analysis of T2*/T2 versus kep = Ktrans/ve revealed two distinct clusters, one with higher T2*/T2 and lower kep, containing only GS 7 lesions, and another with lower T2*/T2 and higher kep, associated with tumor aggressiveness. This latter cluster contained all GS 8&9 lesions, as well as some GS 7. Conclusion: BOLD MRI, in addition to ADC and kep, may play a role (perhaps orthogonal to Gleason score) in

Intraindividual variability of boldness is repeatable across contexts in a wild lizard.

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Laura Highcock

Full Text Available Animals do not behave in exactly the same way when repeatedly tested in the same context or situation, even once systematic variation, such as habituation, has been controlled for. This unpredictability is called intraindividual variability (IIV and has been little studied in animals. Here we investigated how IIV in boldness (estimated by flight initiation distances changed across two seasons--the dry, non-breeding season and the wet, breeding season--in a wild population of the Namibian rock agama, Agama planiceps. We found significant differences in IIV both between individuals and seasons, and IIV was higher in the wet season, suggesting plasticity in IIV. Further, IIV was highly repeatable (r = 0.61 between seasons and we found strong negative correlations between consistent individual differences in flight initiation distances, i.e. their boldness, and individuals' IIVs. We suggest that to understand personality in animals, researchers should generate a personality 'profile' that includes not only the relative level of a trait (i.e. its personality, but also its plasticity and variability under natural conditions.

Single-trial EEG-informed fMRI reveals spatial dependency of BOLD signal on early and late IC-ERP amplitudes during face recognition.

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Wirsich, Jonathan; Bénar, Christian; Ranjeva, Jean-Philippe; Descoins, Médéric; Soulier, Elisabeth; Le Troter, Arnaud; Confort-Gouny, Sylviane; Liégeois-Chauvel, Catherine; Guye, Maxime

2014-10-15

Simultaneous EEG-fMRI has opened up new avenues for improving the spatio-temporal resolution of functional brain studies. However, this method usually suffers from poor EEG quality, especially for evoked potentials (ERPs), due to specific artifacts. As such, the use of EEG-informed fMRI analysis in the context of cognitive studies has particularly focused on optimizing narrow ERP time windows of interest, which ignores the rich diverse temporal information of the EEG signal. Here, we propose to use simultaneous EEG-fMRI to investigate the neural cascade occurring during face recognition in 14 healthy volunteers by using the successive ERP peaks recorded during the cognitive part of this process. N170, N400 and P600 peaks, commonly associated with face recognition, were successfully and reproducibly identified for each trial and each subject by using a group independent component analysis (ICA). For the first time we use this group ICA to extract several independent components (IC) corresponding to the sequence of activation and used single-trial peaks as modulation parameters in a general linear model (GLM) of fMRI data. We obtained an occipital-temporal-frontal stream of BOLD signal modulation, in accordance with the three successive IC-ERPs providing an unprecedented spatio-temporal characterization of the whole cognitive process as defined by BOLD signal modulation. By using this approach, the pattern of EEG-informed BOLD modulation provided improved characterization of the network involved than the fMRI-only analysis or the source reconstruction of the three ERPs; the latter techniques showing only two regions in common localized in the occipital lobe. Copyright © 2014 Elsevier Inc. All rights reserved.

Research progress of BOLD-fMRI in minimal hepatic encephalopathy

International Nuclear Information System (INIS)

Zhou Zhiming; Zhao Jiannong

2013-01-01

The minimal hepatic encephalopathy is the early stage of hepatic encephalopathy. It has few apparent clinical symptoms and specific manifestations, and is difficult to diagnose. In the recent years, BOLD-fMRI has been used to study hepatic encephalopathy gradually. Through detection of the brain neuron activities in different states, it can not only locate the abnormal activity of brain functional areas, but also can find the changes of brain functional connectivity. BOLD- fMRI combining with other MR technologies can explore the pathology and pathogenesis of minimal hepatic encephalopathy from micro to macro and from structure to function. (authors)

A neural measure of behavioral engagement: task-residual low-frequency blood oxygenation level-dependent activity in the precuneus.

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Zhang, Sheng; Li, Chiang-Shan Ray

2010-01-15

Brain imaging has provided a useful tool to examine the neural processes underlying human cognition. A critical question is whether and how task engagement influences the observed regional brain activations. Here we highlighted this issue and derived a neural measure of task engagement from the task-residual low-frequency blood oxygenation level-dependent (BOLD) activity in the precuneus. Using independent component analysis, we identified brain regions in the default circuit - including the precuneus and medial prefrontal cortex (mPFC) - showing greater activation during resting as compared to task residuals in 33 individuals. Time series correlations with the posterior cingulate cortex as the seed region showed that connectivity with the precuneus was significantly stronger during resting as compared to task residuals. We hypothesized that if the task-residual BOLD activity in the precuneus reflects engagement, it should account for a certain amount of variance in task-related regional brain activation. In an additional experiment of 59 individuals performing a stop signal task, we observed that the fractional amplitude of low-frequency fluctuation (fALFF) of the precuneus but not the mPFC accounted for approximately 10% of the variance in prefrontal activation related to attentional monitoring and response inhibition. Taken together, these results suggest that task-residual fALFF in the precuneus may be a potential indicator of task engagement. This measurement may serve as a useful covariate in identifying motivation-independent neural processes that underlie the pathogenesis of a psychiatric or neurological condition.

Measuring vascular reactivity with resting-state blood oxygenation level-dependent (BOLD) signal fluctuations: A potential alternative to the breath-holding challenge?

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Jahanian, Hesamoddin; Christen, Thomas; Moseley, Michael E; Pajewski, Nicholas M; Wright, Clinton B; Tamura, Manjula K; Zaharchuk, Greg

2017-07-01

Measurement of the ability of blood vessels to dilate and constrict, known as vascular reactivity, is often performed with breath-holding tasks that transiently raise arterial blood carbon dioxide (P a CO 2 ) levels. However, following the proper commands for a breath-holding experiment may be difficult or impossible for many patients. In this study, we evaluated two approaches for obtaining vascular reactivity information using blood oxygenation level-dependent signal fluctuations obtained from resting-state functional magnetic resonance imaging data: physiological fluctuation regression and coefficient of variation of the resting-state functional magnetic resonance imaging signal. We studied a cohort of 28 older adults (69 ± 7 years) and found that six of them (21%) could not perform the breath-holding protocol, based on an objective comparison with an idealized respiratory waveform. In the subjects that could comply, we found a strong linear correlation between data extracted from spontaneous resting-state functional magnetic resonance imaging signal fluctuations and the blood oxygenation level-dependent percentage signal change during breath-holding challenge ( R 2  = 0.57 and 0.61 for resting-state physiological fluctuation regression and resting-state coefficient of variation methods, respectively). This technique may eliminate the need for subject cooperation, thus allowing the evaluation of vascular reactivity in a wider range of clinical and research conditions in which it may otherwise be impractical.

Negative BOLD in sensory cortices during verbal memory: a component in generating internal representations?

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Azulay, Haim; Striem, Ella; Amedi, Amir

2009-05-01

People tend to close their eyes when trying to retrieve an event or a visual image from memory. However the brain mechanisms behind this phenomenon remain poorly understood. Recently, we showed that during visual mental imagery, auditory areas show a much more robust deactivation than during visual perception. Here we ask whether this is a special case of a more general phenomenon involving retrieval of intrinsic, internally stored information, which would result in crossmodal deactivations in other sensory cortices which are irrelevant to the task at hand. To test this hypothesis, a group of 9 sighted individuals were scanned while performing a memory retrieval task for highly abstract words (i.e., with low imaginability scores). We also scanned a group of 10 congenitally blind, which by definition do not have any visual imagery per se. In sighted subjects, both auditory and visual areas were robustly deactivated during memory retrieval, whereas in the blind the auditory cortex was deactivated while visual areas, shown previously to be relevant for this task, presented a positive BOLD signal. These results suggest that deactivation may be most prominent in task-irrelevant sensory cortices whenever there is a need for retrieval or manipulation of internally stored representations. Thus, there is a task-dependent balance of activation and deactivation that might allow maximization of resources and filtering out of non relevant information to enable allocation of attention to the required task. Furthermore, these results suggest that the balance between positive and negative BOLD might be crucial to our understanding of a large variety of intrinsic and extrinsic tasks including high-level cognitive functions, sensory processing and multisensory integration.

Non-linear Relationship between BOLD Activation and Amplitude of Beta Oscillations in the Supplementary Motor Area during Rhythmic Finger Tapping and Internal Timing

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Gompf, Florian; Pflug, Anja; Laufs, Helmut; Kell, Christian A.

2017-01-01

Functional imaging studies using BOLD contrasts have consistently reported activation of the supplementary motor area (SMA) both during motor and internal timing tasks. Opposing findings, however, have been shown for the modulation of beta oscillations in the SMA. While movement suppresses beta oscillations in the SMA, motor and non-motor tasks that rely on internal timing increase the amplitude of beta oscillations in the SMA. These independent observations suggest that the relationship between beta oscillations and BOLD activation is more complex than previously thought. Here we set out to investigate this rapport by examining beta oscillations in the SMA during movement with varying degrees of internal timing demands. In a simultaneous EEG-fMRI experiment, 20 healthy right-handed subjects performed an auditory-paced finger-tapping task. Internal timing was operationalized by including conditions with taps on every fourth auditory beat, which necessitates generation of a slow internal rhythm, while tapping to every auditory beat reflected simple auditory-motor synchronization. In the SMA, BOLD activity increased and power in both the low and the high beta band decreased expectedly during each condition compared to baseline. Internal timing was associated with a reduced desynchronization of low beta oscillations compared to conditions without internal timing demands. In parallel with this relative beta power increase, internal timing activated the SMA more strongly in terms of BOLD. This documents a task-dependent non-linear relationship between BOLD and beta-oscillations in the SMA. We discuss different roles of beta synchronization and desynchronization in active processing within the same cortical region. PMID:29249950

Non-linear Relationship between BOLD Activation and Amplitude of Beta Oscillations in the Supplementary Motor Area during Rhythmic Finger Tapping and Internal Timing.

Science.gov (United States)

Gompf, Florian; Pflug, Anja; Laufs, Helmut; Kell, Christian A

2017-01-01

Functional imaging studies using BOLD contrasts have consistently reported activation of the supplementary motor area (SMA) both during motor and internal timing tasks. Opposing findings, however, have been shown for the modulation of beta oscillations in the SMA. While movement suppresses beta oscillations in the SMA, motor and non-motor tasks that rely on internal timing increase the amplitude of beta oscillations in the SMA. These independent observations suggest that the relationship between beta oscillations and BOLD activation is more complex than previously thought. Here we set out to investigate this rapport by examining beta oscillations in the SMA during movement with varying degrees of internal timing demands. In a simultaneous EEG-fMRI experiment, 20 healthy right-handed subjects performed an auditory-paced finger-tapping task. Internal timing was operationalized by including conditions with taps on every fourth auditory beat, which necessitates generation of a slow internal rhythm, while tapping to every auditory beat reflected simple auditory-motor synchronization. In the SMA, BOLD activity increased and power in both the low and the high beta band decreased expectedly during each condition compared to baseline. Internal timing was associated with a reduced desynchronization of low beta oscillations compared to conditions without internal timing demands. In parallel with this relative beta power increase, internal timing activated the SMA more strongly in terms of BOLD. This documents a task-dependent non-linear relationship between BOLD and beta-oscillations in the SMA. We discuss different roles of beta synchronization and desynchronization in active processing within the same cortical region.

Right anterior cerebellum BOLD responses reflect age related changes in Simon task sequential effects.

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Aisenberg, D; Sapir, A; Close, A; Henik, A; d'Avossa, G

2018-01-31

Participants are slower to report a feature, such as color, when the target appears on the side opposite the instructed response, than when the target appears on the same side. This finding suggests that target location, even when task-irrelevant, interferes with response selection. This effect is magnified in older adults. Lengthening the inter-trial interval, however, suffices to normalize the congruency effect in older adults, by re-establishing young-like sequential effects (Aisenberg et al., 2014). We examined the neurological correlates of age related changes by comparing BOLD signals in young and old participants performing a visual version of the Simon task. Participants reported the color of a peripheral target, by a left or right-hand keypress. Generally, BOLD responses were greater following incongruent than congruent targets. Also, they were delayed and of smaller amplitude in old than young participants. BOLD responses in visual and motor regions were also affected by the congruency of the previous target, suggesting that sequential effects may reflect remapping of stimulus location onto the hand used to make a response. Crucially, young participants showed larger BOLD responses in right anterior cerebellum to incongruent targets, when the previous target was congruent, but smaller BOLD responses to incongruent targets when the previous target was incongruent. Old participants, however, showed larger BOLD responses to congruent than incongruent targets, irrespective of the previous target congruency. We conclude that aging may interfere with the trial by trial updating of the mapping between the task-irrelevant target location and response, which takes place during the inter-trial interval in the cerebellum and underlays sequential effects in a Simon task. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

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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.

Linear increases in BOLD response associated with increasing proportion of incongruent trials across time in a colour Stroop task.

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Mitchell, Rachel L C

2010-05-01

Selective attention is popularly assessed with colour Stroop tasks in which participants name the ink colour of colour words, whilst resisting interference from the natural tendency to read the words. Prior studies hinted that the key brain regions (dorsolateral prefrontal (dlPFC) and anterior cingulate cortex (ACC)) may vary their degree of involvement, dependent on attentional demand. This study aimed to determine whether a parametrically varied increase in attentional demand resulted in linearly increased activity in these regions, and/or whether additional regions would be recruited during high attentional demand. Twenty-eight healthy young adults underwent fMRI whilst naming the font colour of colour words. Linear increases in BOLD response were assessed with increasing percentage incongruent trials per block (0, 20, 40, 60, 80, and 100%). Whilst ACC activation increased linearly according to incongruity level, dlPFC activity appeared constant. Together with behavioural evidence of reduced Stroop interference, these data support a load-dependent conflict-related response in ACC, but not dlPFC.

High spatial correspondence at a columnar level between activation and resting state fMRI signals and local field potentials.

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Shi, Zhaoyue; Wu, Ruiqi; Yang, Pai-Feng; Wang, Feng; Wu, Tung-Lin; Mishra, Arabinda; Chen, Li Min; Gore, John C

2017-05-16

Although blood oxygenation level-dependent (BOLD) fMRI has been widely used to map brain responses to external stimuli and to delineate functional circuits at rest, the extent to which BOLD signals correlate spatially with underlying neuronal activity, the spatial relationships between stimulus-evoked BOLD activations and local correlations of BOLD signals in a resting state, and whether these spatial relationships vary across functionally distinct cortical areas are not known. To address these critical questions, we directly compared the spatial extents of stimulated activations and the local profiles of intervoxel resting state correlations for both high-resolution BOLD at 9.4 T and local field potentials (LFPs), using 98-channel microelectrode arrays, in functionally distinct primary somatosensory areas 3b and 1 in nonhuman primates. Anatomic images of LFP and BOLD were coregistered within 0.10 mm accuracy. We found that the point spread functions (PSFs) of BOLD and LFP responses were comparable in the stimulus condition, and both estimates of activations were slightly more spatially constrained than local correlations at rest. The magnitudes of stimulus responses in area 3b were stronger than those in area 1 and extended in a medial to lateral direction. In addition, the reproducibility and stability of stimulus-evoked activation locations within and across both modalities were robust. Our work suggests that the intrinsic resolution of BOLD is not a limiting feature in practice and approaches the intrinsic precision achievable by multielectrode electrophysiology.

Greater BOLD variability in older compared with younger adults during audiovisual speech perception.

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Sarah H Baum

Full Text Available Older adults exhibit decreased performance and increased trial-to-trial variability on a range of cognitive tasks, including speech perception. We used blood oxygen level dependent functional magnetic resonance imaging (BOLD fMRI to search for neural correlates of these behavioral phenomena. We compared brain responses to simple speech stimuli (audiovisual syllables in 24 healthy older adults (53 to 70 years old and 14 younger adults (23 to 39 years old using two independent analysis strategies: region-of-interest (ROI and voxel-wise whole-brain analysis. While mean response amplitudes were moderately greater in younger adults, older adults had much greater within-subject variability. The greatly increased variability in older adults was observed for both individual voxels in the whole-brain analysis and for ROIs in the left superior temporal sulcus, the left auditory cortex, and the left visual cortex. Increased variability in older adults could not be attributed to differences in head movements between the groups. Increased neural variability may be related to the performance declines and increased behavioral variability that occur with aging.

Longitudinal Assessment of Renal Perfusion and Oxygenation in Transplant Donor-Recipient Pairs Using Arterial Spin Labeling and Blood Oxygen Level-Dependent Magnetic Resonance Imaging.

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Niles, David J; Artz, Nathan S; Djamali, Arjang; Sadowski, Elizabeth A; Grist, Thomas M; Fain, Sean B

2016-02-01

The aims of this study were to assess renal function in kidney transplant recipients and their respective donors over 2 years using arterial spin labeling (ASL) and blood oxygen level-dependent (BOLD) magnetic resonance imaging (MRI) and to prospectively evaluate the effect of losartan on functional MRI measures in recipients. The study included 15 matched pairs of renal transplant donors and recipients. Arterial spin labeling and BOLD MRI of the kidneys were performed on donors before transplant surgery (baseline) and on both donors and recipients at 3 months, 1 year, and 2 years after transplant. After 3 months, 7 of the 15 recipients were prescribed 25 to 50 mg/d losartan for the remainder of the study. A linear mixed-effects model was used to evaluate perfusion, R2*, estimated glomerular filtration rate, and fractional excretion of sodium for changes across time or associated with losartan treatment. In donors, cortical perfusion in the remaining kidney decreased by 50 ± 19 mL/min per 100 g (11.8%) between baseline and 2 years (P donors and to 14.6 ± 4.3 mL/min per 1.73 m (33.3%; P donors, and they indicate a potentially beneficial effect of losartan in recipients.

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

Task performance changes the amplitude and timing of the BOLD signal

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Akhrif Atae

2017-12-01

Full Text Available Translational studies comparing imaging data of animals and humans have gained increasing scientific interests. With this upcoming translational approach, however, identifying harmonized statistical analysis as well as shared data acquisition protocols and/or combined statistical approaches is necessary. Following this idea, we applied Bayesian Adaptive Regression Splines (BARS, which have until now mainly been used to model neural responses of electrophysiological recordings from rodent data, on human hemodynamic responses as measured via fMRI. Forty-seven healthy subjects were investigated while performing the Attention Network Task in the MRI scanner. Fluctuations in the amplitude and timing of the BOLD response were determined and validated externally with brain activation using GLM and also ecologically with the influence of task performance (i.e. good vs. bad performers. In terms of brain activation, bad performers presented reduced activation bilaterally in the parietal lobules, right prefrontal cortex (PFC and striatum. This was accompanied by an enhanced left PFC recruitment. With regard to the amplitude of the BOLD-signal, bad performers showed enhanced values in the left PFC. In addition, in the regions of reduced activation such as the parietal and striatal regions, the temporal dynamics were higher in bad performers. Based on the relation between BOLD response and neural firing with the amplitude of the BOLD signal reflecting gamma power and timing dynamics beta power, we argue that in bad performers, an enhanced left PFC recruitment hints towards an enhanced functioning of gamma-band activity in a compensatory manner. This was accompanied by reduced parieto-striatal activity, associated with increased and potentially conflicting beta-band activity.

BOLD responses in somatosensory cortices better reflect heat sensation than pain.

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Moulton, Eric A; Pendse, Gautam; Becerra, Lino R; Borsook, David

2012-04-25

The discovery of cortical networks that participate in pain processing has led to the common generalization that blood oxygen level-dependent (BOLD) responses in these areas indicate the processing of pain. Physical stimuli have fundamental properties that elicit sensations distinguishable from pain, such as heat. We hypothesized that pain intensity coding may reflect the intensity coding of heat sensation during the presentation of thermal stimuli during fMRI. Six 3T fMRI heat scans were collected for 16 healthy subjects, corresponding to perceptual levels of "low innocuous heat," "moderate innocuous heat," "high innocuous heat," "low painful heat," "moderate painful heat," and "high painful heat" delivered by a contact thermode to the face. Subjects rated pain and heat intensity separately after each scan. A general linear model analysis detected different patterns of brain activation for the different phases of the biphasic response to heat. During high painful heat, the early phase was associated with significant anterior insula and anterior cingulate cortex activation. Persistent responses were detected in the right dorsolateral prefrontal cortex and inferior parietal lobule. Only the late phase showed significant correlations with perceptual ratings. Significant heat intensity correlated activation was identified in contralateral primary and secondary somatosensory cortices, motor cortex, and superior temporal lobe. These areas were significantly more related to heat ratings than pain. These results indicate that heat intensity is encoded by the somatosensory cortices, and that pain evaluation may either arise from multimodal evaluative processes, or is a distributed process.

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

Role of 3T multiparametric-MRI with BOLD hypoxia imaging for diagnosis and post therapy response evaluation of postoperative recurrent cervical cancers

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Mahajan, Abhishek; Engineer, Reena; Chopra, Supriya; Mahanshetty, Umesh; Juvekar, S.L.; Shrivastava, S.K.; Desekar, Naresh; Thakur, M.H.

2015-01-01

vaginal vault/local recurrence following primary surgery for cervical cancer. With institutional review board approval and written informed consent 30 women (median age: 45 years) from October 2009 to March 2010 with previous operated carcinoma cervix and suspected clinical vaginal vault/local recurrence were examined with 3.0T-MRI. MRI imaging included conventional and MPMRI sequences [dynamic contrast enhanced (DCE), diffusion weighted (DW), 1H-MR spectroscopy (1HMRS), blood oxygen level dependent hypoxia imaging (BOLD)]. Two radiologists, blinded to pathologic findings, independently assessed the pretherapy MRI findings and then correlated it with histopathology findings. Sensitivity, specificity, positive predictive value, negative predictive value and their confidence intervals were calculated. The pre and post therapy conventional and MPMRI parameters were analyzed and correlated with response to therapy. Of the 30 patients, there were 24 recurrent tumors and 6 benign lesions. The accuracy of diagnosing recurrent vault lesions was highest at combined MPMRI and conventional MRI (100%) than at conventional-MRI (70%) or MPMRI (96.7%) alone. Significant correlation was seen between percentage tumor regression and pre-treatment parameters such as negative enhancement integral (NEI) (p = 0.02), the maximum slope (p = 0.04), mADC value (p = 0.001) and amount of hypoxic fraction on the pretherapy MRI (p = 0.01). Conventional-MR with MPMRI significantly increases the diagnostic accuracy for suspected vaginal vault/local recurrence. Post therapy serial MPMRI with hypoxia imaging follow-up objectively documents the response. MPMRI and BOLD hypoxia imaging provide information regarding tumor biology at the molecular, subcellular, cellular and tissue levels and this information may be used as an appropriate and reliable biologic target for radiation dose painting to optimize therapy in future

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

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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

A comparison of measures of boldness and their relationships to survival in young fish.

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James R White

Full Text Available Boldness is the propensity of an animal to engage in risky behavior. Many variations of novel-object or novel-environment tests have been used to quantify the boldness of animals, although the relationship between test outcomes has rarely been investigated. Furthermore, the relationship of outcomes to any ecological aspect of fitness is generally assumed, rather than measured directly. Our study is the first to compare how the outcomes of the same test of boldness differ among observers and how different tests of boldness relate to the survival of individuals in the field. Newly-metamorphosed lemon damselfish, Pomacentrus moluccensis, were placed onto replicate patches of natural habitat. Individual behavior was quantified using four tests (composed of a total of 12 different measures of behavior: latency to enter a novel environment, activity in a novel environment, and reactions to threatening and benign novel objects. After behavior was quantified, survival was monitored for two days during which time fish were exposed to natural predators. Variation among observers was low for most of the 12 measures, except distance moved and the threat test (reaction to probe thrust, which displayed unacceptable amounts of inter-observer variation. Overall, the results of the behavioral tests suggested that novel environment and novel object tests quantified similar behaviors, yet these behavioral measures were not interchangeable. Multiple measures of behavior within the context of novel environment or object tests were the most robust way to assess boldness and these measures have a complex relationship with survivorship of young fish in the field. Body size and distance ventured from shelter were the only variables that had a direct and positive relationship with survival.

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

that the negative BOLD signal is associated with functional inhibition. Electrical stimulation of the median nerve at 7Hz evoked robust negative BOLD signals in the primary somatosensory cortex (SI) ipsilateral to stimulation, and positive BOLD signals in contralateral SI. The negative BOLD signal in ipsilateral SI......) at the ipsilateral finger during concomitant stimulation of the contralateral median nerve increased significantly, suggesting augmented functional inhibition. Since the CPT in the ipsilateral hallux did not significantly change in response to median nerve stimulation, it is more likely that the CPT......-increase for the finger is due to functional inhibition (Kastrup et al., 2008) than to changes in selective attention. In conclusion, our data provide evidence that stimulus-induced reductions in relative rCBF may underlie the negative BOLD signal, which in turn may reflect increments in functional inhibition....

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

Correlation of BOLD Signal with Linear and Nonlinear Patterns of EEG in Resting State EEG-Informed fMRI

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Galina V. Portnova

2018-01-01

Full Text Available Concurrent EEG and fMRI acquisitions in resting state showed a correlation between EEG power in various bands and spontaneous BOLD fluctuations. However, there is a lack of data on how changes in the complexity of brain dynamics derived from EEG reflect variations in the BOLD signal. The purpose of our study was to correlate both spectral patterns, as linear features of EEG rhythms, and nonlinear EEG dynamic complexity with neuronal activity obtained by fMRI. We examined the relationships between EEG patterns and brain activation obtained by simultaneous EEG-fMRI during the resting state condition in 25 healthy right-handed adult volunteers. Using EEG-derived regressors, we demonstrated a substantial correlation of BOLD signal changes with linear and nonlinear features of EEG. We found the most significant positive correlation of fMRI signal with delta spectral power. Beta and alpha spectral features had no reliable effect on BOLD fluctuation. However, dynamic changes of alpha peak frequency exhibited a significant association with BOLD signal increase in right-hemisphere areas. Additionally, EEG dynamic complexity as measured by the HFD of the 2–20 Hz EEG frequency range significantly correlated with the activation of cortical and subcortical limbic system areas. Our results indicate that both spectral features of EEG frequency bands and nonlinear dynamic properties of spontaneous EEG are strongly associated with fluctuations of the BOLD signal during the resting state condition.

Cortical layers, rhythms and BOLD signals.

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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.

EEG-informed fMRI analysis during a hand grip task: estimating the relationship between EEG rhythms and the BOLD signal

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Roberta eSclocco

2014-04-01

Full Text Available In the last decade, an increasing interest has arisen in investigating the relationship between the electrophysiological and hemodynamic measurements of brain activity, such as EEG and (BOLD fMRI. In particular, changes in BOLD have been shown to be associated with changes in the spectral profile of neural activity, rather than with absolute power. Concurrently, recent findings showed that different EEG rhythms are independently related to changes in the BOLD signal: therefore, it would be important to distinguish between the contributions of the different EEG rhythms to BOLD fluctuations when modeling the relationship between the two signals. Here we propose a method to perform EEG-informed fMRI analysis, in which the EEG regressors take into account both the changes in the spectral profile and the rhythms distinction. We applied it to EEG-fMRI data during a hand grip task in healthy subjects, and compared the results with those obtained by two existing models found in literature. Our results showed that the proposed method better captures the correlations between BOLD signal and EEG rhythms modulations, identifying task-related, well localized activated volumes. Furthermore, we showed that including among the regressors also EEG rhythms not primarily involved in the task enhances the performance of the analysis, even when only correlations with BOLD signal and specific EEG rhythms are explored.

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

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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.

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

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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.

Towards a mechanistic understanding of vulnerability to hook-and-line fishing: Boldness as the basic target of angling-induced selection

DEFF Research Database (Denmark)

Klefoth, Thomas; Skov, Christian; Kuparinen, Anna

2017-01-01

by juvenile growth rate, while morphological traits were only weakly related to angling vulnerability. In addition, we found juvenile growth rate to be moderately correlated with boldness. Hence, direct selection on boldness will also induce indirect selection on juvenile growth and vice versa, but given......In passively operated fishing gear, boldness-related behaviors should fundamentally affect the vulnerability of individual fish and thus be under fisheries selection. To test this hypothesis, we used juvenile common-garden reared carp (Cyprinus carpio) within a narrow size range to investigate...... the mechanistic basis of behavioral selection caused by angling. We focused on one key personality trait (i.e., boldness), measured in groups within ponds, two morphological traits (body shape and head shape), and one life-history trait (juvenile growth capacity) and studied mean standardized selection gradients...

The effect of sleep deprivation on BOLD activity elicited by a divided attention task.

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Jackson, Melinda L; Hughes, Matthew E; Croft, Rodney J; Howard, Mark E; Crewther, David; Kennedy, Gerard A; Owens, Katherine; Pierce, Rob J; O'Donoghue, Fergal J; Johnston, Patrick

2011-06-01

Sleep loss, widespread in today's society and associated with a number of clinical conditions, has a detrimental effect on a variety of cognitive domains including attention. This study examined the sequelae of sleep deprivation upon BOLD fMRI activation during divided attention. Twelve healthy males completed two randomized sessions; one after 27 h of sleep deprivation and one after a normal night of sleep. During each session, BOLD fMRI was measured while subjects completed a cross-modal divided attention task (visual and auditory). After normal sleep, increased BOLD activation was observed bilaterally in the superior frontal gyrus and the inferior parietal lobe during divided attention performance. Subjects reported feeling significantly more sleepy in the sleep deprivation session, and there was a trend towards poorer divided attention task performance. Sleep deprivation led to a down regulation of activation in the left superior frontal gyrus, possibly reflecting an attenuation of top-down control mechanisms on the attentional system. These findings have implications for understanding the neural correlates of divided attention and the neurofunctional changes that occur in individuals who are sleep deprived.

Transfer function between EEG and BOLD signals of epileptic activity

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Marco eLeite

2013-01-01

Full Text Available Simultaneous EEG-fMRI recordings have seen growing application in the evaluation of epilepsy, namely in the characterization of brain networks related to epileptic activity. In EEG-correlated fMRI studies, epileptic events are usually described as boxcar signals based on the timing information retrieved from the EEG, and subsequently convolved with a heamodynamic response function to model the associated BOLD changes. Although more flexible approaches may allow a higher degree of complexity for the haemodynamics, the issue of how to model these dynamics based on the EEG remains an open question. In this work, a new methodology for the integration of simultaneous EEG-fMRI data in epilepsy is proposed, which incorporates a transfer function from the EEG to the BOLD signal. Independent component analysis (ICA of the EEG is performed, and a number of metrics expressing different models of the EEG-BOLD transfer function are extracted from the resulting time courses. These metrics are then used to predict the fMRI data and to identify brain areas associated with the EEG epileptic activity. The methodology was tested on both ictal and interictal EEG-fMRI recordings from one patient with a hypothalamic hamartoma. When compared to the conventional analysis approach, plausible, consistent and more significant activations were obtained. Importantly, frequency-weighted EEG metrics yielded superior results than those weighted solely on the EEG power, which comes in agreement with previous literature. Reproducibility, specificity and sensitivity should be addressed in an extended group of patients in order to further validate the proposed methodology and generalize the presented proof of concept.

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

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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.

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

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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)

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)

The value of blood oxygenation level-dependent (BOLD MR imaging in differentiation of renal solid mass and grading of renal cell carcinoma (RCC: analysis based on the largest cross-sectional area versus the entire whole tumour.

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Guang-Yu Wu

Full Text Available To study the value of assessing renal masses using different methods in parameter approaches and to determine whether BOLD MRI is helpful in differentiating RCC from benign renal masses, differentiating clear-cell RCC from renal masses other than clear-cell RCC and determining the tumour grade.Ninety-five patients with 139 renal masses (93 malignant and 46 benign who underwent abdominal BOLD MRI were enrolled. R2* values were derived from the largest cross-section (R2*largest and from the whole tumour (R2*whole. Intra-observer and inter-observer agreements were analysed based on two measurements by the same observer and the first measurement from each observer, respectively, and these agreements are reported with intra-class correlation coefficients and 95% confidence intervals. The diagnostic value of the R2* value in the evaluation was assessed with receiver-operating characteristic analysis.The intra-observer agreement was very good for R2*largest and R2*whole (all > 0.8. The inter-observer agreement of R2*whole (0.75, 95% confidence interval: 0.69~0.79 was good and was significantly improved compared with the R2*largest (0.61, 95% confidence interval: 0.52~0.68, as there was no overlap in the 95% confidence interval of the intra-class correlation coefficients. The diagnostic value in differentiating renal cell carcinoma from benign lesions with R2*whole (AUC=0.79/0.78[observer1/observer2] and R2*largest (AUC=0.75[observer1] was good and significantly higher (p=0.01 for R2*largest[observer2] vs R2*whole[observer2], p 0.7 and were not significantly different (p=0.89/0.93 for R2*largest vs R2*whole[observer1/observer2], 0.96 for R2*whole[observer1] vs R2*largest[observer2] and 0.96 for R2*whole [observer2] vs R2*largest[observer1].BOLD MRI could provide a feasible parameter for differentiating renal cell carcinoma from benign renal masses and for predicting clear-cell renal cell carcinoma grading. Compared with the largest cross

Boldness in a deep sea hermit crab to simulated tactile predator attacks is unaffected by ocean acidification

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Kim, Tae Won; Barry, James P.

2016-09-01

Despite rapidly growing interest in the effects of ocean acidification on marine animals, the ability of deep-sea animals to acclimate or adapt to reduced pH conditions has received little attention. Deep-sea species are generally thought to be less tolerant of environmental variation than shallow-living species because they inhabit relatively stable conditions for nearly all environmental parameters. To explore whether deep-sea hermit crabs ( Pagurus tanneri) can acclimate to ocean acidification over several weeks, we compared behavioral "boldness," measured as time taken to re-emerge from shells after a simulated predatory attack by a toy octopus, under ambient (pH ˜7.6) and expected future (pH ˜7.1) conditions. The boldness measure for crab behavioral responses did not differ between different pH treatments, suggesting that future deep-sea acidification would not influence anti-predatory behavior. However, we did not examine the effects of olfactory cues released by predators that may affect hermit crab behavior and could be influenced by changes in the ocean carbonate system driven by increasing CO2 levels.

Evidence accumulation detected in BOLD signal using slow perceptual decision making

NARCIS (Netherlands)

Krueger, Paul M.; van Vugt, Marieke K.; Simen, Patrick; Nystrom, Leigh; Holmes, Philip; Cohen, Jonathan D.

2017-01-01

BACKGROUND: We assessed whether evidence accumulation could be observed in the BOLD signal during perceptual decision making. This presents a challenge since the hemodynamic response is slow, while perceptual decisions are typically fast. NEW METHOD: Guided by theoretical predictions of the drift

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.

Effects of Intranasal Oxytocin on the Blood Oxygenation Level-Dependent Signal in Food Motivation and Cognitive Control Pathways in Overweight and Obese Men.

Science.gov (United States)

Plessow, Franziska; Marengi, Dean A; Perry, Sylvia K; Felicione, Julia M; Franklin, Rachel; Holmes, Tara M; Holsen, Laura M; Makris, Nikolaos; Deckersbach, Thilo; Lawson, Elizabeth A

2018-02-01

Recent research indicates that the hypothalamic neuropeptide hormone oxytocin is a key central nervous system factor in the regulation of food intake and weight. However, the mechanisms underlying the anorexigenic effects of oxytocin in humans are unknown and critical to study to consider oxytocin as a neurohormonal weight loss treatment. We performed a randomized, double-blind, placebo-controlled crossover study with single-dose intranasal oxytocin (24 IU) in ten overweight or obese, otherwise healthy men. Following oxytocin/placebo administration, participants completed an established functional magnetic resonance imaging food motivation paradigm. We hypothesized that oxytocin would reduce the blood oxygenation level-dependent (BOLD) signal to high-calorie food vs non-food visual stimuli in the ventral tegmental area (VTA), the origin of the mesolimbic dopaminergic reward system. Following oxytocin administration, compared to placebo, participants showed bilateral VTA hypoactivation to high-calorie food stimuli. A secondary exploratory whole-brain analysis revealed hypoactivation in additional hedonic (orbitofrontal cortex, insula, globus pallidus, putamen, hippocampus, and amygdala) and homeostatic (hypothalamus) food motivation and hyperactivation in cognitive control (anterior cingulate and frontopolar cortex) brain regions following oxytocin administration vs placebo. Oxytocin administration reduces the BOLD signal in reward-related food motivation brain regions, providing a potential neurobiological mechanism for the anorexigenic oxytocin effects in humans. Furthermore, our data indicate that oxytocin administration reduces activation in homeostatic and increases activation in cognitive control brain regions critically involved in regulating food intake and resolving affective conflict, respectively. Future studies are required to link these changes in brain activation to oxytocin effects on food intake and weight.

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

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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.

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)

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

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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

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

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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.

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.

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

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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

Unemployment in chronic airflow obstruction around the world: results from the BOLD study.

Science.gov (United States)

Grønseth, Rune; Erdal, Marta; Tan, Wan C; Obaseki, Daniel O; Amaral, Andre F S; Gislason, Thorarinn; Juvekar, Sanjay K; Koul, Parvaiz A; Studnicka, Michael; Salvi, Sundeep; Burney, Peter; Buist, A Sonia; Vollmer, William M; Johannessen, Ane

2017-09-01

We aimed to examine associations between chronic airflow obstruction (CAO) and unemployment across the world.Cross-sectional data from 26 sites in the Burden of Obstructive Lung Disease (BOLD) study were used to analyse effects of CAO on unemployment. Odds ratios for unemployment in subjects aged 40-65 years were estimated using a multilevel mixed-effects generalised linear model with study site as random effect. Site-by-site heterogeneity was assessed using individual participant data meta-analyses.Out of 18 710 participants, 11.3% had CAO. The ratio of unemployed subjects with CAO divided by subjects without CAO showed large site discrepancies, although these were no longer significant after adjusting for age, sex, smoking and education. The site-adjusted odds ratio (95% CI) for unemployment was 1.79 (1.41-2.27) for CAO cases, decreasing to 1.43 (1.14-1.79) after adjusting for sociodemographic factors, comorbidities and forced vital capacity. Of other covariates that were associated with unemployment, age and education were important risk factors in high-income sites (4.02 (3.53-4.57) and 3.86 (2.80-5.30), respectively), while female sex was important in low- to middle-income sites (3.23 (2.66-3.91)).In the global BOLD study, CAO was associated with increased levels of unemployment, even after adjusting for sociodemographic factors, comorbidities and lung function. Copyright ©ERS 2017.

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.)

