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Sample records for cultured cortical networks

  1. Memory in cultured cortical networks

    NARCIS (Netherlands)

    le Feber, Jakob; Witteveen, T.; Stoyanova, Irina; Rutten, Wim

    2012-01-01

    Tetanic stimulation was applied to affect network connectivity, as assessed by conditional firing probabilities. We showed that the first period(s) of titanic stimulation at a certain electrode significantly alters functional connectivity, but subsequent, identical stimuli do not. These findings

  2. Network bursts in cortical neuronal cultures: 'noise - versus pacemaker'- driven neural network simulations

    NARCIS (Netherlands)

    Gritsun, T.; Stegenga, J.; le Feber, Jakob; Rutten, Wim

    2009-01-01

    In this paper we address the issue of spontaneous bursting activity in cortical neuronal cultures and explain what might cause this collective behavior using computer simulations of two different neural network models. While the common approach to acivate a passive network is done by introducing

  3. Memory in cultured cortical networks: experiment and modeling

    NARCIS (Netherlands)

    Witteveen, Tim; van Veenendaal, Tamar; le Feber, Jakob; Sergeev, A.

    The mechanism behind memory is one of the mysteries in neuroscience. Here we unravel part of the mechanism by showing that cultured neuronal networks develop an activity connectivity balance. External inputs disturb this balance and induce connectivity changes. The new connectivity is no longer

  4. Phase-dependent effects of stimuli locked to oscillatory activity in cultured cortical networks

    NARCIS (Netherlands)

    Stegenga, J.; le Feber, Jakob; Marani, Enrico; Rutten, Wim

    The archetypal activity pattern in cultures of dissociated neurons is spontaneous network-wide bursting. Bursts may interfere with controlled activation of synaptic plasticity, but can be suppressed by the application of stimuli at a sufficient rate. We sinusoidally modulated (4 Hz) the pulse rate

  5. Repeated Stimulation of Cultured Networks of Rat Cortical Neurons Induces Parallel Memory Traces

    Science.gov (United States)

    le Feber, Joost; Witteveen, Tim; van Veenendaal, Tamar M.; Dijkstra, Jelle

    2015-01-01

    During systems consolidation, memories are spontaneously replayed favoring information transfer from hippocampus to neocortex. However, at present no empirically supported mechanism to accomplish a transfer of memory from hippocampal to extra-hippocampal sites has been offered. We used cultured neuronal networks on multielectrode arrays and…

  6. Mapping cortical mesoscopic networks of single spiking cortical or sub-cortical neurons.

    Science.gov (United States)

    Xiao, Dongsheng; Vanni, Matthieu P; Mitelut, Catalin C; Chan, Allen W; LeDue, Jeffrey M; Xie, Yicheng; Chen, Andrew Cn; Swindale, Nicholas V; Murphy, Timothy H

    2017-02-04

    Understanding the basis of brain function requires knowledge of cortical operations over wide-spatial scales, but also within the context of single neurons. In vivo, wide-field GCaMP imaging and sub-cortical/cortical cellular electrophysiology were used in mice to investigate relationships between spontaneous single neuron spiking and mesoscopic cortical activity. We make use of a rich set of cortical activity motifs that are present in spontaneous activity in anesthetized and awake animals. A mesoscale spike-triggered averaging procedure allowed the identification of motifs that are preferentially linked to individual spiking neurons by employing genetically targeted indicators of neuronal activity. Thalamic neurons predicted and reported specific cycles of wide-scale cortical inhibition/excitation. In contrast, spike-triggered maps derived from single cortical neurons yielded spatio-temporal maps expected for regional cortical consensus function. This approach can define network relationships between any point source of neuronal spiking and mesoscale cortical maps.

  7. Large-scale, high-resolution multielectrode-array recording depicts functional network differences of cortical and hippocampal cultures.

    Directory of Open Access Journals (Sweden)

    Shinya Ito

    Full Text Available Understanding the detailed circuitry of functioning neuronal networks is one of the major goals of neuroscience. Recent improvements in neuronal recording techniques have made it possible to record the spiking activity from hundreds of neurons simultaneously with sub-millisecond temporal resolution. Here we used a 512-channel multielectrode array system to record the activity from hundreds of neurons in organotypic cultures of cortico-hippocampal brain slices from mice. To probe the network structure, we employed a wavelet transform of the cross-correlogram to categorize the functional connectivity in different frequency ranges. With this method we directly compare, for the first time, in any preparation, the neuronal network structures of cortex and hippocampus, on the scale of hundreds of neurons, with sub-millisecond time resolution. Among the three frequency ranges that we investigated, the lower two frequency ranges (gamma (30-80 Hz and beta (12-30 Hz range showed similar network structure between cortex and hippocampus, but there were many significant differences between these structures in the high frequency range (100-1000 Hz. The high frequency networks in cortex showed short tailed degree-distributions, shorter decay length of connectivity density, smaller clustering coefficients, and positive assortativity. Our results suggest that our method can characterize frequency dependent differences of network architecture from different brain regions. Crucially, because these differences between brain regions require millisecond temporal scales to be observed and characterized, these results underscore the importance of high temporal resolution recordings for the understanding of functional networks in neuronal systems.

  8. Nanoscaffold's stiffness affects primary cortical cell network formation

    NARCIS (Netherlands)

    Xie, Sijia; Schurink, Bart; Wolbers, F.; Lüttge, Regina; Hassink, Gerrit Cornelis

    2014-01-01

    Networks of neurons cultured on-chip can provide insights into both normal and disease-state brain function. The ability to guide neuronal growth in specific, artificially designed patterns allows us to study how brain function follows form. Primary cortical cells cultured on nanograting scaffolds,

  9. Characterization of Early Cortical Neural Network ...

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    We examined the development of neural network activity using microelectrode array (MEA) recordings made in multi-well MEA plates (mwMEAs) over the first 12 days in vitro (DIV). In primary cortical cultures made from postnatal rats, action potential spiking activity was essentially absent on DIV 2 and developed rapidly between DIV 5 and 12. Spiking activity was primarily sporadic and unorganized at early DIV, and became progressively more organized with time in culture, with bursting parameters, synchrony and network bursting increasing between DIV 5 and 12. We selected 12 features to describe network activity and principal components analysis using these features demonstrated a general segregation of data by age at both the well and plate levels. Using a combination of random forest classifiers and Support Vector Machines, we demonstrated that 4 features (CV of within burst ISI, CV of IBI, network spike rate and burst rate) were sufficient to predict the age (either DIV 5, 7, 9 or 12) of each well recording with >65% accuracy. When restricting the classification problem to a binary decision, we found that classification improved dramatically, e.g. 95% accuracy for discriminating DIV 5 vs DIV 12 wells. Further, we present a novel resampling approach to determine the number of wells that might be needed for conducting comparisons of different treatments using mwMEA plates. Overall, these results demonstrate that network development on mwMEA plates is similar to

  10. Connectivities and synchronous firing in cortical neuronal networks

    International Nuclear Information System (INIS)

    Jia, L.C.; Sano, M.; Lai, P.-Y.; Chan, C.K.

    2004-01-01

    Network connectivities (k-bar) of cortical neural cultures are studied by synchronized firing and determined from measured correlations between fluorescence intensities of firing neurons. The bursting frequency (f) during synchronized firing of the networks is found to be an increasing function of k-bar. With f taken to be proportional to k-bar, a simple random model with a k-bar dependent connection probability p(k-bar) has been constructed to explain our experimental findings successfully

  11. Reduced Synaptic Vesicle Recycling during Hypoxia in Cultured Cortical Neurons

    OpenAIRE

    Fedorovich, Sergei; Hofmeijer, Jeannette; van Putten, Michel Johannes Antonius Maria; le Feber, Jakob

    2017-01-01

    Improvement of neuronal recovery in the ischemic penumbra, an area around the core of a brain infarct with some remaining perfusion, has a large potential for the development of therapy against acute ischemic stroke. However, mechanisms that lead to either recovery or secondary damage in the penumbra largely remain unclear. Recent studies in cultured networks of cortical neurons showed that failure of synaptic transmission (referred to as synaptic failure) is a critical factor in the penumbra...

  12. Response variability in balanced cortical networks

    DEFF Research Database (Denmark)

    Lerchner, Alexander; Ursta, C.; Hertz, J.

    2006-01-01

    We study the spike statistics of neurons in a network with dynamically balanced excitation and inhibition. Our model, intended to represent a generic cortical column, comprises randomly connected excitatory and inhibitory leaky integrate-and-fire neurons, driven by excitatory input from an external...

  13. Mean field methods for cortical network dynamics

    DEFF Research Database (Denmark)

    Hertz, J.; Lerchner, Alexander; Ahmadi, M.

    2004-01-01

    We review the use of mean field theory for describing the dynamics of dense, randomly connected cortical circuits. For a simple network of excitatory and inhibitory leaky integrate- and-fire neurons, we can show how the firing irregularity, as measured by the Fano factor, increases...... with the strength of the synapses in the network and with the value to which the membrane potential is reset after a spike. Generalizing the model to include conductance-based synapses gives insight into the connection between the firing statistics and the high- conductance state observed experimentally in visual...

  14. Signal transfer within a cultured asymmetric cortical neuron circuit.

    Science.gov (United States)

    Isomura, Takuya; Shimba, Kenta; Takayama, Yuzo; Takeuchi, Akimasa; Kotani, Kiyoshi; Jimbo, Yasuhiko

    2015-12-01

    Simplified neuronal circuits are required for investigating information representation in nervous systems and for validating theoretical neural network models. Here, we developed patterned neuronal circuits using micro fabricated devices, comprising a micro-well array bonded to a microelectrode-array substrate. The micro-well array consisted of micrometre-scale wells connected by tunnels, all contained within a silicone slab called a micro-chamber. The design of the micro-chamber confined somata to the wells and allowed axons to grow through the tunnels bidirectionally but with a designed, unidirectional bias. We guided axons into the point of the arrow structure where one of the two tunnel entrances is located, making that the preferred direction. When rat cortical neurons were cultured in the wells, their axons grew through the tunnels and connected to neurons in adjoining wells. Unidirectional burst transfers and other asymmetric signal-propagation phenomena were observed via the substrate-embedded electrodes. Seventy-nine percent of burst transfers were in the forward direction. We also observed rapid propagation of activity from sites of local electrical stimulation, and significant effects of inhibitory synapse blockade on bursting activity. These results suggest that this simple, substrate-controlled neuronal circuit can be applied to develop in vitro models of the function of cortical microcircuits or deep neural networks, better to elucidate the laws governing the dynamics of neuronal networks.

  15. Signal transfer within a cultured asymmetric cortical neuron circuit

    Science.gov (United States)

    Isomura, Takuya; Shimba, Kenta; Takayama, Yuzo; Takeuchi, Akimasa; Kotani, Kiyoshi; Jimbo, Yasuhiko

    2015-12-01

    Objective. Simplified neuronal circuits are required for investigating information representation in nervous systems and for validating theoretical neural network models. Here, we developed patterned neuronal circuits using micro fabricated devices, comprising a micro-well array bonded to a microelectrode-array substrate. Approach. The micro-well array consisted of micrometre-scale wells connected by tunnels, all contained within a silicone slab called a micro-chamber. The design of the micro-chamber confined somata to the wells and allowed axons to grow through the tunnels bidirectionally but with a designed, unidirectional bias. We guided axons into the point of the arrow structure where one of the two tunnel entrances is located, making that the preferred direction. Main results. When rat cortical neurons were cultured in the wells, their axons grew through the tunnels and connected to neurons in adjoining wells. Unidirectional burst transfers and other asymmetric signal-propagation phenomena were observed via the substrate-embedded electrodes. Seventy-nine percent of burst transfers were in the forward direction. We also observed rapid propagation of activity from sites of local electrical stimulation, and significant effects of inhibitory synapse blockade on bursting activity. Significance. These results suggest that this simple, substrate-controlled neuronal circuit can be applied to develop in vitro models of the function of cortical microcircuits or deep neural networks, better to elucidate the laws governing the dynamics of neuronal networks.

  16. Magnetoencephalography from signals to dynamic cortical networks

    CERN Document Server

    Aine, Cheryl

    2014-01-01

    "Magnetoencephalography (MEG) provides a time-accurate view into human brain function. The concerted action of neurons generates minute magnetic fields that can be detected---totally noninvasively---by sensitive multichannel magnetometers. The obtained millisecond accuracycomplements information obtained by other modern brain-imaging tools. Accurate timing is quintessential in normal brain function, often distorted in brain disorders. The noninvasiveness and time-sensitivityof MEG are great assets to developmental studies, as well. This multiauthored book covers an ambitiously wide range of MEG research from introductory to advanced level, from sensors to signals, and from focal sources to the dynamics of cortical networks. Written by active practioners of this multidisciplinary field, the book contains tutorials for newcomers and chapters of new challenging methods and emerging technologies to advanced MEG users. The reader will obtain a firm grasp of the possibilities of MEG in the study of audition, vision...