BOLD/VENTURE-4, Reactor Analysis System with Sensitivity and Burnup

International Nuclear Information System (INIS)

1998-01-01

1 - Description of program or function: The system of codes can be used to solve nuclear reactor core static neutronics and reactor history exposure problems. BOLD/VENTURE-4: First order perturbation and time-dependent sensitivity theories can be applied. Control rod positioning may be modeled explicitly and refueling treated with repositioning and recycle. Special capability is coded to model the continuously fueled core and to solve the importance and dominant harmonics problems. The modules of the code system are: VENTNEUT: VENTURE neutronics module; DRIVER and CONTRL: Control module; BURNER: Exposure calculation for reactor core analysis; FILEDTOR: File editor; INPROSER: Input processor; EXPOSURE: BURNER code module; REACRATE: Reaction rate calculation; CNTRODPO: Control rod positioning; FUELMANG: Fuel management positioning and accounting; PERTUBAT: Perturbation reactivity importance analyses; sensitivity analysis; DEPTHMOD: Static and time-dependent perturbation sensitivity analysis. The special processors are: DVENTR: Handles the input to the VENTURE module; DCMACR: Converts CITATION macroscopic cross sections to microscopic cross sections; DCRSPR: Produces input for the CROSPROS module; DUTLIN: Adds or replaces problem input data without exiting the program; DENMAN: Repositions fuel; DMISLY: Miscellaneous tasks. Standard interface files between modules are binary sequential files that follow a standardized format. VENTURE-PC: The microcomputer version is a subset of the mainframe version. The modules and special processors which are not part of VENTURE-PC are: REACRATE, CNTRODPO, PERTUBAT, FUELMANG, DEPTHMOD, DMISLY. 2 - method of solution: BOLD-VENTURE-4: The neutronics problems are solved by applying the multigroup diffusion theory representation of neutron transport applying an over-relaxation inner iteration, outer iteration scheme. Special modeling is used or source correction is done during iteration to solve importance and harmonics problems. No

Open label smoking cessation with varenicline is associated with decreased glutamate levels and functional changes in anterior cingulate cortex: preliminary findings

Directory of Open Access Journals (Sweden)

Muriah Dawn Wheelock

2014-07-01

Full Text Available Rationale: Varenicline, the most effective single agent for smoking cessation, is a partial agonist at α4β2 nicotinic acetylcholine receptors. Increasing evidence implicates glutamate in the pathophysiology of addiction and one of the benefits of treatment for smoking cessation is the ability to regain cognitive control. Objective: To evaluate the effects of 12 week varenicline administration on glutamate levels in the dorsal anterior cingulate cortex (dACC and functional changes within the cognitive control network.Methods: We used single-voxel proton magnetic resonance spectroscopy (1H-MRS in the dACC and functional MRI (fMRI during performance of a Stroop color-naming task before and after smoking cessation with varenicline in 11 healthy smokers (open label design. Using the dACC as a seed region, we evaluated functional connectivity changes using a psychophysiological interaction (PPI analysis. Results: We observed a significant decrease in dACC glutamate + glutamine (Glx/Cr levels as well as significant blood oxygen level-dependent signal (BOLD decreases in the rostral ACC/medial orbitofrontal cortex and precuneus/posterior cingulate cortex. These BOLD changes are suggestive of alterations in default mode network (DMN function and are further supported by the results of the PPI analysis that revealed changes in connectivity between the dACC and regions of the DMN. Baseline measures of nicotine dependence and craving positively correlated with baseline Glx/Cr levels.Conclusions: These results suggest possible mechanisms of action for varenicline such as reduction in Glx levels in dACC and shifts in BOLD activities between large scale brain networks. They also suggest a role for ACC Glx in the modulation of behavior. Due to the preliminary nature of this study (lack of control group and small sample size, future studies are needed to replicate these findings.

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

to be more accurately localized and quantified based on changes in venous blood oxygenation alone. The normalized BOLD signal induced by the motor task was consistent across different magnetic fields and pulse sequences, and corresponded well with cerebral blood flow measurements. Our data suggest...... size, as well as experimental, such as pulse sequence and static magnetic field strength (B(0)). Thus, it is difficult to compare task-induced fMRI signals across subjects, field strengths, and pulse sequences. This problem can be overcome by normalizing the neural activity-induced BOLD fMRI response...... for global stimulation, subjects breathed a 5% CO(2) gas mixture. Under all conditions, voxels containing primarily large veins and those containing primarily active tissue (i.e., capillaries and small veins) showed distinguishable behavior after hypercapnic normalization. This allowed functional activity...

Spatial-temporal-spectral EEG patterns of BOLD functional network connectivity dynamics

Science.gov (United States)

Lamoš, Martin; Mareček, Radek; Slavíček, Tomáš; Mikl, Michal; Rektor, Ivan; Jan, Jiří

2018-06-01

Objective. Growing interest in the examination of large-scale brain network functional connectivity dynamics is accompanied by an effort to find the electrophysiological correlates. The commonly used constraints applied to spatial and spectral domains during electroencephalogram (EEG) data analysis may leave part of the neural activity unrecognized. We propose an approach that blindly reveals multimodal EEG spectral patterns that are related to the dynamics of the BOLD functional network connectivity. Approach. The blind decomposition of EEG spectrogram by parallel factor analysis has been shown to be a useful technique for uncovering patterns of neural activity. The simultaneously acquired BOLD fMRI data were decomposed by independent component analysis. Dynamic functional connectivity was computed on the component’s time series using a sliding window correlation, and between-network connectivity states were then defined based on the values of the correlation coefficients. ANOVA tests were performed to assess the relationships between the dynamics of between-network connectivity states and the fluctuations of EEG spectral patterns. Main results. We found three patterns related to the dynamics of between-network connectivity states. The first pattern has dominant peaks in the alpha, beta, and gamma bands and is related to the dynamics between the auditory, sensorimotor, and attentional networks. The second pattern, with dominant peaks in the theta and low alpha bands, is related to the visual and default mode network. The third pattern, also with peaks in the theta and low alpha bands, is related to the auditory and frontal network. Significance. Our previous findings revealed a relationship between EEG spectral pattern fluctuations and the hemodynamics of large-scale brain networks. In this study, we suggest that the relationship also exists at the level of functional connectivity dynamics among large-scale brain networks when no standard spatial and spectral

Photoreactivity of the occipital cortex measured by functional magnetic resonance imaging-blood oxygenation level dependent in migraine patients and healthy volunteers: pathophysiological implications.

Science.gov (United States)

Martín, Helena; Sánchez del Río, Margarita; de Silanes, Carlos López; Álvarez-Linera, Juan; Hernández, Juan Antonio; Pareja, Juan A

2011-01-01

The brain of migraineurs is hyperexcitable, particularly the occipital cortex, which is probably hypersensitive to light. Photophobia or hypersensitivity to light may be accounted for by an increased excitability of trigeminal, the visual pathways, and the occipital cortex. To study light sensitivity and photophobia by assessing the response to light stimuli with functional magnetic resonance imaging-blood oxygenation level dependent (fMRI-BOLD) of the occipital cortex in migraineurs and in controls. Also, to try to decipher the contribution of the occipital cortex to photophobia and whether the cortical reactivity of migraineurs may be part of a constitutional (defensive) mechanism or represents an acquired (sensitization) phenomenon. Nineteen patients with migraine (7 with aura and 12 without aura) and 19 controls were studied with fMRI-BOLD during 4 increasing light intensities. Eight axial image sections of 0.5 cm that covered the occipital cortex were acquired for each intensity. We measured the extension and the intensity of activation for every light stimuli. Photophobia was estimated according to a 0 to 3 semiquantitative scale of light discomfort. Migraineurs had a significantly higher number of fMRI-activated voxels at low (320.4 for migraineurs [SD = 253.9] and 164.3 for controls [SD = 102.7], P = .027) and medium-low luminance levels (501.2 for migraineurs [SD = 279.5] and 331.1 for controls [SD = 194.3], P = .034) but not at medium-high (579.5 for migraineurs [SD = 201.4] and 510.2 for controls [SD = 239.5], P = .410) and high light stimuli (496.2 for migraineurs [SD = 216.2] and 394.7 for controls [SD = 240], P = .210). No differences were found with respect to the voxel activation intensity (amplitude of the BOLD wave) between migraineurs and controls (8.98 [SD = 2.58] vs 7.99 [SD = 2.57], P = .25; 10.82 [SD = 3.27] vs 9.81 [SD = 3.19], P = .31; 11.90 [SD = 3.18] vs 11.06 [SD = 2.56], P = .62; 11.45 [SD = 2.65] vs 10.25 [SD = 2.22], P = .16). Light

Rearing environment influences boldness and prey acquisition behavior, and brain and lens development of bull trout

Science.gov (United States)

Brignon, William R.; Pike, Martin M.; Ebbesson, Lars O.E.; Schaller, Howard A.; Peterson, James T.; Schreck, Carl B.

2018-01-01

Animals reared in barren captive environments exhibit different developmental trajectories and behaviors than wild counterparts. Hence, the captive phenotypes may influence the success of reintroduction and recovery programs for threatened and endangered species. We collected wild bull trout embryos from the Metolius River Basin, Oregon and reared them in differing environments to better understand how captivity affects the bull trout Salvelinus confluentusphenotype. We compared the boldness and prey acquisition behaviors and development of the brain and eye lens of bull trout reared in conventional barren and more structurally complex captive environments with that of wild fish. Wild fish and captive reared fish from complex habitats exhibited a greater level of boldness and prey acquisition ability, than fish reared in conventional captive environments. In addition, the eye lens of conventionally reared bull trout was larger than complex reared captive fish or same age wild fish. Interestingly, we detected wild fish had a smaller relative cerebellum than either captive reared treatment. Our results suggest that rearing fish in more complex captive environments can create a more wild-like phenotype than conventional rearing practices. A better understanding of the effects of captivity on the development and behavior of bull trout can inform rearing and reintroduction programs though prediction of the performance of released individuals.

Boldness and intermittent locomotion in the bluegill sunfish, Lepomis macrochirus

OpenAIRE

Alexander D.M. Wilson; Jean-Guy J. Godin

2009-01-01

Intermittent locomotion, characterized by moves interspersed with pauses, is a common pattern of locomotion in animals, but its ecological and evolutionary significance relative to continuous locomotion remains poorly understood. Although many studies have examined individual differences in both intermittent locomotion and boldness separately, to our knowledge, no study to date has investigated the relationship between these 2 traits. Characterizing and understanding this relationship is impo...

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.

A simple solution for model comparison in bold imaging: the special case of reward prediction error and reward outcomes.

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Erdeniz, Burak; Rohe, Tim; Done, John; Seidler, Rachael D

2013-01-01

Conventional neuroimaging techniques provide information about condition-related changes of the BOLD (blood-oxygen-level dependent) signal, indicating only where and when the underlying cognitive processes occur. Recently, with the help of a new approach called "model-based" functional neuroimaging (fMRI), researchers are able to visualize changes in the internal variables of a time varying learning process, such as the reward prediction error or the predicted reward value of a conditional stimulus. However, despite being extremely beneficial to the imaging community in understanding the neural correlates of decision variables, a model-based approach to brain imaging data is also methodologically challenging due to the multicollinearity problem in statistical analysis. There are multiple sources of multicollinearity in functional neuroimaging including investigations of closely related variables and/or experimental designs that do not account for this. The source of multicollinearity discussed in this paper occurs due to correlation between different subjective variables that are calculated very close in time. Here, we review methodological approaches to analyzing such data by discussing the special case of separating the reward prediction error signal from reward outcomes.

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

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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.

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

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)...

Consistent inter-individual differences in common marmosets (Callithrix jacchus) in Boldness-Shyness, Stress-Activity, and Exploration-Avoidance.

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Šlipogor, Vedrana; Gunhold-de Oliveira, Tina; Tadić, Zoran; Massen, Jorg J M; Bugnyar, Thomas

2016-09-01

The study of animal personality, defined as consistent inter-individual differences in correlated behavioral traits stable throughout time and/or contexts, has recently become one of the fastest growing areas in animal biology, with study species ranging from insects to non-human primates. The latter have, however, only occasionally been tested with standardized experiments. Instead their personality has usually been assessed using questionnaires. Therefore, this study aimed to test 21 common marmosets (Callithrix jacchus) living in three family groups, in five different experiments, and their corresponding controls. We found that behavioral differences between our animals were not only consistent over time, but also across different contexts. Moreover, the consistent behaviors formed a construct of four major non-social personality components: Boldness-Shyness in Foraging, Boldness-Shyness in Predation, Stress-Activity, and Exploration-Avoidance. We found no sex or age differences in these components, but our results did reveal differences in Exploration-Avoidance between the three family groups. As social environment can have a large influence on behavior of individuals, our results may suggest group-level similarity in personality (i.e., "group personality") in common marmosets, a species living in highly cohesive social groups. Am. J. Primatol. 78:961-973, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

"To Boldly Go" versus "Last, Best Hope" : The Future of Human Civilization as Depicted in American Science Fiction

OpenAIRE

Glasø, Alexander

2012-01-01

"'To Boldly Go" versus "Last, Best Hope'" examines a total of four American television series from the Star Trek and Babylon 5 franchises, and the portrayal of human civilization in the future. The thesis traces how Star Trek set out "to boldly go" and how Babylon 5 was the "last, best hope" in depicting a coherent, futuristic vision for humanity. The initial chapter focuses on the background of the series and also the ways they differed from one another, while chapter 2 is devoted to the por...

Personality in the cockroach Diploptera punctata: Evidence for stability across developmental stages despite age effects on boldness.

Science.gov (United States)

Stanley, Christina R; Mettke-Hofmann, Claudia; Preziosi, Richard F

2017-01-01

Despite a recent surge in the popularity of animal personality studies and their wide-ranging associations with various aspects of behavioural ecology, our understanding of the development of personality over ontogeny remains poorly understood. Stability over time is a central tenet of personality; ecological pressures experienced by an individual at different life stages may, however, vary considerably, which may have a significant effect on behavioural traits. Invertebrates often go through numerous discrete developmental stages and therefore provide a useful model for such research. Here we test for both differential consistency and age effects upon behavioural traits in the gregarious cockroach Diploptera punctata by testing the same behavioural traits in both juveniles and adults. In our sample, we find consistency in boldness, exploration and sociality within adults whilst only boldness was consistent in juveniles. Both boldness and exploration measures, representative of risk-taking behaviour, show significant consistency across discrete juvenile and adult stages. Age effects are, however, apparent in our data; juveniles are significantly bolder than adults, most likely due to differences in the ecological requirements of these life stages. Size also affects risk-taking behaviour since smaller adults are both bolder and more highly explorative. Whilst a behavioural syndrome linking boldness and exploration is evident in nymphs, this disappears by the adult stage, where links between other behavioural traits become apparent. Our results therefore indicate that differential consistency in personality can be maintained across life stages despite age effects on its magnitude, with links between some personality traits changing over ontogeny, demonstrating plasticity in behavioural syndromes.

Personality in the cockroach Diploptera punctata: Evidence for stability across developmental stages despite age effects on boldness

Science.gov (United States)

Mettke-Hofmann, Claudia; Preziosi, Richard F.

2017-01-01

Despite a recent surge in the popularity of animal personality studies and their wide-ranging associations with various aspects of behavioural ecology, our understanding of the development of personality over ontogeny remains poorly understood. Stability over time is a central tenet of personality; ecological pressures experienced by an individual at different life stages may, however, vary considerably, which may have a significant effect on behavioural traits. Invertebrates often go through numerous discrete developmental stages and therefore provide a useful model for such research. Here we test for both differential consistency and age effects upon behavioural traits in the gregarious cockroach Diploptera punctata by testing the same behavioural traits in both juveniles and adults. In our sample, we find consistency in boldness, exploration and sociality within adults whilst only boldness was consistent in juveniles. Both boldness and exploration measures, representative of risk-taking behaviour, show significant consistency across discrete juvenile and adult stages. Age effects are, however, apparent in our data; juveniles are significantly bolder than adults, most likely due to differences in the ecological requirements of these life stages. Size also affects risk-taking behaviour since smaller adults are both bolder and more highly explorative. Whilst a behavioural syndrome linking boldness and exploration is evident in nymphs, this disappears by the adult stage, where links between other behavioural traits become apparent. Our results therefore indicate that differential consistency in personality can be maintained across life stages despite age effects on its magnitude, with links between some personality traits changing over ontogeny, demonstrating plasticity in behavioural syndromes. PMID:28489864

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

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

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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

Role of 3T multiparametric-MRI with BOLD hypoxia imaging for diagnosis and post therapy response evaluation of postoperative recurrent cervical cancers

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Abhishek Mahajan

2016-01-01

Conclusion: Conventional-MR with MPMRI significantly increases the diagnostic accuracy for suspected vaginal vault/local recurrence. Post therapy serial MPMRI with hypoxia imaging follow-up objectively documents the response. MPMRI and BOLD hypoxia imaging provide information regarding tumor biology at the molecular, subcellular, cellular and tissue levels and this information may be used as an appropriate and reliable biologic target for radiation dose painting to optimize therapy in future.

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...

Driving innovation through big open linked data (BOLD) : Exploring antecedents using interpretive structural modelling

NARCIS (Netherlands)

Dwivedi, Yogesh K.; Janssen, M.F.W.H.A.; Slade, Emma L.; Rana, Nripendra P.; Weerakkody, Vishanth; Millard, Jeremy; Hidders, Jan; Snijders, D.

2016-01-01

Innovation is vital to find new solutions to problems, increase quality, and improve profitability. Big open linked data (BOLD) is a fledgling and rapidly evolving field that creates new opportunities for innovation. However, none of the existing literature has yet considered the

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.

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

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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.

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

Over the last decades MRI has proved to be very useful in the field of drug development and discovery. Pharmacological MRI (phMRI) explores the interaction between brain physiology, neuronal activity and drugs[1]. The BOLD-signal is an indirect method to investigate brain activity by way...... 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....

Study of asymmetry in motor areas related to handedness using the fMRI BOLD response Gaussian convolution model

Energy Technology Data Exchange (ETDEWEB)

Gao Qing [School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu 610054 (China); School of Applied Mathematics, University of Electronic Science and Technology of China, Chengdu 610054 (China); Chen Huafu [School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu 610054 (China); School of Applied Mathematics, University of Electronic Science and Technology of China, Chengdu 610054 (China)], E-mail: Chenhf@uestc.edu.cn; Gong Qiyong [Huaxi MR Research Center (HMRRC), Department of Radiology, West China Hospital of Sichuan University, Chengdu 610041 (China)

2009-10-30

Brain asymmetry is a phenomenon well known for handedness, and has been studied in the motor cortex. However, few studies have quantitatively assessed the asymmetrical cortical activities for handedness in motor areas. In the present study, we systematically and quantitatively investigated asymmetry in the left and right primary motor cortices during sequential finger movements using the Gaussian convolution model approach based on the functional magnetic resonance imaging (fMRI) blood oxygenation level dependent (BOLD) response. Six right-handed and six left-handed subjects were recruited to perform three types of hand movement tasks. The results for the expected value of the Gaussian convolution model showed that it took the dominant hand a longer average interval of response delay regardless of the handedness and bi- or uni-manual performance. The results for the standard deviation of the Gaussian model suggested that in the mass neurons, these intervals of the dominant hand were much more variable than those of the non-dominant hand. When comparing bi-manual movement conditions with uni-manual movement conditions in the primary motor cortex (PMC), both the expected value and standard deviation in the Gaussian function were significantly smaller (p < 0.05) in the bi-manual conditions, showing that the movement of the non-dominant hand influenced that of the dominant hand.

Study of asymmetry in motor areas related to handedness using the fMRI BOLD response Gaussian convolution model

International Nuclear Information System (INIS)

Gao Qing; Chen Huafu; Gong Qiyong

2009-01-01

Brain asymmetry is a phenomenon well known for handedness, and has been studied in the motor cortex. However, few studies have quantitatively assessed the asymmetrical cortical activities for handedness in motor areas. In the present study, we systematically and quantitatively investigated asymmetry in the left and right primary motor cortices during sequential finger movements using the Gaussian convolution model approach based on the functional magnetic resonance imaging (fMRI) blood oxygenation level dependent (BOLD) response. Six right-handed and six left-handed subjects were recruited to perform three types of hand movement tasks. The results for the expected value of the Gaussian convolution model showed that it took the dominant hand a longer average interval of response delay regardless of the handedness and bi- or uni-manual performance. The results for the standard deviation of the Gaussian model suggested that in the mass neurons, these intervals of the dominant hand were much more variable than those of the non-dominant hand. When comparing bi-manual movement conditions with uni-manual movement conditions in the primary motor cortex (PMC), both the expected value and standard deviation in the Gaussian function were significantly smaller (p < 0.05) in the bi-manual conditions, showing that the movement of the non-dominant hand influenced that of the dominant hand.

P300 amplitude variation is related to ventral striatum BOLD response during gain and loss anticipation: an EEG and fMRI experiment.

Science.gov (United States)

Pfabigan, Daniela M; Seidel, Eva-Maria; Sladky, Ronald; Hahn, Andreas; Paul, Katharina; Grahl, Arvina; Küblböck, Martin; Kraus, Christoph; Hummer, Allan; Kranz, Georg S; Windischberger, Christian; Lanzenberger, Rupert; Lamm, Claus

2014-08-01

The anticipation of favourable or unfavourable events is a key component in our daily life. However, the temporal dynamics of anticipation processes in relation to brain activation are still not fully understood. A modified version of the monetary incentive delay task was administered during separate functional magnetic resonance imaging (fMRI) and electroencephalogram (EEG) sessions in the same 25 participants to assess anticipatory processes with a multi-modal neuroimaging set-up. During fMRI, gain and loss anticipation were both associated with heightened activation in ventral striatum and reward-related areas. EEG revealed most pronounced P300 amplitudes for gain anticipation, whereas CNV amplitudes distinguished neutral from gain and loss anticipation. Importantly, P300, but not CNV amplitudes, were correlated to neural activation in the ventral striatum for both gain and loss anticipation. Larger P300 amplitudes indicated higher ventral striatum blood oxygen level dependent (BOLD) response. Early stimulus evaluation processes indexed by EEG seem to be positively related to higher activation levels in the ventral striatum, indexed by fMRI, which are usually associated with reward processing. The current results, however, point towards a more general motivational mechanism processing salient stimuli during anticipation. Copyright © 2014. Published by Elsevier Inc.

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

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.

Neural Correlates of Facial Mimicry: Simultaneous Measurements of EMG and BOLD Responses during Perception of Dynamic Compared to Static Facial Expressions

Science.gov (United States)

Rymarczyk, Krystyna; Żurawski, Łukasz; Jankowiak-Siuda, Kamila; Szatkowska, Iwona

2018-01-01

Facial mimicry (FM) is an automatic response to imitate the facial expressions of others. However, neural correlates of the phenomenon are as yet not well established. We investigated this issue using simultaneously recorded EMG and BOLD signals during perception of dynamic and static emotional facial expressions of happiness and anger. During display presentations, BOLD signals and zygomaticus major (ZM), corrugator supercilii (CS) and orbicularis oculi (OO) EMG responses were recorded simultaneously from 46 healthy individuals. Subjects reacted spontaneously to happy facial expressions with increased EMG activity in ZM and OO muscles and decreased CS activity, which was interpreted as FM. Facial muscle responses correlated with BOLD activity in regions associated with motor simulation of facial expressions [i.e., inferior frontal gyrus, a classical Mirror Neuron System (MNS)]. Further, we also found correlations for regions associated with emotional processing (i.e., insula, part of the extended MNS). It is concluded that FM involves both motor and emotional brain structures, especially during perception of natural emotional expressions. PMID:29467691

Global brain blood-oxygen level responses to autonomic challenges in obstructive sleep apnea.

Directory of Open Access Journals (Sweden)

Paul M Macey

Full Text Available Obstructive sleep apnea (OSA is accompanied by brain injury, perhaps resulting from apnea-related hypoxia or periods of impaired cerebral perfusion. Perfusion changes can be determined indirectly by evaluation of cerebral blood volume and oxygenation alterations, which can be measured rapidly and non-invasively with the global blood oxygen level dependent (BOLD signal, a magnetic resonance imaging procedure. We assessed acute BOLD responses in OSA subjects to pressor challenges that elicit cerebral blood flow changes, using a two-group comparative design with healthy subjects as a reference. We separately assessed female and male patterns, since OSA characteristics and brain injury differ between sexes. We studied 94 subjects, 37 with newly-diagnosed, untreated OSA (6 female (age mean ± std: 52.1±8.1 yrs; apnea/hypopnea index [AHI]: 27.7±15.6 events/hr and 31 male 54.3±8.4 yrs; AHI: 37.4±19.6 events/hr, and 20 female (age 50.5±8.1 yrs and 37 male (age 45.6±9.2 yrs healthy control subjects. We measured brain BOLD responses every 2 s while subjects underwent cold pressor, hand grip, and Valsalva maneuver challenges. The global BOLD signal rapidly changed after the first 2 s of each challenge, and differed in magnitude between groups to two challenges (cold pressor, hand grip, but not to the Valsalva maneuver (repeated measures ANOVA, p<0.05. OSA females showed greater differences from males in response magnitude and pattern, relative to healthy counterparts. Cold pressor BOLD signal increases (mean ± adjusted standard error at the 8 s peak were: OSA 0.14±0.08% vs. Control 0.31±0.06%, and hand grip at 6 s were: OSA 0.08±0.03% vs. Control at 0.30±0.02%. These findings, indicative of reduced cerebral blood flow changes to autonomic challenges in OSA, complement earlier reports of altered resting blood flow and reduced cerebral artery responsiveness. Females are more affected than males, an outcome which may contribute to the sex

Audiovisual synchrony enhances BOLD responses in a brain network including multisensory STS while also enhancing target-detection performance for both modalities

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Marchant, Jennifer L; Ruff, Christian C; Driver, Jon

2012-01-01

The brain seeks to combine related inputs from different senses (e.g., hearing and vision), via multisensory integration. Temporal information can indicate whether stimuli in different senses are related or not. A recent human fMRI study (Noesselt et al. [2007]: J Neurosci 27:11431–11441) used auditory and visual trains of beeps and flashes with erratic timing, manipulating whether auditory and visual trains were synchronous or unrelated in temporal pattern. A region of superior temporal sulcus (STS) showed higher BOLD signal for the synchronous condition. But this could not be related to performance, and it remained unclear if the erratic, unpredictable nature of the stimulus trains was important. Here we compared synchronous audiovisual trains to asynchronous trains, while using a behavioral task requiring detection of higher-intensity target events in either modality. We further varied whether the stimulus trains had predictable temporal pattern or not. Synchrony (versus lag) between auditory and visual trains enhanced behavioral sensitivity (d') to intensity targets in either modality, regardless of predictable versus unpredictable patterning. The analogous contrast in fMRI revealed BOLD increases in several brain areas, including the left STS region reported by Noesselt et al. [2007: J Neurosci 27:11431–11441]. The synchrony effect on BOLD here correlated with the subject-by-subject impact on performance. Predictability of temporal pattern did not affect target detection performance or STS activity, but did lead to an interaction with audiovisual synchrony for BOLD in inferior parietal cortex. PMID:21953980

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

Directory of Open Access Journals (Sweden)

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.

Attention-dependent modulation of cortical taste circuits revealed by Granger causality with signal-dependent noise.

Directory of Open Access Journals (Sweden)

Qiang Luo

2013-10-01

Full Text Available We show, for the first time, that in cortical areas, for example the insular, orbitofrontal, and lateral prefrontal cortex, there is signal-dependent noise in the fMRI blood-oxygen level dependent (BOLD time series, with the variance of the noise increasing approximately linearly with the square of the signal. Classical Granger causal models are based on autoregressive models with time invariant covariance structure, and thus do not take this signal-dependent noise into account. To address this limitation, here we describe a Granger causal model with signal-dependent noise, and a novel, likelihood ratio test for causal inferences. We apply this approach to the data from an fMRI study to investigate the source of the top-down attentional control of taste intensity and taste pleasantness processing. The Granger causality with signal-dependent noise analysis reveals effects not identified by classical Granger causal analysis. In particular, there is a top-down effect from the posterior lateral prefrontal cortex to the insular taste cortex during attention to intensity but not to pleasantness, and there is a top-down effect from the anterior and posterior lateral prefrontal cortex to the orbitofrontal cortex during attention to pleasantness but not to intensity. In addition, there is stronger forward effective connectivity from the insular taste cortex to the orbitofrontal cortex during attention to pleasantness than during attention to intensity. These findings indicate the importance of explicitly modeling signal-dependent noise in functional neuroimaging, and reveal some of the processes involved in a biased activation theory of selective attention.

Using CO5BOLD models to predict the effects of granulation on colours .

Science.gov (United States)

Bonifacio, P.; Caffau, E.; Ludwig, H.-G.; Steffen, M.; Castelli, F.; Gallagher, A. J.; Prakapavičius, D.; Kučinskas, A.; Cayrel, R.; Freytag, B.; Plez, B.; Homeier, D.

In order to investigate the effects of granulation on fluxes and colours, we computed the emerging fluxes from the models in the CO5BOLD grid with metallicities [M/H]=0.0,-1.0,-2.0 and -3.0. These fluxes have been used to compute colours in different photometric systems. We explain here how our computations have been performed and provide some results.

Moment-to-Moment BOLD Signal Variability Reflects Regional Changes in Neural Flexibility across the Lifespan.

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Nomi, Jason S; Bolt, Taylor S; Ezie, C E Chiemeka; Uddin, Lucina Q; Heller, Aaron S

2017-05-31

Variability of neuronal responses is thought to underlie flexible and optimal brain function. Because previous work investigating BOLD signal variability has been conducted within task-based fMRI contexts on adults and older individuals, very little is currently known regarding regional changes in spontaneous BOLD signal variability in the human brain across the lifespan. The current study used resting-state fMRI data from a large sample of male and female human participants covering a wide age range (6-85 years) across two different fMRI acquisition parameters (TR = 0.645 and 1.4 s). Variability in brain regions including a key node of the salience network (anterior insula) increased linearly across the lifespan across datasets. In contrast, variability in most other large-scale networks decreased linearly over the lifespan. These results demonstrate unique lifespan trajectories of BOLD variability related to specific regions of the brain and add to a growing literature demonstrating the importance of identifying normative trajectories of functional brain maturation. SIGNIFICANCE STATEMENT Although brain signal variability has traditionally been considered a source of unwanted noise, recent work demonstrates that variability in brain signals during task performance is related to brain maturation in old age as well as individual differences in behavioral performance. The current results demonstrate that intrinsic fluctuations in resting-state variability exhibit unique maturation trajectories in specific brain regions and systems, particularly those supporting salience detection. These results have implications for investigations of brain development and aging, as well as interpretations of brain function underlying behavioral changes across the lifespan. Copyright © 2017 the authors 0270-6474/17/375539-10$15.00/0.

Brief Report: Anomalous Neural Deactivations and Functional Connectivity during Receptive Language in Autism Spectrum Disorder--A Functional MRI Study

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Karten, Ariel; Hirsch, Joy

2015-01-01

Neural mechanisms that underlie language disability in autism spectrum disorder (ASD) have been associated with reduced excitatory processes observed as positive blood oxygen level dependent (BOLD) responses. However, negative BOLD responses (NBR) associated with language and inhibitory processes have been less studied in ASD. In this study,…

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

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.

fMRI correlates of object-based attentional facilitation versus suppression of irrelevant stimuli, dependent on global grouping and endogenous cueing.

Directory of Open Access Journals (Sweden)

Elliot D Freeman

2014-02-01

Full Text Available Theories of object-based attention often make two assumptions: that attentional resources are facilitatory, and that they spread automatically within grouped objects. Consistent with this, ignored visual stimuli can be easier to process, or more distracting, when perceptually grouped with an attended target stimulus. But in past studies, the ignored stimuli often shared potentially relevant features or locations with the target. In this fMRI study, we measured the effects of attention and grouping on Blood Oxygenation Level Dependent (BOLD responses in the human brain to entirely task-irrelevant events.Two checkerboards were displayed each in opposite hemifields, while participants responded to check-size changes in one pre-cued hemifield, which varied between blocks. Grouping (or segmentation between hemifields was manipulated between blocks, using common (versus distinct motion cues. Task-irrelevant transient events were introduced by randomly changing the colour of either checkerboard, attended or ignored, at unpredictable intervals. The above assumptions predict heightened BOLD signals for irrelevant events in attended versus ignored hemifields for ungrouped contexts, but less such attentional modulation under grouping, due to automatic spreading of facilitation across hemifields. We found the opposite pattern, in primary visual cortex. For ungrouped stimuli, BOLD signals associated with task-irrelevant changes were lower, not higher, in the attended versus ignored hemifield; furthermore, attentional modulation was not reduced but actually inverted under grouping, with higher signals for events in the attended versus ignored hemifield.

An Introduction to Normalization and Calibration Methods in Functional MRI

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Liu, Thomas T.; Glover, Gary H.; Mueller, Bryon A.; Greve, Douglas N.; Brown, Gregory G.

2013-01-01

In functional magnetic resonance imaging (fMRI), the blood oxygenation level dependent (BOLD) signal is often interpreted as a measure of neural activity. However, because the BOLD signal reflects the complex interplay of neural, vascular, and metabolic processes, such an interpretation is not always valid. There is growing evidence that changes…

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

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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

Personality and the collective: bold homing pigeons occupy higher leadership ranks in flocks.

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Sasaki, Takao; Mann, Richard P; Warren, Katherine N; Herbert, Tristian; Wilson, Tara; Biro, Dora

2018-05-19

While collective movement is ecologically widespread and conveys numerous benefits on individuals, it also poses a coordination problem: who controls the group's movements? The role that animal 'personalities' play in this question has recently become a focus of research interest. Although many animal groups have distributed leadership (i.e. multiple individuals influence collective decisions), studies linking personality and leadership have focused predominantly on the group's single most influential individual. In this study, we investigate the relationship between personality and the influence of multiple leaders on collective movement using homing pigeons, Columba livia , a species known to display complex multilevel leadership hierarchies during flock flights. Our results show that more exploratory (i.e. 'bold') birds are more likely to occupy higher ranks in the leadership hierarchy and thus have more influence on the direction of collective movement than less exploratory (i.e. 'shy') birds during both free flights around their lofts and homing flights from a distant site. Our data also show that bold pigeons fly faster than shy birds during solo flights. We discuss our results in light of theories about the evolution of personality, with specific reference to the adaptive value of heterogeneity in animal groups.This article is part of the theme issue 'Collective movement ecology'. © 2018 The Author(s).

Blood oxygenation level dependent functional MRI study on the changes of motor cortex in patients with amyotrophic lateral sclerosis

International Nuclear Information System (INIS)

Han Jing; Ma Lin; Lou Xin; Yu Shengyuan; Li Dejun

2008-01-01

Objective: To study the changes of motor cortex in patients with amyotrophic lateral sclerosis (ALS) while executing sequential finger tapping movement by using blood oxygenation level dependent (BOLD) functional MRI. Methods: Fifteen patients with definite or probable ALS and 15 age and gender matched normal controls were enrolled in the BOLD study, and all the subjects were right-handed with no other diseases or any recent medication history. A 3.0 T MR scanner' was employed and gradient echo EPI (GRE-EPI)sequence was used to acquire the functional images. Subjects executed sequential finger tapping movement at a frequency of 1-2 Hz during a block design task. fMRI data were analyzed by using statistical parametric mapping (SPM) 2. Volume of activated brain areas was compared with the use of a Student's t-test. Results: Bilateral primary sensorimotor cortex (PSM), bilateral posterior aspect of premotor area (PA), bilateral supplementary motor area (SMA), contralateral inferior lateral premotor area (ILPA), bilateral parietal region (PAR), and ipsilateral cerebellum showed activation in both ALS patients and normal controls when executing the same motor task. The activation areas in bilateral PSM and bilateral posterior aspect of PA ( right hand ipsilateral activation: ALS (924.5±141.1) mm 3 , control (829.9± 98.4) mm 3 , P=0.05; right hand contralateral activation: ALS (9143.8±702.8) mm 3 , control (8638.8±506.4) mm 3 P 3 , control (902.5±3 184.2)mm , P 3 , control (5934.6±616.4) mm 3 , P 3 , control (4710.7±416.3) mm 3 , P 3 , control (3688.9±672.3) mm 3 , P 3 , control (254.3±84.4) mm 3 , P 3 , control (1689.0±719.6) mm 3 , P<0.05) were significantly larger in ALS patients than in normal controls. Extra activation areas including ipsilateral ILPA, contralateral cerebellum and bilateral posterior limb of internal capsule were only detected in ALS patients. Conclusions: Similar activation areas were seen in both groups while executing the same motor

Early Changes in Alpha Band Power and DMN BOLD Activity in Alzheimer’s Disease: A Simultaneous Resting State EEG-fMRI Study

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Katharina Brueggen

2017-10-01

Full Text Available Simultaneous resting state functional magnetic resonance imaging (rsfMRI–resting state electroencephalography (rsEEG studies in healthy adults showed robust positive associations of signal power in the alpha band with BOLD signal in the thalamus, and more heterogeneous associations in cortical default mode network (DMN regions. Negative associations were found in occipital regions. In Alzheimer’s disease (AD, rsfMRI studies revealed a disruption of the DMN, while rsEEG studies consistently reported a reduced power within the alpha band. The present study is the first to employ simultaneous rsfMRI-rsEEG in an AD sample, investigating the association of alpha band power and BOLD signal, compared to healthy controls (HC. We hypothesized to find reduced positive associations in DMN regions and reduced negative associations in occipital regions in the AD group. Simultaneous resting state fMRI–EEG was recorded in 14 patients with mild AD and 14 HC, matched for age and gender. Power within the EEG alpha band (8–12 Hz, 8–10 Hz, and 10–12 Hz was computed from occipital electrodes and served as regressor in voxel-wise linear regression analyses, to assess the association with the BOLD signal. Compared to HC, the AD group showed significantly decreased positive associations between BOLD signal and occipital alpha band power in clusters in the superior, middle and inferior frontal cortex, inferior temporal lobe and thalamus (p < 0.01, uncorr., cluster size ≥ 50 voxels. This group effect was more pronounced in the upper alpha sub-band, compared to the lower alpha sub-band. Notably, we observed a high inter-individual heterogeneity. Negative associations were only reduced in the lower alpha range in the hippocampus, putamen and cerebellum. The present study gives first insights into the relationship of resting-state EEG and fMRI characteristics in an AD sample. The results suggest that positive associations between alpha band power and BOLD

Cholinergic enhancement reduces functional connectivity and BOLD variability in visual extrastriate cortex during selective attention.

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Ricciardi, Emiliano; Handjaras, Giacomo; Bernardi, Giulio; Pietrini, Pietro; Furey, Maura L

2013-01-01

Enhancing cholinergic function improves performance on various cognitive tasks and alters neural responses in task specific brain regions. We have hypothesized that the changes in neural activity observed during increased cholinergic function reflect an increase in neural efficiency that leads to improved task performance. The current study tested this hypothesis by assessing neural efficiency based on cholinergically-mediated effects on regional brain connectivity and BOLD signal variability. Nine subjects participated in a double-blind, placebo-controlled crossover fMRI study. Following an infusion of physostigmine (1 mg/h) or placebo, echo-planar imaging (EPI) was conducted as participants performed a selective attention task. During the task, two images comprised of superimposed pictures of faces and houses were presented. Subjects were instructed periodically to shift their attention from one stimulus component to the other and to perform a matching task using hand held response buttons. A control condition included phase-scrambled images of superimposed faces and houses that were presented in the same temporal and spatial manner as the attention task; participants were instructed to perform a matching task. Cholinergic enhancement improved performance during the selective attention task, with no change during the control task. Functional connectivity analyses showed that the strength of connectivity between ventral visual processing areas and task-related occipital, parietal and prefrontal regions reduced significantly during cholinergic enhancement, exclusively during the selective attention task. Physostigmine administration also reduced BOLD signal temporal variability relative to placebo throughout temporal and occipital visual processing areas, again during the selective attention task only. Together with the observed behavioral improvement, the decreases in connectivity strength throughout task-relevant regions and BOLD variability within stimulus

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...

To Boldly Go: Practical Career Advice for Young Scientists

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Fiske, P.

1998-05-01

Young scientists in nearly every field are finding the job market of the 1990's a confusing and frustrating place. Ph.D. supply is far larger than that needed to fill entry-level positions in "traditional" research careers. More new Ph.D. and Master's degree holders are considering a wider range of careers in and out of science, but feel ill-prepared and uninformed about their options. Some feel their Ph.D. training has led them to a dead-end. I present a thorough and practical overview to the process of career planning and job hunting in the 1990's, from the perspective of a young scientist. I cover specific steps that young scientists can take to broaden their horizons, strengthen their skills, and present their best face to potential employers. An important part of this is the realization that most young scientists possess a range of valuable "transferable skills" that are highly sought after by employers in and out of science. I will summarize the specifics of job hunting in the 90's, including informational interviewing, building your network, developing a compelling CV and resume, cover letters, interviewing, based on my book "To Boldly Go: A Practical Career Guide for Scientists". I will also identify other resources available for young scientists. Finally, I will highlight individual stories of Ph.D.-trained scientists who have found exciting and fulfilling careers outside the "traditional" world of academia.

Mapping glucose-mediated gut-to-brain signalling pathways in humans.

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Little, Tanya J; McKie, Shane; Jones, Richard B; D'Amato, Massimo; Smith, Craig; Kiss, Orsolya; Thompson, David G; McLaughlin, John T

2014-08-01

Previous fMRI studies have demonstrated that glucose decreases the hypothalamic BOLD response in humans. However, the mechanisms underlying the CNS response to glucose have not been defined. We recently demonstrated that the slowing of gastric emptying by glucose is dependent on activation of the gut peptide cholecystokinin (CCK1) receptor. Using physiological functional magnetic resonance imaging this study aimed to determine the whole brain response to glucose, and whether CCK plays a central role. Changes in blood oxygenation level-dependent (BOLD) signal were monitored using fMRI in 12 healthy subjects following intragastric infusion (250ml) of: 1M glucose+predosing with dexloxiglumide (CCK1 receptor antagonist), 1M glucose+placebo, or 0.9% saline (control)+placebo, in a single-blind, randomised fashion. Gallbladder volume, blood glucose, insulin, and GLP-1 and CCK concentrations were determined. Hunger, fullness and nausea scores were also recorded. Intragastric glucose elevated plasma glucose, insulin, and GLP-1, and reduced gall bladder volume (an in vivo assay for CCK secretion). Glucose decreased BOLD signal, relative to saline, in the brainstem and hypothalamus as well as the cerebellum, right occipital cortex, putamen and thalamus. The timing of the BOLD signal decrease was negatively correlated with the rise in blood glucose and insulin levels. The glucose+dex arm highlighted a CCK1-receptor dependent increase in BOLD signal only in the motor cortex. Glucose induces site-specific differences in BOLD response in the human brain; the brainstem and hypothalamus show a CCK1 receptor-independent reduction which is likely to be mediated by a circulatory effect of glucose and insulin, whereas the motor cortex shows an early dexloxiglumide-reversible increase in signal, suggesting a CCK1 receptor-dependent neural pathway. Copyright © 2014. Published by Elsevier Inc.

Mapping glucose-mediated gut-to-brain signalling pathways in humans☆

Science.gov (United States)

Little, Tanya J.; McKie, Shane; Jones, Richard B.; D'Amato, Massimo; Smith, Craig; Kiss, Orsolya; Thompson, David G.; McLaughlin, John T.

2014-01-01

Objectives Previous fMRI studies have demonstrated that glucose decreases the hypothalamic BOLD response in humans. However, the mechanisms underlying the CNS response to glucose have not been defined. We recently demonstrated that the slowing of gastric emptying by glucose is dependent on activation of the gut peptide cholecystokinin (CCK1) receptor. Using physiological functional magnetic resonance imaging this study aimed to determine the whole brain response to glucose, and whether CCK plays a central role. Experimental design Changes in blood oxygenation level-dependent (BOLD) signal were monitored using fMRI in 12 healthy subjects following intragastric infusion (250 ml) of: 1 M glucose + predosing with dexloxiglumide (CCK1 receptor antagonist), 1 M glucose + placebo, or 0.9% saline (control) + placebo, in a single-blind, randomised fashion. Gallbladder volume, blood glucose, insulin, and GLP-1 and CCK concentrations were determined. Hunger, fullness and nausea scores were also recorded. Principal observations Intragastric glucose elevated plasma glucose, insulin, and GLP-1, and reduced gall bladder volume (an in vivo assay for CCK secretion). Glucose decreased BOLD signal, relative to saline, in the brainstem and hypothalamus as well as the cerebellum, right occipital cortex, putamen and thalamus. The timing of the BOLD signal decrease was negatively correlated with the rise in blood glucose and insulin levels. The glucose + dex arm highlighted a CCK1-receptor dependent increase in BOLD signal only in the motor cortex. Conclusions Glucose induces site-specific differences in BOLD response in the human brain; the brainstem and hypothalamus show a CCK1 receptor-independent reduction which is likely to be mediated by a circulatory effect of glucose and insulin, whereas the motor cortex shows an early dexloxiglumide-reversible increase in signal, suggesting a CCK1 receptor-dependent neural pathway. PMID:24685436

Shy and bold great tits (Parus major): body temperature and breath rate in response to handling stress

NARCIS (Netherlands)

Carere, C.; Van Oers, K.

2004-01-01

A standard handling protocol was used to test the hypothesis that boldness predicts stress responsiveness in body temperature and breath rate. Great tit (Parus major) nestlings were taken from the field, hand reared until independence, and their response to a novel object was assessed. At the age of

Shy and bold great tits (Parus major) : body temperature and breath rate in response to handling stress

NARCIS (Netherlands)

Carere, C; van Oers, K

2004-01-01

A standard handling protocol was used to test the hypothesis that boldness predicts stress responsiveness in body temperature and breath rate. Great tit (Parus major) nestlings were taken from the field, hand reared until independence, and their response to a novel object was assessed. At the age of

The levels of triglyceride and total cholesterol in methamphetamine dependence.

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Zhang, Meijuan; Lv, Dezhao; Zhou, Wu; Ji, Lili; Zhou, Beibei; Chen, Han; Gu, Yingying; Zhao, Jiyun; He, Jincai

2017-04-01

The serum triglyceride (TG) and total cholesterol (TC) levels have been reported altered in the traditional drug-dependence (such as marijuana and heroin). However, studies assessing the relationships among serum TC, TG, and methamphetamine (MA)-dependence have not been described well. In this study, our aim is to explore the serum TG and TC levels in large sample of MA-dependent patients. A retrospective study was conducted in 938 MA-dependent patients who were recruited between February 2, 2008 and March 11, 2013, with social characteristics and drug-dependence history (duration of MA use, routes of drug administration, and daily dose were collected). Then, the serum levels of TC, TG, glucose (GLU), body mass index (BMI), and blood pressure were measured among the participants. Meanwhile, 985 age- and gender-matched healthy people in the physical examination center were selected as control group. Compared with the control group, significant decreases of TC, TG, GLU, and BMI were observed in MA-dependent patients (P < 0.05). Besides, we found that the daily dose of MA use was associated with TC (β = -0.079, P = 0.015) and the duration of MA use was independently related to BMI (β = -0.071, P = 0.031). This study demonstrated that the levels of TC, TG, GLU, and BMI factors altered in the MA-dependent patients. In addition, there is a negative association between MA dependence and TC and BMI.

Teacherpreneurs: a bold brand of teacher leadership for 21st-century teaching and learning.

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Berry, Barnett

2013-04-19

Challenges facing our public schools demand a bold brand of teacher leadership. Teacherpreneurs, effective teachers who teach students regularly but also incubate and execute the kinds of policies and pedagogies students deserve, represent a new culture of training and ingenuity. Teachers who lead outside the classroom but do not lose their connection to students are best positioned to develop and disseminate best policies and practices for 21st-century teaching and learning.

Boldness towards novelty and translocation success in captive-raised, orphaned Tasmanian devils.

Science.gov (United States)

Sinn, David L; Cawthen, Lisa; Jones, Susan M; Pukk, Chrissy; Jones, Menna E

2014-01-01

Translocation of endangered animals is common, but success is often variable and/or poor. Despite its intuitive appeal, little is known with regards to how individual differences amongst translocated animals influence their post-release survival, growth, and reproduction. We measured consistent pre-release responses to novelty in a familiar environment (boldness; repeatability=0.55) and cortisol response in a group of captive-reared Tasmanian devils, currently listed as "Endangered" by the IUCN. The devils were then released at either a hard- or soft-release site within their mothers' population of origin, and individual growth, movement, reproduction (females only), and survival across 2-8 months post-release was measured. Sex, release method, cohort, behavior, and cortisol response did not affect post-release growth, nor did these factors influence the home range size of orphan devils. Final linear distances moved from the release site were impacted heavily by the release cohort, but translocated devils' movement overall was not different from that in the same-age wild devils. All orphan females of reproductive age were subsequently captured with offspring. Overall survival rates in translocated devils were moderate (∼42%), and were not affected by devil sex, release method, cohort, release weight, or pre-release cortisol response. Devils that survived during the study period were, however, 3.5 times more bold than those that did not (effect size r=0.76). Our results suggest that conservation managers may need to provide developmental conditions in captivity that promote a wide range of behaviors across individuals slated for wild release. © 2013 Wiley Periodicals, Inc.

Study of nuclear level density parameter and its temperature dependence

International Nuclear Information System (INIS)

Nasrabadi, M. N.; Behkami, A. N.

2000-01-01

The nuclear level density ρ is the basic ingredient required for theoretical studies of nuclear reaction and structure. It describes the statistical nuclear properties and is expressed as a function of various constants of motion such as number of particles, excitation energy and angular momentum. In this work the energy and spin dependence of nuclear level density will be presented and discussed. In addition the level density parameter α will be extracted from this level density information, and its temperature and mass dependence will be obtained

Amphetamine modulates brain signal variability and working memory in younger and older adults.

Science.gov (United States)

Garrett, Douglas D; Nagel, Irene E; Preuschhof, Claudia; Burzynska, Agnieszka Z; Marchner, Janina; Wiegert, Steffen; Jungehülsing, Gerhard J; Nyberg, Lars; Villringer, Arno; Li, Shu-Chen; Heekeren, Hauke R; Bäckman, Lars; Lindenberger, Ulman

2015-06-16

Better-performing younger adults typically express greater brain signal variability relative to older, poorer performers. Mechanisms for age and performance-graded differences in brain dynamics have, however, not yet been uncovered. Given the age-related decline of the dopamine (DA) system in normal cognitive aging, DA neuromodulation is one plausible mechanism. Hence, agents that boost systemic DA [such as d-amphetamine (AMPH)] may help to restore deficient signal variability levels. Furthermore, despite the standard practice of counterbalancing drug session order (AMPH first vs. placebo first), it remains understudied how AMPH may interact with practice effects, possibly influencing whether DA up-regulation is functional. We examined the effects of AMPH on functional-MRI-based blood oxygen level-dependent (BOLD) signal variability (SD(BOLD)) in younger and older adults during a working memory task (letter n-back). Older adults expressed lower brain signal variability at placebo, but met or exceeded young adult SD(BOLD) levels in the presence of AMPH. Drug session order greatly moderated change-change relations between AMPH-driven SD(BOLD) and reaction time means (RT(mean)) and SDs (RT(SD)). Older adults who received AMPH in the first session tended to improve in RT(mean) and RT(SD) when SD(BOLD) was boosted on AMPH, whereas younger and older adults who received AMPH in the second session showed either a performance improvement when SD(BOLD) decreased (for RT(mean)) or no effect at all (for RT(SD)). The present findings support the hypothesis that age differences in brain signal variability reflect aging-induced changes in dopaminergic neuromodulation. The observed interactions among AMPH, age, and session order highlight the state- and practice-dependent neurochemical basis of human brain dynamics.

SERUM ACETYLCHOLINESTERASE LEVEL IN THE PATIENTS OF OPIOID (BROWN SUGAR) DEPENDENCE

OpenAIRE

Shah, Nilesh; Dave, Kirti

1992-01-01

The authors compared the serum acetylcholinesterase level in the patients of brown sugar dependence and the normal volunteers. Significantly lower level of serum acetylcholinesterase was found in patients of brown sugar dependence.

The effect of Rickia wasmannii (Ascomycota, Laboulbeniales on the aggression and boldness of Myrmica scabrinodis (Hymenoptera, Formicidae

Directory of Open Access Journals (Sweden)

Ferenc Báthori

2017-08-01

Full Text Available The interactions of ectosymbiotic Laboulbeniales (Ascomycota fungi and their hosts are rather understudied. Rickia wasmannii Cavara is a common ant-associated Laboulbeniales species that has been reported in 17 countries of Europe, and frequently infects Myrmica scabrinodis Nylander, 1846 (Hymenoptera: Formicidae, a common ant species host, in high density. These make M. scabrinodis and R. wasmannii appropriate model organisms for studies on fungal host-ectosymbiont interactions. Aggressiveness and boldness of infected and uninfected M. scabrinodis workers from northern and eastern Hungary were studied in two laboratory-established behavioural experiments. Infected workers were significantly less aggressive and less bold (i.e. less likely to leave nest shelters than the uninfected ones. These results suggest that R. wasmannii has considerable effects on the behaviour of M. scabrinodis. Our study brings an evidence that infection of ants with Laboulbeniales might negatively affect the workers’ behaviour. In special, the competitive abilities might be affected most by these fungi, since remaining inside and behaving submissively is not effective behaviour in the case of significant competition for resources among colonies.

Low prevalence of obstructive lung disease in a suburban population of Malaysia: A BOLD collaborative study.

Science.gov (United States)

Loh, Li Cher; Rashid, Abdul; Sholehah, Siti; Gnatiuc, Louisa; Patel, Jaymini H; Burney, Peter

2016-08-01

As a Burden of Obstructive Lung Disease (BOLD) collaboration, we studied the prevalence of chronic obstructive pulmonary disease (COPD) and its associated risk factors in a suburban population in Malaysia. Nonhospitalized men or women of age ≥ 40 years from a Penang district were recruited by stratified simple random sampling. Participants completed detailed questionnaires on respiratory symptoms and exposure to COPD risk factors. Prebronchodilator and post-bronchodilator spirometry conducted was standardized across all international BOLD sites in device and data quality control. Of the 1218 individuals recruited for the study, 663 (340 men and 323 women) had complete questionnaire data and acceptable post-bronchodilator spirometry. The estimated population prevalence of Global Initiative for Chronic Obstructive Lung Disease (GOLD) ≥ stage I was 6.5% or 3.4% based on either fixed forced expiratory volume in 1 s/forced vital capacity ratio of population-based epidemiology data on COPD for Malaysia. Compared with other sites globally, our estimated population prevalence was relatively low. In addition to cigarette smoking, use of biomass fuel and exposure to dusty job represented significant risk to the development of COPD. © 2016 Asian Pacific Society of Respirology.

Detecting Activation in fMRI Data: An Approach Based on Sparse Representation of BOLD Signal

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Blanca Guillen

2018-01-01

Full Text Available This paper proposes a simple yet effective approach for detecting activated voxels in fMRI data by exploiting the inherent sparsity property of the BOLD signal in temporal and spatial domains. In the time domain, the approach combines the General Linear Model (GLM with a Least Absolute Deviation (LAD based regression method regularized by the pseudonorm l0 to promote sparsity in the parameter vector of the model. In the spatial domain, detection of activated regions is based on thresholding the spatial map of estimated parameters associated with a particular stimulus. The threshold is calculated by exploiting the sparseness of the BOLD signal in the spatial domain assuming a Laplacian distribution model. The proposed approach is validated using synthetic and real fMRI data. For synthetic data, results show that the proposed approach is able to detect most activated voxels without any false activation. For real data, the method is evaluated through comparison with the SPM software. Results indicate that this approach can effectively find activated regions that are similar to those found by SPM, but using a much simpler approach. This study may lead to the development of robust spatial approaches to further simplifying the complexity of classical schemes.

Infraslow Electroencephalographic and Dynamic Resting State Network Activity.

Science.gov (United States)

Grooms, Joshua K; Thompson, Garth J; Pan, Wen-Ju; Billings, Jacob; Schumacher, Eric H; Epstein, Charles M; Keilholz, Shella D

2017-06-01

A number of studies have linked the blood oxygenation level dependent (BOLD) signal to electroencephalographic (EEG) signals in traditional frequency bands (δ, θ, α, β, and γ), but the relationship between BOLD and its direct frequency correlates in the infraslow band (resting state magnetic resonance imaging data were acquired simultaneously. The DC EEG signals were correlated with the BOLD signal in patterns that resembled resting state networks. Subsequent dynamic analysis showed that the correlation between DC EEG and the BOLD signal varied substantially over time, even within individual subjects. The variation in DC EEG appears to reflect the time-varying contribution of different resting state networks. Furthermore, some of the patterns of DC EEG and BOLD correlation are consistent with previous work demonstrating quasiperiodic spatiotemporal patterns of large-scale network activity in resting state. These findings demonstrate that infraslow electrical activity is linked to BOLD fluctuations in humans and that it may provide a basis for large-scale organization comparable to that observed in animal studies.

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

NARCIS (Netherlands)

Jorge, João; Figueiredo, Patrícia; Gruetter, Rolf; Van der Zwaag, W.

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

Functional interactions of HIV-infection and methamphetamine dependence during motor programming.

Science.gov (United States)

Archibald, Sarah L; Jacobson, Mark W; Fennema-Notestine, Christine; Ogasawara, Miki; Woods, Steven P; Letendre, Scott; Grant, Igor; Jernigan, Terry L

2012-04-30

Methamphetamine (METH) dependence is frequently comorbid with HIV infection and both have been linked to alterations of brain structure and function. In a previous study, we showed that the brain volume loss characteristic of HIV infection contrasts with METH-related volume increases in striatum and parietal cortex, suggesting distinct neurobiological responses to HIV and METH (Jernigan et al., 2005). Functional magnetic resonance imaging (fMRI) has the potential to reveal functional interactions between the effects of HIV and METH. In the present study, 50 participants were studied in four groups: an HIV+ group, a recently METH-dependent group, a dually affected group, and a group of unaffected community comparison subjects. An fMRI paradigm consisting of motor sequencing tasks of varying levels of complexity was administered to examine blood oxygenation level dependent (BOLD) changes. Within all groups, activity increased significantly with increasing task complexity in large clusters within sensorimotor and parietal cortex, basal ganglia, cerebellum, and cingulate. The task complexity effect was regressed on HIV status, METH status, and the HIV×METH interaction term in a simultaneous multiple regression. HIV was associated with less complexity-related activation in striatum, whereas METH was associated with less complexity-related activation in parietal regions. Significant interaction effects were observed in both cortical and subcortical regions; and, contrary to expectations, the complexity-related activation was less aberrant in dually affected than in single risk participants, in spite of comparable levels of neurocognitive impairment among the clinical groups. Thus, HIV and METH dependence, perhaps through their effects on dopaminergic systems, may have opposing functional effects on neural circuits involved in motor programming. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Physiological denoising of BOLD fMRI data using Regressor Interpolation at Progressive Time Delays (RIPTiDe) processing of concurrent fMRI and near-infrared spectroscopy (NIRS).

Science.gov (United States)

Frederick, Blaise deB; Nickerson, Lisa D; Tong, Yunjie

2012-04-15

Confounding noise in BOLD fMRI data arises primarily from fluctuations in blood flow and oxygenation due to cardiac and respiratory effects, spontaneous low frequency oscillations (LFO) in arterial pressure, and non-task related neural activity. Cardiac noise is particularly problematic, as the low sampling frequency of BOLD fMRI ensures that these effects are aliased in recorded data. Various methods have been proposed to estimate the noise signal through measurement and transformation of the cardiac and respiratory waveforms (e.g. RETROICOR and respiration volume per time (RVT)) and model-free estimation of noise variance through examination of spatial and temporal patterns. We have previously demonstrated that by applying a voxel-specific time delay to concurrently acquired near infrared spectroscopy (NIRS) data, we can generate regressors that reflect systemic blood flow and oxygenation fluctuations effects. Here, we apply this method to the task of removing physiological noise from BOLD data. We compare the efficacy of noise removal using various sets of noise regressors generated from NIRS data, and also compare the noise removal to RETROICOR+RVT. We compare the results of resting state analyses using the original and noise filtered data, and we evaluate the bias for the different noise filtration methods by computing null distributions from the resting data and comparing them with the expected theoretical distributions. Using the best set of processing choices, six NIRS-generated regressors with voxel-specific time delays explain a median of 10.5% of the variance throughout the brain, with the highest reductions being seen in gray matter. By comparison, the nine RETROICOR+RVT regressors together explain a median of 6.8% of the variance in the BOLD data. Detection of resting state networks was enhanced with NIRS denoising, and there were no appreciable differences in the bias of the different techniques. Physiological noise regressors generated using

Internal representations for face detection: an application of noise-based image classification to BOLD responses.

Science.gov (United States)

Nestor, Adrian; Vettel, Jean M; Tarr, Michael J

2013-11-01

What basic visual structures underlie human face detection and how can we extract such structures directly from the amplitude of neural responses elicited by face processing? Here, we address these issues by investigating an extension of noise-based image classification to BOLD responses recorded in high-level visual areas. First, we assess the applicability of this classification method to such data and, second, we explore its results in connection with the neural processing of faces. To this end, we construct luminance templates from white noise fields based on the response of face-selective areas in the human ventral cortex. Using behaviorally and neurally-derived classification images, our results reveal a family of simple but robust image structures subserving face representation and detection. Thus, we confirm the role played by classical face selective regions in face detection and we help clarify the representational basis of this perceptual function. From a theory standpoint, our findings support the idea of simple but highly diagnostic neurally-coded features for face detection. At the same time, from a methodological perspective, our work demonstrates the ability of noise-based image classification in conjunction with fMRI to help uncover the structure of high-level perceptual representations. Copyright © 2012 Wiley Periodicals, Inc.

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)

Bold Ideas for the 4th H in 4-H: Teen Identified Concerns and Actions

OpenAIRE

Virginia Brown; Bonnie Braun; JoAnne Leatherman

2015-01-01

This article summarizes a literature review; teen-identified health concerns and issues; and teen bold ideas for actions. Findings from the National 4-H Council and Molina Healthcare Teens Take on Health initiative are provided and implications for 4-H programming tied to the new Cooperative Extension National Framework for Health and Wellness are addressed. The article is intended as background for Extension educators, volunteers and administrators as they review the 4-H Healthy Living Missi...

Effects of hypoglycemia on human brain activation measured with fMRI.

Science.gov (United States)

Anderson, Adam W; Heptulla, Rubina A; Driesen, Naomi; Flanagan, Daniel; Goldberg, Philip A; Jones, Timothy W; Rife, Fran; Sarofin, Hedy; Tamborlane, William; Sherwin, Robert; Gore, John C

2006-07-01

Functional magnetic resonance imaging (fMRI) was used to measure the effects of acute hypoglycemia caused by passive sensory stimulation on brain activation. Visual stimulation was used to generate blood-oxygen-level-dependent (BOLD) contrast, which was monitored during hyperinsulinemic hypoglycemic and euglycemic clamp studies. Hypoglycemia (50 +/- 1 mg glucose/dl) decreased the fMRI signal relative to euglycemia in 10 healthy human subjects: the fractional signal change was reduced by 28 +/- 12% (P variations in blood glucose levels may modulate BOLD signals in the healthy brain.

Effect of temperature-dependent energy-level shifts on a semiconductor's Peltier heat

International Nuclear Information System (INIS)

Emin, D.

1984-01-01

The Peltier heat of a charge carrier in a semiconductor is calculated for the situation in which the electronic energy levels are temperature dependent. The temperature dependences of the electronic energy levels, generally observed optically, arise from their dependences on the vibrational energy of the lattice (e.g., as caused by thermal expansion). It has been suggested that these temperature dependences will typically have a major effect on the Peltier heat. The Peltier heat associated with a given energy level is a thermodynamic quantity; it is the product of the temperature and the change of the entropy of the system when a carrier is added in that level. As such, the energy levels cannot be treated as explicitly temperature dependent. The electron-lattice interaction causing the temperature dependence must be expressly considered. It is found that the carrier's interaction with the atomic vibrations lowers its electronic energy. However, the interaction of the carrier with the atomic vibrations also causes an infinitesimal lowering (approx.1/N) of each of the N vibrational frequencies. As a result, there is a finite carrier-induced increase in the average vibrational energy. Above the Debye temperature, this cancels the lowering of the carrier's electronic energy. Thus, the standard Peltier-heat formula, whose derivation generally ignores the temperature dependence of the electronic energy levels, is regained. This explains the apparent success of the standard formula in numerous analyses of electronic transport experiments

NEUROFEEDBACK USING FUNCTIONAL SPECTROSCOPY

OpenAIRE

Hinds, Oliver; Wighton, Paul; Tisdall, M. Dylan; Hess, Aaron; Breiter, Hans; van der Kouwe, André

2014-01-01

Neurofeedback based on real-time measurement of the blood oxygenation level-dependent (BOLD) signal has potential for treatment of neurological disorders and behavioral enhancement. Commonly employed methods are based on functional magnetic resonance imaging (fMRI) sequences that sacrifice speed and accuracy for whole-brain coverage, which is unnecessary in most applications. We present multi-voxel functional spectroscopy (MVFS): a system for computing the BOLD signal from multiple volumes of...

The ap?ritif effect: alcohol's effects on the brain's response to food aromas in women

OpenAIRE

Eiler, William J.A.; D?emid?i?, Mario; Case, K. Rose; Soeurt, Christina M.; Armstrong, Cheryl L.H.; Mattes, Richard D.; O'Connor, Sean J.; Harezlak, Jaroslaw; Acton, Anthony J.; Considine, Robert V.; Kareken, David A.

2015-01-01

Objective Consuming alcohol prior to a meal (an ap?ritif) increases food consumption. This greater food consumption may result from increased activity in brain regions that mediate reward and regulate feeding behavior. Using functional magnetic resonance imaging, we evaluated the blood oxygenation level dependent (BOLD) response to the food aromas of either roast beef or Italian meat sauce following pharmacokinetically controlled intravenous infusion of alcohol. Methods BOLD activation to foo...

Implicit Race Bias Decreases the Similarity of Neural Representations of Black and White Faces

Science.gov (United States)

Brosch, Tobias; Bar-David, Eyal; Phelps, Elizabeth A.

2013-01-01

Implicit race bias has been shown to affect decisions and behaviors. It may also change perceptual experience by increasing perceived differences between social groups. We investigated how this phenomenon may be expressed at the neural level by testing whether the distributed blood-oxygenation-level-dependent (BOLD) patterns representing Black and White faces are more dissimilar in participants with higher implicit race bias. We used multivoxel pattern analysis to predict the race of faces participants were viewing. We successfully predicted the race of the faces on the basis of BOLD activation patterns in early occipital visual cortex, occipital face area, and fusiform face area (FFA). Whereas BOLD activation patterns in early visual regions, likely reflecting different perceptual features, allowed successful prediction for all participants, successful prediction on the basis of BOLD activation patterns in FFA, a high-level face-processing region, was restricted to participants with high pro-White bias. These findings suggest that stronger implicit pro-White bias decreases the similarity of neural representations of Black and White faces. PMID:23300228

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.

Cocaine-associated odor cue re-exposure increases blood oxygenation level dependent signal in memory and reward regions of the maternal rat brain.

Science.gov (United States)

Caffrey, Martha K; Febo, Marcelo

2014-01-01

Cue triggered relapse during the postpartum period can negatively impact maternal care. Given the high reward value of pups in maternal rats, we designed an fMRI experiment to test whether offspring presence reduces the neural response to a cocaine associated olfactory cue. Cocaine conditioned place preference was carried out before pregnancy in the presence of two distinct odors that were paired with cocaine or saline (+Cue and -Cue). The BOLD response to +Cue and -Cue was measured in dams on postpartum days 2-4. Odor cues were delivered to dams in the absence and then the presence of pups. Our data indicate that several limbic and cognitive regions of the maternal rat brain show a greater BOLD signal response to a +Cue versus -Cue. These include dorsal striatum, prelimbic cortex, parietal cortex, habenula, bed nucleus of stria terminalis, lateral septum and the mediodorsal and the anterior thalamic nucleus. Of the aforementioned brain regions, only the parietal cortex of cocaine treated dams showed a significant modulatory effect of pup presence. In this area of the cortex, cocaine exposed maternal rats showed a greater BOLD activation in response to the +Cue in the presence than in the absence of pups. Specific regions of the cocaine exposed maternal rat brain are strongly reactive to drug associated cues. The regions implicated in cue reactivity have been previously reported in clinical imaging work, and previous work supports their role in various motivational and cognitive functions. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

COCAINE-ASSOCIATED ODOR CUE RE-EXPOSURE INCREASES BLOOD OXYGENATION LEVEL DEPENDENT SIGNAL IN MEMORY AND REWARD REGIONS OF THE MATERNAL RAT BRAIN*

Science.gov (United States)

Caffrey, Martha K.; Febo, Marcelo

2013-01-01

BACKGROUND Cue triggered relapse during the postpartum period can negatively impact maternal care. Given the high reward value of pups in maternal rats, we designed an fMRI experiment to test whether offspring presence reduces the neural response to a cocaine associated olfactory cue. METHODS Cocaine conditioned place preference was carried out before pregnancy in the presence of two distinct odors that were paired with cocaine or saline (+Cue and −Cue). The BOLD response to +Cue and −Cue was measured in dams on postpartum days 2–4. Odor cues were delivered to dams in the absence and then the presence of pups. RESULTS Our data indicate that several limbic and cognitive regions of the maternal rat brain show a greater BOLD signal response to a +Cue versus −Cue. These include dorsal striatum, prelimbic cortex, parietal cortex, habenula, bed nucleus of stria terminalis, lateral septum and the mediodorsal and the anterior thalamic nucleus. Of the aforementioned brain regions, only the parietal cortex of cocaine treated dams showed a significant modulatory effect of pup presence. In this area of the cortex, cocaine exposed maternal rats showed a greater BOLD activation in response to the +Cue in the presence than in the absence of pups. CONCLUSIONS Specific regions of the cocaine exposed maternal rat brain are strongly reactive to drug associated cues. The regions implicated in cue reactivity have been previously reported in clinical imaging work, and previous work supports their role in various motivational and cognitive functions. PMID:24183499

Effects of parietal TMS on visual and auditory processing at the primary cortical level -- a concurrent TMS-fMRI study

DEFF Research Database (Denmark)

Leitão, Joana; Thielscher, Axel; Werner, Sebastian

2013-01-01

cortices under 3 sensory contexts: visual, auditory, and no stimulation. IPS-TMS increased activations in auditory cortices irrespective of sensory context as a result of direct and nonspecific auditory TMS side effects. In contrast, IPS-TMS modulated activations in the visual cortex in a state...... deactivations induced by auditory activity to TMS sounds. TMS to IPS may increase the responses in visual (or auditory) cortices to visual (or auditory) stimulation via a gain control mechanism or crossmodal interactions. Collectively, our results demonstrate that understanding TMS effects on (uni......Accumulating evidence suggests that multisensory interactions emerge already at the primary cortical level. Specifically, auditory inputs were shown to suppress activations in visual cortices when presented alone but amplify the blood oxygen level-dependent (BOLD) responses to concurrent visual...

Excitation energy and angular momentum dependence of the nuclear level densities

International Nuclear Information System (INIS)

Razavi, R.; Kakavand, T.; Behkami, A. N.

2007-01-01

We have investigated the excitation energy (E) dependence of nuclear level density for Bethe formula and constant temperature model. The level density parameter aa nd the back shifted energy from the Bethe formula are obtained by fitting the complete level schemes. Also the level density parameters from the constant temperature model have been determined for several nuclei. we have shown that the microscopic theory provides more precise information on the nuclear level densities. On the other hand, the spin cut-off parameter and effective moment of inertia are determined by studying of the angular momentum (J) dependence of the nuclear level density, and effective moment of inertia is compared with rigid body value.

Imaging human reward processing with positron emission tomography and functional magnetic resonance imaging.

Science.gov (United States)

Urban, Nina B L; Slifstein, Mark; Meda, Shashwath; Xu, Xiaoyan; Ayoub, Rawad; Medina, Olga; Pearlson, Godfrey D; Krystal, John H; Abi-Dargham, Anissa

2012-05-01

Functional neuroimaging (fMRI) studies show activation in mesolimbic circuitry in tasks involving reward processing, like the Monetary Incentive Delay Task (MIDT). In voltammetry studies in animals, mesolimbic dopamine release is associated with reward salience. This study examined the relationship between fMRI activation and magnitude of dopamine release measured with Positron emission tomography study (PET) in the same subjects using MIDT in both modalities to test if fMRI activation is related to dopamine release. Eighteen healthy subjects were scanned with [¹¹C]raclopride PET at baseline and after MIDT. Binding potential (BP(ND)) was derived by equilibrium analysis in striatal subregions and percent change across conditions (∆BP(ND)) was measured. Blood oxygen level dependence (BOLD) signal changes with MIDT were measured during fMRI using voxelwise analysis and ROI analysis and correlated with ∆BP(ND). ∆BP(ND) was not significant in the ventral striatum (VST) but reached significance in the posterior caudate. The fMRI BOLD activation was highest in VST. No significant associations between ∆BP(ND) and change in fMRI BOLD were observed with VST using ROI analysis. Voxelwise analysis showed positive correlation between BOLD activation in anticipation of the highest reward and ∆BP(ND) in VST and precommissural putamen. Our study indicates that endogenous dopamine release in VST is of small magnitude and is related to BOLD signal change during performance of the MIDT in only a few voxels when rewarding and nonrewarding conditions are interspersed. The lack of correlation at the ROI level may be due to the small magnitude of release or to the particular dependence of BOLD on glutamatergic signaling.

Brain activation in motor sequence learning is related to the level of native cortical excitability.

Directory of Open Access Journals (Sweden)

Silke Lissek

Full Text Available Cortical excitability may be subject to changes through training and learning. Motor training can increase cortical excitability in motor cortex, and facilitation of motor cortical excitability has been shown to be positively correlated with improvements in performance in simple motor tasks. Thus cortical excitability may tentatively be considered as a marker of learning and use-dependent plasticity. Previous studies focused on changes in cortical excitability brought about by learning processes, however, the relation between native levels of cortical excitability on the one hand and brain activation and behavioral parameters on the other is as yet unknown. In the present study we investigated the role of differential native motor cortical excitability for learning a motor sequencing task with regard to post-training changes in excitability, behavioral performance and involvement of brain regions. Our motor task required our participants to reproduce and improvise over a pre-learned motor sequence. Over both task conditions, participants with low cortical excitability (CElo showed significantly higher BOLD activation in task-relevant brain regions than participants with high cortical excitability (CEhi. In contrast, CElo and CEhi groups did not exhibit differences in percentage of correct responses and improvisation level. Moreover, cortical excitability did not change significantly after learning and training in either group, with the exception of a significant decrease in facilitatory excitability in the CEhi group. The present data suggest that the native, unmanipulated level of cortical excitability is related to brain activation intensity, but not to performance quality. The higher BOLD mean signal intensity during the motor task might reflect a compensatory mechanism in CElo participants.

Linear Discriminant Analysis achieves high classification accuracy for the BOLD fMRI response to naturalistic movie stimuli.

Directory of Open Access Journals (Sweden)

Hendrik eMandelkow

2016-03-01

Full Text Available 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 Neighbour (NN, Gaussian Naïve Bayes (GNB, and (regularised 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 regularised by principal component analysis (PCA achieved high classification accuracies, above 90% on average for single fMRI volumes acquired 2s apart during a 300s movie (chance level 0.7% = 2s/300s. 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

Recalled first reactions to inhaling nicotine predict the level of physical dependence.

Science.gov (United States)

Wellman, Robert J; DiFranza, Joseph R; O'Loughlin, Jennifer

2014-10-01

The level of physical dependence is a measure of addiction that correlates highly with addiction-associated changes in brain structure. We sought to determine whether age at first inhalation and initial reactions to inhaling nicotine are related to level of physical dependence in early adulthood. Young adults (n=312; mean age=24 years; 51% female) from the Nicotine Dependence in Teens study who had smoked at least once in the preceding three months completed self-report questionnaires in 2011-12. We assessed level of physical dependence with three validated self-report items assessing 'wanting,' 'craving' and 'needing' triggered by nicotine deprivation. Survey items assessed smoking behavior, including age at first inhalation, and recalled first reactions to inhaling nicotine. After adjusting for covariates, experiencing relaxation, heart racing/pounding, rush or "buzz" (OR=1.45; 95% CI: 1.08, 1.94) and dizziness (OR=1.58; 95% CI: 1.15, 2.18) at first nicotine inhalation were associated with an increased odds of being at a higher level of physical dependence in young adulthood; the association for experiencing relaxation (OR=1.78; 95% CI: 1.20, 2.64) and heart racing/pounding (OR=1.51; 95% CI: 1.00, 2.28) persisted after additionally controlling for all other first reactions. Neither age at first inhalation nor unpleasant first reactions predicted level of physical dependence. In accordance with prior research, our findings suggest that smokers who are particularly sensitive to the pleasant, "buzz-related" and generally arousing effects of nicotine may be more likely to attain higher levels of physical dependence. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Gamma-ray-induced bold seeded early maturing groundnut selections

Energy Technology Data Exchange (ETDEWEB)

Manoharan, V; Thangavelu, S [Regional Research Station, Vriddhachalam, Tamil Nadu (India)

1990-07-01

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{sub 1} generation was grown during the post rainy season of 1988-1989. The M{sub 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{sub 2} plants being 1,730. All the M{sub 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)

Parity dependence of the nuclear level density at high excitation

International Nuclear Information System (INIS)

Rao, B.V.; Agrawal, H.M.

1995-01-01

The basic underlying assumption ρ(l+1, J)=ρ(l, J) in the level density function ρ(U, J, π) has been checked on the basis of high quality data available on individual resonance parameters (E 0 , Γ n , J π ) for s- and p-wave neutrons in contrast to the earlier analysis where information about p-wave resonance parameters was meagre. The missing level estimator based on the partial integration over a Porter-Thomas distribution of neutron reduced widths and the Dyson-Mehta Δ 3 statistic for the level spacing have been used to ascertain that the s- and p-wave resonance level spacings D(0) and D(1) are not in error because of spurious and missing levels. The present work does not validate the tacit assumption ρ(l+1, J)=ρ(l, J) and confirms that the level density depends upon parity at high excitation. The possible implications of the parity dependence of the level density on the results of statistical model calculations of nuclear reaction cross sections as well as on pre-compound emission have been emphasized. (orig.)

Evaluating nicotine dependence levels in e-cigarette users.

Science.gov (United States)

González Roz, Alba; Secades Villa, Roberto; Weidberg, Sara

2017-01-11

Despite the fact that electronic cigarettes (e-cigarettes) are rapidly growing in popularity and use worldwide, there is scarce scientific data on abuse liability among e-cigarette users, and about whether e-cigarette use is related to nicotine dependence or not. The aim of this study is to explore nicotine dependence levels in a sample of experienced e-cigarette users (n= 39) and to compare them with current tobacco cigarette smokers (n=42). We conducted several face-to-face interviews in order to assess sociodemographic and dependence related characteristics in both e-cigarette users and in smokers. Adapted versions of both the Fagerström test for nicotine dependence (FTND) and the nicotine dependence syndrome scale (NDSS) were used to analyze nicotine dependence in each of the groups. Biochemical markers of carbon monoxide and urinary cotinine analysis were also collected. Results showed that e-cigarette users scored lower than cigarette smokers in both FTND and all NDSS subscales. Our findings extend previous research on e-cigarette use and nicotine addiction and suggest that e-cigarette users are less dependent on nicotine than current tobacco cigarette smokers. Further prospective studies are needed to better ascertain their addictiveness potential, comparing those smokers who switched to e-cigarettes from smoking cigarettes, and those who had never been tobacco cigarette smokers.