  17. State-dependent intrinsic predictability of cortical network dynamics.

    Directory of Open Access Journals (Sweden)

    Leila Fakhraei

    Full Text Available The information encoded in cortical circuit dynamics is fleeting, changing from moment to moment as new input arrives and ongoing intracortical interactions progress. A combination of deterministic and stochastic biophysical mechanisms governs how cortical dynamics at one moment evolve from cortical dynamics in recently preceding moments. Such temporal continuity of cortical dynamics is fundamental to many aspects of cortex function but is not well understood. Here we study temporal continuity by attempting to predict cortical population dynamics (multisite local field potential based on its own recent history in somatosensory cortex of anesthetized rats and in a computational network-level model. We found that the intrinsic predictability of cortical dynamics was dependent on multiple factors including cortical state, synaptic inhibition, and how far into the future the prediction extends. By pharmacologically tuning synaptic inhibition, we obtained a continuum of cortical states with asynchronous population activity at one extreme and stronger, spatially extended synchrony at the other extreme. Intermediate between these extremes we observed evidence for a special regime of population dynamics called criticality. Predictability of the near future (10-100 ms increased as the cortical state was tuned from asynchronous to synchronous. Predictability of the more distant future (>1 s was generally poor, but, surprisingly, was higher for asynchronous states compared to synchronous states. These experimental results were confirmed in a computational network model of spiking excitatory and inhibitory neurons. Our findings demonstrate that determinism and predictability of network dynamics depend on cortical state and the time-scale of the dynamics.

  18. Short-term memory in networks of dissociated cortical neurons.

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    Dranias, Mark R; Ju, Han; Rajaram, Ezhilarasan; VanDongen, Antonius M J

    2013-01-30

    Short-term memory refers to the ability to store small amounts of stimulus-specific information for a short period of time. It is supported by both fading and hidden memory processes. Fading memory relies on recurrent activity patterns in a neuronal network, whereas hidden memory is encoded using synaptic mechanisms, such as facilitation, which persist even when neurons fall silent. We have used a novel computational and optogenetic approach to investigate whether these same memory processes hypothesized to support pattern recognition and short-term memory in vivo, exist in vitro. Electrophysiological activity was recorded from primary cultures of dissociated rat cortical neurons plated on multielectrode arrays. Cultures were transfected with ChannelRhodopsin-2 and optically stimulated using random dot stimuli. The pattern of neuronal activity resulting from this stimulation was analyzed using classification algorithms that enabled the identification of stimulus-specific memories. Fading memories for different stimuli, encoded in ongoing neural activity, persisted and could be distinguished from each other for as long as 1 s after stimulation was terminated. Hidden memories were detected by altered responses of neurons to additional stimulation, and this effect persisted longer than 1 s. Interestingly, network bursts seem to eliminate hidden memories. These results are similar to those that have been reported from similar experiments in vivo and demonstrate that mechanisms of information processing and short-term memory can be studied using cultured neuronal networks, thereby setting the stage for therapeutic applications using this platform.

  19. Influences of brain development and ageing on cortical interactive networks.

    Science.gov (United States)

    Zhu, Chengyu; Guo, Xiaoli; Jin, Zheng; Sun, Junfeng; Qiu, Yihong; Zhu, Yisheng; Tong, Shanbao

    2011-02-01

    To study the effect of brain development and ageing on the pattern of cortical interactive networks. By causality analysis of multichannel electroencephalograph (EEG) with partial directed coherence (PDC), we investigated the different neural networks involved in the whole cortex as well as the anterior and posterior areas in three age groups, i.e., children (0-10 years), mid-aged adults (26-38 years) and the elderly (56-80 years). By comparing the cortical interactive networks in different age groups, the following findings were concluded: (1) the cortical interactive network in the right hemisphere develops earlier than its left counterpart in the development stage; (2) the cortical interactive network of anterior cortex, especially at C3 and F3, is demonstrated to undergo far more extensive changes, compared with the posterior area during brain development and ageing; (3) the asymmetry of the cortical interactive networks declines during ageing with more loss of connectivity in the left frontal and central areas. The age-related variation of cortical interactive networks from resting EEG provides new insights into brain development and ageing. Our findings demonstrated that the PDC analysis of EEG is a powerful approach for characterizing the cortical functional connectivity during brain development and ageing. Copyright © 2010 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  20. Morphometric Changes in the Cortical Microvascular Network in Alzheimer's Disease

    NARCIS (Netherlands)

    Richard, E.; van Gool, W.A.; Hoozemans, J.J.M.; van Haastert, E.S.; Eikelenboom, P.; Rozemuller, A.J.M.; van de Berg, W.D.J.

    2010-01-01

    Alzheimer's disease (AD) pathology is accompanied by abnormalities of the microvasculature. Despite the potential importance of morphometric changes in the cortical capillary network on neuronal dysfunction and cognitive impairment, few autopsy studies have addressed this issue. In the present

  1. Cortical electrophysiological network dynamics of feedback learning

    NARCIS (Netherlands)

    Cohen, M.X.; Wilmes, K.A.; van de Vijver, I.

    2011-01-01

    Understanding the neurophysiological mechanisms of learning is important for both fundamental and clinical neuroscience. We present a neurophysiologically inspired framework for understanding cortical mechanisms of feedback-guided learning. This framework is based on dynamic changes in systems-level

  2. Characterization of Early Cortical Neural Network Development in Multiwell Microelectrode Array Plates

    Science.gov (United States)

    We examined the development of neural network activity using microelectrode array (MEA) recordings made in multi-well MEA plates (mwMEAs) over the first 12 days in vitro (DIV). In primary cortical cultures made from postnatal rats, action potential spiking activity was essentiall...

  3. Altered cortical anatomical networks in temporal lobe epilepsy

    Science.gov (United States)

    Lv, Bin; He, Huiguang; Lu, Jingjing; Li, Wenjing; Dai, Dai; Li, Meng; Jin, Zhengyu

    2011-03-01

    Temporal lobe epilepsy (TLE) is one of the most common epilepsy syndromes with focal seizures generated in the left or right temporal lobes. With the magnetic resonance imaging (MRI), many evidences have demonstrated that the abnormalities in hippocampal volume and the distributed atrophies in cortical cortex. However, few studies have investigated if TLE patients have the alternation in the structural networks. In the present study, we used the cortical thickness to establish the morphological connectivity networks, and investigated the network properties using the graph theoretical methods. We found that all the morphological networks exhibited the small-world efficiency in left TLE, right TLE and normal groups. And the betweenness centrality analysis revealed that there were statistical inter-group differences in the right uncus region. Since the right uncus located at the right temporal lobe, these preliminary evidences may suggest that there are topological alternations of the cortical anatomical networks in TLE, especially for the right TLE.

  4. Cortical Networks for Visual Self-Recognition

    Science.gov (United States)

    Sugiura, Motoaki

    This paper briefly reviews recent developments regarding the brain mechanisms of visual self-recognition. A special cognitive mechanism for visual self-recognition has been postulated based on behavioral and neuropsychological evidence, but its neural substrate remains controversial. Recent functional imaging studies suggest that multiple cortical mechanisms play self-specific roles during visual self-recognition, reconciling the existing controversy. Respective roles for the left occipitotemporal, right parietal, and frontal cortices in symbolic, visuospatial, and conceptual aspects of self-representation have been proposed.

  5. Cortical networks for visual self-recognition

    International Nuclear Information System (INIS)

    Sugiura, Motoaki

    2007-01-01

    This paper briefly reviews recent developments regarding the brain mechanisms of visual self-recognition. A special cognitive mechanism for visual self-recognition has been postulated based on behavioral and neuropsychological evidence, but its neural substrate remains controversial. Recent functional imaging studies suggest that multiple cortical mechanisms play self-specific roles during visual self-recognition, reconciling the existing controversy. Respective roles for the left occipitotemporal, right parietal, and frontal cortices in symbolic, visuospatial, and conceptual aspects of self-representation have been proposed. (author)

  6. Low and High-Frequency Field Potentials of Cortical Networks ...

    Science.gov (United States)

    Neural networks grown on microelectrode arrays (MEAs) have become an important, high content in vitro assay for assessing neuronal function. MEA experiments typically examine high- frequency (HF) (>200 Hz) spikes, and bursts which can be used to discriminate between different pharmacological agents/chemicals. However, normal brain activity is additionally composed of integrated low-frequency (0.5-100 Hz) field potentials (LFPs) which are filtered out of MEA recordings. The objective of this study was to characterize the relationship between HF and LFP neural network signals, and to assess the relative sensitivity of LFPs to selected neurotoxicants. Rat primary cortical cultures were grown on glass, single-well MEA chips. Spontaneous activity was sampled at 25 kHz and recorded (5 min) (Multi-Channel Systems) from mature networks (14 days in vitro). HF (spike, mean firing rate, MFR) and LF (power spectrum, amplitude) components were extracted from each network and served as its baseline (BL). Next, each chip was treated with either 1) a positive control, bicuculline (BIC, 25μM) or domoic acid (DA, 0.3μM), 2) or a negative control, acetaminophen (ACE, 100μM) or glyphosate (GLY, 100μM), 3) a solvent control (H2O or DMSO:EtOH), or 4) a neurotoxicant, (carbaryl, CAR 5, 30μM ; lindane, LIN 1, 10μM; permethrin, PERM 25, 50μM; triadimefon, TRI 5, 65μM). Post treatment, 5 mins of spontaneous activity was recorded and analyzed. As expected posit

  7. Development of global cortical networks in early infancy.

    Science.gov (United States)

    Homae, Fumitaka; Watanabe, Hama; Otobe, Takayuki; Nakano, Tamami; Go, Tohshin; Konishi, Yukuo; Taga, Gentaro

    2010-04-07

    Human cognition and behaviors are subserved by global networks of neural mechanisms. Although the organization of the brain is a subject of interest, the process of development of global cortical networks in early infancy has not yet been clarified. In the present study, we explored developmental changes in these networks from several days to 6 months after birth by examining spontaneous fluctuations in brain activity, using multichannel near-infrared spectroscopy. We set up 94 measurement channels over the frontal, temporal, parietal, and occipital regions of the infant brain. The obtained signals showed complex time-series properties, which were characterized as 1/f fluctuations. To reveal the functional connectivity of the cortical networks, we calculated the temporal correlations of continuous signals between all the pairs of measurement channels. We found that the cortical network organization showed regional dependency and dynamic changes in the course of development. In the temporal, parietal, and occipital regions, connectivity increased between homologous regions in the two hemispheres and within hemispheres; in the frontal regions, it decreased progressively. Frontoposterior connectivity changed to a "U-shaped" pattern within 6 months: it decreases from the neonatal period to the age of 3 months and increases from the age of 3 months to the age of 6 months. We applied cluster analyses to the correlation coefficients and showed that the bilateral organization of the networks begins to emerge during the first 3 months of life. Our findings suggest that these developing networks, which form multiple clusters, are precursors of the functional cerebral architecture.

  8. Mapping human brain networks with cortico-cortical evoked potentials

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    Keller, Corey J.; Honey, Christopher J.; Mégevand, Pierre; Entz, Laszlo; Ulbert, Istvan; Mehta, Ashesh D.

    2014-01-01

    The cerebral cortex forms a sheet of neurons organized into a network of interconnected modules that is highly expanded in humans and presumably enables our most refined sensory and cognitive abilities. The links of this network form a fundamental aspect of its organization, and a great deal of research is focusing on understanding how information flows within and between different regions. However, an often-overlooked element of this connectivity regards a causal, hierarchical structure of regions, whereby certain nodes of the cortical network may exert greater influence over the others. While this is difficult to ascertain non-invasively, patients undergoing invasive electrode monitoring for epilepsy provide a unique window into this aspect of cortical organization. In this review, we highlight the potential for cortico-cortical evoked potential (CCEP) mapping to directly measure neuronal propagation across large-scale brain networks with spatio-temporal resolution that is superior to traditional neuroimaging methods. We first introduce effective connectivity and discuss the mechanisms underlying CCEP generation. Next, we highlight how CCEP mapping has begun to provide insight into the neural basis of non-invasive imaging signals. Finally, we present a novel approach to perturbing and measuring brain network function during cognitive processing. The direct measurement of CCEPs in response to electrical stimulation represents a potentially powerful clinical and basic science tool for probing the large-scale networks of the human cerebral cortex. PMID:25180306

  9. Qualia could arise from information processing in local cortical networks.

    Science.gov (United States)

    Orpwood, Roger

    2013-01-01

    Re-entrant feedback, either within sensory cortex or arising from prefrontal areas, has been strongly linked to the emergence of consciousness, both in theoretical and experimental work. This idea, together with evidence for local micro-consciousness, suggests the generation of qualia could in some way result from local network activity under re-entrant activation. This paper explores the possibility by examining the processing of information by local cortical networks. It highlights the difference between the information structure (how the information is physically embodied), and the information message (what the information is about). It focuses on the network's ability to recognize information structures amongst its inputs under conditions of extensive local feedback, and to then assign information messages to those structures. It is shown that if the re-entrant feedback enables the network to achieve an attractor state, then the message assigned in any given pass of information through the network is a representation of the message assigned in the previous pass-through of information. Based on this ability the paper argues that as information is repeatedly cycled through the network, the information message that is assigned evolves from a recognition of what the input structure is, to what it is like, to how it appears, to how it seems. It could enable individual networks to be the site of qualia generation. The paper goes on to show networks in cortical layers 2/3 and 5a have the connectivity required for the behavior proposed, and reviews some evidence for a link between such local cortical cyclic activity and conscious percepts. It concludes with some predictions based on the theory discussed.