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.

Food intake rates of inactive fish are positively linked to boldness in three‐spined sticklebacks Gasterosteus aculeatus

Science.gov (United States)

Manica, A.; Boogert, N. J.

2016-01-01

To investigate the link between personality and maximum food intake of inactive individuals, food‐deprived three‐spined sticklebacks Gasterosteus aculeatus at rest in their home compartments were provided with ad libitum prey items. Bolder individuals ate considerably more than shyer individuals, even after accounting for body size, while sociability did not have an effect. These findings support pace‐of‐life theory predicting that life‐history strategies are linked to boldness. PMID:26940195

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.

Outcome dependency alters the neural substrates of impression formation

Science.gov (United States)

Ames, Daniel L.; Fiske, Susan T.

2015-01-01

How do people maintain consistent impressions of other people when other people are often inconsistent? The present research addresses this question by combining recent neuroscientific insights with ecologically meaningful behavioral methods. Participants formed impressions of real people whom they met in a personally involving situation. fMRI and supporting behavioral data revealed that outcome dependency (i.e., depending on another person for a desired outcome) alters previously identified neural dynamics of impression formation. Consistent with past research, a functional localizer identified a region of dorsomedial PFC previously linked to social impression formation. In the main task, this ROI revealed the predicted patterns of activity across outcome dependency conditions: greater BOLD response when information confirmed (vs. violated) social expectations if participants were outcome-independent and the reverse pattern if participants were outcome-dependent. We suggest that, although social perceivers often discount expectancy-disconfirming information as noise, being dependent on another person for a desired outcome focuses impression-formation processing on the most diagnostic information, rather than on the most tractable information. PMID:23850465

Potentials and Challenges for Arterial Spin Labeling in Pharmacological Magnetic Resonance Imaging

OpenAIRE

Wang, Danny J. J.; Chen, Yufen; Fernández-Seara, María A.; Detre, John A.

2011-01-01

Pharmacological magnetic resonance imaging (phMRI) is increasingly being used in drug discovery and development to speed the translation from the laboratory to the clinic. The two primary methods in phMRI include blood-oxygen-level-dependent (BOLD) contrast and arterial spin-labeled (ASL) perfusion MRI. BOLD contrast has been widely applied in existing phMRI studies. However, because of the lack of absolute quantification and poor reproducibility over time scales longer than hours or across s...

Magnetic Resonance Imaging-Derived Renal Oxygenation and Perfusion During Continuous, Steady-State Angiotensin-II Infusion in Healthy Humans.

Science.gov (United States)

van der Bel, René; Coolen, Bram F; Nederveen, Aart J; Potters, Wouter V; Verberne, Hein J; Vogt, Liffert; Stroes, Erik S G; Krediet, C T Paul

2016-03-28

The role of kidney hypoxia is considered pivotal in the progression of chronic kidney disease. A widely used method to assess kidney oxygenation is blood oxygen level dependent (BOLD)-magnetic resonance imaging (MRI), but its interpretation remains problematic. The BOLD-MRI signal is the result of kidney oxygen consumption (a proxy of glomerular filtration) and supply (ie, glomerular perfusion). Therefore, we hypothesized that with pharmacological modulation of kidney blood flow, renal oxygenation, as assessed by BOLD-MRI, correlates to filtration fraction (ie, glomerular filtration rate/effective renal plasma flow) in healthy humans. Eight healthy volunteers were subjected to continuous angiotensin-II infusion at 0.3, 0.9, and 3.0 ng/kg per minute. At each dose, renal oxygenation and blood flow were assessed using BOLD and phase-contrast MRI. Subsequently, "gold standard" glomerular filtration rate/effective renal plasma flow measurements were performed under the same conditions. Renal plasma flow decreased dose dependently from 660±146 to 467±103 mL/min per 1.73 m(2) (F[3, 21]=33.3, PMRI, we showed that cortical oxygenation measured by BOLD MRI relates poorly to glomerular filtration rate but is associated with filtration fraction. For future studies, there may be a need to include renal plasma flow measurements when employing renal BOLD-MRI. © 2016 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

Bold Ideas for the 4th H in 4-H: Teen Identified Concerns and Actions

Directory of Open Access Journals (Sweden)

Virginia Brown

2015-03-01

Full Text Available This article summarizes a literature review; teen-identified health concerns and issues; and teen bold ideas for actions. Findings from the National 4-H Council and Molina Healthcare Teens Take on Health initiative are provided and implications for 4-H programming tied to the new Cooperative Extension National Framework for Health and Wellness are addressed. The article is intended as background for Extension educators, volunteers and administrators as they review the 4-H Healthy Living Mission Mandate, learn what mattered to teens and consider how to incorporate the findings into state and local 4-H youth development programming.

Time varying behavior of the loudspeaker suspension: Displacement level dependency

DEFF Research Database (Denmark)

Agerkvist, Finn T.; Pedersen, Bo Rohde

2009-01-01

The compliance of the loudspeaker suspension is known to depend on the recent excitation level history. Previous investigations have shown that the electrical power as well as displacement and velocity plays a role. In this paper the hypothesis that the changes in compliance are caused mainly...... by how much the suspension has been stretched, i.e. the maximum displacement, is investigated. For this purpose the changes in compliance are measured when exposing the speaker to different levels and types of electrical excitation signals, as well as mechanical excitation only. For sinusoidal excitation...... the change in compliance is shown to depend primarily on maximum displacement. But for square pulse excitation the duration of the excitation also plays an important role...

Long-range dependence and sea level forecasting

CERN Document Server

Ercan, Ali; Abbasov, Rovshan K

2013-01-01

This study shows that the Caspian Sea level time series possess long range dependence even after removing linear trends, based on analyses of the Hurst statistic, the sample autocorrelation functions, and the periodogram of the series. Forecasting performance of ARMA, ARIMA, ARFIMA and Trend Line-ARFIMA (TL-ARFIMA) combination models are investigated. The forecast confidence bands and the forecast updating methodology, provided for ARIMA models in the literature, are modified for the ARFIMA models. Sample autocorrelation functions are utilized to estimate the differencing lengths of the ARFIMA

The dependence level analysis between the human actions in NPP Operation

International Nuclear Information System (INIS)

Farcasiu, M.; Nitoi, M.; Apostol, M.; Florescu, G.; Prisecaru, Ilie

2009-01-01

The Human Reliability Analysis (HRA) is an important method in Probabilistic Safety Assessment (PSA) studies and offers desirability for concrete improvement of the man - machine - organization interfaces, reliability and safety. An important step in HRA is the dependence level analysis between the human actions performed by the same person or between the actions performed by different persons, step in quantitative analysis of the human errors probabilities. The purpose of this paper is to develop a model to analyze the dependence level between human actions for Nuclear Power Plant (NPP) operation. The model estimates the conditional human error probabilities (CHEP) and joint human error probabilities (JHEP). The achieved sensitivity analyses determine human performance sensibility to systematic variations for dependence level between human actions. The human error probabilities estimated in this paper are adequate values for integration both in HRA and in PSA realized for NPP. This type of analysis helps in finding and analyzing the ways of reducing the likelihood of human errors, so that the impact of human factor to systems availability, reliability and safety can be realistically estimated. In order to demonstrate the usability of this model an analysis is performed upon the dependences between the necessary human actions in mitigating the consequences of LOCA events, particularly for the case of Cernavoda NPP. (authors)

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

KAUST Repository

Laleg-Kirati, Taous-Meriem; Arabi, Hossein; Tadjine, Mohamed; Zayane, Chadia

2013-01-01

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

Dependence centrality similarity: Measuring the diversity of profession levels of interests

Science.gov (United States)

Yan, Deng-Cheng; Li, Ming; Wang, Bing-Hong

2017-08-01

To understand the relations between developers and software, we study a collaborative coding platform from the perspective of networks, including follower networks, dependence networks and developer-project bipartite networks. Through the analyzing of degree distribution, PageRank and degree-dependent nearest neighbors' centrality, we find that the degree distributions of all networks have a power-law form except the out-degree distributions of dependence networks. The nearest neighbors' centrality is negatively correlated with degree for developers but fluctuates around the average for projects. In order to measure the diversity of profession levels of interests, a new index called dependence centrality similarity is proposed and the correlation between dependence centrality similarity and degree is investigated. The result shows an obvious negative correlations between dependence centrality similarity and degree.

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

Science.gov (United States)

Bright, Molly G; Murphy, Kevin

2013-12-01

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 3 T. 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 (ICC0.4). 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. © 2013.

Angular momentum dependence of the nuclear level density parameter

International Nuclear Information System (INIS)

Aggarwal, Mamta; Kailas, S.

2010-01-01

Dependence of nuclear level density parameter on the angular momentum and temperature is investigated in a theoretical framework using the statistical theory of hot rotating nuclei. The structural effects are incorporated by including shell correction, shape, and deformation. The nuclei around Z≅50 with an excitation energy range of 30 to 40 MeV are considered. The calculations are in good agreement with the experimentally deduced inverse level density parameter values especially for 109 In, 113 Sb, 122 Te, 123 I, and 127 Cs nuclei.

Early disrupted neurovascular coupling and changed event level hemodynamic response function in type 2 diabetes: an fMRI study.

Science.gov (United States)

Duarte, João V; Pereira, João M S; Quendera, Bruno; Raimundo, Miguel; Moreno, Carolina; Gomes, Leonor; Carrilho, Francisco; Castelo-Branco, Miguel

2015-10-01

Type 2 diabetes (T2DM) patients develop vascular complications and have increased risk for neurophysiological impairment. Vascular pathophysiology may alter the blood flow regulation in cerebral microvasculature, affecting neurovascular coupling. Reduced fMRI signal can result from decreased neuronal activation or disrupted neurovascular coupling. The uncertainty about pathophysiological mechanisms (neurodegenerative, vascular, or both) underlying brain function impairments remains. In this cross-sectional study, we investigated if the hemodynamic response function (HRF) in lesion-free brains of patients is altered by measuring BOLD (Blood Oxygenation Level-Dependent) response to visual motion stimuli. We used a standard block design to examine the BOLD response and an event-related deconvolution approach. Importantly, the latter allowed for the first time to directly extract the true shape of HRF without any assumption and probe neurovascular coupling, using performance-matched stimuli. We discovered a change in HRF in early stages of diabetes. T2DM patients show significantly different fMRI response profiles. Our visual paradigm therefore demonstrated impaired neurovascular coupling in intact brain tissue. This implies that functional studies in T2DM require the definition of HRF, only achievable with deconvolution in event-related experiments. Further investigation of the mechanisms underlying impaired neurovascular coupling is needed to understand and potentially prevent the progression of brain function decrements in diabetes.

A Busy period analysis of the level dependent PH/PH/1/K queue

NARCIS (Netherlands)

Al Hanbali, Ahmad

2011-01-01

In this paper, we study the transient behavior of a level dependent single server queuing system with a waiting room of finite size during the busy period. The focus is on the level dependent PH/PH/1/K queue. We derive in closed form the joint transform of the length of the busy period, the number

Food intake rates of inactive fish are positively linked to boldness in three-spined sticklebacks Gasterosteus aculeatus.

Science.gov (United States)

Jolles, J W; Manica, A; Boogert, N J

2016-04-01

To investigate the link between personality and maximum food intake of inactive individuals, food-deprived three-spined sticklebacks Gasterosteus aculeatus at rest in their home compartments were provided with ad libitum prey items. Bolder individuals ate considerably more than shyer individuals, even after accounting for body size, while sociability did not have an effect. These findings support pace-of-life theory predicting that life-history strategies are linked to boldness. © 2016 The Authors. Journal of Fish Biology published by John Wiley & Sons Ltd on behalf of The Fisheries Society of the British Isles.

Comparison of CO2 in air versus carbogen for the measurement of cerebrovascular reactivity with magnetic resonance imaging.

Science.gov (United States)

Hare, Hannah V; Germuska, Michael; Kelly, Michael E; Bulte, Daniel P

2013-11-01

Measurement of cerebrovascular reactivity (CVR) can give valuable information about existing pathology and the risk of adverse events, such as stroke. A common method of obtaining regional CVR values is by measuring the blood flow response to carbon dioxide (CO2)-enriched air using arterial spin labeling (ASL) or blood oxygen level-dependent (BOLD) imaging. Recently, several studies have used carbogen gas (containing only CO2 and oxygen) as an alternative stimulus. A direct comparison was performed between CVR values acquired by ASL and BOLD imaging using stimuli of (1) 5% CO2 in air and (2) 5% CO2 in oxygen (carbogen-5). Although BOLD and ASL CVR values are shown to be correlated for CO2 in air (mean response 0.11±0.03% BOLD, 4.46±1.80% ASL, n=16 hemispheres), this correlation disappears during a carbogen stimulus (0.36±0.06% BOLD, 4.97±1.30% ASL). It is concluded that BOLD imaging should generally not be used in conjunction with a carbogen stimulus when measuring CVR, and that care must be taken when interpreting CVR as measured by ASL, as values obtained from different stimuli (CO2 in air versus carbogen) are not directly comparable.

Dual-echo ASL based assessment of motor networks: a feasibility study

Science.gov (United States)

Storti, Silvia Francesca; Boscolo Galazzo, Ilaria; Pizzini, Francesca B.; Menegaz, Gloria

2018-04-01

Objective. Dual-echo arterial spin labeling (DE-ASL) technique has been recently proposed for the simultaneous acquisition of ASL and blood-oxygenation-level-dependent (BOLD)-functional magnetic resonance imaging (fMRI) data. The assessment of this technique in detecting functional connectivity at rest or during motor and motor imagery tasks is still unexplored both per-se and in comparison with conventional methods. The purpose is to quantify the sensitivity of the DE-ASL sequence with respect to the conventional fMRI sequence (cvBOLD) in detecting brain activations, and to assess and compare the relevance of node features in decoding the network structure. Approach. Thirteen volunteers were scanned acquiring a pseudo-continuous DE-ASL sequence from which the concomitant BOLD (ccBOLD) simultaneously to the ASL can be extracted. The approach consists of two steps: (i) model-based analyses for assessing brain activations at individual and group levels, followed by statistical analysis for comparing the activation elicited by the three sequences under two conditions (motor and motor imagery), respectively; (ii) brain connectivity graph-theoretical analysis for assessing and comparing the network models properties. Main results. Our results suggest that cvBOLD and ccBOLD have comparable sensitivity in detecting the regions involved in the active task, whereas ASL offers a higher degree of co-localization with smaller activation volumes. The connectivity results and the comparative analysis of node features across sequences revealed that there are no strong changes between rest and tasks and that the differences between the sequences are limited to few connections. Significance. Considering the comparable sensitivity of the ccBOLD and cvBOLD sequences in detecting activated brain regions, the results demonstrate that DE-ASL can be successfully applied in functional studies allowing to obtain both ASL and BOLD information within a single sequence. Further, DE-ASL is a

Development of a parallel zoomed EVI sequence for high temporal resolution analysis of the BOLD response

International Nuclear Information System (INIS)

Rabrait, C.

2006-01-01

The hemodynamic impulse response to any short stimulus typically lasts around 20 seconds. Thus, the detection of the Blood Oxygenation Level Dependent (BOLD) effect is usually performed using a 2D Echo Planar Imaging (EPI) sequence, with repetition times on the order of 1 or 2 seconds. This temporal resolution is generally enough for detection purposes. Nevertheless, when trying to accurately estimate the hemodynamic response functions (HRF), higher scanning rates represent a real advantage. Thus, in order to reach a temporal resolution around 200 ms, we developed a new acquisition method, based on Echo Volumar Imaging and 2D parallel acquisition (1). Echo Volumar Imaging (EVI) has been proposed in 1977 by Mansfield (2). EVI intrinsically possesses a lot of advantages for functional neuroimaging, as a 3 D single shot acquisition method. Nevertheless, to date, only a few applications have been reported (3, 4). Actually, very restricting hardware requirements make EVI difficult to perform in satisfactory experimental conditions, even today. The critical point in EVI is the echo train duration, which is longer than in EPI, due to 3D acquisition. Indeed, at equal field of view and spatial resolutions, EVI echo train duration must be approximately equal to EPI echo train duration multiplied by the number of slices acquired in EPI. Consequently, EVI is much more sensitive than EPI to geometric distortions, which are related to phase errors, and also to signal losses, which are due to long echo times (TE). Thus, a first improvement has been brought by 'zoomed' or 'localized' EVI (5), which allows to focus on a small volume of interest and thus limit echo train durations compared to full FOV acquisitions.To reduce echo train durations, we chose to apply parallel acquisition. Moreover, since EVI is a 3D acquisition method, we are able to perform parallel acquisition and SENSE reconstruction along the two phase directions (6). The R = 4 under-sampling consists in the

Nicotine Dependence and Urinary Nicotine, Cotinine and Hydroxycotinine Levels in Daily Smokers.

Science.gov (United States)

Van Overmeire, Ilse P I; De Smedt, Tom; Dendale, Paul; Nackaerts, Kristiaan; Vanacker, Hilde; Vanoeteren, Jan F A; Van Laethem, Danny M G; Van Loco, Joris; De Cremer, Koen A J

2016-09-01

Nicotine dependence and smoking frequency are critical factors for smoking cessation. The aims of this study are (1) to determine if nicotine dependence Fagerström Test for Nicotine Dependence (FTND) scores are associated with urinary levels of nicotine metabolites, (2) to assess the relationship of hydroxycotinine/cotinine ratio with FTND score and cigarettes smoked per day (CPD), and (3) to identify significant predictors of cigarettes per day among biomarker concentrations and individual FTND items. Urine samples and questionnaire data of 239 daily smokers were obtained. Nicotine, cotinine and hydroxycotinine urinary levels were determined by UPLC MS/MS.Multiple linear regression models were developed to explore the relationship between nicotine, cotinine, hydroxycotinine levels and separate FTND scores (for all six items). We found significant correlations between the different urinary biomarker concentrations, and the FTND score. The time before the first cigarette after waking (TTFC) was significantly associated with the nicotine, cotinine and hydroxycotinine concentrations. No association was found between the ratio of hydroxycotinine to cotinine and either the FTND or the CPD. A model including four FTND questions, sex, age, and the cotinine concentration, accounted for 45% of the variance of CPD. There are significant relationships between urinary levels of nicotine, cotinine, and hydroxycotinine and the FTND score. Especially the FTND question about TTFC is relevant for explaining the biomarker concentrations. CPD (below 15) was significantly explained by four FTND dependence items and urinary cotinine levels in a regression model. We investigated associations between urinary levels of nicotine, cotinine, and hydroxycotinine in daily smokers and the FTND scores for nicotine dependence. We did not find association between the hydroxycotinine/cotinine ratio and CPD. We developed a model that explains the cigarettes smoked daily (CPD) in a group of light

Dependency of high coastal water level and river discharge at the global scale

Science.gov (United States)

Ward, P.; Couasnon, A.; Haigh, I. D.; Muis, S.; Veldkamp, T.; Winsemius, H.; Wahl, T.

2017-12-01

It is widely recognized that floods cause huge socioeconomic impacts. From 1980-2013, global flood losses exceeded $1 trillion, with 220,000 fatalities. These impacts are particularly hard felt in low-lying densely populated deltas and estuaries, whose location at the coast-land interface makes them naturally prone to flooding. When river and coastal floods coincide, their impacts in these deltas and estuaries are often worse than when they occur in isolation. Such floods are examples of so-called `compound events'. In this contribution, we present the first global scale analysis of the statistical dependency of high coastal water levels (and the storm surge component alone) and river discharge. We show that there is statistical dependency between these components at more than half of the stations examined. We also show time-lags in the highest correlation between peak discharges and coastal water levels. Finally, we assess the probability of the simultaneous occurrence of design discharge and design coastal water levels, assuming both independence and statistical dependence. For those stations where we identified statistical dependency, the probability is between 1 and 5 times greater, when the dependence structure is accounted for. This information is essential for understanding the likelihood of compound flood events occurring at locations around the world as well as for accurate flood risk assessments and effective flood risk management. The research was carried out by analysing the statistical dependency between observed coastal water levels (and the storm surge component) from GESLA-2 and river discharge using gauged data from GRDC stations all around the world. The dependence structure was examined using copula functions.

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

The quest for EEG power band correlation with ICA derived fMRI resting state networks

NARCIS (Netherlands)

Meyer, M.C.; Janssen, R.J.; van Oort, E.S.B.; Beckmann, Christian; Barth, M.

2013-01-01

The neuronal underpinnings of blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI) resting state networks (RSNs) are still unclear. To investigate the underlying mechanisms, specifically the relation to the electrophysiological signal, we used simultaneous recordings of

Dependence levels in users of electronic cigarettes, nicotine gums and tobacco cigarettes.

Science.gov (United States)

Etter, Jean-François; Eissenberg, Thomas

2015-02-01

To assess dependence levels in users of e-cigarettes, and compare them with dependence levels in users of nicotine gums and tobacco cigarettes. Self-reports from cross-sectional Internet and mail surveys. Comparisons of: (a) 766 daily users of nicotine-containing e-cigarettes with 30 daily users of nicotine-free e-cigarettes; (b) 911 former smokers who used the e-cigarette daily with 451 former smokers who used the nicotine gum daily (but no e-cigarette); (c) 125 daily e-cigarette users who smoked daily (dual users) with two samples of daily smokers who did not use e-cigarettes (2206 enrolled on the Internet and 292 enrolled by mail from the general population of Geneva). We used the Fagerström test for nicotine dependence, the nicotine dependence syndrome scale, the cigarette dependence scale and versions of these scales adapted for e-cigarettes and nicotine gums. Dependence ratings were slightly higher in users of nicotine-containing e-cigarettes than in users of nicotine-free e-cigarettes. In former smokers, long-term (>3 months) users of e-cigarettes were less dependent on e-cigarettes than long-term users of the nicotine gum were dependent on the gum. There were few differences in dependence ratings between short-term (≤3 months) users of gums or e-cigarettes. Dependence on e-cigarettes was generally lower in dual users than dependence on tobacco cigarettes in the two other samples of daily smokers. Some e-cigarette users were dependent on nicotine-containing e-cigarettes, but these products were less addictive than tobacco cigarettes. E-cigarettes may be as or less addictive than nicotine gums, which themselves are not very addictive. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

The association between chronic airflow obstruction and poverty in 12 sites of the multinational BOLD study.

Science.gov (United States)

Townend, John; Minelli, Cosetta; Mortimer, Kevin; Obaseki, Daniel O; Al Ghobain, Mohammed; Cherkaski, Hamid; Denguezli, Myriam; Gunesekera, Kirthi; Hafizi, Hasan; Koul, Parvaiz A; Loh, Li C; Nejjari, Chakib; Patel, Jaymini; Sooronbayev, Talant; Buist, Sonia A; Burney, Peter G J

2017-06-01

Poverty is strongly associated with mortality from COPD, but little is known of its relation to airflow obstruction.In a cross-sectional study of adults aged ≥40 years from 12 sites (N=9255), participating in the Burden of Obstructive Lung Disease (BOLD) study, poverty was evaluated using a wealth score (0-10) based on household assets. Obstruction, measured as forced expiratory volume in 1 s (FEV 1 )/forced vital capacity (FVC) (%) after administration of 200 μg salbutamol, and prevalence of FEV 1 /FVCwealth scores ranged from 4 in Blantyre (Malawi) and Kashmir (India) to 10 in Riyadh (Saudi Arabia), and the prevalence of obstruction, from 16% in Kashmir to 3% in Riyadh and Penang (Malaysia). Following adjustments for age and sex, FEV 1 /FVC increased by 0.36% (absolute change) (95%CI: 0.22, 0.49; pwealth score. Adjustments for other confounders reduced this effect to 0.23% (0.11, 0.34), but even this value remained highly significant (pwealth scores explained 38% of the variation in mean FEV 1 /FVC between sites (r 2 =0.385, p=0.031).Airflow obstruction is consistently associated with poverty at individual and community levels across several countries. Copyright ©ERS 2017.

Temperature dependent energy levels of methylammonium lead iodide perovskite

Science.gov (United States)

Foley, Benjamin J.; Marlowe, Daniel L.; Sun, Keye; Saidi, Wissam A.; Scudiero, Louis; Gupta, Mool C.; Choi, Joshua J.

2015-06-01

Temperature dependent energy levels of methylammonium lead iodide are investigated using a combination of ultraviolet photoemission spectroscopy and optical spectroscopy. Our results show that the valence band maximum and conduction band minimum shift down in energy by 110 meV and 77 meV as temperature increases from 28 °C to 85 °C. Density functional theory calculations using slab structures show that the decreased orbital splitting due to thermal expansion is a major contribution to the experimentally observed shift in energy levels. Our results have implications for solar cell performance under operating conditions with continued sunlight exposure and increased temperature.

Age-related differences in the neural correlates of trial-to-trial variations of reaction time

Directory of Open Access Journals (Sweden)

Nancy E. Adleman

2016-06-01

Full Text Available Intra-subject variation in reaction time (ISVRT is a developmentally-important phenomenon that decreases from childhood through young adulthood in parallel with the development of executive functions and networks. Prior work has shown a significant association between trial-by-trial variations in reaction time (RT and trial-by-trial variations in brain activity as measured by the blood-oxygenated level-dependent (BOLD response in functional magnetic resonance imaging (fMRI studies. It remains unclear, however, whether such “RT-BOLD” relationships vary with age. Here, we determined whether such trial-by-trial relationships vary with age in a cross-sectional design. We observed an association between age and RT-BOLD relationships in 11 clusters located in visual/occipital regions, frontal and parietal association cortex, precentral/postcentral gyrus, and thalamus. Some of these relationships were negative, reflecting increased BOLD associated with decreased RT, manifesting around the time of stimulus presentation and positive several seconds later. Critically for present purposes, all RT-BOLD relationships increased with age. Thus, RT-BOLD relationships may reflect robust, measurable changes in the brain-behavior relationship across development.

Effect of CGRP and sumatriptan on the BOLD response in visual cortex

DEFF Research Database (Denmark)

Asghar, Mohammed Sohail; Hansen, Adam E; Larsson, Henrik B W

2012-01-01

To test the hypothesis that calcitonin gene-related peptide (CGRP) modulates brain activity, we investigated the effect of intravenous CGRP on brain activity in response to a visual stimulus. In addition, we examined if possible alteration in brain activity was reversed by the anti-migraine drug......% of the participants reported headache after CGRP. We found no changes in brain activity after CGRP (P = 0.12) or after placebo (P = 0.41). Sumatriptan did not affect brain activity after CGRP (P = 0.71) or after placebo (P = 0.98). Systemic CGRP or sumatriptan has no direct effects on the BOLD activity in visual...... sumatriptan. Eighteen healthy volunteers were randomly allocated to receive CGRP infusion (1.5 µg/min for 20 min) or placebo. In vivo activity in the visual cortex was recorded before, during and after infusion and after 6 mg subcutaneous sumatriptan by functional magnetic resonance imaging (3 T). 77...

Nicotine Dependence and Urinary Nicotine, Cotinine and Hydroxycotinine Levels in Daily Smokers

OpenAIRE

Van Overmeire, Ilse P. I.; De Smedt, Tom; Dendale, Paul; Nackaerts, Kristiaan; Vanacker, Hilde; Vanoeteren, Jan F. A.; Van Laethem, Danny M. G.; Van Loco, Joris; De Cremer, Koen A. J.

2016-01-01

Nicotine dependence and smoking frequency are critical factors for smoking cessation. The aims of this study are (1) to determine if nicotine dependence Fagerstrom Test for Nicotine Dependence (FTND) scores are associated with urinary levels of nicotine metabolites, (2) to assess the relationship of hydroxycotinine/cotinine ratio with FTND score and cigarettes smoked per day (CPD), and (3) to identify significant predictors of cigarettes per day among biomarker concentrations and individual F...

The impact of susceptibility gradients on cartesian and spiral EPI for BOLD fMRI

DEFF Research Database (Denmark)

Sangill, Ryan; Wallentin, Mikkel; Østergaard, Leif

2006-01-01

, with special emphasis on spiral EPI (spiral) and cartesian EPI (EPI) and their performance under influence of induced field gradients (SFGs) and stochastic noise. A numerical method for calculating synthetic MR images is developed and used to simulate BOLD fMRI experiments using EPI and spirals. The data...... is then examined for activation using a pixel-wise t test. Nine subjects are scanned with both techniques while performing a motor task. SPM99 is used for analysing the experimental data. The simulated spirals provide generally higher t scores at low SFGs but lose more strength than EPI at higher SFGs, where EPI...... activation is offset from the true position. In the primary motor area spirals provide significantly higher t scores (P SFG areas spirals provide stronger activation than...

Simultaneous reflection masking: dependency on direct sound level and hearing-impairment

DEFF Research Database (Denmark)

Buchholz, Jörg; Mihai, Paul Glad

2008-01-01

B-SL direct sound level, NH-listeners showed a binaural suppression effect for delays smaller than 7-10 ms and a binaural enhancement effect for larger delays. When decreasing the direct sound level to 15 dB-SL, the only significant change observed was that the dichotic RMT increased for delays larger than...... expected from changed auditory filter bandwidth and audi-bility. However, the stimulus level-dependency of the auditory filters’ bandwidth was not reflected in the SRMT data....

Functional magnetic resonance imaging of the primary motor cortex ...

Indian Academy of Sciences (India)

Unknown

Abbreviations used: BOLD, Blood oxygenation level dependent; CBF, cerebral blood flow; fMRI, functional magnetic resonance imaging; EPI, eco-planar imaging; FOV, field of view; MRI, Magnetic resonance imaging; MRS, magnetic resonance spectroscopy;. PET, position emission tomography; rCBF, regional cerebral ...

Temperature dependent energy levels of methylammonium lead iodide perovskite

Energy Technology Data Exchange (ETDEWEB)

Foley, Benjamin J.; Marlowe, Daniel L.; Choi, Joshua J., E-mail: jjc6z@virginia.edu, E-mail: mgupta@virginia.edu, E-mail: scudiero@wsu.edu [Department of Chemical Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States); Sun, Keye; Gupta, Mool C., E-mail: jjc6z@virginia.edu, E-mail: mgupta@virginia.edu, E-mail: scudiero@wsu.edu [Department of Electrical and Computer Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States); Saidi, Wissam A. [Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, Pennsylvania 15261 (United States); Scudiero, Louis, E-mail: jjc6z@virginia.edu, E-mail: mgupta@virginia.edu, E-mail: scudiero@wsu.edu [Chemistry Department and Materials Science and Engineering Program, Washington State University, Pullman, Washington 99164 (United States)

2015-06-15

Temperature dependent energy levels of methylammonium lead iodide are investigated using a combination of ultraviolet photoemission spectroscopy and optical spectroscopy. Our results show that the valence band maximum and conduction band minimum shift down in energy by 110 meV and 77 meV as temperature increases from 28 °C to 85 °C. Density functional theory calculations using slab structures show that the decreased orbital splitting due to thermal expansion is a major contribution to the experimentally observed shift in energy levels. Our results have implications for solar cell performance under operating conditions with continued sunlight exposure and increased temperature.

Nuclear level density parameter 's dependence on angular momentum

International Nuclear Information System (INIS)

Aggarwal, Mamta; Kailas, S.

2009-01-01

Nuclear level densities represent a very important ingredient in the statistical Model calculations of nuclear reaction cross sections and help to understand the microscopic features of the excited nuclei. Most of the earlier experimental nuclear level density measurements are confined to low excitation energy and low spin region. A recent experimental investigation of nuclear level densities in high excitation energy and angular momentum domain with some interesting results on inverse level density parameter's dependence on angular momentum in the region around Z=50 has motivated us to study and analyse these experimental results in a microscopic theoretical framework. In the experiment, heavy ion fusion reactions are used to populate the excited and rotating nuclei and measured the α particle evaporation spectra in coincidence with ray multiplicity. Residual nuclei are in the range of Z R 48-55 with excitation energy range 30 to 40 MeV and angular momentum in 10 to 25. The inverse level density parameter K is found to be in the range of 9.0 - 10.5 with some exceptions

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

International Nuclear Information System (INIS)

Landuyt, W.; Bogaert, W. van den; Lambin, P.; Hermans, R.; Bosmans, H.; Sunaert, S.; Beatse, E.; Farina, D.; Meijerink, M.; Zhang, H.; Marchal, G.

2001-01-01

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 2 +95% O 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 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.)

Capillary pericytes regulate cerebral blood flow in health and disease

DEFF Research Database (Denmark)

Hall, Catherine N; Reynell, Clare; Gesslein, Bodil

2014-01-01

Increases in brain blood flow, evoked by neuronal activity, power neural computation and form the basis of BOLD (blood-oxygen-level-dependent) functional imaging. Whether blood flow is controlled solely by arteriole smooth muscle, or also by capillary pericytes, is controversial. We demonstrate t...

Strategies for memory-based decision making : Modeling behavioral and neural signatures within a cognitive architecture

NARCIS (Netherlands)

Fechner, Hanna B; Pachur, Thorsten; Schooler, Lael J; Mehlhorn, Katja; Battal, Ceren; Volz, Kirsten G; Borst, Jelmer P.

2016-01-01

How do people use memories to make inferences about real-world objects? We tested three strategies based on predicted patterns of response times and blood-oxygen-level-dependent (BOLD) responses: one strategy that relies solely on recognition memory, a second that retrieves additional knowledge, and

Oral glucose intake inhibits hypothalamic neuronal activity more effectively than glucose infusion

NARCIS (Netherlands)

Smeets, P.A.M.; Vidarsdottir, S.; Graaf, C. de; Stafleu, A.; Osch, M.J.P. van; Viergever, M.A.; Pijl, H.; Grond, J. van der

2007-01-01

We previously showed that hypothalamic neuronal activity, as measured by the blood oxygen level-dependent (BOLD) functional MRI signal, declines in response to oral glucose intake. To further explore the mechanism driving changes in hypothalamic neuronal activity in response to an oral glucose load,

Decreased serum level of NGF in alcohol-dependent patients with declined executive function

Directory of Open Access Journals (Sweden)

Bae H

2014-11-01

Full Text Available Hwallip Bae,1 Youngsun Ra,1 Changwoo Han,2 Dai-Jin Kim3 1Department of Psychiatry, Myongji Hospital, Goyang, 2Department of Psychiatry, Keyo Hospital, Uiwang, 3Department of Psychiatry, Seoul St Mary’s Hospital, College of Medicine, Catholic University of Korea, Seoul, South Korea Abstract: The role of neurotrophic factors has been highlighted as a cause of decline in the cognitive function of alcohol-dependent patients. It is known that nerve-growth factor (NGF, one of the neurotrophins, is related to the growth and differentiation of nerve cells, as well as to a decline in cognitive function. The purpose of this study was to investigate the relationship between decreased NGF levels and cognitive decline in alcohol-dependent patients. The serum concentration of NGF was measured in 38 patients with chronic alcohol dependence, and several neuropsychological tests were also performed for cognitive function assessment. The results indicated a significant correlation between serum NGF level and the trail-making test part B, which evaluates executive function, but did not show a significant correlation with other cognitive function tests. An increased serum level of NGF was associated with a decreased completion time in the trail-making test B, and this finding indicates that a high serum level of NGF is related to greater executive function. This finding may imply a protective role of NGF in preventing neuron damage among patients with alcohol dependence. Larger controlled studies will be necessary in the future to investigate this issue further. Keywords: nerve-growth factor, alcohol dependence, executive function, trail-making test

Multiband multi-echo imaging of simultaneous oxygenation and flow timeseries for resting state connectivity.

Science.gov (United States)

Cohen, Alexander D; Nencka, Andrew S; Lebel, R Marc; Wang, Yang

2017-01-01

A novel sequence has been introduced that combines multiband imaging with a multi-echo acquisition for simultaneous high spatial resolution pseudo-continuous arterial spin labeling (ASL) and blood-oxygenation-level dependent (BOLD) echo-planar imaging (MBME ASL/BOLD). Resting-state connectivity in healthy adult subjects was assessed using this sequence. Four echoes were acquired with a multiband acceleration of four, in order to increase spatial resolution, shorten repetition time, and reduce slice-timing effects on the ASL signal. In addition, by acquiring four echoes, advanced multi-echo independent component analysis (ME-ICA) denoising could be employed to increase the signal-to-noise ratio (SNR) and BOLD sensitivity. Seed-based and dual-regression approaches were utilized to analyze functional connectivity. Cerebral blood flow (CBF) and BOLD coupling was also evaluated by correlating the perfusion-weighted timeseries with the BOLD timeseries. These metrics were compared between single echo (E2), multi-echo combined (MEC), multi-echo combined and denoised (MECDN), and perfusion-weighted (PW) timeseries. Temporal SNR increased for the MECDN data compared to the MEC and E2 data. Connectivity also increased, in terms of correlation strength and network size, for the MECDN compared to the MEC and E2 datasets. CBF and BOLD coupling was increased in major resting-state networks, and that correlation was strongest for the MECDN datasets. These results indicate our novel MBME ASL/BOLD sequence, which collects simultaneous high-resolution ASL/BOLD data, could be a powerful tool for detecting functional connectivity and dynamic neurovascular coupling during the resting state. The collection of more than two echoes facilitates the use of ME-ICA denoising to greatly improve the quality of resting state functional connectivity MRI.

Organization of the human motor system as studied by functional magnetic resonance imaging

International Nuclear Information System (INIS)

Mattay, Venkata S.; Weinberger, Daniel R.

1999-01-01

Blood oxygenation level dependent functional magnetic resonance imaging (BOLD fMRI), because of its superior resolution and unlimited repeatability, can be particularly useful in studying functional aspects of the human motor system, especially plasticity, and somatotopic and temporal organization. In this survey, while describing studies that have reliably used BOLD fMRI to examine these aspects of the motor system, we also discuss studies that investigate the neural substrates underlying motor skill acquisition, motor imagery, production of motor sequences; effect of rate and force of movement on brain activation and hemispheric control of motor function. In the clinical realm, in addition to the presurgical evaluation of neurosurgical patients, BOLD fMRI has been used to explore the mechanisms underlying motor abnormalities in patients with neuropsychiatric disorders and the mechanisms underlying reorganization or plasticity of the motor system following a cerebral insult

Special regulatory T-cell review: T-cell dependent suppression revisited.

Science.gov (United States)

Basten, Antony; Fazekas de St Groth, Barbara

2008-01-01

The concept of T-cell dependent regulation of immune responses has been a central tenet of immunological thinking since the delineation of the two cell system in the 1960s. Indeed T-cell dependent suppression was discovered before MHC restriction. When reviewing the data from the original wave of suppression, it is intriguing to reflect not just on the decline and fall of suppressor T cells in the 1980s, but on their equally dramatic return to respectability over the past decade. Hopefully their resurgence will be supported by solid mechanistic data that will underpin their central place in our current and future understanding of the immune system. Cannon to right of them, Cannon to left of them, Cannon in front of them Volley'd and thunder'd Storm'd at with shot and shell, Boldly they rode and well, Into the jaws of Death, Into the mouth of Hell, Rode the six hundred (suppressionists). (Adapted from The Charge of the Light Brigade, Alfred, Lord Tennyson)

Back pain in seniors: the Back pain Outcomes using Longitudinal Data (BOLD) cohort baseline data.