  10. Cortical hubs form a module for multisensory integration on top of the hierarchy of cortical networks

    Directory of Open Access Journals (Sweden)

    Gorka Zamora-López

    2010-03-01

    Full Text Available Sensory stimuli entering the nervous system follow particular paths of processing, typically separated (segregated from the paths of other modal information. However, sensory perception, awareness and cognition emerge from the combination of information (integration. The corticocortical networks of cats and macaque monkeys display three prominent characteristics: (i modular organisation (facilitating the segregation, (ii abundant alternative processing paths and (iii the presence of highly connected hubs. Here, we study in detail the organisation and potential function of the cortical hubs by graph analysis and information theoretical methods. We find that the cortical hubs form a spatially delocalised, but topologically central module with the capacity to integrate multisensory information in a collaborative manner. With this, we resolve the underlying anatomical substrate that supports the simultaneous capacity of the cortex to segregate and to integrate multisensory information.

  11. Cortical network during deception detection by functional neuroimaging

    International Nuclear Information System (INIS)

    Saito, Keiichi

    2008-01-01

    We examined the coherence of cortical network during deception detection. First, we performed combined EEG-MRI experiments during the Guilty Knowledge Test (GKT) using number cards which has been used to model deception and 5 right-handed healthy participants performed the experiment. The superior frontal gyrus, the anterior cingulate cortex and the inferior parietal lobule were activated and the P 300 event-related brain potential (300-450 ms) was detected at only 'Lie' card. Secondary, we measured magnetoencephalography (MEG) data during GKT and the other 5 right-handed healthy subjects participated in the next experiment. The coherence between the superior frontal gyrus and the inferior parietal lobule showed significant differences between 'Lie' card and 'truth' cards during P 300 emerging. This results indicates that the coherence of cortical network is useful for GKT. (author)

  12. Growth of cortical neuronal network in vitro: Modeling and analysis

    International Nuclear Information System (INIS)

    Lai, P.-Y.; Jia, L. C.; Chan, C. K.

    2006-01-01

    We present a detailed analysis and theoretical growth models to account for recent experimental data on the growth of cortical neuronal networks in vitro [Phys. Rev. Lett. 93, 088101 (2004)]. The experimentally observed synchronized firing frequency of a well-connected neuronal network is shown to be proportional to the mean network connectivity. The growth of the network is consistent with the model of an early enhanced growth of connection, but followed by a retarded growth once the synchronized cluster is formed. Microscopic models with dominant excluded volume interactions are consistent with the observed exponential decay of the mean connection probability as a function of the mean network connectivity. The biological implications of the growth model are also discussed

  13. Alterations of cortical GABA neurons and network oscillations in schizophrenia.

    Science.gov (United States)

    Gonzalez-Burgos, Guillermo; Hashimoto, Takanori; Lewis, David A

    2010-08-01

    The hypothesis that alterations of cortical inhibitory gamma-aminobutyric acid (GABA) neurons are a central element in the pathology of schizophrenia has emerged from a series of postmortem studies. How such abnormalities may contribute to the clinical features of schizophrenia has been substantially informed by a convergence with basic neuroscience studies revealing complex details of GABA neuron function in the healthy brain. Importantly, activity of the parvalbumin-containing class of GABA neurons has been linked to the production of cortical network oscillations. Furthermore, growing knowledge supports the concept that gamma band oscillations (30-80 Hz) are an essential mechanism for cortical information transmission and processing. Herein we review recent studies further indicating that inhibition from parvalbumin-positive GABA neurons is necessary to produce gamma oscillations in cortical circuits; provide an update on postmortem studies documenting that deficits in the expression of glutamic acid decarboxylase67, which accounts for most GABA synthesis in the cortex, are widely observed in schizophrenia; and describe studies using novel, noninvasive approaches directly assessing potential relations between alterations in GABA, oscillations, and cognitive function in schizophrenia.

  14. Functional Cortical Network in Alpha Band Correlates with Social Bargaining

    Science.gov (United States)

    Billeke, Pablo; Zamorano, Francisco; Chavez, Mario; Cosmelli, Diego; Aboitiz, Francisco

    2014-01-01

    Solving demanding tasks requires fast and flexible coordination among different brain areas. Everyday examples of this are the social dilemmas in which goals tend to clash, requiring one to weigh alternative courses of action in limited time. In spite of this fact, there are few studies that directly address the dynamics of flexible brain network integration during social interaction. To study the preceding, we carried out EEG recordings while subjects played a repeated version of the Ultimatum Game in both human (social) and computer (non-social) conditions. We found phase synchrony (inter-site-phase-clustering) modulation in alpha band that was specific to the human condition and independent of power modulation. The strength and patterns of the inter-site-phase-clustering of the cortical networks were also modulated, and these modulations were mainly in frontal and parietal regions. Moreover, changes in the individuals’ alpha network structure correlated with the risk of the offers made only in social conditions. This correlation was independent of changes in power and inter-site-phase-clustering strength. Our results indicate that, when subjects believe they are participating in a social interaction, a specific modulation of functional cortical networks in alpha band takes place, suggesting that phase synchrony of alpha oscillations could serve as a mechanism by which different brain areas flexibly interact in order to adapt ongoing behavior in socially demanding contexts. PMID:25286240

  15. Population spikes in cortical networks during different functional states.

    Directory of Open Access Journals (Sweden)

    Shirley eMark

    2012-07-01

    Full Text Available Brain computational challenges vary between behavioral states. Engaged animals react according to incoming sensory information, while in relaxed and sleeping states consolidation of the learned information is believed to take place. Different states are characterized by different forms of cortical activity. We study a possible neuronal mechanism for generating these diverse dynamics and suggest their possible functional significance. Previous studies demonstrated that brief synchronized increase in a neural firing (Population Spikes can be generated in homogenous recurrent neural networks with short-term synaptic depression. Here we consider more realistic networks with clustered architecture. We show that the level of synchronization in neural activity can be controlled smoothly by network parameters. The network shifts from asynchronous activity to a regime in which clusters synchronized separately, then, the synchronization between the clusters increases gradually to fully synchronized state. We examine the effects of different synchrony levels on the transmission of information by the network. We find that the regime of intermediate synchronization is preferential for the flow of information between sparsely connected areas. Based on these results, we suggest that the regime of intermediate synchronization corresponds to engaged behavioral state of the animal, while global synchronization is exhibited during relaxed and sleeping states.

  16. Cortical Thinning and Altered Cortico-Cortical Structural Covariance of the Default Mode Network in Patients with Persistent Insomnia Symptoms.

    Science.gov (United States)

    Suh, Sooyeon; Kim, Hosung; Dang-Vu, Thien Thanh; Joo, Eunyeon; Shin, Chol

    2016-01-01

    Recent studies have suggested that structural abnormalities in insomnia may be linked with alterations in the default-mode network (DMN). This study compared cortical thickness and structural connectivity linked to the DMN in patients with persistent insomnia (PI) and good sleepers (GS). The current study used a clinical subsample from the longitudinal community-based Korean Genome and Epidemiology Study (KoGES). Cortical thickness and structural connectivity linked to the DMN in patients with persistent insomnia symptoms (PIS; n = 57) were compared to good sleepers (GS; n = 40). All participants underwent MRI acquisition. Based on literature review, we selected cortical regions corresponding to the DMN. A seed-based structural covariance analysis measured cortical thickness correlation between each seed region of the DMN and other cortical areas. Association of cortical thickness and covariance with sleep quality and neuropsychological assessments were further assessed. Compared to GS, cortical thinning was found in PIS in the anterior cingulate cortex, precentral cortex, and lateral prefrontal cortex. Decreased structural connectivity between anterior and posterior regions of the DMN was observed in the PIS group. Decreased structural covariance within the DMN was associated with higher PSQI scores. Cortical thinning in the lateral frontal lobe was related to poor performance in executive function in PIS. Disrupted structural covariance network in PIS might reflect malfunctioning of antero-posterior disconnection of the DMN during the wake to sleep transition that is commonly found during normal sleep. The observed structural network alteration may further implicate commonly observed sustained sleep difficulties and cognitive impairment in insomnia. © 2016 Associated Professional Sleep Societies, LLC.

  17. Order-based representation in random networks of cortical neurons.

    Directory of Open Access Journals (Sweden)

    Goded Shahaf

    2008-11-01

    Full Text Available The wide range of time scales involved in neural excitability and synaptic transmission might lead to ongoing change in the temporal structure of responses to recurring stimulus presentations on a trial-to-trial basis. This is probably the most severe biophysical constraint on putative time-based primitives of stimulus representation in neuronal networks. Here we show that in spontaneously developing large-scale random networks of cortical neurons in vitro the order in which neurons are recruited following each stimulus is a naturally emerging representation primitive that is invariant to significant temporal changes in spike times. With a relatively small number of randomly sampled neurons, the information about stimulus position is fully retrievable from the recruitment order. The effective connectivity that makes order-based representation invariant to time warping is characterized by the existence of stations through which activity is required to pass in order to propagate further into the network. This study uncovers a simple invariant in a noisy biological network in vitro; its applicability under in vivo constraints remains to be seen.

  18. Calcium dynamics of cortical astrocytic networks in vivo.

    Directory of Open Access Journals (Sweden)

    Hajime Hirase

    2004-04-01

    Full Text Available Large and long-lasting cytosolic calcium surges in astrocytes have been described in cultured cells and acute slice preparations. The mechanisms that give rise to these calcium events have been extensively studied in vitro. However, their existence and functions in the intact brain are unknown. We have topically applied Fluo-4 AM on the cerebral cortex of anesthetized rats, and imaged cytosolic calcium fluctuation in astrocyte populations of superficial cortical layers in vivo, using two-photon laser scanning microscopy. Spontaneous [Ca(2+](i events in individual astrocytes were similar to those observed in vitro. Coordination of [Ca(2+](i events among astrocytes was indicated by the broad cross-correlograms. Increased neuronal discharge was associated with increased astrocytic [Ca(2+](i activity in individual cells and a robust coordination of [Ca(2+](i signals in neighboring astrocytes. These findings indicate potential neuron-glia communication in the intact brain.

  19. Cortical networks involved in visual awareness independent of visual attention.

    Science.gov (United States)

    Webb, Taylor W; Igelström, Kajsa M; Schurger, Aaron; Graziano, Michael S A

    2016-11-29

    It is now well established that visual attention, as measured with standard spatial attention tasks, and visual awareness, as measured by report, can be dissociated. It is possible to attend to a stimulus with no reported awareness of the stimulus. We used a behavioral paradigm in which people were aware of a stimulus in one condition and unaware of it in another condition, but the stimulus drew a similar amount of spatial attention in both conditions. The paradigm allowed us to test for brain regions active in association with awareness independent of level of attention. Participants performed the task in an MRI scanner. We looked for brain regions that were more active in the aware than the unaware trials. The largest cluster of activity was obtained in the temporoparietal junction (TPJ) bilaterally. Local independent component analysis (ICA) revealed that this activity contained three distinct, but overlapping, components: a bilateral, anterior component; a left dorsal component; and a right dorsal component. These components had brain-wide functional connectivity that partially overlapped the ventral attention network and the frontoparietal control network. In contrast, no significant activity in association with awareness was found in the banks of the intraparietal sulcus, a region connected to the dorsal attention network and traditionally associated with attention control. These results show the importance of separating awareness and attention when testing for cortical substrates. They are also consistent with a recent proposal that awareness is associated with ventral attention areas, especially in the TPJ.

  20. Examining the volume efficiency of the cortical architecture in a multi-processor network model.

    Science.gov (United States)

    Ruppin, E; Schwartz, E L; Yeshurun, Y

    1993-01-01

    The convoluted form of the sheet-like mammalian cortex naturally raises the question whether there is a simple geometrical reason for the prevalence of cortical architecture in the brains of higher vertebrates. Addressing this question, we present a formal analysis of the volume occupied by a massively connected network or processors (neurons) and then consider the pertaining cortical data. Three gross macroscopic features of cortical organization are examined: the segregation of white and gray matter, the circumferential organization of the gray matter around the white matter, and the folded cortical structure. Our results testify to the efficiency of cortical architecture.

  1. Inhibitory neurons modulate spontaneous signaling in cultured cortical neurons: density-dependent regulation of excitatory neuronal signaling

    International Nuclear Information System (INIS)

    Serra, Michael; Guaraldi, Mary; Shea, Thomas B

    2010-01-01

    Cortical neuronal activity depends on a balance between excitatory and inhibitory influences. Culturing of neurons on multi-electrode arrays (MEAs) has provided insight into the development and maintenance of neuronal networks. Herein, we seeded MEAs with murine embryonic cortical/hippocampal neurons at different densities ( 1000 cells mm −2 ) and monitored resultant spontaneous signaling. Sparsely seeded cultures displayed a large number of bipolar, rapid, high-amplitude individual signals with no apparent temporal regularity. By contrast, densely seeded cultures instead displayed clusters of signals at regular intervals. These patterns were observed even within thinner and thicker areas of the same culture. GABAergic neurons (25% of total neurons in our cultures) mediated the differential signal patterns observed above, since addition of the inhibitory antagonist bicuculline to dense cultures and hippocampal slice cultures induced the signal pattern characteristic of sparse cultures. Sparsely seeded cultures likely lacked sufficient inhibitory neurons to modulate excitatory activity. Differential seeding of MEAs can provide a unique model for analyses of pertubation in the interaction between excitatory and inhibitory function during aging and neuropathological conditions where dysregulation of GABAergic neurons is a significant component

  2. Cultured Cortical Neurons Can Perform Blind Source Separation According to the Free-Energy Principle

    Science.gov (United States)

    Isomura, Takuya; Kotani, Kiyoshi; Jimbo, Yasuhiko

    2015-01-01

    Blind source separation is the computation underlying the cocktail party effect––a partygoer can distinguish a particular talker’s voice from the ambient noise. Early studies indicated that the brain might use blind source separation as a signal processing strategy for sensory perception and numerous mathematical models have been proposed; however, it remains unclear how the neural networks extract particular sources from a complex mixture of inputs. We discovered that neurons in cultures of dissociated rat cortical cells could learn to represent particular sources while filtering out other signals. Specifically, the distinct classes of neurons in the culture learned to respond to the distinct sources after repeating training stimulation. Moreover, the neural network structures changed to reduce free energy, as predicted by the free-energy principle, a candidate unified theory of learning and memory, and by Jaynes’ principle of maximum entropy. This implicit learning can only be explained by some form of Hebbian plasticity. These results are the first in vitro (as opposed to in silico) demonstration of neural networks performing blind source separation, and the first formal demonstration of neuronal self-organization under the free energy principle. PMID:26690814

  3. Cultured Cortical Neurons Can Perform Blind Source Separation According to the Free-Energy Principle.

    Directory of Open Access Journals (Sweden)

    Takuya Isomura

    2015-12-01

    Full Text Available Blind source separation is the computation underlying the cocktail party effect--a partygoer can distinguish a particular talker's voice from the ambient noise. Early studies indicated that the brain might use blind source separation as a signal processing strategy for sensory perception and numerous mathematical models have been proposed; however, it remains unclear how the neural networks extract particular sources from a complex mixture of inputs. We discovered that neurons in cultures of dissociated rat cortical cells could learn to represent particular sources while filtering out other signals. Specifically, the distinct classes of neurons in the culture learned to respond to the distinct sources after repeating training stimulation. Moreover, the neural network structures changed to reduce free energy, as predicted by the free-energy principle, a candidate unified theory of learning and memory, and by Jaynes' principle of maximum entropy. This implicit learning can only be explained by some form of Hebbian plasticity. These results are the first in vitro (as opposed to in silico demonstration of neural networks performing blind source separation, and the first formal demonstration of neuronal self-organization under the free energy principle.

  4. An experimental approach towards the development of an in vitro cortical-thalamic co-culture model.

    Science.gov (United States)

    Kanagasabapathi, Thirukumaran T; Massobrio, Paolo; Tedesco, Mariateresa; Martinoia, Sergio; Wadman, Wytse J; Decré, Michel M J

    2011-01-01

    In this paper, we propose an experimental approach to develop an in vitro dissociated cortical-thalamic co-culture model using a dual compartment neurofluidic device. The device has two compartments separated by 10 μm wide and 3 μm high microchannels. The microchannels provide a physical isolation of neurons allowing only neurites to grow between the compartments. Long-term viable co-culture was maintained in the compartmented device, neurite growth through the microchannels was verified using immunofluorescence staining, and electrophysiological recordings from the co-culture system was investigated. Preliminary analysis of spontaneous activities from the co-culture shows a distinctively different firing pattern associated with cultures of individual cell types and further analysis is proposed for a deeper understanding of the dynamics involved in the network connectivity in such a co-culture system.

  5. Dynamics of myosin II organization into cortical contractile networks and fibers

    Science.gov (United States)

    Nie, Wei; Wei, Ming-Tzo; Ou-Yang, Daniel; Jedlicka, Sabrina; Vavylonis, Dimitrios

    2014-03-01

    The morphology of adhered cells critically depends on the formation of a contractile meshwork of parallel and cross-linked stress fibers along the contacting surface. The motor activity and mini-filament assembly of non-muscle myosin II is an important component of cell-level cytoskeletal remodeling during mechanosensing. To monitor the dynamics of myosin II, we used confocal microscopy to image cultured HeLa cells that stably express myosin regulatory light chain tagged with GFP (MRLC-GFP). MRLC-GFP was monitored in time-lapse movies at steady state and during the response of cells to varying concentrations of blebbistatin which disrupts actomyosin stress fibers. Using image correlation spectroscopy analysis, we quantified the kinetics of disassembly and reassembly of actomyosin networks and compared them to studies by other groups. This analysis suggested that the following processes contribute to the assembly of cortical actomyosin into fibers: random myosin mini-filament assembly and disassembly along the cortex; myosin mini-filament aligning and contraction; stabilization of cortical myosin upon increasing contractile tension. We developed simple numerical simulations that include those processes. The results of simulations of cells at steady state and in response to blebbistatin capture some of the main features observed in the experiments. This study provides a framework to help interpret how different cortical myosin remodeling kinetics may contribute to different cell shape and rigidity depending on substrate stiffness.

  6. Mouse embryonic stem cell culture for generation of three-dimensional retinal and cortical tissues.

    Science.gov (United States)

    Eiraku, Mototsugu; Sasai, Yoshiki

    2011-12-15

    Generation of compound tissues with complex structures is a major challenge in cell biology. In this article, we describe a protocol for mouse embryonic stem cell (ESC) culture for in vitro generation of three-dimensional retinal tissue, comparing it with the culture protocol for cortical tissue generation. Dissociated ESCs are reaggregated in a 96-well plate with reduced cell-plate adhesion and cultured as floating aggregates. Retinal epithelium is efficiently generated when ESC aggregates are cultured in serum-free medium containing extracellular matrix proteins, spontaneously forming hemispherical vesicles and then progressively transforming into a shape reminiscent of the embryonic optic cup in 9-10 d. In long-term culture, the ESC-derived optic cup generates a fully stratified retinal tissue consisting of all major neural retinal components. In contrast, the cortical differentiation culture can be started without exogenous extracellular matrix proteins, and it generates stratified cortical epithelia consisting of four distinct layers in 13 d.

  7. The maturation of cortical sleep rhythms and networks over early development

    OpenAIRE

    Chu, Catherine Jean; Leahy, J.; Pathmanathan, Jay Sriram; Kramer, M.A.; Cash, Sydney S.

    2014-01-01

    Objective: Although neuronal activity drives all aspects of cortical development, how human brain rhythms spontaneously mature remains an active area of research. We sought to systematically evaluate the emergence of human brain rhythms and functional cortical networks over early development. Methods: We examined cortical rhythms and coupling patterns from birth through adolescence in a large cohort of healthy children (n=384) using scalp electroencephalogram (EEG) in the sleep state. ...

  8. Neural synchrony in cortical networks: history, concept and current status

    Directory of Open Access Journals (Sweden)

    Peter Uhlhaas

    2009-07-01

    Full Text Available Following the discovery of context-dependent synchronization of oscillatory neuronal responses in the visual system, the role of neural synchrony in cortical networks has been expanded to provide a general mechanism for the coordination of distributed neural activity patterns. In the current paper, we present an update of the status of this hypothesis through summarizing recent results from our laboratory that suggest important new insights regarding the mechanisms, function and relevance of this phenomenon. In the first part, we present recent results derived from animal experiments and mathematical simulations that provide novel explanations and mechanisms for zero and nero-zero phase lag synchronization. In the second part, we shall discuss the role of neural synchrony for expectancy during perceptual organization and its role in conscious experience. This will be followed by evidence that indicates that in addition to supporting conscious cognition, neural synchrony is abnormal in major brain disorders, such as schizophrenia and autism spectrum disorders. We conclude this paper with suggestions for further research as well as with critical issues that need to be addressed in future studies.

  9. Viability of dielectrophoretically trapped neuronal cortical cells in culture

    NARCIS (Netherlands)

    Heida, Tjitske; Vulto, P; Rutten, Wim; Marani, Enrico

    2001-01-01

    Negative dielectrophoretic trapping of neural cells is an efficient way to position neural cells on the electrode sites of planar micro-electrode arrays. The preservation of viability of the neural cells is essential for this approach. This study investigates the viability of postnatal cortical rat

  10. Longitudinal Development of Cortical Thickness, Folding, and Fiber Density Networks in the First 2 Years of Life

    OpenAIRE

    Nie, Jingxin; Li, Gang; Wang, Li; Shi, Feng; Lin, Weili; Gilmore, John H.; Shen, Dinggang

    2013-01-01

    Quantitatively characterizing the development of cortical anatomical networks during the early stage of life plays an important role in revealing the relationship between cortical structural connection and high-level functional development. The development of correlation networks of cortical-thickness, cortical folding, and fiber-density is systematically analyzed in this article to study the relationship between different anatomical properties during the first 2 years of life. Specifically, ...

  11. Altered brain structural networks in attention deficit/hyperactivity disorder children revealed by cortical thickness.

    Science.gov (United States)

    Liu, Tian; Chen, Yanni; Li, Chenxi; Li, Youjun; Wang, Jue

    2017-07-04

    This study investigated the cortical thickness and topological features of human brain anatomical networks related to attention deficit/hyperactivity disorder. Data were collected from 40 attention deficit/hyperactivity disorder children and 40 normal control children. Interregional correlation matrices were established by calculating the correlations of cortical thickness between all pairs of cortical regions (68 regions) of the whole brain. Further thresholds were applied to create binary matrices to construct a series of undirected and unweighted graphs, and global, local, and nodal efficiencies were computed as a function of the network cost. These experimental results revealed abnormal cortical thickness and correlations in attention deficit/hyperactivity disorder, and showed that the brain structural networks of attention deficit/hyperactivity disorder subjects had inefficient small-world topological features. Furthermore, their topological properties were altered abnormally. In particular, decreased global efficiency combined with increased local efficiency in attention deficit/hyperactivity disorder children led to a disorder-related shift of the network topological structure toward regular networks. In addition, nodal efficiency, cortical thickness, and correlation analyses revealed that several brain regions were altered in attention deficit/hyperactivity disorder patients. These findings are in accordance with a hypothesis of dysfunctional integration and segregation of the brain in patients with attention deficit/hyperactivity disorder and provide further evidence of brain dysfunction in attention deficit/hyperactivity disorder patients by observing cortical thickness on magnetic resonance imaging.

  12. Trade-off of cerebello-cortical and cortico-cortical functional networks for planning in 6-year-old children.

    Science.gov (United States)

    Kipping, Judy A; Margulies, Daniel S; Eickhoff, Simon B; Lee, Annie; Qiu, Anqi

    2018-05-03

    Childhood is a critical period for the development of cognitive planning. There is a lack of knowledge on its neural mechanisms in children. This study aimed to examine cerebello-cortical and cortico-cortical functional connectivity in association with planning skills in 6-year-olds (n = 76). We identified the cerebello-cortical and cortico-cortical functional networks related to cognitive planning using activation likelihood estimation (ALE) meta-analysis on existing functional imaging studies on spatial planning, and data-driven independent component analysis (ICA) of children's resting-state functional MRI (rs-fMRI). We investigated associations of cerebello-cortical and cortico-cortical functional connectivity with planning ability in 6-year-olds, as assessed using the Stockings of Cambridge task. Long-range functional connectivity of two cerebellar networks (lobules VI and lateral VIIa) with the prefrontal and premotor cortex were greater in children with poorer planning ability. In contrast, cortico-cortical association networks were not associated with the performance of planning in children. These results highlighted the key contribution of the lateral cerebello-frontal functional connectivity, but not cortico-cortical association functional connectivity, for planning ability in 6-year-olds. Our results suggested that brain adaptation to the acquisition of planning ability during childhood is partially achieved through the engagement of the cerebello-cortical functional connectivity. Copyright © 2018 Elsevier Inc. All rights reserved.

  13. Functional specialisation within the cortical language network: effects of cortical dysfunction.

    Science.gov (United States)

    Vandenberghe, R

    2007-01-01

    In the 1990's neuroanatomical models of language and semantic memory have been mainly based on functional neuroimaging studies of brain activity in healthy volunteers and correlational studies between structural lesions in patients and behavioral deficits. In this paper we present a novel approach where we test models that have been developed in healthy volunteers by means of functional imaging in patients in combination with behavioral studies. Study populations consist of patients with focal cortical stroke (n = 2), amnestic mild cognitive impairment (n = 14) and primary progressive aphasia (n = 18). The experiments provide converging evidence that 1. the integrity of the right mid- and anterior fusiform gyrus is required for full and detailed retrieval of knowledge of visual attributes of concrete entities 2. the left posterior superior temporal sulcus is critically involved in lexical-semantic retrieval 3. the anterior temporal pole to the left functions as an associative structure that links the representations of meaning that are distribured over the cortical brain surface. Our experiments also provide us with new insight into the degradation and re-organisation of the language system in cortical neurodegenerative disease.