Science.gov (United States)

Jarvik, Jeffrey G; Comstock, Bryan A; Heagerty, Patrick J; Turner, Judith A; Sullivan, Sean D; Shi, Xu; Nerenz, David R; Nedeljkovic, Srdjan S; Kessler, Larry; James, Kathryn; Friedly, Janna L; Bresnahan, Brian W; Bauer, Zoya; Avins, Andrew L; Deyo, Richard A

2014-04-23

Back pain represents a substantial burden globally, ranking first in a recent assessment among causes of years lived with disability. Though back pain is widely studied among working age adults, there are gaps with respect to basic descriptive epidemiology among seniors, especially in the United States. Our goal was to describe how pain, function and health-related quality of life vary by demographic and geographic factors among seniors presenting to primary care providers with new episodes of care for back pain. We examined baseline data from the Back pain Outcomes using Longitudinal Data (BOLD) registry, the largest inception cohort to date of seniors presenting to a primary care provider for back pain. The sample included 5,239 patients ≥ 65 years old with a new primary care visit for back pain at three integrated health systems (Northern California Kaiser-Permanente, Henry Ford Health System [Detroit], and Harvard Vanguard Medical Associates [Boston]). We examined differences in patient characteristics across healthcare sites and associations of patient sociodemographic and clinical characteristics with baseline patient-reported measures of pain, function, and health-related quality of life. Patients differed across sites in demographic and other characteristics. The Detroit site had more African-American patients (50%) compared with the other sites (7-8%). The Boston site had more college graduates (68%) compared with Detroit (20%). Female sex, lower educational status, African-American race, and older age were associated with worse functional disability as measured by the Roland-Morris Disability Questionnaire. Except for age, these factors were also associated with worse pain. Baseline pain and functional impairment varied substantially with a number of factors in the BOLD cohort. Healthcare site was an important factor. After controlling for healthcare site, lower education, female sex, African-American race, and older age were associated with worse

CVTresh: R Package for Level-Dependent Cross-Validation Thresholding

Directory of Open Access Journals (Sweden)

Donghoh Kim

2006-04-01

Full Text Available The core of the wavelet approach to nonparametric regression is thresholding of wavelet coefficients. This paper reviews a cross-validation method for the selection of the thresholding value in wavelet shrinkage of Oh, Kim, and Lee (2006, and introduces the R package CVThresh implementing details of the calculations for the procedures. This procedure is implemented by coupling a conventional cross-validation with a fast imputation method, so that it overcomes a limitation of data length, a power of 2. It can be easily applied to the classical leave-one-out cross-validation and K-fold cross-validation. Since the procedure is computationally fast, a level-dependent cross-validation can be developed for wavelet shrinkage of data with various sparseness according to levels.

CVTresh: R Package for Level-Dependent Cross-Validation Thresholding

Directory of Open Access Journals (Sweden)

Donghoh Kim

2006-04-01

Full Text Available The core of the wavelet approach to nonparametric regression is thresholding of wavelet coefficients. This paper reviews a cross-validation method for the selection of the thresholding value in wavelet shrinkage of Oh, Kim, and Lee (2006, and introduces the R package CVThresh implementing details of the calculations for the procedures.This procedure is implemented by coupling a conventional cross-validation with a fast imputation method, so that it overcomes a limitation of data length, a power of 2. It can be easily applied to the classical leave-one-out cross-validation and K-fold cross-validation. Since the procedure is computationally fast, a level-dependent cross-validation can be developed for wavelet shrinkage of data with various sparseness according to levels.

Lateralized Spatial and Object Memory Encoding in Entorhinal and Perirhinal Cortices

Science.gov (United States)

Bellgowan, Patrick S. F.; Buffalo, Elizabeth A.; Bodurka, Jerzy; Martin, Alex

2009-01-01

The perirhinal and entorhinal cortices are critical components of the medial temporal lobe (MTL) declarative memory system. Study of their specific functions using blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI), however, has suffered from severe magnetic susceptibility signal dropout resulting in poor…

Effects of Intensified Vasodilatory Antihypertensive Treatment on Renal Function, Blood supply and Oxygenation in Chronic Kidney Disease

DEFF Research Database (Denmark)

Khatir, Dinah Sherzad; Pedersen, Michael; Ivarsen, Per

2015-01-01

-blocker metoprolol). At baseline and following 18 months of therapy we determined forearm resistance by venous occlusion plethysmography. Using magnetic resonance imaging (MRI) renal artery blood flow was measured for calculation of RVR, and blood oxygen level dependent (BOLD) MRI was used as a marker of renal...

Frequency-Dependent Modulation of Regional Synchrony in the Human Brain by Eyes Open and Eyes Closed Resting-States.

Science.gov (United States)

Song, Xiaopeng; Zhou, Shuqin; Zhang, Yi; Liu, Yijun; Zhu, Huaiqiu; Gao, Jia-Hong

2015-01-01

The eyes-open (EO) and eyes-closed (EC) states have differential effects on BOLD-fMRI signal dynamics, affecting both the BOLD oscillation frequency of a single voxel and the regional homogeneity (ReHo) of several neighboring voxels. To explore how the two resting-states modulate the local synchrony through different frequency bands, we decomposed the time series of each voxel into several components that fell into distinct frequency bands. The ReHo in each of the bands was calculated and compared between the EO and EC conditions. The cross-voxel correlations between the mean frequency and the overall ReHo of each voxel's original BOLD series in different brain areas were also calculated and compared between the two states. Compared with the EC state, ReHo decreased with EO in a wide frequency band of 0.01-0.25 Hz in the bilateral thalamus, sensorimotor network, and superior temporal gyrus, while ReHo increased significantly in the band of 0-0.01 Hz in the primary visual cortex, and in a higher frequency band of 0.02-0.1 Hz in the higher order visual areas. The cross-voxel correlations between the frequency and overall ReHo were negative in all the brain areas but varied from region to region. These correlations were stronger with EO in the visual network and the default mode network. Our results suggested that different frequency bands of ReHo showed different sensitivity to the modulation of EO-EC states. The better spatial consistency between the frequency and overall ReHo maps indicated that the brain might adopt a stricter frequency-dependent configuration with EO than with EC.

Fermi level dependent native defect formation: Consequences for metal-semiconductor and semiconductor-semiconductor interfaces

International Nuclear Information System (INIS)

Walukiewicz, W.

1988-02-01

The amphoteric native defect model of the Schottky barrier formation is used to analyze the Fermi level pinning at metal/semiconductor interfaces for submonolayer metal coverages. It is assumed that the energy required for defect generation is released in the process of surface back-relaxation. Model calculations for metal/GaAs interfaces show a weak dependence of the Fermi level pinning on the thickness of metal deposited at room temperature. This weak dependence indicates a strong dependence of the defect formation energy on the Fermi level, a unique feature of amphoteric native defects. This result is in very good agreement with experimental data. It is shown that a very distinct asymmetry in the Fermi level pinning on p- and n-type GaAs observed at liquid nitrogen temperatures can be understood in terms of much different recombination rates for amphoteric native defects in those two types of materials. Also, it is demonstrated that the Fermi level stabilization energy, a central concept of the amphoteric defect system, plays a fundamental role in other phenomena in semiconductors such as semiconductor/semiconductor heterointerface intermixing and saturation of free carrier concentration. 33 refs., 6 figs

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.

Levels of physical dependence on tobacco among adolescent smokers in Cyprus.

Science.gov (United States)

Christophi, Costas A; Pampaka, Despina; Paisi, Martha; Ioannou, Solonas; DiFranza, Joseph R

2016-09-01

The purpose of this study is to assess tobacco dependence among Cypriot adolescents and examine its association to cigarette consumption and attitudes towards smoking. The current study used cross-sectional data from the 2011 Cyprus Global Youth Tobacco Survey which adopted multistage cluster sampling methods to select adolescents registered in middle and high schools in Cyprus. Tobacco use, physical dependence on tobacco, and attitudes towards tobacco use were measured in 187 adolescents aged 13-18years old who reported that they had smoked at least once in the preceding 30days. Physical dependence was assessed using the Levels of Physical Dependence scale. Physical dependence was present in 86% of the adolescent smokers. The mean latency to needing among smokers in the highest dependence group was 101h. Significant associations were observed between physical dependence and the perceived difficulty in quitting (OR=13.1, 95% CI: 4.0, 43.0) as well as the expectation to continue smoking for the next five years (OR=3.3, 95% CI: 1.3, 8.4). Significant associations were also observed between physical dependence and the number of smoking days per month, daily smoking, daily cigarette consumption, lifetime cigarette consumption, and perceived difficulty in abstaining from smoking for one week. Physical dependence provides a symptom-based approach to assess dependence and it is a strong predictor of adolescents' perceptions of their ability to quit or to refrain from smoking for a week. Physical dependence on tobacco was highly prevalent among adolescent smokers in Cyprus and it was associated with greater perceived difficulty in quitting. Interventions targeting adolescent smoking must account for the high prevalence of physical dependence. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Local order dependent impurity levels in alloy semiconductors

International Nuclear Information System (INIS)

Silva, C.E.T.G. da; Ecole Normale Superieure, 75 - Paris

1981-01-01

We develop a one band/may sites model for an isoelectronic impurity in a semiconductor alloy. The cluster-Bethe-lattice approximation is used to study the dependence of the impurity energy level upon the short range order (SRO) of the alloy. The Kikuchi parametrization is used to describe the latter. We take into account diagonal disorder only, with possible off-diagonal relaxation around the impurity site. All the inequivalent clusters of the impurity site and its first nearest neighbours are considered, thus including the important short range alloy potential fluctuations. Results are presented for the local density of impurity states, for different degrees of SRO in the alloy. (Author) [pt

Seeing Double: Exploring the Phenomenology of Self-Reported Absence of Rivalry in Bistable Pictures.

Science.gov (United States)

Filevich, Elisa; Becker, Maxi; Wu, Yuan-Hao; Kühn, Simone

2017-01-01

Ambiguous images such as Rubin's vase-face can be interpreted in at least two different ways. These interpretations are typically taken to be mutually exclusive, and ambiguous images have thus served as models of perceptual competition. Here, we present data that challenges this view. In an online survey, we found that a large proportion of people within the general population reported that the two percepts were not competing but could be perceived simultaneously. Of those who reported that they could see both percepts simultaneously, we invited 17 participants to take part in a functional magnetic resonance imaging (fMRI) experiment. In the scanner, participants saw images that could be interpreted as either a landscape or a face and reported at every point in time whether they perceived predominantly the face, the landscape, or both simultaneously. We explored behavioral and neurophysiological (with fMRI) correlates of the reported subjective experience of entertaining two percepts simultaneously by comparing them to those of the simple percepts (i.e., face or landscape). First, by comparing percept durations, we found that the simultaneous state was as stable as the two other percepts. Second, by measuring blood-oxygen-level-dependent (BOLD) signal levels within the fusiform face area (FFA), occipital face area (OFA) and parahippocampal place area (PPA), we found evidence from objective data that confirmed the subjective reports. While the results in FFA and OFA were not conclusive, in PPA, BOLD signal levels during subjective reports of perceiving both a landscape and a face were lower than the BOLD signal levels associated with reports of perceiving a landscape (and, in turn, reports of seeing a landscape were associated with greater BOLD signal levels than reports of seeing a face, thus suggesting that BOLD signal levels in PPA are a valid correlate of subjective experience in this task). In sum, the objective measures suggest that entertaining two percepts

Neural substrate of the late positive potential in emotional processing

Science.gov (United States)

Liu, Yuelu; Huang, Haiqing; McGinnis, Menton; Keil, Andreas; Ding, Mingzhou

2012-01-01

The late positive potential (LPP) is a reliable electrophysiological index of emotional perception in humans. Despite years of research the brain structures that contribute to the generation and modulation of LPP are not well understood. Recording EEG and fMRI simultaneously, and applying a recently proposed single-trial ERP analysis method, we addressed the problem by correlating the single-trial LPP amplitude evoked by affective pictures with the blood-oxygen-level-dependent (BOLD) activity. Three results were found. First, relative to neutral pictures, pleasant and unpleasant pictures elicited enhanced LPP, as well as heightened BOLD activity in both visual cortices and emotion-processing structures such as amygdala and prefrontal cortex, consistent with previous findings. Second, the LPP amplitude across three picture categories was significantly correlated with BOLD activity in visual cortices, temporal cortices, amygdala, orbitofrontal cortex, and insula. Third, within each picture category, LPP-BOLD coupling revealed category-specific differences. For pleasant pictures, the LPP amplitude was coupled with BOLD in occipitotemporal junction, medial prefrontal cortex, amygdala, and precuneus, whereas for unpleasant pictures, significant LPP-BOLD correlation was observed in ventrolateral prefrontal cortex, insula, and posterior cingulate cortex. These results suggest that LPP is generated and modulated by an extensive brain network comprised of both cortical and subcortical structures associated with visual and emotional processing and the degree of contribution by each of these structures to the LPP modulation is valence-specific. PMID:23077042

Modelling Cardiac Signal as a Confound in EEG-fMRI and its Application in Focal Epilepsy

DEFF Research Database (Denmark)

Liston, Adam David; Salek-Haddadi, Afraim; Hamandi, Khalid

2005-01-01

Cardiac noise has been shown to reduce the sensitivity of functional Magnetic Resonance Imaging (fMRI) to an experimental effect due to its confounding presence in the blood oxygenation level-dependent (BOLD) signal. Its effect is most severe in particular regions of the brain and a method is yet...

Brain response to food cues varying in portion size is associated with individual differences in the portion size effect in children

NARCIS (Netherlands)

Keller, Kathleen L.; English, Laural K.; Fearnbach, S.N.; Lasschuijt, Marlou; Anderson, Kaitlin; Bermudez, Maria; Fisher, Jennifer O.; Rolls, Barbara J.; Wilson, Stephen J.

2018-01-01

Large portions promote intake of energy dense foods (i.e., the portion size effect–PSE), but the neurobiological drivers of this effect are not known. We tested the association between blood oxygen level dependent (BOLD) brain response to food images varied by portion size (PS) and energy density

Initial Validation for the Estimation of Resting-State fMRI Effective Connectivity by a Generalization of the Correlation Approach

Directory of Open Access Journals (Sweden)

Nan Xu

2017-05-01

Full Text Available Resting-state functional MRI (rs-fMRI is widely used to noninvasively study human brain networks. Network functional connectivity is often estimated by calculating the timeseries correlation between blood-oxygen-level dependent (BOLD signal from different regions of interest (ROIs. However, standard correlation cannot characterize the direction of information flow between regions. In this paper, we introduce and test a new concept, prediction correlation, to estimate effective connectivity in functional brain networks from rs-fMRI. In this approach, the correlation between two BOLD signals is replaced by a correlation between one BOLD signal and a prediction of this signal via a causal system driven by another BOLD signal. Three validations are described: (1 Prediction correlation performed well on simulated data where the ground truth was known, and outperformed four other methods. (2 On simulated data designed to display the “common driver” problem, prediction correlation did not introduce false connections between non-interacting driven ROIs. (3 On experimental data, prediction correlation recovered the previously identified network organization of human brain. Prediction correlation scales well to work with hundreds of ROIs, enabling it to assess whole brain interregional connectivity at the single subject level. These results provide an initial validation that prediction correlation can capture the direction of information flow and estimate the duration of extended temporal delays in information flow between regions of interest ROIs based on BOLD signal. This approach not only maintains the high sensitivity to network connectivity provided by the correlation analysis, but also performs well in the estimation of causal information flow in the brain.

Visual cortex reactivity in sedated children examined with perfusion MRI (FAIR)

DEFF Research Database (Denmark)

Born, A.P.; Rostrup, Egill; Miranda Gimenez-Ricco, Maria Jo

2002-01-01

Sleeping and sedated children can respond to visual stimulation with a decrease in blood oxygenation level dependent (BOLD) functional MRI signal response. The contribution of metabolic and hemodynamic parameters to this inverse signal response is incompletely understood. It has been hypothesized...... that it is caused by a relatively greater increase of oxygen consumption compared to rCBF (regional cerebral blood flow) increase. We studied the rCBF changes during visual stimulation in four sedated children, aged 4-71 months, and four alert adults, with an arterial water spin labeling technique (FAIR) and BOLD f.......99-2.93), respectively. Thus, in the children, an rCBF increase could not be detected by perfusion MRI, but indications of a FAIR signal decrease were found. An rCBF decrease in the primary visual cortex during stimulation has not been reported previously, but it is a possible explanation for the negative BOLD response...

Level of khat dependence, use patterns, and psychosocial correlates in Yemen: a cross-sectional investigation.

Science.gov (United States)

Nakajima, Motohiro; Hoffman, Richard; al'Absi, Mustafa

2017-05-01

Chronic khat use is associated with negative health consequences. However, no study has fully characterized individuals who are khat dependent. This paper examines socio-demographic and psychosocial correlates of adult khat dependence. A total of 270 khat users (129 women) in Yemen completed face-to-face interviews and provided demographic information and data on patterns of khat use, subjective mood, and sleep quality. The Severity of Dependence Scale-Khat (SDS-khat) was used to assess level of khat dependence. A series of analysis of variance was conducted. Khat users, on average, used khat for 5.2 hours a day (SD = 2.3) for 5.7 days a week (SD = 2.0). Individuals who screened positive for khat dependence reported longer duration of khat sessions per day, higher frequency of khat use per week, greater levels of negative mood and sleep disturbances, and were more likely to endorse physical symptoms after khat use (P < 0.05). Future research should elucidate mechanisms responsible for khat dependence symptomatology.

Ridding fMRI data of motion-related influences: Removal of signals with distinct spatial and physical bases in multiecho data.

Science.gov (United States)

Power, Jonathan D; Plitt, Mark; Gotts, Stephen J; Kundu, Prantik; Voon, Valerie; Bandettini, Peter A; Martin, Alex

2018-02-27

"Functional connectivity" techniques are commonplace tools for studying brain organization. A critical element of these analyses is to distinguish variance due to neurobiological signals from variance due to nonneurobiological signals. Multiecho fMRI techniques are a promising means for making such distinctions based on signal decay properties. Here, we report that multiecho fMRI techniques enable excellent removal of certain kinds of artifactual variance, namely, spatially focal artifacts due to motion. By removing these artifacts, multiecho techniques reveal frequent, large-amplitude blood oxygen level-dependent (BOLD) signal changes present across all gray matter that are also linked to motion. These whole-brain BOLD signals could reflect widespread neural processes or other processes, such as alterations in blood partial pressure of carbon dioxide (pCO 2 ) due to ventilation changes. By acquiring multiecho data while monitoring breathing, we demonstrate that whole-brain BOLD signals in the resting state are often caused by changes in breathing that co-occur with head motion. These widespread respiratory fMRI signals cannot be isolated from neurobiological signals by multiecho techniques because they occur via the same BOLD mechanism. Respiratory signals must therefore be removed by some other technique to isolate neurobiological covariance in fMRI time series. Several methods for removing global artifacts are demonstrated and compared, and were found to yield fMRI time series essentially free of motion-related influences. These results identify two kinds of motion-associated fMRI variance, with different physical mechanisms and spatial profiles, each of which strongly and differentially influences functional connectivity patterns. Distance-dependent patterns in covariance are nearly entirely attributable to non-BOLD artifacts.

Pseudo-reorganization of language cortical function at fMR imaging: a consequence of tumor-induced neurovascular uncoupling.

Science.gov (United States)

Ulmer, John L; Krouwer, Hendrikus G; Mueller, Wade M; Ugurel, M Sahin; Kocak, Mehmet; Mark, Leighton P

2003-02-01

A left-handed patient with a grade II left frontal lobe astrocytoma had spontaneous seizures causing speech arrest and uncontrolled right upper extremity movements. Word-generation functional MR (fMR) imaging showed activity nearly exclusively in the right inferior frontal gyrus. The clinical history of the speech arrest and the intraoperative mapping proved left-hemisphere language dominance. Tumor involvement of the left inferior frontal gyrus caused uncoupling of the blood oxygenation level-dependent (BOLD) and neuronal response, leading to the erroneous fMR imaging appearance of right-hemisphere language dominance. Discrepancies between BOLD and intraoperative mapping in areas near lesions illustrate the complementary nature of these techniques.

Brain signal variability is modulated as a function of internal and external demand in younger and older adults.

Science.gov (United States)

Grady, Cheryl L; Garrett, Douglas D

2018-04-01

Variability in the Blood Oxygen-Level Dependent (BOLD) signal from fMRI is often associated with better cognitive performance and younger age. It has been proposed that neural variability enables flexible responding to uncertainty in a changing environment. However, signal variability reflecting environmental uncertainty may reduce to the extent that a task depends on internally-directed attention and is supported by neural "solutions" that are schematic and relatively stable within each individual. Accordingly, we examined the hypothesis that BOLD variability will be low at rest, higher during internally-directed tasks, and higher still during externally-directed tasks, and that this effect will be reduced with aging. Modulation of BOLD variability across conditions was consistent with these hypotheses, and was associated with faster and more stable behavioral performance in both young and older adults. These data support the idea that brain signal variability may modulate in response to environmental uncertainty, which is presumed to be greater in the external environment than in the internal milieu. Reduced flexibility of signal variability with age may indicate less ability to switch between internal and external brain states. Copyright © 2017 Elsevier Inc. All rights reserved.

Defects level evaluation of LiTiZn ferrite ceramics using temperature dependence of initial permeability

Science.gov (United States)

Malyshev, A. V.; Petrova, A. B.; Sokolovskiy, A. N.; Surzhikov, A. P.

2018-06-01

The method for evaluating the integral defects level and chemical homogeneity of ferrite ceramics based on temperature dependence analysis of initial permeability is suggested. A phenomenological expression for the description of such dependence was suggested and an interpretation of its main parameters was given. It was shown, that the main criterion of the integral defects level of ferrite ceramics is relation of two parameters correlating with elastic stress value in a material. An indicator of structural perfection can be a maximum value of initial permeability close to Curie point as well. The temperature dependences of initial permeability have analyzed for samples sintered in laboratory conditions and for the ferrite industrial product. The proposed method allows controlling integral defects level of the soft ferrite products and has high sensitivity compare to typical X-ray methods.

An age-structured approach to modelling behavioural variation maintained by life-history trade-offs.

Directory of Open Access Journals (Sweden)

Matthew H T Chan

Full Text Available There have been numerous empirical studies on the fitness consequences of behavioural syndromes in various animal taxa; however, the ecological and evolutionary implications on a population level are still poorly understood. To better understand these implications, we develop a non-linear age-structured mathematical model to qualitatively examine the evolutionary consequences of a heritable boldness personality trait within an animal population. We assume that this heritable boldness trait is positively correlated with boldness towards predators and intraspecific aggressiveness. This assumption leads to a growth/reproductive success versus mortality trade-off, which is thoroughly investigated and documented in the literature. Another life-history trade-off we include in the model is future versus current reproduction, which was shown by Wolf et al. to be a possible mechanism for the evolution of behavioural syndromes within an animal population. The stability of the system is analysed, whereby the characteristic equation is in the form of a homogeneous Fredholm equation of the second kind which depends on both the perturbation and equilibrium solution. The system is found to be stable due to the competition between individuals of similar boldness acting as a negative feedback mechanism. Using numerical simulations we examine the qualitative features of the solution to the system. In particular, we investigate the interplay between the mutation and competition strength between two individuals with different boldness, whereby we find that an increasing competition range acts to push individuals to both extremes of the shy-bold axis, while an increasing mutation range counteracts this effect. This qualitative trait of aggregation of individuals around the shy and bold extremes is also found when examining different birth, mortality and competition functions.

Effect of sound intensity on tonotopic fMRI maps in the unanesthetized monkey.

Science.gov (United States)

Tanji, Kazuyo; Leopold, David A; Ye, Frank Q; Zhu, Charles; Malloy, Megan; Saunders, Richard C; Mishkin, Mortimer

2010-01-01

The monkey's auditory cortex includes a core region on the supratemporal plane (STP) made up of the tonotopically organized areas A1, R, and RT, together with a surrounding belt and a lateral parabelt region. The functional studies that yielded the tonotopic maps and corroborated the anatomical division into core, belt, and parabelt typically used low-amplitude pure tones that were often restricted to threshold-level intensities. Here we used functional magnetic resonance imaging in awake rhesus monkeys to determine whether, and if so how, the tonotopic maps and the pattern of activation in core, belt, and parabelt are affected by systematic changes in sound intensity. Blood oxygenation level-dependent (BOLD) responses to groups of low- and high-frequency pure tones 3-4 octaves apart were measured at multiple sound intensity levels. The results revealed tonotopic maps in the auditory core that reversed at the putative areal boundaries between A1 and R and between R and RT. Although these reversals of the tonotopic representations were present at all intensity levels, the lateral spread of activation depended on sound amplitude, with increasing recruitment of the adjacent belt areas as the intensities increased. Tonotopic organization along the STP was also evident in frequency-specific deactivation (i.e. "negative BOLD"), an effect that was intensity-specific as well. Regions of positive and negative BOLD were spatially interleaved, possibly reflecting lateral inhibition of high-frequency areas during activation of adjacent low-frequency areas, and vice versa. These results, which demonstrate the strong influence of tonal amplitude on activation levels, identify sound intensity as an important adjunct parameter for mapping the functional architecture of auditory cortex.

Age and dosage-level dependence of radium retention in beagles

International Nuclear Information System (INIS)

Parks, N.J.; Pool, R.R.; Williams, J.R.; Wolf, H.G.

1978-01-01

Radium retention was measured over the lifespan of 46 beagles exposed by eight semimonthly injections at 60 to 160, 120 to 220, or 435 to 535 days of age. Injection dosage levels ranged from 0.37 to 10 μCi of 226 Ra/kg. The fractional retention of each animal is described in terms of a modified power function, R = [(t + d)/d] - /sup b/. Young adult beagles (approximately equal to 10 kg) injected at a mean age (A) of 485 days with 226 Ra at dosage levels of 10, 3.3, 1.11, and 0.37 μCi/kg had mean values for d and b of [0.897; 0.187], [2.015; 0.206], [2.778; 0.257], and [3.894; 0.274], respectively. Juvenile beagles injected with 10 μCi/kg at A = 110 days (average weight approximately equal to 6 kg) and at A = 170 days (average weight approximately equal to 10 kg) had mean values for d and b of [137; 0.277] and [5.53; 0.086], respectively. The d values are geometric means and the units are days; b values are arithmetic means. The formula for deriving the age-dependent retention function for dogs is given. The beagle results were correlated with human data in terms of age-to-equivalent fraction of adult body calcium content and were used to construct a similar age-dependent retention function for chronically exposed people. The correlation of age-dependent retention functions for beagles and humans is used to estimate scaling factors between the two species for the fraction of injected dosage associated with bone for various ages of exposure

Multi-level comparison of empathy in schizophrenia: an fMRI study of a cartoon task.

Science.gov (United States)

Lee, Seung Jae; Kang, Do Hyung; Kim, Chi-Won; Gu, Bon Mi; Park, Ji-Young; Choi, Chi-Hoon; Shin, Na Young; Lee, Jong-Min; Kwon, Jun Soo

2010-02-28

Empathy deficits might play a role in social dysfunction in schizophrenia. However, few studies have investigated the neuroanatomical underpinnings of the subcomponents of empathy in schizophrenia. This study investigated the hemodynamic responses to three subcomponents of empathy in patients with schizophrenia (N=15) and healthy volunteers (N=18), performing an empathy cartoon task during functional magnetic resonance imaging. The experiment used a block design with four conditions: cognitive, emotional, and inhibitory empathy, and physical causality control. Data were analyzed by comparing the blood-oxygen-level-dependent (BOLD) signal activation between the two groups. The cognitive empathy condition activated the right temporal pole to a lesser extent in the patient group than in comparison subjects. In the emotional and inhibitory conditions, the patients showed greater activation in the left insula and in the right middle/inferior frontal cortex, respectively. These findings add to our understanding of the impaired empathy in patients with schizophrenia by identifying a multi-level cortical dysfunction that underlies a deficit in each subcomponent of empathy and highlighting the importance of the fronto-temporal cortical network in ability to empathize. Copyright (c) 2009 Elsevier Ireland Ltd. All rights reserved.

Association Between Brain Activation and Functional Connectivity.

Science.gov (United States)

Tomasi, Dardo; Volkow, Nora D

2018-04-13

The origin of the "resting-state" brain activity recorded with functional magnetic resonance imaging (fMRI) is still uncertain. Here we provide evidence for the neurovascular origins of the amplitude of the low-frequency fluctuations (ALFF) and the local functional connectivity density (lFCD) by comparing them with task-induced blood-oxygen level dependent (BOLD) responses, which are considered a proxy for neuronal activation. Using fMRI data for 2 different tasks (Relational and Social) collected by the Human Connectome Project in 426 healthy adults, we show that ALFF and lFCD have linear associations with the BOLD response. This association was significantly attenuated by a novel task signal regression (TSR) procedure, indicating that task performance enhances lFCD and ALFF in activated regions. We also show that lFCD predicts BOLD activation patterns, as was recently shown for other functional connectivity metrics, which corroborates that resting functional connectivity architecture impacts brain activation responses. Thus, our findings indicate a common source for BOLD responses, ALFF and lFCD, which is consistent with the neurovascular origin of local hemodynamic synchrony presumably reflecting coordinated fluctuations in neuronal activity. This study also supports the development of task-evoked functional connectivity density mapping.

Neurobiological evidence for attention bias to food, emotional dysregulation, disinhibition and deficient somatosensory awareness in obesity with binge eating disorder.

Science.gov (United States)

Aviram-Friedman, Roni; Astbury, Nerys; Ochner, Christopher N; Contento, Isobel; Geliebter, Allan

2018-02-01

To refine the biobehavioral markers of binge eating disorder (BED). We conducted fMRI brain scans using images of high energy processed food (HEPF), low energy unprocessed food (LEUF), or non-foods (NF) in 42 adults (obese with BED [obese -BED; n=13] and obese with no BED [obese non-BED; n=29]) selected via ads. Two blood oxygenated level dependent (BOLD) signal contrast maps were examined: food versus nonfood, and HEPF versus LEUF. In addition, score differences on the disinhibition scale were correlated with BOLD signals. food versus nonfood showed greater BOLD activity for BED in emotional, motivational and somatosensory brain areas: insula, anterior cingulate cortex (ACC), Brodmann areas (BA) 19 & 32, inferior parietal lobule (IPL), posterior cingulate cortex (PCC), and lingual, postcentral, middle temporal and cuneate gyri (p≤0.005; k≥88). HEPF versus LEUF showed greater BOLD activity for BED in inhibitory brain regions: BA 6, middle and superior frontal gyri (pFood images elicited neural activity indicating attention bias (cuneate & PCG), emotion dysregulation (BA 19 & 32), and disinhibition (MFG, BA6 & SFG) in obese with BED. These may help tailor a treatment for the obesity with BED phenotype. Copyright © 2017. Published by Elsevier Inc.

Order Level Inventory Models for Deteriorating Seasonable/Fashionable Products with Time Dependent Demand and Shortages

OpenAIRE

Skouri, K.; Konstantaras, I.

2009-01-01

An order level inventory model for seasonable/fashionable products subject to a period of increasing demand followed by a period of level demand and then by a period of decreasing demand rate (three branches ramp type demand rate) is considered. The unsatisfied demand is partially backlogged with a time dependent backlogging rate. In addition, the product deteriorates with a time dependent, namely, Weibull, deterioration rate. The model is studied under the following different replenishment p...

Novel fMRI working memory paradigm accurately detects cognitive impairment in Multiple Sclerosis

Science.gov (United States)

Nelson, Flavia; Akhtar, Mohammad A.; Zúñiga, Edward; Perez, Carlos A.; Hasan, Khader M.; Wilken, Jeffrey; Wolinsky, Jerry S.; Narayana, Ponnada A.; Steinberg, Joel L.

2016-01-01

Background Cognitive impairment (CI) cannot be diagnosed by MRI. Functional MRI (fMRI) paradigms such as the immediate/delayed memory task (I/DMT), detect varying degrees of working memory. Preliminary findings using I/DMT, showed differences in Blood Oxygenation Level Dependent (BOLD) activation between impaired (MSCI, n=12) and non-impaired (MSNI, n=9) MS patients. Objectives To confirm CI detection based on I/DMT’ BOLD activation in a larger cohort of MS patients. The role of T2 lesion volume (LV) and EDSS in magnitude of BOLD signal were also sought. Methods Fifty patients [EDSS mean (m) = 3.2, DD m =12 yr., age m =40yr.] underwent the Minimal Assessment of Cognitive Function in MS (MACFIMS) and the I/DMT. Working-memory activation (WMa) represents BOLD signal during DMT minus signal during IMT. CI was based on MACFIMS. Results 10 MSNI, 30 MSCI and 4 borderline patients were included in analyses. ANOVA showed MSNI had significantly greater WMa than MSCI, in the left (L) prefrontal cortex and L supplementary motor area (p = 0.032). Regression analysis showed significant inverse correlations between WMa and T2 LV/EDSS in similar areas (p = 0.005, 0.004 respectively). Conclusion I/DMT-based BOLD activation detects CI in MS, larger studies are needed to confirm these findings. PMID:27613119

Neural correlates of working memory in first episode and recurrent depression: An fMRI study.

Science.gov (United States)

Yüksel, Dilara; Dietsche, Bruno; Konrad, Carsten; Dannlowski, Udo; Kircher, Tilo; Krug, Axel

2018-06-08

Patients suffering from major depressive disorder (MDD) show deficits in working memory (WM) performance accompanied by bilateral fronto-parietal BOLD signal changes. It is unclear whether patients with a first depressive episode (FDE) exhibit the same signal changes as patients with recurrent depressive episodes (RDE). We investigated seventy-four MDD inpatients (48 RDE, 26 FDE) and 74 healthy control (HC) subjects performing an n-back WM task (0-back, 2-back, 3-back condition) in a 3T-fMRI. FMRI analyses revealed deviating BOLD signal in MDD in the thalamus (0-back vs. 2-back), the angular gyrus (0-back vs. 3-back), and the superior frontal gyrus (2-back vs. 3-back). Further effects were observed between RDE vs. FDE. Thus, RDE displayed differing neural activation in the middle frontal gyrus (2-back vs. 3-back), the inferior frontal gyrus, and the precentral gyrus (0-back vs. 2-back). In addition, both HC and FDE indicated a linear activation trend depending on task complexity. Although we failed to find behavioral differences between the groups, results suggest differing BOLD signal in fronto-parietal brain regions in MDD vs. HC, and in RDE vs. FDE. Moreover, both HC and FDE show similar trends in activation shapes. This indicates a link between levels of complexity-dependent activation in fronto-parietal brain regions and the stage of MDD. We therefore assume that load-dependent BOLD signal during WM is impaired in MDD, and that it is particularly affected in RDE. We also suspect neurobiological compensatory mechanisms of the reported brain regions in (working) memory functioning. Copyright © 2018 Elsevier Inc. All rights reserved.

Mapping of cerebral metabolic rate of oxygen using dynamic susceptibility contrast and blood oxygen level dependent MR imaging in acute ischemic stroke

Energy Technology Data Exchange (ETDEWEB)

Gersing, Alexandra S.; Schwaiger, Benedikt J. [Technical University Munich, Klinikum rechts der Isar, Department of Neuroradiology, Munich (Germany); University of California, Department of Radiology and Biomedical Imaging, San Francisco, CA (United States); Ankenbrank, Monika; Toth, Vivien; Bauer, Jan S.; Zimmer, Claus [Technical University Munich, Klinikum rechts der Isar, Department of Neuroradiology, Munich (Germany); Janssen, Insa [Technical University Munich, Department of Neurosurgery, Munich (Germany); Kooijman, Hendrik [Philips Healthcare, Hamburg (Germany); Wunderlich, Silke [Technical University Munich, Department of Neurology, Munich (Germany); Preibisch, Christine [Technical University Munich, Klinikum rechts der Isar, Department of Neuroradiology, Munich (Germany); Technical University Munich, Department of Neurology, Munich (Germany)

2015-12-15

MR-derived cerebral metabolic rate of oxygen utilization (CMRO{sub 2}) has been suggested to be analogous to PET-derived CMRO{sub 2} and therefore may be used for detection of viable tissue at risk for infarction. The purpose of this study was to evaluate MR-derived CMRO{sub 2} mapping in acute ischemic stroke in relation to established diffusion- and perfusion-weighted imaging. In 23 patients (mean age 63 ± 18.7 years, 11 women) with imaging findings for acute ischemic stroke, relative oxygen extraction fraction was calculated from quantitative transverse relaxation times (T2, T2*) and relative cerebral blood volume using a quantitative blood oxygenation level dependent (BOLD) approach in order to detect a local increase of deoxyhemoglobin. Relative CMRO{sub 2} (rCMRO{sub 2}) maps were calculated by multiplying relative oxygen extraction fraction (rOEF) by cerebral blood flow, derived from PWI. After co-registration, rCMRO{sub 2} maps were evaluated in comparison with apparent diffusion coefficient (ADC) and time-to-peak (TTP) maps. Mean rCMRO{sub 2} values in areas with diffusion-restriction or TTP/ADC mismatch were compared with rCMRO{sub 2} values in the contralateral tissue. In tissue with diffusion restriction, mean rCMRO{sub 2} values were significantly decreased compared to perfusion-impaired (17.9 [95 % confidence interval 10.3, 25.0] vs. 58.1 [95 % confidence interval 50.1, 70.3]; P < 0.001) and tissue in the contralateral hemisphere (68.2 [95 % confidence interval 61.4, 75.0]; P < 0.001). rCMRO{sub 2} in perfusion-impaired tissue showed no significant change compared to tissue in the contralateral hemisphere (58.1 [95 % confidence interval 50.1, 70.3] vs. 66.7 [95 % confidence interval 53.4, 73.4]; P = 0.34). MR-derived CMRO{sub 2} was decreased within diffusion-restricted tissue and stable within perfusion-impaired tissue, suggesting that this technique may be adequate to reveal different pathophysiological stages in acute stroke. (orig.)

Spin-dependent level density in interacting Boson-Fermion-Fermion model of the Odd-Odd Nucleus 196Au

International Nuclear Information System (INIS)

Kabashi, S.; Bekteshi, S.; Ahmetaj, S.; Shaqiri, Z.

2009-01-01

The level density of the odd-odd nucleus 196 Au is investigated in the interacting boson-fermion-fermion model (IBFFM) which accounts for collectivity and complex interaction between quasiparticle and collective modes.The IBFFM spin-dependent level densities show high-spin reduction with respect to Bethe formula.This can be well accounted for by a modified spin-dependent level density formula. (authors)

Gender Differences in the Effect of Tobacco Use on Brain Phosphocreatine Levels in Methamphetamine Dependent Subjects

Science.gov (United States)

Sung, Young-Hoon; Yurgelun-Todd, Deborah A.; Kondo, Douglas G.; Shi, Xian-Feng; Lundberg, Kelly J.; Hellem, Tracy L.; Huber, Rebekah S.; McGlade, Erin C.; Jeong, Eun-Kee; Renshaw, Perry F.