  14. Impairment of GABA transporter GAT-1 terminates cortical recurrent network activity via enhanced phasic inhibition

    Directory of Open Access Journals (Sweden)

    Daniel Simon Razik

    2013-09-01

    Full Text Available In the central nervous system, GABA transporters (GATs very efficiently clear synaptically released GABA from the extracellular space, and thus exert a tight control on GABAergic inhibition. In neocortex, GABAergic inhibition is heavily recruited during recurrent phases of spontaneous action potential activity which alternate with neuronally quiet periods. Therefore, such activity should be quite sensitive to minute alterations of GAT function. Here, we explored the effects of a gradual impairment of GAT-1 and GAT-2/3 on spontaneous recurrent network activity – termed network bursts and silent periods – in organotypic slice cultures of rat neocortex. The GAT-1 specific antagonist NO-711 depressed activity already at nanomolar concentrations (IC50 for depression of spontaneous multiunit firing rate of 42 nM, reaching a level of 80% at 500-1000 nM. By contrast, the GAT-2/3 preferring antagonist SNAP-5114 had weaker and less consistent effects. Several lines of evidence pointed towards an enhancement of phasic GABAergic inhibition as the dominant activity-depressing mechanism: network bursts were drastically shortened, phasic GABAergic currents decayed slower, and neuronal excitability during ongoing activity was diminished. In silent periods, NO-711 had little effect on neuronal excitability or membrane resistance, quite in contrast to the effects of muscimol, a GABA mimetic which activates GABAA receptors tonically. Our results suggest that an enhancement of phasic GABAergic inhibition efficiently curtails cortical recurrent activity and may mediate antiepileptic effects of therapeutically relevant concentrations of GAT-1 antagonists.

  15. Cortical Network Dynamics of Perceptual Decision-Making in the Human Brain

    Directory of Open Access Journals (Sweden)

    Markus eSiegel

    2011-02-01

    Full Text Available Goal-directed behavior requires the flexible transformation of sensory evidence about our environment into motor actions. Studies of perceptual decision-making have shown that this transformation is distributed across several widely separated brain regions. Yet, little is known about how decision-making emerges from the dynamic interactions among these regions. Here, we review a series of studies, in which we characterized the cortical network interactions underlying a perceptual decision process in the human brain. We used magnetoencephalography (MEG to measure the large-scale cortical population dynamics underlying each of the sub-processes involved in this decision: the encoding of sensory evidence and action plan, the mapping between the two, and the attentional selection of task-relevant evidence. We found that these sub-processes are mediated by neuronal oscillations within specific frequency ranges. Localized gamma-band oscillations in sensory and motor cortices reflect the encoding of the sensory evidence and motor plan. Large-scale oscillations across widespread cortical networks mediate the integrative processes connecting these local networks: Gamma- and beta-band oscillations across frontal, parietal and sensory cortices serve the selection of relevant sensory evidence and its flexible mapping onto action plans. In sum, our results suggest that perceptual decisions are mediated by oscillatory interactions within overlapping local and large-scale cortical networks.

  16. Longitudinal development of cortical thickness, folding, and fiber density networks in the first 2 years of life.

    Science.gov (United States)

    Nie, Jingxin; Li, Gang; Wang, Li; Shi, Feng; Lin, Weili; Gilmore, John H; Shen, Dinggang

    2014-08-01

    Quantitatively characterizing the development of cortical anatomical networks during the early stage of life plays an important role in revealing the relationship between cortical structural connection and high-level functional development. The development of correlation networks of cortical-thickness, cortical folding, and fiber-density is systematically analyzed in this article to study the relationship between different anatomical properties during the first 2 years of life. Specifically, longitudinal MR images of 73 healthy subjects from birth to 2 year old are used. For each subject at each time point, its measures of cortical thickness, cortical folding, and fiber density are projected to its cortical surface that has been partitioned into 78 cortical regions. Then, the correlation matrices for cortical thickness, cortical folding, and fiber density at each time point can be constructed, respectively, by computing the inter-regional Pearson correlation coefficient (of any pair of ROIs) across all 73 subjects. Finally, the presence/absence pattern (i.e., binary pattern) of the connection network is constructed from each inter-regional correlation matrix, and its statistical and anatomical properties are adopted to analyze the longitudinal development of anatomical networks. The results show that the development of anatomical network could be characterized differently by using different anatomical properties (i.e., using cortical thickness, cortical folding, or fiber density). Copyright © 2013 Wiley Periodicals, Inc.

  17. Ketamine-induced apoptosis in cultured rat cortical neurons

    International Nuclear Information System (INIS)

    Takadera, Tsuneo; Ishida, Akira; Ohyashiki, Takao

    2006-01-01

    Recent data suggest that anesthetic drugs cause neurodegeneration during development. Ketamine is frequently used in infants and toddlers for elective surgeries. The purpose of this study is to determine whether glycogen synthase kinase-3 (GSK-3) is involved in ketamine-induced apoptosis. Ketamine increased apoptotic cell death with morphological changes which were characterized by cell shrinkage, nuclear condensation or fragmentation. In addition, insulin growth factor-1 completely blocked the ketamine-induced apoptotic cell death. Ketamine decreased Akt phosphorylation. GSK-3 is known as a downstream target of Akt. The selective inhibitors of GSK-3 prevented the ketamine-induced apoptosis. Moreover, caspase-3 activation was accompanied by the ketamine-induced cell death and inhibited by the GSK-3 inhibitors. These results suggest that activation of GSK-3 is involved in ketamine-induced apoptosis in rat cortical neurons

  18. Can Cultural Worldviews Influence Network Composition?

    Science.gov (United States)

    Vaisey, Stephen; Lizardo, Omar

    2010-01-01

    Most sociological research assumes that social network composition shapes individual beliefs. Network theory and research has not adequately considered that internalized cultural worldviews might affect network composition. Drawing on a synthetic, dual-process theory of culture and two waves of nationally-representative panel data, this article…

  19. High-conductance states in a mean-field cortical network model

    CERN Document Server

    Lerchner, A; Hertz, J

    2004-01-01

    Measured responses from visual cortical neurons show that spike times tend to be correlated rather than exactly Poisson distributed. Fano factors vary and are usually greater than 1 due to the tendency of spikes being clustered into bursts. We show that this behavior emerges naturally in a balanced cortical network model with random connectivity and conductance-based synapses. We employ mean field theory with correctly colored noise to describe temporal correlations in the neuronal activity. Our results illuminate the connection between two independent experimental findings: high conductance states of cortical neurons in their natural environment, and variable non-Poissonian spike statistics with Fano factors greater than 1.

  20. Biophysical Model of Cortical Network Activity and the Influence of Electrical Stimulation

    Science.gov (United States)

    2015-11-13

    model, multicompartment model, subdural cortical stimulation, anode, cathode, epilepsy REPORT DOCUMENTATION PAGE 11. SPONSOR/MONITOR’S REPORT NUMBER(S...and axon orientation in respect to the electrode position. 4) A single stimulation pulse causes a sequence of action potentials ectopically generated...Bergey, P.J. Franaszczuk. Phase-dependent stimulation effects on bursting activity in a neural network cortical simulation, Epilepsy Research (07 2008

  1. The maturation of cortical sleep rhythms and networks over early development.

    Science.gov (United States)

    Chu, C J; Leahy, J; Pathmanathan, J; Kramer, M A; Cash, S S

    2014-07-01

    Although neuronal activity drives all aspects of cortical development, how human brain rhythms spontaneously mature remains an active area of research. We sought to systematically evaluate the emergence of human brain rhythms and functional cortical networks over early development. We examined cortical rhythms and coupling patterns from birth through adolescence in a large cohort of healthy children (n=384) using scalp electroencephalogram (EEG) in the sleep state. We found that the emergence of brain rhythms follows a stereotyped sequence over early development. In general, higher frequencies increase in prominence with striking regional specificity throughout development. The coordination of these rhythmic activities across brain regions follows a general pattern of maturation in which broadly distributed networks of low-frequency oscillations increase in density while networks of high frequency oscillations become sparser and more highly clustered. Our results indicate that a predictable program directs the development of key rhythmic components and physiological brain networks over early development. This work expands our knowledge of normal cortical development. The stereotyped neurophysiological processes observed at the level of rhythms and networks may provide a scaffolding to support critical periods of cognitive growth. Furthermore, these conserved patterns could provide a sensitive biomarker for cortical health across development. Copyright © 2013 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  2. Imprint lithography provides topographical nanocues to guide cell growth in primary cortical cell culture

    NARCIS (Netherlands)

    Xie, S.; Luttge, R.

    2014-01-01

    In this paper, we describe a technology platform to study the effect of nanocues on the cell growth direction in primary cortical cell culture. Topographical cues to cells are provided using nanoscale features created by Jet and Flash Imprint Lithography, coated with polyethylenimine. We

  3. Chronic 14-day exposure to insecticides or methylmercury modulates neuronal activity in primary rat cortical cultures

    NARCIS (Netherlands)

    Dingemans, Milou; Schütte, Marijke G; Wiersma, Daphne M M; de Groot, Aart; van Kleef, Gina; Wijnolts, Fiona; Westerink, Remco

    2016-01-01

    There is an increasing demand for in vitro test systems to detect neurotoxicity for use in chemical risk assessment. In this study, we evaluated the applicability of rat primary cortical cultures grown on multi-well micro-electrode arrays (mwMEAs) to detect effects of chronic 14-day exposure to

  4. Cytokines effects on radio-induced apoptosis in cortical and hippocampal rat cells in culture

    International Nuclear Information System (INIS)

    Coffigny, H.; Briot, D.; Le Nin, I.

    2000-01-01

    In the central nervous system in development the radio-induced cell death occurs mainly by apoptosis. The effects of modulating factors like cytokines were studied on this kind of death. To handle more easily parameters implicated in nerve cell apoptosis, we studied the effects of radiation with a in vitro system. Cells were isolated from rat foetal cortex and hippocampus, two of the major structures implicated in human mental retardation observed after exposition in utero at Hiroshima and Nagasaki. Cortical or hippocampal cells were isolated from 17 day-old rat foetuses by enzymatic and mechanical treatments and irradiated with 0.50 or 1 Gy. The cells from both structures were cultured 1 or 3 days in serum free medium. Cytokines like βNGF, NT3, EGF, βTGF, α and βFGF, IGF I and II, interleukines like Il 1β, Il 2 and IL 6 were added to the medium. In 3 days cortical cell culture, only βFGF increased cell survival with as little as 10 ng/ml. This effect was dose dependent. In hippocampal cell culture, no significant increase of cell survival occurred with 10 ng/ml of any cytokines. In the same system culture with 1 Gy irradiation, the positive or negative effect of the association of βFGF with another cytokine was tested on cell survival. Only the association with EGF induced higher cell survival in cortical cell culture. In hippocampal cell culture where βFGF alone had no effect, the cell survival was not modified by the association. In the same system, the triple association of βFGF-EGF with another cytokine was tested on hippocampal and cortical cell cultures. No significant effect was observed in both cultures but cell survival trented to decrease with βTGF. In order to avoid the mitotic effect of cytokines in the 3 day-old culture, experiments were carried out on 20 hours cell culture, before the end of the first round of the cell cycle, with the selected cytokines (βFGF or βFGF-EGF). Without irradiation, the percentage of cortical cell survival

  5. Anti-correlated cortical networks of intrinsic connectivity in the rat brain.

    Science.gov (United States)

    Schwarz, Adam J; Gass, Natalia; Sartorius, Alexander; Risterucci, Celine; Spedding, Michael; Schenker, Esther; Meyer-Lindenberg, Andreas; Weber-Fahr, Wolfgang

    2013-01-01

    In humans, resting-state blood oxygen level-dependent (BOLD) signals in the default mode network (DMN) are temporally anti-correlated with those from a lateral cortical network involving the frontal eye fields, secondary somatosensory and posterior insular cortices. Here, we demonstrate the existence of an analogous lateral cortical network in the rat brain, extending laterally from anterior secondary sensorimotor regions to the insular cortex and exhibiting low-frequency BOLD fluctuations that are temporally anti-correlated with a midline "DMN-like" network comprising posterior/anterior cingulate and prefrontal cortices. The primary nexus for this anti-correlation relationship was the anterior secondary motor cortex, close to regions that have been identified with frontal eye fields in the rat brain. The anti-correlation relationship was corroborated after global signal removal, underscoring this finding as a robust property of the functional connectivity signature in the rat brain. These anti-correlated networks demonstrate strong anatomical homology to networks identified in human and monkey connectivity studies, extend the known preserved functional connectivity relationships between rodent and primates, and support the use of resting-state functional magnetic resonance imaging as a translational imaging method between rat models and humans.

  6. Graph properties of synchronized cortical networks during visual working memory maintenance.

    Science.gov (United States)

    Palva, Satu; Monto, Simo; Palva, J Matias

    2010-02-15

    Oscillatory synchronization facilitates communication in neuronal networks and is intimately associated with human cognition. Neuronal activity in the human brain can be non-invasively imaged with magneto- (MEG) and electroencephalography (EEG), but the large-scale structure of synchronized cortical networks supporting cognitive processing has remained uncharacterized. We combined simultaneous MEG and EEG (MEEG) recordings with minimum-norm-estimate-based inverse modeling to investigate the structure of oscillatory phase synchronized networks that were active during visual working memory (VWM) maintenance. Inter-areal phase-synchrony was quantified as a function of time and frequency by single-trial phase-difference estimates of cortical patches covering the entire cortical surfaces. The resulting networks were characterized with a number of network metrics that were then compared between delta/theta- (3-6 Hz), alpha- (7-13 Hz), beta- (16-25 Hz), and gamma- (30-80 Hz) frequency bands. We found several salient differences between frequency bands. Alpha- and beta-band networks were more clustered and small-world like but had smaller global efficiency than the networks in the delta/theta and gamma bands. Alpha- and beta-band networks also had truncated-power-law degree distributions and high k-core numbers. The data converge on showing that during the VWM-retention period, human cortical alpha- and beta-band networks have a memory-load dependent, scale-free small-world structure with densely connected core-like structures. These data further show that synchronized dynamic networks underlying a specific cognitive state can exhibit distinct frequency-dependent network structures that could support distinct functional roles. Copyright 2009 Elsevier Inc. All rights reserved.