2015-01-01

Background A high prevalence of tobacco smoking has been observed in methamphetamine users, but there have been no in vivo brain neurochemistry studies addressing gender effects of tobacco smoking in methamphetamine users. Methamphetamine addiction is associated with increased risk of depression and anxiety in females. There is increasing evidence that selective analogues of nicotine, a principal active component of tobacco smoking, may improve depression and cognitive performance in animals and humans. Objectives To investigate the effects of tobacco smoking and gender on brain phosphocreatine (PCr) levels, a marker of brain energy metabolism reported to be reduced in methamphetamine-dependent subjects. Methods Thirty female and twenty-seven male methamphetamine-dependent subjects were evaluated with phosphorus-31 magnetic resonance spectroscopy (31P-MRS) to measure PCr levels within the pregenual anterior cingulate, which has been implicated in methamphetamine neurotoxicity. Results Analysis of covariance revealed that there were statistically significant slope (PCr versus lifetime amount of tobacco smoking) differences between female and male methamphetamine-dependent subjects (p=0.03). In females, there was also a statistically significant interaction between lifetime amounts of tobacco smoking and methamphetamine in regard to PCr levels (p=0.01), which suggests that tobacco smoking may have a more significant positive impact on brain PCr levels in heavy, as opposed to light to moderate, methamphetamine-dependent females. Conclusion These results indicate that tobacco smoking has gender-specific effects in terms of increased anterior cingulate high energy PCr levels in methamphetamine-dependent subjects. Cigarette smoking in methamphetamine-dependent women, particularly those with heavy methamphetamine use, may have a potentially protective effect upon neuronal metabolism. PMID:25871447

Cortical and brain stem changes in neural activity during static handgrip and postexercise ischemia in humans

DEFF Research Database (Denmark)

Sander, Mikael; Macefield, Vaughan G; Henderson, Luke A

2010-01-01

, and to differentiate between central command and reflex inputs, we used blood oxygen level-dependent (BOLD) functional MRI (fMRI) of the whole brain (3 T). Subjects performed submaximal static handgrip exercise for 2 min followed by 6 min of PEI; MSNA was recorded on a separate day. During the contraction phase...

Neural correlates of value, risk, and risk aversion contributing to decision making under risk.

Science.gov (United States)

Christopoulos, George I; Tobler, Philippe N; Bossaerts, Peter; Dolan, Raymond J; Schultz, Wolfram

2009-10-07

Decision making under risk is central to human behavior. Economic decision theory suggests that value, risk, and risk aversion influence choice behavior. Although previous studies identified neural correlates of decision parameters, the contribution of these correlates to actual choices is unknown. In two different experiments, participants chose between risky and safe options. We identified discrete blood oxygen level-dependent (BOLD) correlates of value and risk in the ventral striatum and anterior cingulate, respectively. Notably, increasing inferior frontal gyrus activity to low risk and safe options correlated with higher risk aversion. Importantly, the combination of these BOLD responses effectively decoded the behavioral choice. Striatal value and cingulate risk responses increased the probability of a risky choice, whereas inferior frontal gyrus responses showed the inverse relationship. These findings suggest that the BOLD correlates of decision factors are appropriate for an ideal observer to detect behavioral choices. More generally, these biological data contribute to the validity of the theoretical decision parameters for actual decisions under risk.

Temperature profiles from mechanical bathythermograph (MBT) casts from the USS BOLD in the Mediterranean Sea in support of the Fleet Observations of Oceanographic Data (FLOOD) project for 1955-08-25 (NODC Accession 5500036)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — MBT data were collected from the USS BOLD in support of the Fleet Observations of Oceanographic Data (FLOOD) project. Data were collected by US Navy; Ships of...

Information entropy of a time-dependent three-level trapped ion interacting with a laser field

International Nuclear Information System (INIS)

Abdel-Aty, Mahmoud

2005-01-01

Trapped and laser-cooled ions are increasingly used for a variety of modern high-precision experiments, frequency standard applications and quantum information processing. Therefore, in this communication we present a comprehensive analysis of the pattern of information entropy arising in the time evolution of an ion interacting with a laser field. A general analytic approach is proposed for a three-level trapped-ion system in the presence of the time-dependent couplings. By working out an exact analytic solution, we conclusively analyse the general properties of the von Neumann entropy and quantum information entropy. It is shown that the information entropy is affected strongly by the time-dependent coupling and exhibits long time periodic oscillations. This feature attributed to the fact that in the time-dependent region Rabi oscillation is time dependent. Using parameters corresponding to a specific three-level ionic system, a single beryllium ion in a RF-(Paul) trap, we obtain illustrative examples of some novel aspects of this system in the dynamical evolution. Our results establish an explicit relation between the exact information entropy and the entanglement between the multi-level ion and the laser field. We show that different nonclassical effects arise in the dynamics of the ionic population inversion, depending on the initial states of the vibrational motion/field and on the values of Lamb-Dicke parameter η

Mechanistic Mathematical Modeling Tests Hypotheses of the Neurovascular Coupling in fMRI.

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Karin Lundengård

2016-06-01

Full Text Available Functional magnetic resonance imaging (fMRI measures brain activity by detecting the blood-oxygen-level dependent (BOLD response to neural activity. The BOLD response depends on the neurovascular coupling, which connects cerebral blood flow, cerebral blood volume, and deoxyhemoglobin level to neuronal activity. The exact mechanisms behind this neurovascular coupling are not yet fully investigated. There are at least three different ways in which these mechanisms are being discussed. Firstly, mathematical models involving the so-called Balloon model describes the relation between oxygen metabolism, cerebral blood volume, and cerebral blood flow. However, the Balloon model does not describe cellular and biochemical mechanisms. Secondly, the metabolic feedback hypothesis, which is based on experimental findings on metabolism associated with brain activation, and thirdly, the neurotransmitter feed-forward hypothesis which describes intracellular pathways leading to vasoactive substance release. Both the metabolic feedback and the neurotransmitter feed-forward hypotheses have been extensively studied, but only experimentally. These two hypotheses have never been implemented as mathematical models. Here we investigate these two hypotheses by mechanistic mathematical modeling using a systems biology approach; these methods have been used in biological research for many years but never been applied to the BOLD response in fMRI. In the current work, model structures describing the metabolic feedback and the neurotransmitter feed-forward hypotheses were applied to measured BOLD responses in the visual cortex of 12 healthy volunteers. Evaluating each hypothesis separately shows that neither hypothesis alone can describe the data in a biologically plausible way. However, by adding metabolism to the neurotransmitter feed-forward model structure, we obtained a new model structure which is able to fit the estimation data and successfully predict new

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.

Ghrelin system in alcohol-dependent subjects: role of plasma ghrelin levels in alcohol drinking and craving.

Science.gov (United States)

Leggio, Lorenzo; Ferrulli, Anna; Cardone, Silvia; Nesci, Antonio; Miceli, Antonio; Malandrino, Noemi; Capristo, Esmeralda; Canestrelli, Benedetta; Monteleone, Palmiero; Kenna, George A; Swift, Robert M; Addolorato, Giovanni

2012-03-01

Animal studies suggest that the gut-brain peptide ghrelin plays an important role in the neurobiology of alcohol dependence (AD). Human studies show an effect of alcohol on ghrelin levels and a correlation between ghrelin levels and alcohol craving in alcoholics. This investigation consisted of two studies. Study 1 was a 12-week study with alcohol-dependent subjects, where plasma ghrelin determinations were assessed four times (T0-T3) and related to alcohol intake and craving [Penn Alcohol Craving Score (PACS) and Obsessive Compulsive Drinking Scale (OCDS)]. Serum growth hormone levels and assessment of the nutritional/metabolic status were also performed. Study 2 was a pilot case-control study to assess ghrelin gene polymorphisms (Arg51Gln and Leu72Met) in alcohol-dependent individuals. Study 1 showed no significant differences in ghrelin levels in the whole sample, while there was a statistical difference for ghrelin between non-abstinent and abstinent subjects. Baseline ghrelin levels were significantly and positively correlated with the PACS score at T1 and with all craving scores both at T2 and T3 (PACS, OCDS, obsessive and compulsive OCDS subscores). In Study 2, although there was a higher frequency of the Leu72Met ghrelin gene polymorphism in alcohol-dependent individuals, the distribution between healthy controls and alcohol dependent individuals was not statistically significant. This investigation suggests that ghrelin is potentially able to affect alcohol-seeking behaviors, such as alcohol drinking and craving, representing a new potential neuropharmacological target for AD. © 2011 The Authors, Addiction Biology © 2011 Society for the Study of Addiction.

Age-related changes in brain hemodynamics; A calibrated MRI study

DEFF Research Database (Denmark)

De Vis, J B; Hendrikse, J; Bhogal, A

2015-01-01

INTRODUCTION: Blood oxygenation-level dependent (BOLD) magnetic resonance imaging signal changes in response to stimuli have been used to evaluate age-related changes in neuronal activity. Contradictory results from these types of experiments have been attributed to differences in cerebral blood....... A dual-echo pseudocontinuous arterial spin labeling (ASL) sequence was performed during normocapnic, hypercapnic, and hyperoxic breathing challenges. Whole brain and regional gray matter values of CBF, ASL cerebrovascular reactivity (CVR), BOLD CVR, oxygen extraction fraction (OEF), and CMRO2 were...... calculated. RESULTS: Whole brain CBF was 49 ± 14 and 40 ± 9 ml/100 g/min in young and older subjects respectively (P brain, in the frontal...

DEPENDENCE OF COUNTRY RISK COMPARED TO THE FOREIGN DEBT LEVEL

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Angelica BĂCESCU-CĂRBUNARU

2012-11-01

Full Text Available The article presents some of the fundamental aspects of country risk’dependence compared to foreign debt level. Starting from external debt burden we analyze the usage of foreign loans, foreign debt bearing capacity as well as the availability of data regarding the external debt. Country risk represents the exposure to losses which may occur in a business with a foreign partner, caused by specific events that are, at least partially, controlled by the partner country’ government. Macroeconomic analysis of economic and financial component of country risk involves how this risk is influenced by government policy, by the economic role of government, bypricing strategies, investment priorities, financial structures, macroeconomic policy, by the ability to obtain foreign funds, the level of external debt as well as the liquidity and cash flows in that country.

The BDNF Val66Met polymorphism and plasma brain-derived neurotrophic factor levels in Han Chinese heroin-dependent patients.

Science.gov (United States)

Chen, Shiou-Lan; Lee, Sheng-Yu; Chang, Yun-Hsuan; Wang, Tzu-Yun; Chen, Shih-Heng; Chu, Chun-Hsien; Chen, Po See; Yang, Yen Kuang; Hong, Jau-Shyong; Lu, Ru-Band

2015-02-02

BDNF and its gene polymorphism may be important in synaptic plasticity and neuron survival, and may become a key target in the physiopathology of long-term heroin use. Thus, we investigated the relationships between brain-derived neurotrophic factor (BDNF) plasma concentrations and the BDNF Val66Met nucleotide polymorphism (SNP) in heroin-dependent patients. The pretreatment expression levels of plasma BDNF and the BDNF Val66Met SNP in 172 heroin-dependent patients and 102 healthy controls were checked. BDNF levels were significantly lower in patients (F = 52.28, p BDNF levels significantly different between Met/Met, Met/Val, and Val/Val carriers in each group, which indicated that the BDNF Val66Met SNP did not affect plasma BDNF levels in our participants. In heroin-dependent patients, plasma BDNF levels were negatively correlated with the length of heroin dependency. Long-term (>15 years) users had significantly lower plasma BDNF levels than did short-term (BDNF concentration in habitual heroin users are not affected by BDNF Val66Met gene variants, but by the length of the heroin dependency.

Correcting for Blood Arrival Time in Global Mean Regression Enhances Functional Connectivity Analysis of Resting State fMRI-BOLD Signals.

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Erdoğan, Sinem B; Tong, Yunjie; Hocke, Lia M; Lindsey, Kimberly P; deB Frederick, Blaise

2016-01-01

Resting state functional connectivity analysis is a widely used method for mapping intrinsic functional organization of the brain. Global signal regression (GSR) is commonly employed for removing systemic global variance from resting state BOLD-fMRI data; however, recent studies have demonstrated that GSR may introduce spurious negative correlations within and between functional networks, calling into question the meaning of anticorrelations reported between some networks. In the present study, we propose that global signal from resting state fMRI is composed primarily of systemic low frequency oscillations (sLFOs) that propagate with cerebral blood circulation throughout the brain. We introduce a novel systemic noise removal strategy for resting state fMRI data, "dynamic global signal regression" (dGSR), which applies a voxel-specific optimal time delay to the global signal prior to regression from voxel-wise time series. We test our hypothesis on two functional systems that are suggested to be intrinsically organized into anticorrelated networks: the default mode network (DMN) and task positive network (TPN). We evaluate the efficacy of dGSR and compare its performance with the conventional "static" global regression (sGSR) method in terms of (i) explaining systemic variance in the data and (ii) enhancing specificity and sensitivity of functional connectivity measures. dGSR increases the amount of BOLD signal variance being modeled and removed relative to sGSR while reducing spurious negative correlations introduced in reference regions by sGSR, and attenuating inflated positive connectivity measures. We conclude that incorporating time delay information for sLFOs into global noise removal strategies is of crucial importance for optimal noise removal from resting state functional connectivity maps.

Relations between vegetation and water level in groundwater dependent terrestrial ecosystems (GWDTEs)

DEFF Research Database (Denmark)

Munch Johansen, Ole; Andersen, Dagmar Kappel; Ejrnæs, Rasmus

2018-01-01

, management and conservation of fens are constrained by limited knowledge on the relations between vegetation and measurable hydrological conditions. This study investigates the relations between vegetation and water level dynamics in groundwater dependent wetlands in Denmark. A total of 35 wetland sites...... across Denmark were included in the study. The sites represent a continuum of wetlands with respect to vegetation and hydrological conditions. Water level was measured continuously using pressure transducers at each site. Metrics expressing different hydrological characteristics, such as mean water level...... and low and high water level periods, were calculated based on the water level time series. A complete plant species list was recorded in plots covering 78.5 m2 at each site. Community metrics such as total number of species and the number of bryophytes were generated from the species lists and Ellenberg...

BOLD data representing activation and connectivity for rare no-go versus frequent go cues

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Harma Meffert

2016-06-01

Full Text Available The neural circuitry underlying response control is often studied using go/no-go tasks, in which participants are required to respond as fast as possible to go cues and withhold from responding to no-go stimuli. In the current task, response control was studied using a fully counterbalanced design in which blocks with a low frequency of no-go cues (75% go, 25% no-go were alternated with blocks with a low frequency of go cues (25% go, 75% no-go; see also “Segregating attention from response control when performing a motor inhibition task: Segregating attention from response control” [1]. We applied a whole brain corrected, paired t-test to the data assessing for regions differentially activated by low frequency no-go cues relative to high frequency go cues. In addition, we conducted a generalized psychophysiological interaction analysis on the data using a right inferior frontal gyrus seed region. This region was identified through the BOLD response t-test and was chosen because right inferior gyrus is highly implicated in response inhibition.

Neurophysiological model of tinnitus: dependence of the minimal masking level on treatment outcome.

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Jastreboff, P J; Hazell, J W; Graham, R L

1994-11-01

Validity of the neurophysiological model of tinnitus (Jastreboff, 1990), outlined in this paper, was tested on data from multicenter trial of tinnitus masking (Hazell et al., 1985). Minimal masking level, intensity match of tinnitus, and the threshold of hearing have been evaluated on a total of 382 patients before and after 6 months of treatment with maskers, hearing aids, or combination devices. The data has been divided into categories depending on treatment outcome and type of approach used. Results of analysis revealed that: i) the psychoacoustical description of tinnitus does not possess a predictive value for the outcome of the treatment; ii) minimal masking level changed significantly depending on the treatment outcome, decreasing on average by 5.3 dB in patients reporting improvement, and increasing by 4.9 dB in those whose tinnitus remained the same or worsened; iii) 73.9% of patients reporting improvement had their minimal masking level decreased as compared with 50.5% for patients not showing improvement, which is at the level of random change; iv) the type of device used has no significant impact on the treatment outcome and minimal masking level change; v) intensity match and threshold of hearing did not exhibit any significant changes which can be related to treatment outcome. These results are fully consistent with the neurophysiological interpretation of mechanisms involved in the phenomenon of tinnitus and its alleviation.

Seeing Double: Exploring the Phenomenology of Self-Reported Absence of Rivalry in Bistable Pictures

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Elisa Filevich

2017-06-01

Full Text Available Ambiguous images such as Rubin’s vase-face can be interpreted in at least two different ways. These interpretations are typically taken to be mutually exclusive, and ambiguous images have thus served as models of perceptual competition. Here, we present data that challenges this view. In an online survey, we found that a large proportion of people within the general population reported that the two percepts were not competing but could be perceived simultaneously. Of those who reported that they could see both percepts simultaneously, we invited 17 participants to take part in a functional magnetic resonance imaging (fMRI experiment. In the scanner, participants saw images that could be interpreted as either a landscape or a face and reported at every point in time whether they perceived predominantly the face, the landscape, or both simultaneously. We explored behavioral and neurophysiological (with fMRI correlates of the reported subjective experience of entertaining two percepts simultaneously by comparing them to those of the simple percepts (i.e., face or landscape. First, by comparing percept durations, we found that the simultaneous state was as stable as the two other percepts. Second, by measuring blood-oxygen-level-dependent (BOLD signal levels within the fusiform face area (FFA, occipital face area (OFA and parahippocampal place area (PPA, we found evidence from objective data that confirmed the subjective reports. While the results in FFA and OFA were not conclusive, in PPA, BOLD signal levels during subjective reports of perceiving both a landscape and a face were lower than the BOLD signal levels associated with reports of perceiving a landscape (and, in turn, reports of seeing a landscape were associated with greater BOLD signal levels than reports of seeing a face, thus suggesting that BOLD signal levels in PPA are a valid correlate of subjective experience in this task. In sum, the objective measures suggest that entertaining

DIFFERENCES REGARDING SELF-ESTEEM AND THE COMMUNICATION STYLE DEPENDING ON THE LEVEL OF EDUCATION

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Georgeta PÂNIȘOARĂ

2015-12-01

Full Text Available The present paper aims to study the differences in self-esteem and the communication style, depending on the level of education (at high school and university subjects. It is analyzed also how the positive self-esteem can correlate with a style of communication and assertively-positive approach. The participants are 120 subjects, 60 high school students and 60 students. The data was collected using two instruments: the Rosenberg questionnaire and a questionnaire on communication style. The data analyzed using a t test for independent samples and a Pearson correlation test with SPSS statistical software. The results show that there are differences regarding the self-esteem and the communication style depending on the level of education.

Continuous EEG-fMRI in Pre-Surgical Evaluation of a Patient with Symptomatic Seizures: Bold Activation Linked to Interictal Epileptic Discharges Caused by Cavernoma.

Science.gov (United States)

Avesani, M; Formaggio, E; Milanese, F; Baraldo, A; Gasparini, A; Cerini, R; Bongiovanni, L G; Pozzi Mucelli, R; Fiaschi, A; Manganotti, P

2008-04-07

We used continuous electroencephalography-functional magnetic resonance imaging (EEG-fMRI) to identify the linkage between the "epileptogenic" and the "irritative" area in a patient with symptomatic epilepsy (cavernoma, previously diagnosed and surgically treated), i.e. a patient with a well known "epileptogenic area", and to increase the possibility of a non invasive pre-surgical evaluation of drug-resistant epilepsies. A compatible MRI system was used (EEG with 29 scalp electrodes and two electrodes for ECG and EMG) and signals were recorded with a 1.5 Tesla MRI scanner. After the recording session and MRI artifact removal, EEG data were analyzed offline and used as paradigms in fMRI study. Activation (EEG sequences with interictal slow-spiked-wave activity) and rest (sequences of normal EEG) conditions were compared to identify the potential resulting focal increase in BOLD signal and to consider if this is spatially linked to the interictal focus used as a paradigm and to the lesion. We noted an increase in the BOLD signal in the left neocortical temporal region, laterally and posteriorly to the poro-encephalic cavity (residual of cavernoma previously removed), that is around the "epileptogenic area". In our study "epileptogenic" and "irritative" areas were connected with each other. Combined EEG-fMRI may become routine in clinical practice for a better identification of an irritative and lesional focus in patients with symptomatic drug-resistant epilepsy.

Continuum corrections to the level density and its dependence on excitation energy, n-p asymmetry, and deformation

International Nuclear Information System (INIS)

Charity, R.J.; Sobotka, L.G.

2005-01-01

In the independent-particle model, the nuclear level density is determined from the neutron and proton single-particle level densities. The single-particle level density for the positive-energy continuum levels is important at high excitation energies for stable nuclei and at all excitation energies for nuclei near the drip lines. This single-particle level density is subdivided into compound-nucleus and gas components. Two methods are considered for this subdivision: In the subtraction method, the single-particle level density is determined from the scattering phase shifts. In the Gamov method, only the narrow Gamov states or resonances are included. The level densities calculated with these two methods are similar; both can be approximated by the backshifted Fermi-gas expression with level-density parameters that are dependent on A, but with very little dependence on the neutron or proton richness of the nucleus. However, a small decrease in the level-density parameter is predicted for some nuclei very close to the drip lines. The largest difference between the calculations using the two methods is the deformation dependence of the level density. The Gamov method predicts a very strong peaking of the level density at sphericity for high excitation energies. This leads to a suppression of deformed configurations and, consequently, the fission rate predicted by the statistical model is reduced in the Gamov method

Population-Level Density Dependence Influences the Origin and Maintenance of Parental Care.

Science.gov (United States)

Reyes, Elijah; Thrasher, Patsy; Bonsall, Michael B; Klug, Hope

2016-01-01

Parental care is a defining feature of animal breeding systems. We now know that both basic life-history characteristics and ecological factors influence the evolution of care. However, relatively little is known about how these factors interact to influence the origin and maintenance of care. Here, we expand upon previous work and explore the relationship between basic life-history characteristics (stage-specific rates of mortality and maturation) and the fitness benefits associated with the origin and the maintenance of parental care for two broad ecological scenarios: the scenario in which egg survival is density dependent and the case in which adult survival is density dependent. Our findings suggest that high offspring need is likely critical in driving the origin, but not the maintenance, of parental care regardless of whether density dependence acts on egg or adult survival. In general, parental care is more likely to result in greater fitness benefits when baseline adult mortality is low if 1) egg survival is density dependent or 2) adult mortality is density dependent and mutant density is relatively high. When density dependence acts on egg mortality, low rates of egg maturation and high egg densities are less likely to lead to strong fitness benefits of care. However, when density dependence acts on adult mortality, high levels of egg maturation and increasing adult densities are less likely to maintain care. Juvenile survival has relatively little, if any, effect on the origin and maintenance of egg-only care. More generally, our results suggest that the evolution of parental care will be influenced by an organism's entire life history characteristics, the stage at which density dependence acts, and whether care is originating or being maintained.

Iterative analysis of cerebrovascular reactivity dynamic response by temporal decomposition.

Science.gov (United States)

van Niftrik, Christiaan Hendrik Bas; Piccirelli, Marco; Bozinov, Oliver; Pangalu, Athina; Fisher, Joseph A; Valavanis, Antonios; Luft, Andreas R; Weller, Michael; Regli, Luca; Fierstra, Jorn

2017-09-01

To improve quantitative cerebrovascular reactivity (CVR) measurements and CO 2 arrival times, we present an iterative analysis capable of decomposing different temporal components of the dynamic carbon dioxide- Blood Oxygen-Level Dependent (CO 2 -BOLD) relationship. Decomposition of the dynamic parameters included a redefinition of the voxel-wise CO 2 arrival time, and a separation from the vascular response to a stepwise increase in CO 2 (Delay to signal Plateau - DTP) and a decrease in CO 2 (Delay to signal Baseline -DTB). Twenty-five (normal) datasets, obtained from BOLD MRI combined with a standardized pseudo-square wave CO 2 change, were co-registered to generate reference atlases for the aforementioned dynamic processes to score the voxel-by-voxel deviation probability from normal range. This analysis is further illustrated in two subjects with unilateral carotid artery occlusion using these reference atlases. We have found that our redefined CO 2 arrival time resulted in the best data fit. Additionally, excluding both dynamic BOLD phases (DTP and DTB) resulted in a static CVR, that is maximal response, defined as CVR calculated only over a normocapnic and hypercapnic calibrated plateau. Decomposition and novel iterative modeling of different temporal components of the dynamic CO 2 -BOLD relationship improves quantitative CVR measurements.

Order Level Inventory Models for Deteriorating Seasonable/Fashionable Products with Time Dependent Demand and Shortages

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K. Skouri

2009-01-01

Full Text Available An order level inventory model for seasonable/fashionable products subject to a period of increasing demand followed by a period of level demand and then by a period of decreasing demand rate (three branches ramp type demand rate is considered. The unsatisfied demand is partially backlogged with a time dependent backlogging rate. In addition, the product deteriorates with a time dependent, namely, Weibull, deterioration rate. The model is studied under the following different replenishment policies: (a starting with no shortages and (b starting with shortages. The optimal replenishment policy for the model is derived for both the above mentioned policies.

The effect of opioid receptor blockade on the neural processing of thermal stimuli.

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Eszter D Schoell

Full Text Available The endogenous opioid system represents one of the principal systems in the modulation of pain. This has been demonstrated in studies of placebo analgesia and stress-induced analgesia, where anti-nociceptive activity triggered by pain itself or by cognitive states is blocked by opioid antagonists. The aim of this study was to characterize the effect of opioid receptor blockade on the physiological processing of painful thermal stimulation in the absence of cognitive manipulation. We therefore measured BOLD (blood oxygen level dependent signal responses and intensity ratings to non-painful and painful thermal stimuli in a double-blind, cross-over design using the opioid receptor antagonist naloxone. On the behavioral level, we observed an increase in intensity ratings under naloxone due mainly to a difference in the non-painful stimuli. On the neural level, painful thermal stimulation was associated with a negative BOLD signal within the pregenual anterior cingulate cortex, and this deactivation was abolished by naloxone.

Reducing the substrate dependent scanner leveling effect in low-k1 contact printing

Science.gov (United States)

Chang, C. S.; Tseng, C. F.; Huang, C. H.; Yang, Elvis; Yang, T. H.; Chen, K. C.

2015-03-01

As the scaling down of design rule for high-density memory device, the small depth of focus (DoF) budget may be deteriorated by focus leveling errors, which arises in unpredicted reflectivity from multilayer structures on the topographic wafer. The leveling sensors of ASML scanner use near infrared (NIR) range wavelength which can penetrate through most of films using in semiconductor fabrication such as photo-resist, bottom anti reflective coating (BARC) and dielectric materials. Consequently, the reflected light from underlying substructures would disturb leveling sensors from accurate leveling. The different pattern densities and layout characteristics between array and periphery of a memory chip are expected to result in different leveling signals. Furthermore, the process dependent variations between wafer central and edge areas are also considered to yield different leveling performances during wafer exposure. In this study, lower blind contact immunity was observed for peripheral contacts comparing to the array contacts especially around wafer edge region. In order to overcome this problem, a series of investigations have been carried out. The wafer edge leveling optimization through circuit dependent focus edge clearance (CDFEC) option doesn't get improvement. Air gauge improved process leveling (AGILE) function of ASML immersion scanner doesn't show improved result either. The ILD uniformity improvement and step height treatments around wafer edge such as edge exclusion of film deposition and bevel etching are also ineffective to mitigate the blind contact problem of peripheral patterns. Altering the etch hard-mask stack is finally found to be an effective approach to alleviate the issue. For instance, through either containing high temperature deposition advanced patterning film (APF) in the hard-mask or inserting higher opaque film such as amorphous Si in between the hard-mask stack.

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

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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

Panel Data with Cross-Sectional Dependence Characterized by a Multi-Level Factor Structure

DEFF Research Database (Denmark)

Rodríguez-Caballero, Carlos Vladimir

A panel data model with a multi-level cross-sectional dependence is proposed. The factor structure is driven by top-level common factors as well as non-pervasive factors. I propose a simple method to filter out the full factor structure that overcomes limitations in standard procedures which may...... mix up both levels of unobservable factors and may hamper the identification of the model. The model covers both stationary and non-stationary cases and takes into account other relevant features that make the model well suited to the analysis of many types of time series frequently addressed...

Non-invasive pre-clinical MR imaging of prostate tumor hypoxia for radiation therapy prognosis

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Derek White

2014-03-01

Full Text Available Purpose: To investigate the usefulness of Oxygen-Enhanced Magnetic Resonance Imaging (OE-MRI changes in signal intensity related to oxygen challenge for predicting tumor response to radiation therapy.Methods: Dynamic MR signal changes were acquired using Varian 4.7T small animal MR scanner prior to image-guided radiation therapy (IGRT of small (n = 6 and large subcutaneous (n = 5 prostate tumors in adult male rats. An interleaved blood-oxygen level dependent (BOLD and tissue-oxygen level dependent (TOLD data acquisition or (IBT was performed using a baseline of medical air as positive control and using medical oxygen as a breathing challenge. BOLD used a 2-D multi-slice spoiled gradient-echo with multi-echo sequence. TOLD used a 2-D multi-slice spoiled gradient-echo sequence. Voxel changes in signal intensity were determined by a correlation coefficient mapping technique. Irradiation technique planned consisted of 1F × 15 Gy AP/PA or 2F × 7.5 Gy AP/PA to the gross tumor volume (GTV. Tumor growth measurements were recorded over time to assess the response to IGRT.Results: BOLD and TOLD signals variously illustrated positive or negative impulse responses in the tumor ROI due to inhaling medical oxygen. Correlation coefficient mapping demonstrated heterogeneity in tumors after inhaling medical oxygen. BOLD and TOLD signals exhibited increased changes in signal intensities after the first fraction of dose. Multi-fractionation had minimum effect until the second fraction of dose was applied. Tumor growth delays were observed when inhaling medical oxygen during IGRT.Conclusion: OE-MRI is a non-invasive imaging modality that can provide insight to the oxygen status of tumors. Observed increase percent changes in BOLD and TOLD signal intensities after the first fraction of dose suggest tumors experienced reoxygenation. OE-MRI could be used for predicting tumor response to IGRT when using medical oxygen for increasing GTV radiosensitivity, suggesting

Population-Level Density Dependence Influences the Origin and Maintenance of Parental Care.

Directory of Open Access Journals (Sweden)

Elijah Reyes

Full Text Available Parental care is a defining feature of animal breeding systems. We now know that both basic life-history characteristics and ecological factors influence the evolution of care. However, relatively little is known about how these factors interact to influence the origin and maintenance of care. Here, we expand upon previous work and explore the relationship between basic life-history characteristics (stage-specific rates of mortality and maturation and the fitness benefits associated with the origin and the maintenance of parental care for two broad ecological scenarios: the scenario in which egg survival is density dependent and the case in which adult survival is density dependent. Our findings suggest that high offspring need is likely critical in driving the origin, but not the maintenance, of parental care regardless of whether density dependence acts on egg or adult survival. In general, parental care is more likely to result in greater fitness benefits when baseline adult mortality is low if 1 egg survival is density dependent or 2 adult mortality is density dependent and mutant density is relatively high. When density dependence acts on egg mortality, low rates of egg maturation and high egg densities are less likely to lead to strong fitness benefits of care. However, when density dependence acts on adult mortality, high levels of egg maturation and increasing adult densities are less likely to maintain care. Juvenile survival has relatively little, if any, effect on the origin and maintenance of egg-only care. More generally, our results suggest that the evolution of parental care will be influenced by an organism's entire life history characteristics, the stage at which density dependence acts, and whether care is originating or being maintained.

Implicit Race Bias Decreases the Similarity of Neural Representations of Black and White Faces

OpenAIRE

Brosch, Tobias; Bar-David, Eyal; Phelps, Elizabeth A.

2013-01-01

Implicit race bias has been shown to affect decisions and behaviors. It may also change perceptual experience by increasing perceived differences between social groups. We investigated how this phenomenon may be expressed at the neural level by testing whether the distributed blood-oxygenation-level-dependent (BOLD) patterns representing Black and White faces are more dissimilar in participants with higher implicit race bias. We used multivoxel pattern analysis to predict the race of faces pa...

N-Acetylcysteine Normalizes Glutamate Levels in Cocaine-Dependent Patients: A Randomized Crossover Magnetic Resonance Spectroscopy Study

NARCIS (Netherlands)

Schmaal, Lianne; Veltman, Dick J.; Nederveen, Aart; van den Brink, Wim; Goudriaan, Anna E.

2012-01-01

Treatment with N-acetylcysteine (NAC) normalizes glutamate (Glu) homeostasis and prevents relapse in drug-dependent animals. However, the effect of NAC on brain Glu levels in substance-dependent humans has not yet been investigated. Proton magnetic resonance spectroscopy (H-1 MRS) was used to

N-Acetylcysteine Normalizes Glutamate Levels in Cocaine-Dependent Patients: A Randomized Crossover Magnetic Resonance Spectroscopy Study

NARCIS (Netherlands)

Schmaal, L.; Veltman, D.J.; Nederveen, A.; van den Brink, W.; Goudriaan, A.E.

2012-01-01

Treatment with N-acetylcysteine (NAC) normalizes glutamate (Glu) homeostasis and prevents relapse in drug-dependent animals. However, the effect of NAC on brain Glu levels in substance-dependent humans has not yet been investigated. Proton magnetic resonance spectroscopy (1 H MRS) was used to

Pulsed low-level infrared laser alters mRNA levels from muscle repair genes dependent on power output in Wistar rats

Science.gov (United States)

Trajano, L. A. S. N.; Trajano, E. T. L.; Thomé, A. M. C.; Sergio, L. P. S.; Mencalha, A. L.; Stumbo, A. C.; Fonseca, A. S.

2017-10-01

Satellite cells are present in skeletal muscle functioning in the repair and regeneration of muscle injury. Activation of these cells depends on the expression of myogenic factor 5 (Myf5), myogenic determination factor 1(MyoD), myogenic regulatory factor 4 (MRF4), myogenin (MyoG), paired box transcription factors 3 (Pax3), and 7 (Pax7). Low-level laser irradiation accelerates the repair of muscle injuries. However, data from the expression of myogenic factors have been controversial. Furthermore, the effects of different laser beam powers on the repair of muscle injuries have been not evaluated. The aim of this study was to evaluate the effects of low-level infrared laser at different powers and in pulsed emission mode on the expression of myogenic regulatory factors and on Pax3 and Pax7 in injured skeletal muscle from Wistar rats. Animals that underwent cryoinjury were divided into three groups: injury, injury laser 25 Mw, and injury laser 75 mW. Low-level infrared laser irradiation (904 nm, 3 J cm-2, 5 kHz) was carried out at 25 and 75 mW. After euthanasia, skeletal muscle samples were withdrawn and the total RNA was extracted for the evaluation of mRNA levels from the MyoD, MyoG, MRF4, Myf5, Pax3, and Pax7 gene. Pax 7 mRNA levels did not alter, but Pax3 mRNA levels increased in the injured and laser-irradiated group at 25 mW. MyoD, MyoG, and MYf5 mRNA levels increased in the injured and laser-irradiated animals at both powers, and MRF4 mRNA levels decreased in the injured and laser-irradiated group at 75 mW. In conclusion, exposure to pulsed low-level infrared laser, by power-dependent effect, could accelerate the muscle repair process altering mRNA levels from paired box transcription factors and myogenic regulatory factors.

Aspects of two-level systems under external time-dependent fields

Energy Technology Data Exchange (ETDEWEB)

Bagrov, V.G.; Wreszinski, W.F. [Tomsk State University and Tomsk Institute of High Current Electronics (Russian Federation); Barata, J.C.A.; Gitman D.M. [Universidade de Sao Paulo, Instituto de Fisica (Brazil)]. E-mails: jbarata@fma.if.usp.br; gitman@fma.if.usp.br

2001-12-14

The dynamics of two-level systems in time-dependent backgrounds is under consideration. We present some new exact solutions in special backgrounds decaying in time. On the other hand, following ideas of Feynman et al, we discuss in detail the possibility of reducing the quantum dynamics to a classical Hamiltonian system. This, in particular, opens the possibility of directly applying powerful methods of classical mechanics (e.g. KAM methods) to study the quantum system. Following such an approach, we draw conclusions of relevance for 'quantum chaos' when the external background is periodic or quasi-periodic in time. (author)

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.

Vitamin D Status in Population of Bukovyna and Subcarpathia Depending on Residence above Sea Level

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V.V. Povoroznyuk

2016-04-01

ding on the residence above sea level. Objective: to determine the level of vitamin D in the blood serum of people, who live in different regions of the Subcarpathia and Bukovyna, depending on the location of the settlement above sea le-vel. Material and methods. In the cross-sectional study, we have examined 353 individuals, aged 18 to 86 years, permanently residing in different parts of the Subcarpathia (Kolomyia, Kosiv, Verhovyna districts and Bukovyna (Vyzhny-tsia district. Results. Only in 28 cases (7.9 %, the content of 25(OHD in the blood serum was in the normal range, and in other cases (92.1 %, there was a deficiency and a lack of vitamin D. The severe form of vitamin D deficiency has been detected in 7 (1.9 % patients. When comparing the performance of 25(OHD in the areas of inspection, it was found that the level of vitamin D in the blood serum was significantly higher in residents of Verkhovyna and Kosiv districts (located higher than 450 meters above sea level as compared with residents of Vyzhnytsia and Kolomyia. Conclusion. The average level of vitamin D in the blood serum of the adult population depends on residence and increases with height above sea level.

Sex Differences in Stress Response Circuitry Activation Dependent on Female Hormonal Cycle

Science.gov (United States)

Goldstein, Jill M.; Jerram, Matthew; Abbs, Brandon; Whitfield-Gabrieli, Susan; Makris, Nikos

2010-01-01

Understanding sex differences in stress regulation has important implications for understanding basic physiological differences in the male and female brain and their impact on vulnerability to sex differences in chronic medical disorders associated with stress response circuitry. In this fMRI study, we demonstrated that significant sex differences in brain activity in stress response circuitry were dependent on women's menstrual cycle phase. Twelve healthy Caucasian premenopausal women were compared to a group of healthy men from the same population, based on age, ethnicity, education, and right-handedness. Subjects were scanned using negative valence/high arousal versus neutral visual stimuli that we demonstrated activated stress response circuitry (amygdala, hypothalamus, hippocampus, brainstem, orbitofrontal and medial prefrontal cortices (OFC and mPFC), and anterior cingulate gyrus (ACG). Women were scanned twice based on normal variation in menstrual cycle hormones (i.e., early follicular (EF) compared with late follicular-midcycle menstrual phases (LF/MC)). Using SPM8b, there were few significant differences in BOLD signal changes in men compared to EF women, except ventromedial (VMN) and lateral (LHA) hypothalamus, left amygdala, and ACG. In contrast, men exhibited significantly greater BOLD signal changes compared to LF/MC women on bilateral ACG and OFC, mPFC, LHA, VMN, hippocampus, and periaqueductal gray, with largest effect sizes in mPFC and OFC. Findings suggest that sex differences in stress response circuitry are hormonally regulated via the impact of subcortical brain activity on the cortical control of arousal, and demonstrate that females have been endowed with a natural hormonal capacity to regulate the stress response that differs from males. PMID:20071507

Functional evaluation of transplanted kidneys in normal function and acute rejection using BOLD MR imaging

International Nuclear Information System (INIS)

Xiao Wenbo; Xu Jingjing; Wang Qindong; Xu Ying; Zhang Minming

2012-01-01

In this study, we evaluated a large number of subjects using BOLD MRI to provide more information about oxygen metabolism in the normal function of transplanted kidneys and to distinguish acute graft rejection from normal function kidneys. This study included 122 subjects (20 volunteers, 72 patients with normal functioning transplants, and 21 patients with acute rejection), and 9 patients had normal function grafts received examination while grafts dysfunction occurred within 6 months during the follow-up. The R2* (1/s) values in the cortex and medulla as well as the R2* ratio of the medulla to cortex (R2* ratio of M/C) were recorded. The R2* values of the medulla were higher than those of the cortex in the normal function group and the volunteers which have a steep R2* ratio of M/C. All the R2* values in the acute rejection group were lower than those in the normal function grafts group (P 1.1) is an important reason for keeping clinical normal function.