  7. Traumatic Brain Injury Increases Cortical Glutamate Network Activity by Compromising GABAergic Control.

    Science.gov (United States)

    Cantu, David; Walker, Kendall; Andresen, Lauren; Taylor-Weiner, Amaro; Hampton, David; Tesco, Giuseppina; Dulla, Chris G

    2015-08-01

    Traumatic brain injury (TBI) is a major risk factor for developing pharmaco-resistant epilepsy. Although disruptions in brain circuitry are associated with TBI, the precise mechanisms by which brain injury leads to epileptiform network activity is unknown. Using controlled cortical impact (CCI) as a model of TBI, we examined how cortical excitability and glutamatergic signaling was altered following injury. We optically mapped cortical glutamate signaling using FRET-based glutamate biosensors, while simultaneously recording cortical field potentials in acute brain slices 2-4 weeks following CCI. Cortical electrical stimulation evoked polyphasic, epileptiform field potentials and disrupted the input-output relationship in deep layers of CCI-injured cortex. High-speed glutamate biosensor imaging showed that glutamate signaling was significantly increased in the injured cortex. Elevated glutamate responses correlated with epileptiform activity, were highest directly adjacent to the injury, and spread via deep cortical layers. Immunoreactivity for markers of GABAergic interneurons were significantly decreased throughout CCI cortex. Lastly, spontaneous inhibitory postsynaptic current frequency decreased and spontaneous excitatory postsynaptic current increased after CCI injury. Our results suggest that specific cortical neuronal microcircuits may initiate and facilitate the spread of epileptiform activity following TBI. Increased glutamatergic signaling due to loss of GABAergic control may provide a mechanism by which TBI can give rise to post-traumatic epilepsy. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  8. Modulation of Cortical-subcortical Networks in Parkinson’s Disease by Applied Field Effects

    Directory of Open Access Journals (Sweden)

    Christopher William Hess

    2013-09-01

    Full Text Available Studies suggest that endogenous field effects may play a role in neuronal oscillations and communication. Non-invasive transcranial electrical stimulation with low-intensity currents can also have direct effects on the underlying cortex as well as distant network effects. While Parkinson's disease (PD is amenable to invasive neuromodulation in the basal ganglia by deep brain stimulation, techniques of non-invasive neuromodulation like transcranial direct current stimulation (tDCS and transcranial alternating current stimulation (tACS are being investigated as possible therapies. tDCS and tACS have the potential to influence the abnormal cortical-subcortical network activity that occurs in PD through sub-threshold changes in cortical excitability or through entrainment or disruption of ongoing rhythmic cortical activity. This may allow for the targeting of specific features of the disease involving abnormal oscillatory activity, as well as the enhancement of potential cortical compensation for basal ganglia dysfunction and modulation of cortical plasticity in neurorehabilitation. However, little is currently known about how cortical stimulation will affect subcortical structures, the size of any effect, and the factors of stimulation that will influence these effects.

  9. Molecular Correlates of Cortical Network Modulation by Long-Term Sensory Experience in the Adult Rat Barrel Cortex

    Science.gov (United States)

    Vallès, Astrid; Granic, Ivica; De Weerd, Peter; Martens, Gerard J. M.

    2014-01-01

    Modulation of cortical network connectivity is crucial for an adaptive response to experience. In the rat barrel cortex, long-term sensory stimulation induces cortical network modifications and neuronal response changes of which the molecular basis is unknown. Here, we show that long-term somatosensory stimulation by enriched environment…

  10. Cortical Thinning in Network-Associated Regions in Cognitively Normal and Below-Normal Range Schizophrenia

    Directory of Open Access Journals (Sweden)

    R. Walter Heinrichs

    2017-01-01

    Full Text Available This study assessed whether cortical thickness across the brain and regionally in terms of the default mode, salience, and central executive networks differentiates schizophrenia patients and healthy controls with normal range or below-normal range cognitive performance. Cognitive normality was defined using the MATRICS Consensus Cognitive Battery (MCCB composite score (T=50 ± 10 and structural magnetic resonance imaging was used to generate cortical thickness data. Whole brain analysis revealed that cognitively normal range controls (n=39 had greater cortical thickness than both cognitively normal (n=17 and below-normal range (n=49 patients. Cognitively normal controls also demonstrated greater thickness than patients in regions associated with the default mode and salience, but not central executive networks. No differences on any thickness measure were found between cognitively normal range and below-normal range controls (n=24 or between cognitively normal and below-normal range patients. In addition, structural covariance between network regions was high and similar across subgroups. Positive and negative symptom severity did not correlate with thickness values. Cortical thinning across the brain and regionally in relation to the default and salience networks may index shared aspects of the psychotic psychopathology that defines schizophrenia with no relation to cognitive impairment.

  11. Spatial interactions reveal inhibitory cortical networks in human amblyopia.

    Science.gov (United States)

    Wong, Erwin H; Levi, Dennis M; McGraw, Paul V

    2005-10-01

    Humans with amblyopia have a well-documented loss of sensitivity for first-order, or luminance defined, visual information. Recent studies show that they also display a specific loss of sensitivity for second-order, or contrast defined, visual information; a type of image structure encoded by neurons found predominantly in visual area A18/V2. In the present study, we investigate whether amblyopia disrupts the normal architecture of spatial interactions in V2 by determining the contrast detection threshold of a second-order target in the presence of second-order flanking stimuli. Adjacent flanks facilitated second-order detectability in normal observers. However, in marked contrast, they suppressed detection in each eye of the majority of amblyopic observers. Furthermore, strabismic observers with no loss of visual acuity show a similar pattern of detection suppression. We speculate that amblyopia results in predominantly inhibitory cortical interactions between second-order neurons.

  12. From cognitive networks to seizures: Stimulus evoked dynamics in a coupled cortical network

    Science.gov (United States)

    Lee, Jaejin; Ermentrout, Bard; Bodner, Mark

    2013-12-01

    Epilepsy is one of the most common neuropathologies worldwide. Seizures arising in epilepsy or in seizure disorders are characterized generally by uncontrolled spread of excitation and electrical activity to a limited region or even over the entire cortex. While it is generally accepted that abnormal excessive firing and synchronization of neuron populations lead to seizures, little is known about the precise mechanisms underlying human epileptic seizures, the mechanisms of transitions from normal to paroxysmal activity, or about how seizures spread. Further complication arises in that seizures do not occur with a single type of dynamics but as many different phenotypes and genotypes with a range of patterns, synchronous oscillations, and time courses. The concept of preventing, terminating, or modulating seizures and/or paroxysmal activity through stimulation of brain has also received considerable attention. The ability of such stimulation to prevent or modulate such pathological activity may depend on identifiable parameters. In this work, firing rate networks with inhibitory and excitatory populations were modeled. Network parameters were chosen to model normal working memory behaviors. Two different models of cognitive activity were developed. The first model consists of a single network corresponding to a local area of the brain. The second incorporates two networks connected through sparser recurrent excitatory connectivity with transmission delays ranging from approximately 3 ms within local populations to 15 ms between populations residing in different cortical areas. The effect of excitatory stimulation to activate working memory behavior through selective persistent activation of populations is examined in the models, and the conditions and transition mechanisms through which that selective activation breaks down producing spreading paroxysmal activity and seizure states are characterized. Specifically, we determine critical parameters and architectural

  13. Enhancement of synaptic transmission induced by BDNF in cultured cortical neurons

    Science.gov (United States)

    He, Jun; Gong, Hui; Zeng, Shaoqun; Li, Yanling; Luo, Qingming

    2005-03-01

    Brain-derived neurotrophic factor (BDNF), like other neurotrophins, has long-term effects on neuronal survival and differentiation; furthermore, BDNF has been reported to exert an acute potentiation of synaptic activity and are critically involved in long-term potentiation (LTP). We found that BDNF rapidly induced potentiation of synaptic activity and an increase in the intracellular Ca2+ concentration in cultured cortical neurons. Within minutes of BDNF application to cultured cortical neurons, spontaneous firing rate was dramatically increased as were the frequency and amplitude of excitatory spontaneous postsynaptic currents (EPSCs). Fura-2 recordings showed that BDNF acutely elicited an increase in intracellular calcium concentration ([Ca2+]c). This effect was partially dependent on [Ca2+]o; The BDNF-induced increase in [Ca2+]c can not be completely blocked by Ca2+-free solution. It was completely blocked by K252a and partially blocked by Cd2+ and TTX. The results demonstrate that BDNF can enhances synaptic transmission and that this effect is accompanied by a rise in [Ca2+]c that requires two route: the release of Ca2+ from intracellular calcium stores and influx of extracellular Ca2+ through voltage-dependent Ca2+ channels in cultured cortical neurons.

  14. Cortical morphometry in frontoparietal and default mode networks in math-gifted adolescents.

    Science.gov (United States)

    Navas-Sánchez, Francisco J; Carmona, Susana; Alemán-Gómez, Yasser; Sánchez-González, Javier; Guzmán-de-Villoria, Juan; Franco, Carolina; Robles, Olalla; Arango, Celso; Desco, Manuel

    2016-05-01

    Math-gifted subjects are characterized by above-age performance in intelligence tests, exceptional creativity, and high task commitment. Neuroimaging studies reveal enhanced functional brain organization and white matter microstructure in the frontoparietal executive network of math-gifted individuals. However, the cortical morphometry of these subjects remains largely unknown. The main goal of this study was to compare the cortical morphometry of math-gifted adolescents with that of an age- and IQ-matched control group. We used surface-based methods to perform a vertex-wise analysis of cortical thickness and surface area. Our results show that math-gifted adolescents present a thinner cortex and a larger surface area in key regions of the frontoparietal and default mode networks, which are involved in executive processing and creative thinking, respectively. The combination of reduced cortical thickness and larger surface area suggests above-age neural maturation of these networks in math-gifted individuals. Hum Brain Mapp 37:1893-1902, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  15. Functional networks in parallel with cortical development associate with executive functions in children.

    Science.gov (United States)

    Zhong, Jidan; Rifkin-Graboi, Anne; Ta, Anh Tuan; Yap, Kar Lai; Chuang, Kai-Hsiang; Meaney, Michael J; Qiu, Anqi

    2014-07-01

    Children begin performing similarly to adults on tasks requiring executive functions in late childhood, a transition that is probably due to neuroanatomical fine-tuning processes, including myelination and synaptic pruning. In parallel to such structural changes in neuroanatomical organization, development of functional organization may also be associated with cognitive behaviors in children. We examined 6- to 10-year-old children's cortical thickness, functional organization, and cognitive performance. We used structural magnetic resonance imaging (MRI) to identify areas with cortical thinning, resting-state fMRI to identify functional organization in parallel to cortical development, and working memory/response inhibition tasks to assess executive functioning. We found that neuroanatomical changes in the form of cortical thinning spread over bilateral frontal, parietal, and occipital regions. These regions were engaged in 3 functional networks: sensorimotor and auditory, executive control, and default mode network. Furthermore, we found that working memory and response inhibition only associated with regional functional connectivity, but not topological organization (i.e., local and global efficiency of information transfer) of these functional networks. Interestingly, functional connections associated with "bottom-up" as opposed to "top-down" processing were more clearly related to children's performance on working memory and response inhibition, implying an important role for brain systems involved in late childhood. © The Author 2013. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  16. Organizational Culture and Network Embeddedness

    NARCIS (Netherlands)

    Noorderhaven, N.G.; Koen, C.I.; Beugelsdijk, S.

    2002-01-01

    A question that has been neglected in network research is where differences in network embeddedness come from.The network literature reveals that there are three key characteristics of embedded relationships: trust, open communication, and joint problem solving.On the basis of the sparse empirical

  17. UP-DOWN cortical dynamics reflect state transitions in a bistable network.

    Science.gov (United States)

    Jercog, Daniel; Roxin, Alex; Barthó, Peter; Luczak, Artur; Compte, Albert; de la Rocha, Jaime

    2017-08-04

    In the idling brain, neuronal circuits transition between periods of sustained firing (UP state) and quiescence (DOWN state), a pattern the mechanisms of which remain unclear. Here we analyzed spontaneous cortical population activity from anesthetized rats and found that UP and DOWN durations were highly variable and that population rates showed no significant decay during UP periods. We built a network rate model with excitatory (E) and inhibitory (I) populations exhibiting a novel bistable regime between a quiescent and an inhibition-stabilized state of arbitrarily low rate. Fluctuations triggered state transitions, while adaptation in E cells paradoxically caused a marginal decay of E-rate but a marked decay of I-rate in UP periods, a prediction that we validated experimentally. A spiking network implementation further predicted that DOWN-to-UP transitions must be caused by synchronous high-amplitude events. Our findings provide evidence of bistable cortical networks that exhibit non-rhythmic state transitions when the brain rests.

  18. The causal inference of cortical neural networks during music improvisations.

    Science.gov (United States)

    Wan, Xiaogeng; Crüts, Björn; Jensen, Henrik Jeldtoft

    2014-01-01

    We present an EEG study of two music improvisation experiments. Professional musicians with high level of improvisation skills were asked to perform music either according to notes (composed music) or in improvisation. Each piece of music was performed in two different modes: strict mode and "let-go" mode. Synchronized EEG data was measured from both musicians and listeners. We used one of the most reliable causality measures: conditional Mutual Information from Mixed Embedding (MIME), to analyze directed correlations between different EEG channels, which was combined with network theory to construct both intra-brain and cross-brain networks. Differences were identified in intra-brain neural networks between composed music and improvisation and between strict mode and "let-go" mode. Particular brain regions such as frontal, parietal and temporal regions were found to play a key role in differentiating the brain activities between different playing conditions. By comparing the level of degree centralities in intra-brain neural networks, we found a difference between the response of musicians and the listeners when comparing the different playing conditions.

  19. Dynamic interactions of the cortical networks during thought suppression.

    Science.gov (United States)

    Aso, Toshihiko; Nishimura, Kazuo; Kiyonaka, Takashi; Aoki, Takaaki; Inagawa, Michiyo; Matsuhashi, Masao; Tobinaga, Yoshikazu; Fukuyama, Hidenao

    2016-08-01

    Thought suppression has spurred extensive research in clinical and preclinical fields, particularly with regard to the paradoxical aspects of this behavior. However, the involvement of the brain's inhibitory system in the dynamics underlying the continuous effort to suppress thoughts has yet to be clarified. This study aims to provide a unified perspective for the volitional suppression of internal events incorporating the current understanding of the brain's inhibitory system. Twenty healthy volunteers underwent functional magnetic resonance imaging while they performed thought suppression blocks alternating with visual imagery blocks. The whole dataset was decomposed by group-independent component analysis into 30 components. After discarding noise components, the 20 valid components were subjected to further analysis of their temporal properties including task-relatedness and between-component residual correlation. Combining a long task period and a data-driven approach, we observed a right-side-dominant, lateral frontoparietal network to be strongly suppression related. This network exhibited increased fluctuation during suppression, which is compatible with the well-known difficulty of suppression maintenance. Between-network correlation provided further insight into the coordinated engagement of the executive control and dorsal attention networks, as well as the reciprocal activation of imagery-related components, thus revealing neural substrates associated with the rivalry between intrusive thoughts and the suppression process.

  20. The Causal Inference of Cortical Neural Networks during Music Improvisations

    Science.gov (United States)

    Wan, Xiaogeng; Crüts, Björn; Jensen, Henrik Jeldtoft

    2014-01-01

    We present an EEG study of two music improvisation experiments. Professional musicians with high level of improvisation skills were asked to perform music either according to notes (composed music) or in improvisation. Each piece of music was performed in two different modes: strict mode and “let-go” mode. Synchronized EEG data was measured from both musicians and listeners. We used one of the most reliable causality measures: conditional Mutual Information from Mixed Embedding (MIME), to analyze directed correlations between different EEG channels, which was combined with network theory to construct both intra-brain and cross-brain networks. Differences were identified in intra-brain neural networks between composed music and improvisation and between strict mode and “let-go” mode. Particular brain regions such as frontal, parietal and temporal regions were found to play a key role in differentiating the brain activities between different playing conditions. By comparing the level of degree centralities in intra-brain neural networks, we found a difference between the response of musicians and the listeners when comparing the different playing conditions. PMID:25489852

  1. The causal inference of cortical neural networks during music improvisations.

    Directory of Open Access Journals (Sweden)

    Xiaogeng Wan

    Full Text Available We present an EEG study of two music improvisation experiments. Professional musicians with high level of improvisation skills were asked to perform music either according to notes (composed music or in improvisation. Each piece of music was performed in two different modes: strict mode and "let-go" mode. Synchronized EEG data was measured from both musicians and listeners. We used one of the most reliable causality measures: conditional Mutual Information from Mixed Embedding (MIME, to analyze directed correlations between different EEG channels, which was combined with network theory to construct both intra-brain and cross-brain networks. Differences were identified in intra-brain neural networks between composed music and improvisation and between strict mode and "let-go" mode. Particular brain regions such as frontal, parietal and temporal regions were found to play a key role in differentiating the brain activities between different playing conditions. By comparing the level of degree centralities in intra-brain neural networks, we found a difference between the response of musicians and the listeners when comparing the different playing conditions.

  2. Cortical radial glia: identification in tissue culture and evidence for their transformation to astrocytes.

    Science.gov (United States)

    Culican, S M; Baumrind, N L; Yamamoto, M; Pearlman, A L

    1990-02-01

    Radial glia are transiently present in the developing cerebral cortex, where they are thought to guide the migration of neurons from the proliferative zone to the forming cortical plate. To provide a framework for experimental studies of radial glia, we have defined morphological and immunocytochemical criteria to identify them in primary cultures of cortical cells obtained at embryonic day 13 in the mouse. Cortical radial glia in culture for 1-2 d resemble radial glia in vivo: they have a long, thin, unbranched process extending from one or both ends of the elongated cell body and are labeled with the monoclonal antibody RC1 but not with antibodies to glial fibrillary acidic protein (abGFAP). We tested the specificity of RC1 by double-labeling with a panel of cell-type specific antibodies, and found that it labels radial glia, astrocytes, and fibroblast-like cells, but not neurons. Fibroblasts are easily distinguished from glia by morphology and by labeling with antibodies to fibronectin. To test the hypothesis that radial glia become astrocytes when their developmental role is complete, we examined their morphological and immunocytochemical development in culture. After 3-4 d in vitro radial glia develop several branched processes; in this transitional stage they are labeled by both RC1 and abGFAP. Many radial glia lose RC1 immunoreactivity as they become increasingly branched and immunoreactive to abGFAP. In areas of the cultures that have few neurons and in cultures depleted of neurons by washing, flat, nonprocess-bearing glia predominate. These cells do not lose immunoreactivity to RC1 during the 9-d period of observation even though they acquire GFAP.(ABSTRACT TRUNCATED AT 250 WORDS)

  3. High-conductance states in a mean-field cortical network model

    DEFF Research Database (Denmark)

    Lerchner, Alexander; Ahmadi, Mandana; Hertz, John

    2004-01-01

    cortical network model with random connectivity and conductance-based synapses. We employ mean-field theory with correctly colored noise to describe temporal correlations in the neuronal activity. Our results illuminate the connection between two independent experimental findings: high-conductance states......Measured responses from visual cortical neurons show that spike times tend to be correlated rather than exactly Poisson distributed. Fano factors vary and are usually greater than 1, indicating a tendency toward spikes being clustered. We show that this behavior emerges naturally in a balanced...... of cortical neurons in their natural environment, and variable non-Poissonian spike statistics with Fano factors greater than 1. (C) 2004 Elsevier B.V. All rights reserved....

  4. Deep Residual Network Predicts Cortical Representation and Organization of Visual Features for Rapid Categorization.

    Science.gov (United States)

    Wen, Haiguang; Shi, Junxing; Chen, Wei; Liu, Zhongming

    2018-02-28

    The brain represents visual objects with topographic cortical patterns. To address how distributed visual representations enable object categorization, we established predictive encoding models based on a deep residual network, and trained them to predict cortical responses to natural movies. Using this predictive model, we mapped human cortical representations to 64,000 visual objects from 80 categories with high throughput and accuracy. Such representations covered both the ventral and dorsal pathways, reflected multiple levels of object features, and preserved semantic relationships between categories. In the entire visual cortex, object representations were organized into three clusters of categories: biological objects, non-biological objects, and background scenes. In a finer scale specific to each cluster, object representations revealed sub-clusters for further categorization. Such hierarchical clustering of category representations was mostly contributed by cortical representations of object features from middle to high levels. In summary, this study demonstrates a useful computational strategy to characterize the cortical organization and representations of visual features for rapid categorization.

  5. Altered cortical hubs in functional brain networks in amyotrophic lateral sclerosis.

    Science.gov (United States)

    Ma, Xujing; Zhang, Jiuquan; Zhang, Youxue; Chen, Heng; Li, Rong; Wang, Jian; Chen, Huafu

    2015-11-01

    Cortical hubs are highly connected nodes in functional brain networks that play vital roles in the efficient transfer of information across brain regions. Although altered functional connectivity has been found in amyotrophic lateral sclerosis (ALS), the changing pattern in functional network hubs in ALS remains unknown. In this study, we applied a voxel-wise method to investigate the changing pattern of cortical hubs in ALS. Through resting-state fMRI, we constructed whole-brain voxel-wise functional networks by measuring the temporal correlations of each pair of brain voxels and identified hubs using the graph theory method. Specifically, a functional connectivity strength (FCS) map was derived from the data on 20 patients with ALS and 20 healthy controls. The brain regions with high FCS values were regarded as functional network hubs. Functional hubs were found mainly in the bilateral precuneus, parietal cortex, medial prefrontal cortex, and in several visual regions and temporal areas in both groups. Within the hub regions, the ALS patients exhibited higher FCS in the prefrontal cortex compared with the healthy controls. The FCS value in the significantly abnormal hub regions was correlated with clinical variables. Results indicated the presence of altered cortical hubs in the ALS patients and could therefore shed light on the pathophysiology mechanisms underlying ALS.

  6. Visual cortical areas of the mouse: comparison of parcellation and network structure with primates

    Directory of Open Access Journals (Sweden)

    Marie-Eve eLaramée

    2015-01-01

    Full Text Available Brains have evolved to optimize sensory processing. In primates, complex cognitive tasks must be executed and evolution led to the development of large brains with many cortical areas. Rodents do not accomplish cognitive tasks of the same level of complexity as primates and remain with small brains both in relative and absolute terms. But is a small brain necessarily a simple brain? In this review, several aspects of the visual cortical networks have been compared between rodents and primates. The visual system has been used as a model to evaluate the level of complexity of the cortical circuits at the anatomical and functional levels. The evolutionary constraints are first presented in order to appreciate the rules for the development of the brain and its underlying circuits. The organization of sensory pathways, with their parallel and cross-modal circuits, is also examined. Other features of brain networks, often considered as imposing constraints on the development of underlying circuitry, are also discussed and their effect on the complexity of the mouse and primate brain are inspected. In this review, we discuss the common features of cortical circuits in mice and primates and see how these can be useful in understanding visual processing in these animals.

  7. Visual cortical areas of the mouse: comparison of parcellation and network structure with primates

    Science.gov (United States)

    Laramée, Marie-Eve; Boire, Denis

    2015-01-01

    Brains have evolved to optimize sensory processing. In primates, complex cognitive tasks must be executed and evolution led to the development of large brains with many cortical areas. Rodents do not accomplish cognitive tasks of the same level of complexity as primates and remain with small brains both in relative and absolute terms. But is a small brain necessarily a simple brain? In this review, several aspects of the visual cortical networks have been compared between rodents and primates. The visual system has been used as a model to evaluate the level of complexity of the cortical circuits at the anatomical and functional levels. The evolutionary constraints are first presented in order to appreciate the rules for the development of the brain and its underlying circuits. The organization of sensory pathways, with their parallel and cross-modal circuits, is also examined. Other features of brain networks, often considered as imposing constraints on the development of underlying circuitry, are also discussed and their effect on the complexity of the mouse and primate brain are inspected. In this review, we discuss the common features of cortical circuits in mice and primates and see how these can be useful in understanding visual processing in these animals. PMID:25620914

  8. Visual cortical areas of the mouse: comparison of parcellation and network structure with primates.

    Science.gov (United States)

    Laramée, Marie-Eve; Boire, Denis

    2014-01-01

    Brains have evolved to optimize sensory processing. In primates, complex cognitive tasks must be executed and evolution led to the development of large brains with many cortical areas. Rodents do not accomplish cognitive tasks of the same level of complexity as primates and remain with small brains both in relative and absolute terms. But is a small brain necessarily a simple brain? In this review, several aspects of the visual cortical networks have been compared between rodents and primates. The visual system has been used as a model to evaluate the level of complexity of the cortical circuits at the anatomical and functional levels. The evolutionary constraints are first presented in order to appreciate the rules for the development of the brain and its underlying circuits. The organization of sensory pathways, with their parallel and cross-modal circuits, is also examined. Other features of brain networks, often considered as imposing constraints on the development of underlying circuitry, are also discussed and their effect on the complexity of the mouse and primate brain are inspected. In this review, we discuss the common features of cortical circuits in mice and primates and see how these can be useful in understanding visual processing in these animals.