Using novel control groups to dissect the amygdala's role in Williams syndrome.

Science.gov (United States)

Thornton-Wells, Tricia A; Avery, Suzanne N; Blackford, Jennifer Urbano

2011-07-01

Williams syndrome is a neurodevelopmental disorder with an intriguing behavioral phenotype-hypersociability combined with significant non-social fears. Previous studies have demonstrated abnormalities in amygdala function in individuals with Williams syndrome compared to typically-developing controls. However, it remains unclear whether the findings are related to the atypical neurodevelopment of Williams syndrome, or are also associated with behavioral traits at the extreme end of a normal continuum. We used functional magnetic resonance imaging (fMRI) to compare amygdala blood-oxygenation-level-dependent (BOLD) responses to non-social and social images in individuals with Williams syndrome compared to either individuals with inhibited temperament (high non-social fear) or individuals with uninhibited temperament (high sociability). Individuals with Williams syndrome had larger amygdala BOLD responses when viewing the non-social fear images than the inhibited temperament control group. In contrast, when viewing both fear and neutral social images, individuals with Williams syndrome did not show smaller amygdala BOLD responses relative to the uninhibited temperament control group, but instead had amygdala responses proportionate to their sociability. These results suggest heightened amygdala response to non-social fear images is characteristic of WS, whereas, variability in amygdala response to social fear images is proportionate to, and might be explained by, levels of trait sociability.

Sensing the effects of mouth breathing by using 3-tesla MRI

Science.gov (United States)

Park, Chan-A.; Kang, Chang-Ki

2017-06-01

We investigated the effects of mouth breathing and typical nasal breathing on brain function by using blood-oxygenation-level-dependent (BOLD) functional magnetic resonance imaging (fMRI). The study had two parts: the first test was a simple contrast between mouth and nasal breathing, and the second test involved combined breathing modes, e.g., mouth inspiration and nasal expiration. Eleven healthy participants performed the combined breathing task while undergoing 3T fMRI. In the group-level analysis, contrast images acquired by using an individual participantlevel analysis were processed using the one-sample t test. We also conducted a region-of-interest analysis comparing signal intensity changes between the breathing modes; the region was selected using an automated anatomical labeling map. The results demonstrated that the BOLD signal in the hippocampus and brainstem was significantly decreased in mouth breathing relative to nasal breathing. On the other hand, both the precentral and postcentral gyri showed activation that was more significant in mouth breathing compared to nasal breathing. This study suggests that the BOLD activity patterns between mouth and nasal breathing may be induced differently, especially in the hippocampus, which could provide clues to explain the effects on brain cognitive function due to mouth breathing.

Resting-state FMRI confounds and cleanup

Science.gov (United States)

Murphy, Kevin; Birn, Rasmus M.; Bandettini, Peter A.

2013-01-01

The goal of resting-state functional magnetic resonance imaging (FMRI) is to investigate the brain’s functional connections by using the temporal similarity between blood oxygenation level dependent (BOLD) signals in different regions of the brain “at rest” as an indicator of synchronous neural activity. Since this measure relies on the temporal correlation of FMRI signal changes between different parts of the brain, any non-neural activity-related process that affects the signals will influence the measure of functional connectivity, yielding spurious results. To understand the sources of these resting-state FMRI confounds, this article describes the origins of the BOLD signal in terms of MR physics and cerebral physiology. Potential confounds arising from motion, cardiac and respiratory cycles, arterial CO2 concentration, blood pressure/cerebral autoregulation, and vasomotion are discussed. Two classes of techniques to remove confounds from resting-state BOLD time series are reviewed: 1) those utilising external recordings of physiology and 2) data-based cleanup methods that only use the resting-state FMRI data itself. Further methods that remove noise from functional connectivity measures at a group level are also discussed. For successful interpretation of resting-state FMRI comparisons and results, noise cleanup is an often over-looked but essential step in the analysis pipeline. PMID:23571418

Response of single bacterial cells to stress gives rise to complex history dependence at the population level

Science.gov (United States)

Mathis, Roland; Ackermann, Martin

2016-01-01

Most bacteria live in ever-changing environments where periods of stress are common. One fundamental question is whether individual bacterial cells have an increased tolerance to stress if they recently have been exposed to lower levels of the same stressor. To address this question, we worked with the bacterium Caulobacter crescentus and asked whether exposure to a moderate concentration of sodium chloride would affect survival during later exposure to a higher concentration. We found that the effects measured at the population level depended in a surprising and complex way on the time interval between the two exposure events: The effect of the first exposure on survival of the second exposure was positive for some time intervals but negative for others. We hypothesized that the complex pattern of history dependence at the population level was a consequence of the responses of individual cells to sodium chloride that we observed: (i) exposure to moderate concentrations of sodium chloride caused delays in cell division and led to cell-cycle synchronization, and (ii) whether a bacterium would survive subsequent exposure to higher concentrations was dependent on the cell-cycle state. Using computational modeling, we demonstrated that indeed the combination of these two effects could explain the complex patterns of history dependence observed at the population level. Our insight into how the behavior of single cells scales up to processes at the population level provides a perspective on how organisms operate in dynamic environments with fluctuating stress exposure. PMID:26960998

Mycorrhizal dependency of mangaba tree under increasing phosphorus levels Dependência micorrízica de mangabeira em doses crescentes de fósforo

Directory of Open Access Journals (Sweden)

Júlio Alves Cardoso Filho

2008-07-01

Full Text Available The objective of this study was to evaluate the mycorrhizal dependency of mangaba tree (Hancornia speciosa plantlets, under increasing levels of phosphorus fertilization. The experimental design was completely randomized in a 4×5 factorial arrangement with three mycorrhizal fungi inocula - Gigaspora margarita, Glomus etunicatum, or a pool of native mycorrhizal fungi (Acaulospora longula, Glomus clarum, Gigaspora albida, Paraglomus sp. -, and a nonmycorrhizal control, in combination with five levels of phosphorus applied to the substrate: 0, 25, 50, 75, and 100 mg kg-1. After 180 days of growth, plantlets with inoculation of native mycorrhizal pool produced more shoot and root dry biomass and had higher shoot phosphorus content and accumulation. The noninoculated control showed the lowest values, independently of the phosphorus level. The highest relative mycorrhizal dependency occurred with the inoculation of native mycorrhizal fungi. Plants with mycorrhizal fungi did not respond to phosphorus addition above 50 mg kg-1. Mangaba tree is highly dependent on mycorrhiza, but the degree of dependency varies according to phosphorus levels and fungal inocula. In general, mangaba tree is more responsive to mycorrhizal fungi inoculation than to phosphorus addition.O objetivo deste trabalho foi avaliar a dependência micorrízica de mudas de mangaba (Hancornia speciosa, em doses crescentes de fósforo. O delineamento experimental foi inteiramente casualizado, em arranjo fatorial 4´5 com três inóculos de fungos micorrízicos - Gigaspora margarita, Glomus etunicatum, ou uma mistura de espécies de fungos micorrízicos nativos (Acaulospora longula, Glomus clarum, Gigaspora albida e Paraglomus sp. -, e um controle não micorrízico, combinados a cinco doses de fósforo no substrato: 0, 25, 50, 75 e 100 mg kg-1. Após 180 dias, as mudas com inoculação dos fungos micorrízicos nativos produziram mais biomassa seca de parte aérea e raízes e apresentaram

Orientation-specific contextual modulation of the fMRI BOLD response to luminance and chromatic gratings in human visual cortex.

Science.gov (United States)

McDonald, J Scott; Seymour, Kiley J; Schira, Mark M; Spehar, Branka; Clifford, Colin W G

2009-05-01

The responses of orientation-selective neurons in primate visual cortex can be profoundly affected by the presence and orientation of stimuli falling outside the classical receptive field. Our perception of the orientation of a line or grating also depends upon the context in which it is presented. For example, the perceived orientation of a grating embedded in a surround tends to be repelled from the predominant orientation of the surround. Here, we used fMRI to investigate the basis of orientation-specific surround effects in five functionally-defined regions of visual cortex: V1, V2, V3, V3A/LO1 and hV4. Test stimuli were luminance-modulated and isoluminant gratings that produced responses similar in magnitude. Less BOLD activation was evident in response to gratings with parallel versus orthogonal surrounds across all the regions of visual cortex investigated. When an isoluminant test grating was surrounded by a luminance-modulated inducer, the degree of orientation-specific contextual modulation was no larger for extrastriate areas than for V1, suggesting that the observed effects might originate entirely in V1. However, more orientation-specific modulation was evident in extrastriate cortex when both test and inducer were luminance-modulated gratings than when the test was isoluminant; this difference was significant in area V3. We suggest that the pattern of results in extrastriate cortex may reflect a refinement of the orientation-selectivity of surround suppression specific to the colour of the surround or, alternatively, processes underlying the segmentation of test and inducer by spatial phase or orientation when no colour cue is available.

Analysis of Two-Level Support Systems with Time-Dependent Overflow - A Banking Application

DEFF Research Database (Denmark)

Barth, Wolfgang; Manitz, Michael; Stolletz, Raik

2010-01-01

In this paper, we analyze the performance of call centers of financial service providers with two levels of support and a time-dependent overflow mechanism. Waiting calls from the front-office queue flow over to the back office if a waiting-time limit is reached and at least one back-office agent...

Functional magnetic resonance imaging in awake transgenic fragile X rats: evidence of dysregulation in reward processing in the mesolimbic/habenular neural circuit.

Science.gov (United States)

Kenkel, W M; Yee, J R; Moore, K; Madularu, D; Kulkarni, P; Gamber, K; Nedelman, M; Ferris, C F

2016-03-22

Anxiety and social deficits, often involving communication impairment, are fundamental clinical features of fragile X syndrome. There is growing evidence that dysregulation in reward processing is a contributing factor to the social deficits observed in many psychiatric disorders. Hence, we hypothesized that transgenic fragile X mental retardation 1 gene (fmr1) KO (FX) rats would display alterations in reward processing. To this end, awake control and FX rats were imaged for changes in blood oxygen level dependent (BOLD) signal intensity in response to the odor of almond, a stimulus to elicit the innate reward response. Subjects were 'odor naive' to this evolutionarily conserved stimulus. The resulting changes in brain activity were registered to a three-dimensional segmented, annotated rat atlas delineating 171 brain regions. Both wild-type (WT) and FX rats showed robust brain activation to a rewarding almond odor, though FX rats showed an altered temporal pattern and tended to have a higher number of voxels with negative BOLD signal change from baseline. This pattern of greater negative BOLD was especially apparent in the Papez circuit, critical to emotional processing and the mesolimbic/habenular reward circuit. WT rats showed greater positive BOLD response in the supramammillary area, whereas FX rats showed greater positive BOLD response in the dorsal lateral striatum, and greater negative BOLD response in the retrosplenial cortices, the core of the accumbens and the lateral preoptic area. When tested in a freely behaving odor-investigation paradigm, FX rats failed to show the preference for almond odor which typifies WT rats. However, FX rats showed investigation profiles similar to WT when presented with social odors. These data speak to an altered processing of this highly salient novel odor in the FX phenotype and lend further support to the notion that altered reward systems in the brain may contribute to fragile X syndrome symptomology.

Neural correlate of resting-state functional connectivity under α2 adrenergic receptor agonist, medetomidine.

Science.gov (United States)

Nasrallah, Fatima A; Lew, Si Kang; Low, Amanda Si-Min; Chuang, Kai-Hsiang

2014-01-01

Correlative fluctuations in functional MRI (fMRI) signals across the brain at rest have been taken as a measure of functional connectivity, but the neural basis of this resting-state MRI (rsMRI) signal is not clear. Previously, we found that the α2 adrenergic agonist, medetomidine, suppressed the rsMRI correlation dose-dependently but not the stimulus evoked activation. To understand the underlying electrophysiology and neurovascular coupling, which might be altered due to the vasoconstrictive nature of medetomidine, somatosensory evoked potential (SEP) and resting electroencephalography (EEG) were measured and correlated with corresponding BOLD signals in rat brains under three dosages of medetomidine. The SEP elicited by electrical stimulation to both forepaws was unchanged regardless of medetomidine dosage, which was consistent with the BOLD activation. Identical relationship between the SEP and BOLD signal under different medetomidine dosages indicates that the neurovascular coupling was not affected. Under resting state, EEG power was the same but a depression of inter-hemispheric EEG coherence in the gamma band was observed at higher medetomidine dosage. Different from medetomidine, both resting EEG power and BOLD power and coherence were significantly suppressed with increased isoflurane level. Such reduction was likely due to suppressed neural activity as shown by diminished SEP and BOLD activation under isoflurane, suggesting different mechanisms of losing synchrony at resting-state. Even though, similarity between electrophysiology and BOLD under stimulation and resting-state implicates a tight neurovascular coupling in both medetomidine and isoflurane. Our results confirm that medetomidine does not suppress neural activity but dissociates connectivity in the somatosensory cortex. The differential effect of medetomidine and its receptor specific action supports the neuronal origin of functional connectivity and implicates the mechanism of its sedative

Novel fMRI working memory paradigm accurately detects cognitive impairment in multiple sclerosis.

Science.gov (United States)

Nelson, Flavia; Akhtar, Mohammad A; Zúñiga, Edward; Perez, Carlos A; Hasan, Khader M; Wilken, Jeffrey; Wolinsky, Jerry S; Narayana, Ponnada A; Steinberg, Joel L

2017-05-01

Cognitive impairment (CI) cannot be diagnosed by magnetic resonance imaging (MRI). Functional magnetic resonance imaging (fMRI) paradigms, such as the immediate/delayed memory task (I/DMT), detect varying degrees of working memory (WM). Preliminary findings using I/DMT showed differences in blood oxygenation level dependent (BOLD) activation between impaired (MSCI, n = 12) and non-impaired (MSNI, n = 9) multiple sclerosis (MS) patients. The aim of the study was to confirm CI detection based on I/DMT BOLD activation in a larger cohort of MS patients. The role of T2 lesion volume (LV) and Expanded Disability Status Scale (EDSS) in magnitude of BOLD signal was also sought. A total of 50 patients (EDSS mean ( m) = 3.2, disease duration (DD) m = 12 years, and age m = 40 years) underwent the Minimal Assessment of Cognitive Function in Multiple Sclerosis (MACFIMS) and I/DMT. Working memory activation (WMa) represents BOLD signal during DMT minus signal during IMT. CI was based on MACFIMS. A total of 10 MSNI, 30 MSCI, and 4 borderline patients were included in the analyses. Analysis of variance (ANOVA) showed MSNI had significantly greater WMa than MSCI, in the left prefrontal cortex and left supplementary motor area ( p = 0.032). Regression analysis showed significant inverse correlations between WMa and T2 LV/EDSS in similar areas ( p = 0.005, 0.004, respectively). I/DMT-based BOLD activation detects CI in MS. Larger studies are needed to confirm these findings.

The time-course of cortico-limbic neural responses to air hunger.

Science.gov (United States)

Binks, Andrew P; Evans, Karleyton C; Reed, Jeffrey D; Moosavi, Shakeeb H; Banzett, Robert B

2014-12-01

Several studies have mapped brain regions associated with acute dyspnea perception. However, the time-course of brain activity during sustained dyspnea is unknown. Our objective was to determine the time-course of neural activity when dyspnea is sustained. Eight healthy subjects underwent brain blood oxygen level dependent functional magnetic imaging (BOLD-fMRI) during mechanical ventilation with constant mild hypercapnia (∼ 45 mm Hg). Subjects rated dyspnea (air hunger) via visual analog scale (VAS). Tidal volume (V(T)) was alternated every 90 s between high VT (0.96 ± 0.23 L) that provided respiratory comfort (12 ± 6% full scale) and low V(T) (0.48 ± 0.08 L) which evoked air hunger (56 ± 11% full scale). BOLD signal was extracted from a priori brain regions and combined with VAS data to determine air hunger related neural time-course. Air hunger onset was associated with BOLD signal increases that followed two distinct temporal profiles within sub-regions of the anterior insula, anterior cingulate and prefrontal cortices (cortico-limbic circuitry): (1) fast, BOLD signal peak 40s. BOLD signal during air hunger offset followed fast and slow temporal profiles symmetrical, but inverse (signal decreases) to the time-courses of air hunger onset. We conclude that differential cortico-limbic circuit elements have unique contributions to dyspnea sensation over time. We suggest that previously unidentified sub-regions are responsible for either the acute awareness or maintenance of dyspnea. These data enhance interpretation of previous studies and inform hypotheses for future dyspnea research. Copyright © 2014 Elsevier B.V. All rights reserved.

Being asked to tell an unpleasant truth about another person activates anterior insula and medial prefrontal cortex.

Science.gov (United States)

Littlefield, Melissa M; Dietz, Martin J; Fitzgerald, Des; Knudsen, Kasper J; Tonks, James

2015-01-01

"Truth" has been used as a baseline condition in several functional magnetic resonance imaging (fMRI) studies of deception. However, like deception, telling the truth is an inherently social construct, which requires consideration of another person's mental state, a phenomenon known as Theory of Mind. Using a novel ecological paradigm, we examined blood oxygenation level dependent (BOLD) responses during social and simple truth telling. Participants (n = 27) were randomly divided into two competing teams. Post-competition, each participant was scanned while evaluating performances from in-group and out-group members. Participants were asked to be honest and were told that their evaluations would be made public. We found increased BOLD responses in the medial prefrontal cortex, bilateral anterior insula and precuneus when participants were asked to tell social truths compared to simple truths about another person. At the behavioral level, participants were slower at responding to social compared to simple questions about another person. These findings suggest that telling the truth is a nuanced cognitive operation that is dependent on the degree of mentalizing. Importantly, we show that the cortical regions engaged by truth telling show a distinct pattern when the task requires social reasoning.

Regional Reproducibility of BOLD Calibration Parameter M, OEF and Resting-State CMRO2 Measurements with QUO2 MRI.

Directory of Open Access Journals (Sweden)

Isabelle Lajoie

Full Text Available The current generation of calibrated MRI methods goes beyond simple localization of task-related responses to allow the mapping of resting-state cerebral metabolic rate of oxygen (CMRO2 in micromolar units and estimation of oxygen extraction fraction (OEF. Prior to the adoption of such techniques in neuroscience research applications, knowledge about the precision and accuracy of absolute estimates of CMRO2 and OEF is crucial and remains unexplored to this day. In this study, we addressed the question of methodological precision by assessing the regional inter-subject variance and intra-subject reproducibility of the BOLD calibration parameter M, OEF, O2 delivery and absolute CMRO2 estimates derived from a state-of-the-art calibrated BOLD technique, the QUantitative O2 (QUO2 approach. We acquired simultaneous measurements of CBF and R2* at rest and during periods of hypercapnia (HC and hyperoxia (HO on two separate scan sessions within 24 hours using a clinical 3 T MRI scanner. Maps of M, OEF, oxygen delivery and CMRO2, were estimated from the measured end-tidal O2, CBF0, CBFHC/HO and R2*HC/HO. Variability was assessed by computing the between-subject coefficients of variation (bwCV and within-subject CV (wsCV in seven ROIs. All tests GM-averaged values of CBF0, M, OEF, O2 delivery and CMRO2 were: 49.5 ± 6.4 mL/100 g/min, 4.69 ± 0.91%, 0.37 ± 0.06, 377 ± 51 μmol/100 g/min and 143 ± 34 μmol/100 g/min respectively. The variability of parameter estimates was found to be the lowest when averaged throughout all GM, with general trends toward higher CVs when averaged over smaller regions. Among the MRI measurements, the most reproducible across scans was R2*0 (wsCVGM = 0.33% along with CBF0 (wsCVGM = 3.88% and R2*HC (wsCVGM = 6.7%. CBFHC and R2*HO were found to have a higher intra-subject variability (wsCVGM = 22.4% and wsCVGM = 16% respectively, which is likely due to propagation of random measurement errors, especially for CBFHC due to the

Self-perceived level of competitiveness, tension, and dependency and lifestyles in the 'Seguimiento Universidad de Navarra' cohort study.

Science.gov (United States)

Unzueta, C R; Lahortiga-Ramos, F; Santiago, S; Zazpe, I; Molero, P; Sánchez-Villegas, A; Martínez-González, M A

2018-04-01

The objective of this study is to assess the differences in lifestyles according to levels of self-perceived competitiveness, psychological tension, and dependency in a Mediterranean cohort of university graduates. Levels of personality traits, food consumption, nutrient intake, eating attitudes, physical activity, sedentary lifestyle, and alcohol and tobacco consumption were assessed through a questionnaire administered at baseline. This was a cross-sectional study in the context of the Seguimiento Universidad de Navarra cohort. Participants are 15,346 Spanish adults. Participants with a high level of self-perceived competitiveness consumed more vegetables and fish but less refined grains; they had higher protein intake and healthier eating attitudes. They were more physically active and less likely to be smokers. Participants with a high level of tension or dependency were less physically active, and participants more dependent also had poorer adherence to the Mediterranean diet. Self-perceived personality traits, especially the trait of competitiveness, are likely to be associated with healthier dietary patterns, better nutrient profile, better eating attitudes, physical activity, and less exposure to smoking. The use of short questions about self-perceived levels of competitiveness, psychological tension, and dependency can contribute to add additional information when assessing lifestyles and diet in adults. Copyright © 2018 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.

Models of consumer behavior of households depending on the income level

Directory of Open Access Journals (Sweden)

Melnikova A.S.

2016-11-01

Full Text Available the consumer behavior of households is defined by a complex of internal and external factors: income of the population, motives and incentives of behavior, behavioral norms and personal preferences. As the example of structure analysis of the income and expenses of households of Sverdlovsk region during research models of consumer behavior of households are allocated, characteristics and structure of the population depending on their welfare are allocated. Author's approach allows forecasting of the consumer market, proceeding from the socio-economic factors forming the level of the population income in the region.

On the Perpetual American Put Options for Level Dependent Volatility Models with Jumps

OpenAIRE

Bayraktar, Erhan

2007-01-01

We prove that the perpetual American put option price of level dependent volatility model with compound Poisson jumps is convex and is the classical solution of its associated quasi-variational inequality, that it is $C^2$ except at the stopping boundary and that it is $C^1$ everywhere (i.e. the smooth pasting condition always holds).

Influence of time dependent effects on the disposal environments of low and intermediate level radioactive wastes

International Nuclear Information System (INIS)

1984-12-01

Reviews are presented firstly of potential events and processes which may affect the evolution of the disposal environments of low and intermediate level radioactive wastes in Britain and secondly of previous studies carried out worldwide in the field of time dependent effects. From the latter review available methodologies for incorporating time dependence into radiological assessments are identified. Finally, proposals are presented for the design and development of a time dependent effects model, based on the existing far field state model (FFSM) developed for ONWI in USA. (author)

Neurofeedback fMRI-mediated learning and consolidation of regional brain activation during motor imagery

Science.gov (United States)

Yoo, Seung-Schik; Lee, Jong-Hwan; O’Leary, Heather; Panych, Lawrence P.; Jolesz, Ferenc A.

2009-01-01

We report the long-term effect of real-time functional MRI (rtfMRI) training on voluntary regulation of the level of activation from a hand motor area. During the performance of a motor imagery task of a right hand, blood-oxygenation-level-dependent (BOLD) signal originating from a primary motor area was presented back to the subject in real-time. Demographically matched individuals also received the same procedure without valid feedback information. Followed by the initial rtfMRI sessions, both groups underwent two-week long, daily-practice of the task. Off-line data analysis revealed that the individuals in the experimental group were able to increase the level of BOLD signal from the regulatory target to a greater degree compared to the control group. Furthermore, the learned level of activation was maintained after the two-week period, with the recruitment of additional neural circuitries such as the hippocampus and the limbo-thalamo-cortical pathway. The activation obtained from the control group, in the absence of proper feedback, was indifferent across the training conditions. The level of BOLD activity from the target regulatory region was positively correlated with a self evaluative score within the experimental group, while the majority of control subjects had difficulty adopting a strategy to attain the desired level of functional regulation. Our results suggest that rtfMRI helped individuals learn how to increase region-specific cortical activity associated with a motor imagery task, and the level of increased activation in motor areas was consolidated after the two-week self-practice period, with the involvement of neural circuitries implicated in motor skill learning. PMID:19526048

Load-dependent dysfunction of the putamen during attentional processing in patients with clinically isolated syndrome suggestive of multiple sclerosis.

Science.gov (United States)

Tortorella, C; Romano, R; Direnzo, V; Taurisano, P; Zoccolella, S; Iaffaldano, P; Fazio, L; Viterbo, R; Popolizio, T; Blasi, G; Bertolino, A; Trojano, M

2013-08-01

Load-related functional magnetic resonance imaging (fMRI) abnormalities of brain activity during performance of attention tasks have been described in definite multiple sclerosis (MS). No data are available in clinically isolated syndrome (CIS) suggestive of MS. The objective of this research is to evaluate in CIS patients the fMRI pattern of brain activation during an attention task and to explore the effect of increasing task load demand on neurofunctional modifications. Twenty-seven untreated CIS patients and 32 age- and sex-matched healthy controls (HCs) underwent fMRI while performing the Variable Attentional Control (VAC) task, a cognitive paradigm requiring increasing levels of attentional control processing. Random-effects models were used for statistical analyses of fMRI data. CIS patients had reduced accuracy and greater reaction time at the VAC task compared with HCs (p=0.007). On blood oxygenation level-dependent (BOLD)-fMRI, CIS patients had greater activity in the right parietal cortex (p=0.0004) compared with HCs. Furthermore, CIS patients had greater activity at the lower (p=0.05) and reduced activity at the greater (p=0.04) level of attentional control demand in the left putamen, compared with HCs. This study demonstrates the failure of attentional control processing in CIS. The load-related fMRI dysfunction of the putamen supports the role of basal ganglia in the failure of attention observed at the earliest stage of MS.

Cortical deactivation induced by visual stimulation in human slow-wave sleep

DEFF Research Database (Denmark)

Born, Alfred Peter; Law, Ian; Lund, Torben E

2002-01-01

. It is unresolved whether this negative BOLD response pattern is of developmental neurobiological origin particular to a given age or to a general effect of sleep or sedative drugs. To further elucidate this issue, we used fMRI and positron emission tomography (PET) to study the brain activation pattern during......It has previously been demonstrated that sleeping and sedated young children respond with a paradoxical decrease in the blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) signal in the rostro-medial occipital visual cortex during visual stimulation...... visual stimulation in spontaneously sleeping adult volunteers. In five sleeping volunteers fMRI studies confirmed a robust signal decrease during stimulation in the rostro-medial occipital cortex. A similar relative decrease at the same location was found during visual stimulation...

Correlation between near-infrared spectroscopy and magnetic resonance imaging of rat brain oxygenation modulation

International Nuclear Information System (INIS)

Chen Yu; Tailor, Dharmesh R; Intes, Xavier; Chance, Britton

2003-01-01

We measure the tissue oxygen and haemoglobin concentrations in the rat brain during modulation of inhaled oxygen concentration (FiO 2 ), using non-invasive frequency domain near-infrared oximetry. The rise in oxygenated haemoglobin concentration and the decline in deoxygenated haemoglobin concentration are demonstrated in correspondence with the modulation of FiO 2 , which is changed from 20% to 100% in increments of 20%. Furthermore, the tissue oxygenation saturation also shows the corresponding trend and changes ranging from approximately 70% to 90%. The relative changes in deoxygenated haemoglobin concentration are compared to the blood-oxygenation-level-dependent (BOLD) MRI signal recorded during a similar FiO 2 protocol. A linear relationship with high correlation coefficient between the relative changes in the BOLD MRI signal and the NIRS signal is observed

Correlation between near-infrared spectroscopy and magnetic resonance imaging of rat brain oxygenation modulation

Energy Technology Data Exchange (ETDEWEB)

Chen Yu [Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA (United States); Tailor, Dharmesh R [Department of Bioengineering, University of Pennsylvania, Philadelphia, PA (United States); Intes, Xavier [Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA (United States); Chance, Britton [Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA (United States)

2003-02-21

We measure the tissue oxygen and haemoglobin concentrations in the rat brain during modulation of inhaled oxygen concentration (FiO{sub 2}), using non-invasive frequency domain near-infrared oximetry. The rise in oxygenated haemoglobin concentration and the decline in deoxygenated haemoglobin concentration are demonstrated in correspondence with the modulation of FiO{sub 2}, which is changed from 20% to 100% in increments of 20%. Furthermore, the tissue oxygenation saturation also shows the corresponding trend and changes ranging from approximately 70% to 90%. The relative changes in deoxygenated haemoglobin concentration are compared to the blood-oxygenation-level-dependent (BOLD) MRI signal recorded during a similar FiO{sub 2} protocol. A linear relationship with high correlation coefficient between the relative changes in the BOLD MRI signal and the NIRS signal is observed.

Cognitive control in auditory working memory is enhanced in musicians

DEFF Research Database (Denmark)

Pallesen, Karen Johanne; Brattico, Elvira; Bailey, Christopher J

2010-01-01

focus on task-relevant stimuli, a skill which is crucial to working memory. We measured the blood oxygenation-level dependent (BOLD) activation signal in musicians and non-musicians during working memory of musical sounds to determine the relation among performance, musical competence and generally...... hemisphere, and bilaterally in the posterior dorsal prefrontal cortex and anterior cingulate gyrus. The relationship between the task performance and the magnitude of the BOLD response was more positive in musicians than in non-musicians, particularly during the most difficult working memory task....... The results confirm previous findings that neural activity increases during enhanced working memory performance. The results also suggest that superior working memory task performance in musicians rely on an enhanced ability to exert sustained cognitive control. This cognitive benefit in musicians may...

An Analysis of Some Variables Affecting the Internet Dependency Level of Turkish Adolescents by Using Decision Tree Methods

Science.gov (United States)

Kayri, Murat; Gunuc, Selim

2010-01-01

Internet dependency is going to expand into social life in wide area whereas it has been accepted as a pathological and psychological disease. Knowing the basic effects of internet dependency is an inevitable approach to use the internet technology healthy. In this study, internet dependency levels of 754 students were examined with the Internet…

Correlation analysis between bone density measured by quantitative CT and blood sugar level of aged patients with non-insulin-dependent diabetes mellitus

International Nuclear Information System (INIS)

Wang Guizhi; Liang Ping; Qiao Junhua; Liu Chunyan

2008-01-01

Objective: To approach the correlation between the bone density measured by quantitative CT and the blood sugar level of the aged patients with non-insulin-dependent diabetes mellitus, and observe the effects of the blood sugar level on the bone density. Methods: The lumbar bone densities and the blood sugar levels of 160 aged patients with non-insulin-dependent diabetes mellitus (hyperglycemia group 80 cases, euglycemia group 80 cases ) and the healthy aged people (80 cases) were detected by quantitative CT and serum biochemical detection; the correlation between the blood sugar level and the bone density and the osteoporosis occurrence status of aged people in various groups were analyzed. Results: The bone density in the non-insulin-dependent diabetes and hyperglycemia group was lower than those in normal (control) group and non-insulin-dependent diabetes and euglycemia group (P<0.05); the morbility of osteoporosis in the non-insulin-dependent diabetes and hyperglycemia group was higher than those in normal (control) group and non-insulin-dependent diabetes and euglycemia group (P<0.05); negative correlation was found between the bone density and the blood sugar level (aged male group: r=-0.7382, P=0.0013; aged female group: r=-0.8343, P=0.0007). Conclusion: The blood sugar level affects the bone density of the aged patients with non-insulin-dependent diabetes mellitus; the higher the blood sugar level, the lower the bone density. The non-insulin-dependent diabetes aged patients with hyperglycemia have the liability of osteoporosis. (authors)

Multi-Level Simulated Fault Injection for Data Dependent Reliability Analysis of RTL Circuit Descriptions

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NIMARA, S.

2016-02-01

Full Text Available This paper proposes data-dependent reliability evaluation methodology for digital systems described at Register Transfer Level (RTL. It uses a hybrid hierarchical approach, combining the accuracy provided by Gate Level (GL Simulated Fault Injection (SFI and the low simulation overhead required by RTL fault injection. The methodology comprises the following steps: the correct simulation of the RTL system, according to a set of input vectors, hierarchical decomposition of the system into basic RTL blocks, logic synthesis of basic RTL blocks, data-dependent SFI for the GL netlists, and RTL SFI. The proposed methodology has been validated in terms of accuracy on a medium sized circuit – the parallel comparator used in Check Node Unit (CNU of the Low-Density Parity-Check (LDPC decoders. The methodology has been applied for the reliability analysis of a 128-bit Advanced Encryption Standard (AES crypto-core, for which the GL simulation was prohibitive in terms of required computational resources.

Recognition for old Arabic manuscripts using spatial gray level dependence (SGLD

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Ahmad M. Abd Al-Aziz

2011-03-01

Full Text Available Texture analysis forms the basis of object recognition and classification in several domains, one of these domains is historical document manuscripts because the manuscripts hold our culture heritage and also large numbers of undated manuscripts exist. This paper presents results for historical document classification of old Arabic manuscripts using texture analysis and a segmentation free approach. The main objective is to discriminate between historical documents of different writing styles to three different ages: Contemporary (Modern Age, Ottoman Age and Mamluk Age. This classification depends on a Spatial Gray-level Dependence (SGLD technique which provides eight distinct texture features for each sample document. We applied Stepwise Discriminant Analysis and Multiple discriminant analysis methods to decrease the dimensionality of features and extract training vector features from samples. To classify historical documents into three main historical age classes the decision tree classification is applied. The system has been tested on 48 Arabic historical manuscripts documents from the Dar Al-Kotob Al-Masria Library. Our results so far yield 95.83% correct classification for the historical Arabic documents.

Personality, foraging behavior and specialization: integrating behavioral and food web ecology at the individual level.

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Toscano, Benjamin J; Gownaris, Natasha J; Heerhartz, Sarah M; Monaco, Cristián J

2016-09-01

Behavioral traits and diet were traditionally thought to be highly plastic within individuals. This view was espoused in the widespread use of optimality models, which broadly predict that individuals can modify behavioral traits and diet across ecological contexts to maximize fitness. Yet, research conducted over the past 15 years supports an alternative view; fundamental behavioral traits (e.g., activity level, exploration, sociability, boldness and aggressiveness) and diet often vary among individuals and this variation persists over time and across contexts. This phenomenon has been termed animal personality with regard to behavioral traits and individual specialization with regard to diet. While these aspects of individual-level phenotypic variation have been thus far studied in isolation, emerging evidence suggests that personality and individual specialization may covary, or even be causally related. Building on this work, we present the overarching hypothesis that animal personality can drive specialization through individual differences in various aspects of consumer foraging behavior. Specifically, we suggest pathways by which consumer personality traits influence foraging activity, risk-dependent foraging, roles in social foraging groups, spatial aspects of foraging and physiological drivers of foraging, which in turn can lead to consistent individual differences in food resource use. These pathways provide a basis for generating testable hypotheses directly linking animal personality to ecological dynamics, a major goal in contemporary behavioral ecology.

Spinal cord injury-induced immune deficiency syndrome enhances infection susceptibility dependent on lesion level.

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Brommer, Benedikt; Engel, Odilo; Kopp, Marcel A; Watzlawick, Ralf; Müller, Susanne; Prüss, Harald; Chen, Yuying; DeVivo, Michael J; Finkenstaedt, Felix W; Dirnagl, Ulrich; Liebscher, Thomas; Meisel, Andreas; Schwab, Jan M

2016-03-01

Pneumonia is the leading cause of death after acute spinal cord injury and is associated with poor neurological outcome. In contrast to the current understanding, attributing enhanced infection susceptibility solely to the patient's environment and motor dysfunction, we investigate whether a secondary functional neurogenic immune deficiency (spinal cord injury-induced immune deficiency syndrome, SCI-IDS) may account for the enhanced infection susceptibility. We applied a clinically relevant model of experimental induced pneumonia to investigate whether the systemic SCI-IDS is functional sufficient to cause pneumonia dependent on spinal cord injury lesion level and investigated whether findings are mirrored in a large prospective cohort study after human spinal cord injury. In a mouse model of inducible pneumonia, high thoracic lesions that interrupt sympathetic innervation to major immune organs, but not low thoracic lesions, significantly increased bacterial load in lungs. The ability to clear the bacterial load from the lung remained preserved in sham animals. Propagated immune susceptibility depended on injury of central pre-ganglionic but not peripheral postganglionic sympathetic innervation to the spleen. Thoracic spinal cord injury level was confirmed as an independent increased risk factor of pneumonia in patients after motor complete spinal cord injury (odds ratio = 1.35, P spinal cord injury directly causes increased risk for bacterial infection in mice as well as in patients. Besides obvious motor and sensory paralysis, spinal cord injury also induces a functional SCI-IDS ('immune paralysis'), sufficient to propagate clinically relevant infection in an injury level dependent manner. © The Author (2016). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

On the dependence of the OH* Meinel emission altitude on vibrational level: SCIAMACHY observations and model simulations

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J. P. Burrows

2012-09-01

Full Text Available Measurements of the OH Meinel emissions in the terrestrial nightglow are one of the standard ground-based techniques to retrieve upper mesospheric temperatures. It is often assumed that the emission peak altitudes are not strongly dependent on the vibrational level, although this assumption is not based on convincing experimental evidence. In this study we use Envisat/SCIAMACHY (Scanning Imaging Absorption spectroMeter for Atmospheric CHartographY observations in the near-IR spectral range to retrieve vertical volume emission rate profiles of the OH(3-1, OH(6-2 and OH(8-3 Meinel bands in order to investigate whether systematic differences in emission peak altitudes can be observed between the different OH Meinel bands. The results indicate that the emission peak altitudes are different for the different vibrational levels, with bands originating from higher vibrational levels having higher emission peak altitudes. It is shown that this finding is consistent with the majority of the previously published results. The SCIAMACHY observations yield differences in emission peak altitudes of up to about 4 km between the OH(3-1 and the OH(8-3 band. The observations are complemented by model simulations of the fractional population of the different vibrational levels and of the vibrational level dependence of the emission peak altitude. The model simulations reproduce the observed vibrational level dependence of the emission peak altitude well – both qualitatively and quantitatively – if quenching by atomic oxygen as well as multi-quantum collisional relaxation by O2 is considered. If a linear relationship between emission peak altitude and vibrational level is assumed, then a peak altitude difference of roughly 0.5 km per vibrational level is inferred from both the SCIAMACHY observations and the model simulations.

Local activity determines functional connectivity in the resting human brain: a simultaneous FDG-PET/fMRI study.

Science.gov (United States)

Riedl, Valentin; Bienkowska, Katarzyna; Strobel, Carola; Tahmasian, Masoud; Grimmer, Timo; Förster, Stefan; Friston, Karl J; Sorg, Christian; Drzezga, Alexander

2014-04-30

Over the last decade, synchronized resting-state fluctuations of blood oxygenation level-dependent (BOLD) signals between remote brain areas [so-called BOLD resting-state functional connectivity (rs-FC)] have gained enormous relevance in systems and clinical neuroscience. However, the neural underpinnings of rs-FC are still incompletely understood. Using simultaneous positron emission tomography/magnetic resonance imaging we here directly investigated the relationship between rs-FC and local neuronal activity in humans. Computational models suggest a mechanistic link between the dynamics of local neuronal activity and the functional coupling among distributed brain regions. Therefore, we hypothesized that the local activity (LA) of a region at rest determines its rs-FC. To test this hypothesis, we simultaneously measured both LA (glucose metabolism) and rs-FC (via synchronized BOLD fluctuations) during conditions of eyes closed or eyes open. During eyes open, LA increased in the visual system, and the salience network (i.e., cingulate and insular cortices) and the pattern of elevated LA coincided almost exactly with the spatial pattern of increased rs-FC. Specifically, the voxelwise regional profile of LA in these areas strongly correlated with the regional pattern of rs-FC among the same regions (e.g., LA in primary visual cortex accounts for ∼ 50%, and LA in anterior cingulate accounts for ∼ 20% of rs-FC with the visual system). These data provide the first direct evidence in humans that local neuronal activity determines BOLD FC at rest. Beyond its relevance for the neuronal basis of coherent BOLD signal fluctuations, our procedure may translate into clinical research particularly to investigate potentially aberrant links between local dynamics and remote functional coupling in patients with neuropsychiatric disorders.

Vertex Stimulation as a Control Site for Transcranial Magnetic Stimulation: A Concurrent TMS/fMRI Study.

Science.gov (United States)

Jung, JeYoung; Bungert, Andreas; Bowtell, Richard; Jackson, Stephen R

2016-01-01

A common control condition for transcranial magnetic stimulation (TMS) studies is to apply stimulation at the vertex. An assumption of vertex stimulation is that it has relatively little influence over on-going brain processes involved in most experimental tasks, however there has been little attempt to measure neural changes linked to vertex TMS. Here we directly test this assumption by using a concurrent TMS/fMRI paradigm in which we investigate fMRI blood-oxygenation-level-dependent (BOLD) signal changes across the whole brain linked to vertex stimulation. Thirty-two healthy participants to part in this study. Twenty-one were stimulated at the vertex, at 120% of resting motor threshold (RMT), with short bursts of 1 Hz TMS, while functional magnetic resonance imaging (fMRI) BOLD images were acquired. As a control condition, we delivered TMS pulses over the left primary motor cortex using identical parameters to 11 other participants. Vertex stimulation did not evoke increased BOLD activation at the stimulated site. By contrast we observed widespread BOLD deactivations across the brain, including regions within the default mode network (DMN). To examine the effects of vertex stimulation a functional connectivity analysis was conducted. The results demonstrated that stimulating the vertex with suprathreshold TMS reduced neural activity in brain regions related to the DMN but did not influence the functional connectivity of this network. Our findings provide brain imaging evidence in support of the use of vertex simulation as a control condition in TMS but confirm that vertex TMS induces regional widespread decreases in BOLD activation. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

A novel Bayesian approach to accounting for uncertainty in fMRI-derived estimates of cerebral oxygen metabolism fluctuations.

Science.gov (United States)

Simon, Aaron B; Dubowitz, David J; Blockley, Nicholas P; Buxton, Richard B

2016-04-01

Calibrated blood oxygenation level dependent (BOLD) imaging is a multimodal functional MRI technique designed to estimate changes in cerebral oxygen metabolism from measured changes in cerebral blood flow and the BOLD signal. This technique addresses fundamental ambiguities associated with quantitative BOLD signal analysis; however, its dependence on biophysical modeling creates uncertainty in the resulting oxygen metabolism estimates. In this work, we developed a Bayesian approach to estimating the oxygen metabolism response to a neural stimulus and used it to examine the uncertainty that arises in calibrated BOLD estimation due to the presence of unmeasured model parameters. We applied our approach to estimate the CMRO2 response to a visual task using the traditional hypercapnia calibration experiment as well as to estimate the metabolic response to both a visual task and hypercapnia using the measurement of baseline apparent R2' as a calibration technique. Further, in order to examine the effects of cerebral spinal fluid (CSF) signal contamination on the measurement of apparent R2', we examined the effects of measuring this parameter with and without CSF-nulling. We found that the two calibration techniques provided consistent estimates of the metabolic response on average, with a median R2'-based estimate of the metabolic response to CO2 of 1.4%, and R2'- and hypercapnia-calibrated estimates of the visual response of 27% and 24%, respectively. However, these estimates were sensitive to different sources of estimation uncertainty. The R2'-calibrated estimate was highly sensitive to CSF contamination and to uncertainty in unmeasured model parameters describing flow-volume coupling, capillary bed characteristics, and the iso-susceptibility saturation of blood. The hypercapnia-calibrated estimate was relatively insensitive to these parameters but highly sensitive to the assumed metabolic response to CO2. Copyright © 2016 Elsevier Inc. All rights reserved.

A novel Bayesian approach to accounting for uncertainty in fMRI-derived estimates of cerebral oxygen metabolism fluctuations

Science.gov (United States)

Simon, Aaron B.; Dubowitz, David J.; Blockley, Nicholas P.; Buxton, Richard B.

2016-01-01

Calibrated blood oxygenation level dependent (BOLD) imaging is a multimodal functional MRI technique designed to estimate changes in cerebral oxygen metabolism from measured changes in cerebral blood flow and the BOLD signal. This technique addresses fundamental ambiguities associated with quantitative BOLD signal analysis; however, its dependence on biophysical modeling creates uncertainty in the resulting oxygen metabolism estimates. In this work, we developed a Bayesian approach to estimating the oxygen metabolism response to a neural stimulus and used it to examine the uncertainty that arises in calibrated BOLD estimation due to the presence of unmeasured model parameters. We applied our approach to estimate the CMRO2 response to a visual task using the traditional hypercapnia calibration experiment as well as to estimate the metabolic response to both a visual task and hypercapnia using the measurement of baseline apparent R2′ as a calibration technique. Further, in order to examine the effects of cerebral spinal fluid (CSF) signal contamination on the measurement of apparent R2′, we examined the effects of measuring this parameter with and without CSF-nulling. We found that the two calibration techniques provided consistent estimates of the metabolic response on average, with a median R2′-based estimate of the metabolic response to CO2 of 1.4%, and R2′- and hypercapnia-calibrated estimates of the visual response of 27% and 24%, respectively. However, these estimates were sensitive to different sources of estimation uncertainty. The R2′-calibrated estimate was highly sensitive to CSF contamination and to uncertainty in unmeasured model parameters describing flow-volume coupling, capillary bed characteristics, and the iso-susceptibility saturation of blood. The hypercapnia-calibrated estimate was relatively insensitive to these parameters but highly sensitive to the assumed metabolic response to CO2. PMID:26790354

How doctors diagnose diseases and prescribe treatments: an fMRI study of diagnostic salience

OpenAIRE

Melo, Marcio; Gusso, Gustavo D. F.; Levites, Marcelo; Amaro Jr., Edson; Massad, Eduardo; Lotufo, Paulo A.; Zeidman, Peter; Price, Cathy J.; Friston, Karl J.

2017-01-01

Understanding the brain mechanisms involved in diagnostic reasoning may contribute to the development of methods that reduce errors in medical practice. In this study we identified similar brain systems for diagnosing diseases, prescribing treatments, and naming animals and objects using written information as stimuli. Employing time resolved modeling of blood oxygen level dependent (BOLD) responses enabled time resolved (400 milliseconds epochs) analyses. With this approach it was possible t...

Methodological Improvements in Combining TMS and Functional MRI

OpenAIRE

Moisa, Marius

2011-01-01

Since 1997, when Bohning and colleagues demonstrated for the first time the feasibility of interleaving transcranial magnetic stimulation (TMS) with blood oxygenation level dependency functional magnetic resonance imaging (BOLD fMRI), this combination became a very promising techniques to study brain connectivity. However, the implementation of a reliable setup for interleaved TMS/fMRI is still technically challenging. In this thesis, I intended to further explore and develop methodological i...

Principles of Functional Magnetic Resonance Imaging and its Applications in Cognitive Neuroscience

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Şule Tınaz

2005-02-01

Full Text Available Functional magnetic resonance imaging (fMRI is a neuroimaging technique that provides brain activation maps with a spatial resolution of a few millimeters. The BOLD (blood oxygenation level dependent fMRI method is the most commonly used technique. It measures the hemodynamic response to neural activity. The BOLD fMRI signal is based on the magnetic properties of the oxygenated / deoxygenated hemoglobin which is the oxygen carrier in blood. FMRI is noninvasive, and unlike in positron emission tomography (PET individuals are not exposed to radiation. This allows data collection from the same individual over multiple sessions. The relatively high temporal resolution of fMRI compared to PET provides flexibility in experimental designs of cognitive tasks. In this paper we review the key principles of MRI physics, and the underlying metabolic, hemodynamic, and electrophysiological mechanisms of BOLD signal. We introduce frequently used experimental design paradigms and present examples. Next, we give an overview of theoretical considerations and applications of analysis methods in fMRI time series. Neural network modeling based on fMRI data is also discussed. Finally, we present an ongoing study in our laboratory to demonstrate the application of design types and analysis methods

Renal Tissue Oxygenation in Essential Hypertension and Chronic Kidney Disease

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Menno Pruijm

2013-01-01

Full Text Available Animal studies suggest that renal tissue hypoxia plays an important role in the development of renal damage in hypertension and renal diseases, yet human data were scarce due to the lack of noninvasive methods. Over the last decade, blood oxygenation level-dependent magnetic resonance imaging (BOLD-MRI, detecting deoxyhemoglobin in hypoxic renal tissue, has become a powerful tool to assess kidney oxygenation noninvasively in humans. This paper provides an overview of BOLD-MRI studies performed in patients suffering from essential hypertension or chronic kidney disease (CKD. In line with animal studies, acute changes in cortical and medullary oxygenation have been observed after the administration of medication (furosemide, blockers of the renin-angiotensin system or alterations in sodium intake in these patient groups, underlining the important role of renal sodium handling in kidney oxygenation. In contrast, no BOLD-MRI studies have convincingly demonstrated that renal oxygenation is chronically reduced in essential hypertension or in CKD or chronically altered after long-term medication intake. More studies are required to clarify this discrepancy and to further unravel the role of renal oxygenation in the development and progression of essential hypertension and CKD in humans.

Integrative curriculum reform, domain dependent knowing, and teachers` epistemological theories: Implications for middle-level teaching

Energy Technology Data Exchange (ETDEWEB)

Powell, R.R. [Texas Tech Univ., Lubbock, TX (United States). College of Education

1998-12-01

Integrative curriculum as both a theoretical construct and a practical reality, and as a theme-based, problem-centered, democratic way of schooling, is becoming more widely considered as a feasible alternative to traditional middle-level curricula. Importantly for teaching and learning, domain dependence requires teachers to view one area of knowledge as fully interdependent with other areas of knowledge during the learning process. This requires teachers to adopt personal epistemological theories that reflect integrative, domain dependent knowing. This study explored what happened when teachers from highly traditional domain independent school settings encountered an ambitious college-level curriculum project that was designed to help the teachers understand the potential that integrative, domain dependent teaching holds for precollege settings. This study asked: What influence does an integrative, domain dependent curriculum project have on teachers` domain independent, epistemological theories for teaching and learning? Finding an answer to this question is essential if we, as an educational community, are to understand how integrative curriculum theory is transformed by teachers into systemic curriculum reform. The results suggest that the integrative curriculum project that teachers participated in did not explicitly alter their classroom practices in a wholesale manner. Personal epistemological theories of teachers collectively precluded teachers from making any wholesale changes in their individual classroom teaching. However, teachers became aware of integrative curriculum as an alternative, and they expressed interest in infusing integrative practices into their classrooms as opportunities arise.

Investigating the Neural Bases for Intra-Subject Cognitive Efficiency Using Functional Magnetic Resonance Imaging

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Neena K. Rao

2014-10-01

Full Text Available Several fMRI studies have examined brain regions mediating inter-subject variability in cognitive efficiency, but none have examined regions mediating intra-subject variability in efficiency. Thus, the present study was designed to identify brain regions involved in intra-subject variability in cognitive efficiency via participant-level correlations between trial-level reaction time (RT and trial-level fMRI BOLD percent signal change on a processing speed task. On each trial, participants indicated whether a digit-symbol probe-pair was present or absent in an array of nine digit-symbol probe-pairs while fMRI data were collected. Deconvolution analyses, using RT time-series models (derived from the proportional scaling of an event-related hemodynamic response function model by trial-level RT, were used to evaluate relationships between trial-level RTs and BOLD percent signal change. Although task-related patterns of activation and deactivation were observed in regions including bilateral occipital, bilateral parietal, portions of the medial wall such as the precuneus, default mode network regions including anterior cingulate, posterior cingulate, bilateral temporal, right cerebellum, and right cuneus, RT-BOLD correlations were observed in a more circumscribed set of regions. Positive RT-related patterns, or RT-BOLD correlations where fast RTs were associated with lower BOLD percent signal change, were observed in regions including bilateral occipital, bilateral parietal, and the precuneus. RT-BOLD correlations were not observed in the default mode network indicating a smaller set of regions associated with intra-subject variability in cognitive efficiency. The results are discussed in terms of a distributed area of regions that mediate variability in the cognitive efficiency that might underlie processing speed differences between individuals.

MORTALITY FROM SUICIDE AND ALCOHOLISM, DEPENDING ON THE LEVEL OF ALCOHOL CONSUMPTION

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L. A. Radkevich

2017-01-01

Full Text Available According to WHO, the world takes place every year approximately 500 000 suicides and suicide attempts of 7 million. Since 1994, Russia ranks 2nd in the world after Lithuania, in the level of suicides, and is among the countries with the linear dependence of frequency of suicides on the level of alcohol consumption.Purpose. Install a quantitative connection between the frequency of suicide with alcohol consumption and mortality from alcoholism in the world.Material and method. For studies we used the mortality coefficient (MK from suicide and alcohol abuse (number of people/100 thousand of age standardized the population in 159 countries according to the WHO in 2004, the average daily consumption levels of alcoholic beverages: spirits, wine and beer (g/person/day according to the FAO (Food and Agriculture Organization of the United Nations. For data analysis we used correlation and regression methods.Results. We found significant positive correlation of mortality coefficient (MK from suicide for men and women with consumption of alcoholic beverages (spirits, wine and beer and mortality from alcoholism. The gender differences are revealed. Included in the regression model independent variables (levels of alcohol consumption and mortality from alcoholism explain 66% and 52% of the variability in the frequency of suicides of men and women (dependent variables. A complete rejection of the consumption of alcohol reduces the MK from suicide of men in the world at 39.5 percent, in Russia — at 76.5%; women — 37.9%, in Russia — by 54.3%. According to the regression analysis the average daily level of consumption of strong alcohol in the world is 10.4 g (3.8 kg per year for men, in Russia — 91.8 g (of 33.5 kg per year. The increase in the consumption of strong alcohol to 3 g per day (1 kg per year increases the MK from suicide in men up to 10.8% (1.6 people in the world, in Russia — 2.4% (1.6 people. The increase in the MK of alcoholism of men

WHO Better Outcomes in Labour Difficulty (BOLD) project: innovating to improve quality of care around the time of childbirth.

Science.gov (United States)

Oladapo, Olufemi T; Souza, João Paulo; Bohren, Meghan A; Tunçalp, Özge; Vogel, Joshua P; Fawole, Bukola; Mugerwa, Kidza; Gülmezoglu, A Metin

2015-05-26

As most pregnancy-related deaths and morbidities are clustered around the time of childbirth, quality of care during this period is critical to the survival of pregnant women and their babies. Despite the wide acceptance of partograph as the central tool to optimize labour outcomes for over 40 years, its use has not successfully improved outcomes in many settings for several reasons. There are also increasing questions about the validity and applicability of its central feature - "the alert line" - to all women regardless of their labour characteristics. Apart from the known deficiencies in labour care, attempts to improve quality of care in low resource settings have also failed to address and integrate women's birth experience into quality improvement processes. It was against this background that the World Health Organization (WHO) embarked on the Better Outcomes in Labour Difficulty (BOLD) project to improve the quality of intrapartum care in low- and middle-income countries. The main goal of the BOLD project is to reduce intrapartum-related stillbirths, maternal and newborn mortalities and morbidities by addressing the critical barriers to the process of good quality intrapartum care and enhancing the connection between health systems and communities. The project seeks to achieve this goal by (1) developing an evidence-based, easy to use, labour monitoring-to-action decision-support tool (currently termed Simplified, Effective, Labour Monitoring-to-Action - SELMA); and (2) by developing innovative service prototypes/tools, co-designed with users of health services (women, their families and communities) and health providers, to promote access to respectful, dignified and emotionally supportive care for pregnant women and their companions at the time of birth ("Passport to Safer Birth"). This two-pronged approach is expected to positively impact on important domains of quality of care relating to both provision and experience of care. In this paper, we briefly

Effects of BDNF receptor antagonist on the severity of physical and psychological dependence, morphine-induced locomotor sensitization and the ventral tegmental area-nucleus accumbens BDNF levels in morphine- dependent and withdrawn rats.

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Khalil-Khalili, Masoumeh; Rashidy-Pour, Ali; Bandegi, Ahmad Reza; Yousefi, Behpoor; Jorjani, Hassan; Miladi-Gorji, Hossein

2018-03-06

This study examined the effects of systemic administration of the TrkB receptor antagonist (ANA-12) on the severity of physical and psychological dependence and morphine-induced locomotor sensitization, the ventral tegmental area (VTA)-nucleus accumbens (NAc) BDNF levels in morphine-dependent and withdrawn rats. Rats were injected with bi-daily doses (10 mg/kg, at 12 h intervals) of morphine for 10 days. Then, rats were tested for naloxone-precipitated morphine withdrawal signs, the anxiety (the elevated plus maze-EPM) after the last morphine injection and injection of ANA12 (ip). Also, morphine-induced locomotor sensitization was evaluated after morphine challenge followed by an injection of ANA-12 in morphine-withdrawn rats. The VTA-NAc BDNF levels were assessed in morphine-dependent and withdrawn rats. The overall Gellert-Holtzman score was significantly higher in morphine-dependent rats receiving ANA-12 than in those receiving saline. Also, the percentage of time spent in the open arms in control and morphine-dependent rats receiving ANA-12 were higher compared to the Cont/Sal and D/Sal rats, respectively. There was no significant difference in the locomotor activity and the VTA-NAc BDNF levels between D/Sal/morphine and D/ANA-12/morphine groups after morphine withdrawal. We conclude that the systemic administration of ANA-12 exacerbates the severity of physical dependence on morphine and partially attenuates the anxiety-like behavior in morphine-dependent rats. However, ANA-12 did not affect morphine-induced locomotor sensitization and the VTA-NAc BDNF levels in morphine-dependent and withdrawn rats. Copyright © 2017 Elsevier B.V. All rights reserved.

Carbamazepine reduces memory induced activation of mesial temporal lobe structures: a pharmacological fMRI-study

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Okujava Michael

2001-11-01

Full Text Available Abstract Background and Purpose It is not known whether carbamazepine (CBZ; a drug widely used in neurology and psychiatry influences the blood oxygenation level dependent (BOLD contrast changes induced by neuronal activation and measured by functional MRI (fMRI. We aimed to investigate the influence of CBZ on memory induced activation of the mesial temporal lobes in patients with symptomatic temporal lobe epilepsy (TLE. Material and Methods Twenty-one individual patients with refractory symptomatic TLE with different CBZ serum levels and 20 healthy controls were studied using BOLD fMRI. Mesial temporal lobe (MTL activation was induced by a task that is based on the retrieval of individually familiar visuo-spatial knowledge. The extent of significant MTL fMRI activation was measured and correlated with the CBZ serum level. Results In TLE patients, the extent of significant fMRI activation over both MTL was negatively correlated to the CBZ serum level (Spearman r = -0.654, P Conclusions In TLE patients, carbamazepine reduces the fMRI-detectable changes within the mesial temporal lobes as induced by effortful memory retrieval. FMRI appears to be suitable to study the effects of chronic drug treatment in patients with epilepsy.

Modeling the time-varying and level-dependent effects of the medial olivocochlear reflex in auditory nerve responses.

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Smalt, Christopher J; Heinz, Michael G; Strickland, Elizabeth A

2014-04-01

The medial olivocochlear reflex (MOCR) has been hypothesized to provide benefit for listening in noisy environments. This advantage can be attributed to a feedback mechanism that suppresses auditory nerve (AN) firing in continuous background noise, resulting in increased sensitivity to a tone or speech. MOC neurons synapse on outer hair cells (OHCs), and their activity effectively reduces cochlear gain. The computational model developed in this study implements the time-varying, characteristic frequency (CF) and level-dependent effects of the MOCR within the framework of a well-established model for normal and hearing-impaired AN responses. A second-order linear system was used to model the time-course of the MOCR using physiological data in humans. The stimulus-level-dependent parameters of the efferent pathway were estimated by fitting AN sensitivity derived from responses in decerebrate cats using a tone-in-noise paradigm. The resulting model uses a binaural, time-varying, CF-dependent, level-dependent OHC gain reduction for both ipsilateral and contralateral stimuli that improves detection of a tone in noise, similarly to recorded AN responses. The MOCR may be important for speech recognition in continuous background noise as well as for protection from acoustic trauma. Further study of this model and its efferent feedback loop may improve our understanding of the effects of sensorineural hearing loss in noisy situations, a condition in which hearing aids currently struggle to restore normal speech perception.

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

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

2014-01-01

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...... and asymptomatic hemispheres during the interictal phase and between migraine patients and controls. BOLD responses were selectively increased in the symptomatic hemispheres. This was found in the inferior parietal lobule (P = 0.002), the inferior frontal gyrus (P = 0.003), and the superior parietal lobule (P = 0.......017). The affected cortical areas comprise a visually driven functional network involved in oculomotor control, guidance of movement, motion perception, visual attention, and visual spatial memory. The patients also had significantly increased response in the same cortical areas when compared to controls (P

Functional MRI of the visual cortex and visual testing in patients with previous optic neuritis

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Langkilde, Annika Reynberg; Frederiksen, J.L.; Rostrup, Egill

2002-01-01

of the activated area and the signal change following ON, and compared the results with results of neuroophthalmological testing. We studied nine patients with previous acute ON and 10 healthy persons served as controls using fMRI with visual stimulation. In addition to a reduced activated volume, patients showed...... a reduced blood oxygenation level dependent (BOLD) signal increase and a greater asymmetry in the visual cortex, compared with controls. The volume of visual cortical activation was significantly correlated to the result of the contrast sensitivity test. The BOLD signal increase correlated significantly......The volume of cortical activation as detected by functional magnetic resonance imaging (fMRI) in the visual cortex has previously been shown to be reduced following optic neuritis (ON). In order to understand the cause of this change, we studied the cortical activation, both the size...

Simultaneous fMRI-PET of the opioidergic pain system in human brain

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Wey, Hsiao-Ying; Catana, Ciprian; Hooker, Jacob M

2014-01-01

distinct components of the blood oxygenation level dependent (BOLD) fMRI signal has not yet been shown. We obtained sixteen fMRI-PET data sets from eight healthy volunteers. Each subject participated in randomized order in a pain scan and a control (nonpainful pressure) scan on the same day. Dynamic PET......MRI and PET provide complementary information for studying brain function. While the potential use of simultaneous MRI/PET for clinical diagnostic and disease staging has been demonstrated recently; the biological relevance of concurrent functional MRI-PET brain imaging to dissect neurochemically...... data were acquired with an opioid radioligand, [(11)C]diprenorphine, to detect endogenous opioid releases in response to pain. BOLD fMRI data were collected at the same time to capture hemodynamic responses. In this simultaneous human fMRI-PET imaging study, we show co-localized responses in thalamus...

Objective methods for the assessment of the spinal and supraspinal effects of opioids

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Fischer, Iben W; Hansen, Tine M; Lelic, Dina

2017-01-01

: The literature search was conducted in Pub Med (http://www.ncbi.nlm.nih.gov/pubmed) from November 2014 to June 2016, using free-text terms: "opioid", "morphine" and "oxycodone" combined with the terms "pupillometry," "magnetic resonance spectroscopy," "fMRI," "BOLD," "PET," "pharmaco-EEG", "electroencephalogram...... imaging (fMRI), positron emission tomography (PET), spontaneous electroencephalogram (EEG) and evoked potentials (EPs). Pupillometry is a non-invasive tool used in research as well as in the clinical setting. Proton magnetic resonance spectroscopy has been used for the last decades and it is a non......-invasive technique for measurement of in vivo brain metabolite concentrations. fMRI has been a widely used non-invasive method to estimate brain activity, where typically from the blood oxygen level-dependent (BOLD) signal. PET is a nuclear imaging technique based on tracing radio labeled molecules injected...

Task-dependent output of human parasternal intercostal motor units across spinal levels.

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Hudson, Anna L; Gandevia, Simon C; Butler, Jane E

2017-12-01

During breathing, there is differential activity in the human parasternal intercostal muscles and the activity is tightly coupled to the known mechanical advantages for inspiration of the same regions of muscles. It is not known whether differential activity is preserved for the non-respiratory task of ipsilateral trunk rotation. In the present study, we compared single motor units during resting breathing and axial rotation of the trunk during apnoea. We not only confirmed non-uniform recruitment of motor units across parasternal intercostal muscles in breathing, but also demonstrated that the same motor units show an altered pattern of recruitment in the non-respiratory task of trunk rotation. The output of parasternal intercostal motoneurones is modulated differently across spinal levels depending on the task and these results help us understand the mechanisms that may govern task-dependent differences in motoneurone output. During inspiration, there is differential activity in the human parasternal intercostal muscles across interspaces. We investigated whether the earlier recruitment of motor units in the rostral interspaces compared to more caudal spaces during inspiration is preserved for the non-respiratory task of ipsilateral trunk rotation. Single motor unit activity (SMU) was recorded from the first, second and fourth parasternal interspaces on the right side in five participants in two tasks: resting breathing and 'isometric' axial rotation of the trunk during apnoea. Recruitment of the same SMUs was compared between tasks (n = 123). During resting breathing, differential activity was indicated by earlier recruitment of SMUs in the first and second interspaces compared to the fourth space in inspiration (P motor units showed an altered pattern of recruitment because SMUs in the first interspace were recruited later and at a higher rotation torque than those in the second and fourth interspaces (P recruitment measures, was good-excellent [intraclass

A Systems-Level Approach to Building Sustainable Assessment Cultures: Moderation, Quality Task Design and Dependability of Judgement

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Colbert, Peta; Wyatt-Smith, Claire; Klenowski, Val

2012-01-01

This article considers the conditions that are necessary at system and local levels for teacher assessment to be valid, reliable and rigorous. With sustainable assessment cultures as a goal, the article examines how education systems can support local-level efforts for quality learning and dependable teacher assessment. This is achieved through…

Atherosclerotic renal artery stenosis is associated with elevated cell cycle arrest markers related to reduced renal blood flow and postcontrast hypoxia.

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Saad, Ahmed; Wang, Wei; Herrmann, Sandra M S; Glockner, James F; Mckusick, Michael A; Misra, Sanjay; Bjarnason, Haraldur; Lerman, Lilach O; Textor, Stephen C

2016-11-01

Atherosclerotic renal artery stenosis (ARAS) reduces renal blood flow (RBF), ultimately leading to kidney hypoxia and inflammation. Insulin-like growth factor binding protein-7 (IGFBP-7) and tissue inhibitor of metalloproteinases-2 (TIMP-2) are biomarkers of cell cycle arrest, often increased in ischemic conditions and predictive of acute kidney injury (AKI). This study sought to examine the relationships between renal vein levels of IGFBP-7, TIMP-2, reductions in RBF and postcontrast hypoxia as measured by blood oxygen level-dependent (BOLD) magnetic resonance imaging. Renal vein levels of IGFBP-7 and TIMP-2 were obtained in an ARAS cohort (n= 29) scheduled for renal artery stenting and essential hypertensive (EH) healthy controls (n = 32). Cortical and medullary RBFs were measured by multidetector computed tomography (CT) immediately before renal artery stenting and 3 months later. BOLD imaging was performed before and 3 months after stenting in all patients, and a subgroup (N = 12) underwent repeat BOLD imaging 24 h after CT/stenting to examine postcontrast/procedure levels of hypoxia. Preintervention IGFBP-7 and TIMP-2 levels were elevated in ARAS compared with EH (18.5 ± 2.0 versus 15.7 ± 1.5 and 97.4 ± 23.1 versus 62.7 ± 9.2 ng/mL, respectively; Pblood flow (r = -0.59, P= 0.004). These data demonstrate elevated IGFBP-7 and TIMP-2 levels in ARAS as a function of the degree of reduced RBF. Elevated baseline IGFBP-7 levels were associated with protection against postimaging hypoxia, consistent with 'ischemic preconditioning'. Despite contrast injection and stenting, AKI in these high-risk ARAS subjects with elevated IGFBP-7/TIMP-2 was rare and did not affect long-term kidney function. © The Author 2016. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved.

Association between tobacco industry denormalization beliefs, tobacco control community discontent and smokers' level of nicotine dependence.

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Kushnir, Vladyslav; Selby, Peter; Cunningham, John A

2013-07-01

Tobacco industry denormalization (TID) informs the public about the tobacco industry's role in the tobacco epidemic and is an important component of a comprehensive tobacco control strategy. Although TID beliefs have been noted in adult smokers and associated with intent to quit, research has not evaluated whether they are affected by smokers' level of nicotine dependence. The present article sought to concurrently examine how attitudes towards the tobacco industry and tobacco control groups may differ among smokers of varying levels of nicotine dependence. In addition, it evaluated how these attitudes and beliefs may be associated with smokers' intentions to reduce or quit smoking. A random digit dialing telephone survey was conducted of 889 Canadian current daily smokers, 18 years and older. Attitudes towards the tobacco industry were mixed among the entire cohort and differences in beliefs towards the tobacco industry were not found among smokers of varying levels of nicotine dependence. However, smokers that held strong TID beliefs were 5 times more intent to quit smoking than those without such beliefs. Compared to smokers with low level of nicotine dependence, heavy smokers were more likely to report strong overall displeasure with the tobacco control community (OR=1.98, 95% CI=1.23-3.19, p=0.005), however there were no differences with regards to future intent to quit. The absence of strong negative sentiment toward the tobacco industry among smokers as a whole suggests that more targeted anti-industry messages are needed, raising greater awareness of tobacco industry practices within smokers and non-smokers alike. As heavier smokers' discontent with the tobacco control community highlights increasing social disapproval and pressure to quit smoking, future educational and media strategies used for smoking cessation purposes may benefit from emphasizing more of the positive attributes associated with quitting smoking, as opposed to the negative features of

Insulin sensitivity affects corticolimbic brain responses to visual food cues in polycystic ovary syndrome patients.

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Alsaadi, Hanin M; Van Vugt, Dean A

2015-11-01

This study examined the effect of insulin sensitivity on the responsiveness of appetite regulatory brain regions to visual food cues. Nineteen participants diagnosed with polycystic ovary syndrome (PCOS) were divided into insulin-sensitive (n=8) and insulin-resistant (n=11) groups based on the homeostatic model assessment of insulin resistance (HOMA2-IR). Subjects underwent functional magnetic resonance imaging (fMRI) while viewing food pictures following water or dextrose consumption. The corticolimbic blood oxygen level dependent (BOLD) responses to high-calorie (HC) or low-calorie (LC) food pictures were compared within and between groups. BOLD responses to food pictures were reduced during a glucose challenge in numerous corticolimbic brain regions in insulin-sensitive but not insulin-resistant subjects. Furthermore, the degree of insulin resistance positively correlated with the corticolimbic BOLD response in the medial prefrontal cortex (mPFC), orbitofrontal cortex (OFC), anterior cingulate and ventral tegmental area (VTA) in response to HC pictures, and in the dorsolateral prefrontal cortex (DLPFC), mPFC, anterior cingulate, and insula in response to LC pictures following a glucose challenge. BOLD signal in the OFC, midbrain, hippocampus, and amygdala following a glucose challenge correlated with HOMA2-IR in response to HC-LC pictures. We conclude that the normal inhibition of corticolimbic brain responses to food pictures during a glucose challenge is compromised in insulin-resistant subjects. The increase in brain responsiveness to food pictures during postprandial hyperinsulinemia may lead to greater non-homeostatic eating and perpetuate obesity in insulin-resistant subjects.

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

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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

Fish Oil Supplementation Increases Event-Related Posterior Cingulate Activation in Older Adults with Subjective Memory Impairment.

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Boespflug, E L; McNamara, R K; Eliassen, J C; Schidler, M D; Krikorian, R

2016-02-01

To determine the effects of long-chain omega-3 (LCn-3) fatty acids found in fish oil, including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), on cortical blood oxygen level-dependent (BOLD) activity during a working memory task in older adults with subjective memory impairment. Randomized, double-blind, placebo-controlled study. Academic medical center. Healthy older adults (62-80 years) with subjective memory impairment, but not meeting criteria for mild cognitive impairment or dementia. Fish oil (EPA+DHA: 2.4 g/d, n=11) or placebo (corn oil, n=10) for 24 weeks. Cortical BOLD response patterns during performance of a sequential letter n-back working memory task were determined at baseline and week 24 by functional magnetic resonance imaging (fMRI). At 24 weeks erythrocyte membrane EPA+DHA composition increased significantly from baseline in participants receiving fish oil (+31%, p ≤ 0.0001) but not placebo (-17%, p=0.06). Multivariate modeling of fMRI data identified a significant interaction among treatment, visit, and memory loading in the right cingulate (BA 23/24), and in the right sensorimotor area (BA 3/4). In the fish oil group, BOLD increases at 24 weeks were observed in the right posterior cingulate and left superior frontal regions during memory loading. A region-of-interest analysis indicated that the baseline to endpoint change in posterior cingulate cortex BOLD activity signal was significantly greater in the fish oil group compared with the placebo group during the 1-back (p=0.0003) and 2-back (p=0.0005) conditions. Among all participants, the change in erythrocyte EPA+DHA during the intervention was associated with performance in the 2-back working memory task (p = 0.01), and with cingulate BOLD signal during the 1-back (p = 0.005) with a trend during the 2-back (p = 0.09). Further, cingulate BOLD activity was related to performance in the 2-back condition. Dietary fish oil supplementation increases red blood cell omega-3 content

The application of preoperative functional MRI in neurosurgical treatment of intraoperative electrical stimulation for gliomas involving motor areas at 3 T

International Nuclear Information System (INIS)

Li Zixiao; Dai Jianping; Li Shaowu; Li Changhong; Gao Peiyi; Jiang Tao; Sun Yilin

2006-01-01

Objective: To assess the value of preoperative blood oxygen level dependent (BOLD) 3 T functional magnetic resonance imaging (fMRI) to identify motor cortical areas in neurosurgical treatment of intraoperative electrical stimulation for gliomas involving motor areas. Methods: The study included 26 consecutive preoperative BOLD-fMRI sessions in patients with brain gliomas in or near senorimotor cortices. The bilateral hand movement fMRI paradigm was preformed in all patients. The BOLD data were analyzed by the workstation (Leonardo Syngo 2003A, Siemens)to obtain the BOLD-fMRI images, which were used to guide the preoperative neurosurgical planning. With guidance of preoperative mapping, all patients received microsurgery under anaesthesia retaining consciousness using intraoperative motor functional brain mapping with the method of direct electrical stimulations. The brain lesions were removed as far as possible in the case of eloquent areas preservation. The preoperative and postoperative KPS of all patients were operated to evaluate the state of patients. Results: The preoperative mappings of the hand area on primary sensorimotor cortex using BOLD-fMRI were obtained successfully in twenty-three of twenty-six patients. Under anaesthesia retaining consciousness, the primary motor area was monitored by the method of direct electrical stimulations with the guidance of preoperative BOLD-fMRI. There was good correlation between preoperative fMRI findings and intraoperative cortical stimulation. Furthermore, the preoperative mappings could make up for the un-monitored areas during operative cortical stimulation. For the 21 patients of the pre-KPS from 80.0 to 90.0, the pre-KPS and post-KPS are 85.7 and 95.2 respectively, and for the 5 patients of the pre-KPS from 40. 0 to 70.0, the pre-KPS and post-KPS are 68.0 and 90.0 respectively. Conclusion: The preoperative mapping of the hand area on primary sensorimotor cortex using BOLD-fMRI could non-invasively localize the

DNA barcoding discriminates freshwater fishes from southeastern Nigeria and provides river system-level phylogeographic resolution within some species.

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Nwani, Christopher D; Becker, Sven; Braid, Heather E; Ude, Emmanuel F; Okogwu, Okechukwu I; Hanner, Robert

2011-10-01

Fishes are the main animal protein source for human beings and play a vital role in aquatic ecosystems and food webs. Fish identification can be challenging, especially in the tropics (due to high diversity), and this is particularly true for larval forms or fragmentary remains. DNA barcoding, which uses the 5' region of the mitochondrial cytochrome c oxidase subunit I (COI) as a target gene, is an efficient method for standardized species-level identification for biodiversity assessment and conservation, pending the establishment of reference sequence libraries. In this study, fishes were collected from three rivers in southeastern Nigeria, identified morphologically, and imaged digitally. DNA was extracted, PCR-amplified, and the standard barcode region was bidirectionally sequenced for 363 individuals belonging to 70 species in 38 genera. All specimen provenance data and associated sequence information were recorded in the barcode of life data systems (BOLD; www.barcodinglife.org ). Analytical tools on BOLD were used to assess the performance of barcoding to identify species. Using neighbor-joining distance comparison, the average genetic distance was 60-fold higher between species than within species, as pairwise genetic distance estimates averaged 10.29% among congeners and only 0.17% among conspecifics. Despite low levels of divergence within species, we observed river system-specific haplotype partitioning within eight species (11.4% of all species). Our preliminary results suggest that DNA barcoding is very effective for species identification of Nigerian freshwater fishes.

Attenuation of Morphine Physical Dependence and Blood Levels of Cortisol by Central and Systemic Administration of Ramelteon in Rat

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Majid Motaghinejad

2015-05-01

Full Text Available Background: Chronic administration of morphine cause physical dependence but the exact mechanism of this phenomenon remains unclear. The aim of this study is the assessment of systemic and intracerebroventricular (icv administration of ramelteon (a melatonin receptor agonist on morphine physical dependence. Methods: 88 adult male rats were divided into 2 major groups, namely “systematic” and “central” administration of ramelteon. In the first category, systemic administration of ramelteon at various dosages (10, 20, and 40 mg/kg was assessed on dependent animals and withdrawal signs were compared with positive (received morphine and saline as systemic administration, negative control (saline and group under treatment by ramelteon (40 mg/kg groups. In the second category, central administration of ramelteon at various dosages (25, 50, or 100 μg, was assessed on dependent animals and withdrawal signs were compared with the positive control (received morphine and saline as icv and negative control (saline groups, and the group under treatment by ramelteon (50 μg/5 μl/rat. On the test day, all animals received naloxone (3 mg/kg and were observed for withdrawal signs. Total withdrawal score (TWS was also determined. Finally, to evaluate the stress level of dependent rats, blood cortisols were measured. Results: Central administration of ramelteon in all doses and systemic administration in high doses attenuate withdrawal syndrome in comparison with the dependent positive control group (P<0.05. Both central and systemic administrations of ramelteon can attenuate the blood cortisol level in comparison with the dependent positive control group (P<0.05. Conclusion: In conclusion, we found that central administration of ramelteon attenuated morphine withdrawal symptoms and cortisol level as a stress marker.