  9. Subthalamic stimulation modulates cortical motor network activity and synchronization in Parkinson’s disease

    Science.gov (United States)

    Klotz, Rosa; Govindan, Rathinaswamy B.; Scholten, Marlieke; Naros, Georgios; Ramos-Murguialday, Ander; Bunjes, Friedemann; Meisner, Christoph; Plewnia, Christian; Krüger, Rejko

    2015-01-01

    Dynamic modulations of large-scale network activity and synchronization are inherent to a broad spectrum of cognitive processes and are disturbed in neuropsychiatric conditions including Parkinson’s disease. Here, we set out to address the motor network activity and synchronization in Parkinson’s disease and its modulation with subthalamic stimulation. To this end, 20 patients with idiopathic Parkinson’s disease with subthalamic nucleus stimulation were analysed on externally cued right hand finger movements with 1.5-s interstimulus interval. Simultaneous recordings were obtained from electromyography on antagonistic muscles (right flexor digitorum and extensor digitorum) together with 64-channel electroencephalography. Time-frequency event-related spectral perturbations were assessed to determine cortical and muscular activity. Next, cross-spectra in the time-frequency domain were analysed to explore the cortico-cortical synchronization. The time-frequency modulations enabled us to select a time-frequency range relevant for motor processing. On these time-frequency windows, we developed an extension of the phase synchronization index to quantify the global cortico-cortical synchronization and to obtain topographic differentiations of distinct electrode sites with respect to their contributions to the global phase synchronization index. The spectral measures were used to predict clinical and reaction time outcome using regression analysis. We found that movement-related desynchronization of cortical activity in the upper alpha and beta range was significantly facilitated with ‘stimulation on’ compared to ‘stimulation off’ on electrodes over the bilateral parietal, sensorimotor, premotor, supplementary-motor, and prefrontal areas, including the bilateral inferior prefrontal areas. These spectral modulations enabled us to predict both clinical and reaction time improvement from subthalamic stimulation. With ‘stimulation on’, interhemispheric cortico-cortical

  10. The Cortical Network for Braille Writing in the Blind.

    Science.gov (United States)

    Likova, Lora T; Tyler, Christopher W; Cacciamani, Laura; Mineff, Kristyo; Nicholas, Spero

    2016-01-01

    Fundamental forms of high-order cognition, such as reading and writing, are usually studied in the context of one modality - vision. People without sight, however, use the kinesthetic-based Braille writing, and haptic-based Braille reading. We asked whether the cognitive and motor control mechanisms underlying writing and reading are modality-specific or supramodal. While a number of previous functional Magnetic Resonance Imaging (fMRI) studies have investigated the brain network for Braille reading in the blind, such studies on Braille writing are lacking. Consequently, no comparative network analysis of Braille writing vs. reading exists. Here, we report the first study of Braille writing, and a comparison of the brain organization for Braille writing vs Braille reading. FMRI was conducted in a Siemens 3T Trio scanner. Our custom MRI-compatible drawing/writing lectern was further modified to provide for Braille reading and writing. Each of five paragraphs of novel Braille text describing objects, faces and navigation sequences was read, then reproduced twice by Braille writing from memory, then read a second time. During Braille reading, the haptic-sensing of the Braille letters strongly activated not only the early visual area V1 and V2, but some highly specialized areas, such as the classical visual grapheme area and the Exner motor grapheme area. Braille-writing-from-memory, engaged a significantly more extensive network in dorsal motor, somatosensory/kinesthetic, dorsal parietal and prefrontal cortex. However, in contrast to the largely extended V1 activation in drawing-from-memory in the blind after training (Likova, 2012), Braille writing from memory generated focal activation restricted to the most foveal part of V1, presumably reflecting topographically the focal demands of such a "pin-pricking" task.

  11. Mobile Social Network in a Cultural Context

    DEFF Research Database (Denmark)

    Liu, Jun

    2010-01-01

    , and mobile phone rumours, this study observes that mobile social networks are a way that Chinese people cultivate, maintain and strengthen their guanxi networks. Embedding the reliability of guanxi, the message spreading via mobile communication always enjoys high credibility, while mutual obligation...... of mobile social network in China therefore emanate not only from Information and Communication Technologies, but also from the socio-cultural source - guanxi - deeply rooted in Chinese society.......the chapter “Mobile Social Network in a Cultural Context” examines the guanxi-embedded mobile social network in China. By focusing on three concrete case studies with 56 in-depth interviews, including New Year text message greetings, mobile social networks for job allocations among migrant workers...

  12. Regulating Cortical Oscillations in an Inhibition-Stabilized Network.

    Science.gov (United States)

    Jadi, Monika P; Sejnowski, Terrence J

    2014-04-21

    Understanding the anatomical and functional architecture of the brain is essential for designing neurally inspired intelligent systems. Theoretical and empirical studies suggest a role for narrowband oscillations in shaping the functional architecture of the brain through their role in coding and communication of information. Such oscillations are ubiquitous signals in the electrical activity recorded from the brain. In the cortex, oscillations detected in the gamma range (30-80 Hz) are modulated by behavioral states and sensory features in complex ways. How is this regulation achieved? Although several underlying principles for the genesis of these oscillations have been proposed, a unifying account for their regulation has remained elusive. In a network of excitatory and inhibitory neurons operating in an inhibition-stabilized regime, we show that strongly superlinear responses of inhibitory neurons facilitate bidirectional regulation of oscillation frequency and power. In such a network, the balance of drives to the excitatory and inhibitory populations determines how the power and frequency of oscillations are modulated. The model accounts for the puzzling increase in their frequency with the salience of visual stimuli, and a decrease with their size. Oscillations in our model grow stronger as the mean firing level is reduced, accounting for the size dependence of visually evoked gamma rhythms, and suggesting a role for oscillations in improving the signal-to-noise ratio (SNR) of signals in the brain. Empirically testing such predictions is still challenging, and implementing the proposed coding and communication strategies in neuromorphic systems could assist in our understanding of the biological system.

  13. Math anxiety: Brain cortical network changes in anticipation of doing mathematics.

    Science.gov (United States)

    Klados, Manousos A; Pandria, Niki; Micheloyannis, Sifis; Margulies, Daniel; Bamidis, Panagiotis D

    2017-12-01

    Following our previous work regarding the involvement of math anxiety (MA) in math-oriented tasks, this study tries to explore the differences in the cerebral networks' topology between self-reported low math-anxious (LMA) and high math-anxious (HMA) individuals, during the anticipation phase prior to a mathematical related experiment. For this reason, multichannel EEG recordings were adopted, while the solution of the inverse problem was applied in a generic head model, in order to obtain the cortical signals. The cortical networks have been computed for each band separately, using the magnitude square coherence metric. The main graph theoretical parameters, showed differences in segregation and integration in almost all EEG bands of the HMAs in comparison to LMAs, indicative of a great influence of the anticipatory anxiety prior to mathematical performance. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Extensive video-game experience alters cortical networks for complex visuomotor transformations.

    Science.gov (United States)

    Granek, Joshua A; Gorbet, Diana J; Sergio, Lauren E

    2010-10-01

    Using event-related functional magnetic resonance imaging (fMRI), we examined the effect of video-game experience on the neural control of increasingly complex visuomotor tasks. Previously, skilled individuals have demonstrated the use of a more efficient movement control brain network, including the prefrontal, premotor, primary sensorimotor and parietal cortices. Our results extend and generalize this finding by documenting additional prefrontal cortex activity in experienced video gamers planning for complex eye-hand coordination tasks that are distinct from actual video-game play. These changes in activation between non-gamers and extensive gamers are putatively related to the increased online control and spatial attention required for complex visually guided reaching. These data suggest that the basic cortical network for processing complex visually guided reaching is altered by extensive video-game play. Crown Copyright © 2009. Published by Elsevier Srl. All rights reserved.

  15. Anti-correlated cortical networks arise from spontaneous neuronal dynamics at slow timescales.

    Science.gov (United States)

    Kodama, Nathan X; Feng, Tianyi; Ullett, James J; Chiel, Hillel J; Sivakumar, Siddharth S; Galán, Roberto F

    2018-01-12

    In the highly interconnected architectures of the cerebral cortex, recurrent intracortical loops disproportionately outnumber thalamo-cortical inputs. These networks are also capable of generating neuronal activity without feedforward sensory drive. It is unknown, however, what spatiotemporal patterns may be solely attributed to intrinsic connections of the local cortical network. Using high-density microelectrode arrays, here we show that in the isolated, primary somatosensory cortex of mice, neuronal firing fluctuates on timescales from milliseconds to tens of seconds. Slower firing fluctuations reveal two spatially distinct neuronal ensembles, which correspond to superficial and deeper layers. These ensembles are anti-correlated: when one fires more, the other fires less and vice versa. This interplay is clearest at timescales of several seconds and is therefore consistent with shifts between active sensing and anticipatory behavioral states in mice.

  16. Altered modular organization of structural cortical networks in children with autism.

    Directory of Open Access Journals (Sweden)

    Feng Shi

    Full Text Available Autism is a complex developmental disability that characterized by deficits in social interaction, language skills, repetitive stereotyped behaviors and restricted interests. Although great heterogeneity exists, previous findings suggest that autism has atypical brain connectivity patterns and disrupted small-world network properties. However, the organizational alterations in the autistic brain network are still poorly understood. We explored possible organizational alterations of 49 autistic children and 51 typically developing controls, by investigating their brain network metrics that are constructed upon cortical thickness correlations. Three modules were identified in controls, including cortical regions associated with brain functions of executive strategic, spatial/auditory/visual, and self-reference/episodic memory. There are also three modules found in autistic children with similar patterns. Compared with controls, autism demonstrates significantly reduced gross network modularity, and a larger number of inter-module connections. However, the autistic brain network demonstrates increased intra- and inter-module connectivity in brain regions including middle frontal gyrus, inferior parietal gyrus, and cingulate, suggesting one underlying compensatory mechanism associated with brain functions of self-reference and episodic memory. Results also show that there is increased correlation strength between regions inside frontal lobe, as well as impaired correlation strength between frontotemporal and frontoparietal regions. This alteration of correlation strength may contribute to the organization alteration of network structures in autistic brains.

  17. Reconfiguration of Cortical Networks in MDD Uncovered by Multiscale Community Detection with fMRI.

    Science.gov (United States)

    He, Ye; Lim, Sol; Fortunato, Santo; Sporns, Olaf; Zhang, Lei; Qiu, Jiang; Xie, Peng; Zuo, Xi-Nian

    2018-04-01

    Major depressive disorder (MDD) is known to be associated with altered interactions between distributed brain regions. How these regional changes relate to the reorganization of cortical functional systems, and their modulation by antidepressant medication, is relatively unexplored. To identify changes in the community structure of cortical functional networks in MDD, we performed a multiscale community detection algorithm on resting-state functional connectivity networks of unmedicated MDD (uMDD) patients (n = 46), medicated MDD (mMDD) patients (n = 38), and healthy controls (n = 50), which yielded a spectrum of multiscale community partitions. we selected an optimal resolution level by identifying the most stable community partition for each group. uMDD and mMDD groups exhibited a similar reconfiguration of the community structure of the visual association and the default mode systems but showed different reconfiguration profiles in the frontoparietal control (FPC) subsystems. Furthermore, the central system (somatomotor/salience) and 3 frontoparietal subsystems showed strengthened connectivity with other communities in uMDD but, with the exception of 1 frontoparietal subsystem, returned to control levels in mMDD. These findings provide evidence for reconfiguration of specific cortical functional systems associated with MDD, as well as potential effects of medication in restoring disease-related network alterations, especially those of the FPC system.

  18. Cortical networks for encoding near and far space in the non-human primate.

    Science.gov (United States)

    Cléry, Justine; Guipponi, Olivier; Odouard, Soline; Wardak, Claire; Ben Hamed, Suliann

    2018-04-19

    While extra-personal space is often erroneously considered as a unique entity, early neuropsychological studies report a dissociation between near and far space processing both in humans and in monkeys. Here, we use functional MRI in a naturalistic 3D environment to describe the non-human primate near and far space cortical networks. We describe the co-occurrence of two extended functional networks respectively dedicated to near and far space processing. Specifically, far space processing involves occipital, temporal, parietal, posterior cingulate as well as orbitofrontal regions not activated by near space, possibly subserving the processing of the shape and identity of objects. In contrast, near space processing involves temporal, parietal, prefrontal and premotor regions not activated by far space, possibly subserving the preparation of an arm/hand mediated action in this proximal space. Interestingly, this network also involves somatosensory regions, suggesting a cross-modal anticipation of touch by a nearby object. Last, we also describe cortical regions that process both far and near space with a preference for one or the other. This suggests a continuous encoding of relative distance to the body, in the form of a far-to-near gradient. We propose that these cortical gradients in space representation subserve the physically delineable peripersonal spaces described in numerous psychology and psychophysics studies. Copyright © 2018 Elsevier Inc. All rights reserved.

  19. Alterations in Normal Aging Revealed by Cortical Brain Network Constructed Using IBASPM.

    Science.gov (United States)

    Li, Wan; Yang, Chunlan; Shi, Feng; Wang, Qun; Wu, Shuicai; Lu, Wangsheng; Li, Shaowu; Nie, Yingnan; Zhang, Xin

    2018-04-16

    Normal aging has been linked with the decline of cognitive functions, such as memory and executive skills. One of the prominent approaches to investigate the age-related alterations in the brain is by examining the cortical brain connectome. IBASPM is a toolkit to realize individual atlas-based volume measurement. Hence, this study seeks to determine what further alterations can be revealed by cortical brain networks formed by IBASPM-extracted regional gray matter volumes. We found the reduced strength of connections between the superior temporal pole and middle temporal pole in the right hemisphere, global hubs as the left fusiform gyrus and right Rolandic operculum in the young and aging groups, respectively, and significantly reduced inter-module connection of one module in the aging group. These new findings are consistent with the phenomenon of normal aging mentioned in previous studies and suggest that brain network built with the IBASPM could provide supplementary information to some extent. The individualization of morphometric features extraction deserved to be given more attention in future cortical brain network research.

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

    Directory of Open Access Journals (Sweden)

    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.

  1. Increased cortical-limbic anatomical network connectivity in major depression revealed by diffusion tensor imaging.

    Directory of Open Access Journals (Sweden)

    Peng Fang

    Full Text Available Magnetic resonance imaging studies have reported significant functional and structural differences between depressed patients and controls. Little attention has been given, however, to the abnormalities in anatomical connectivity in depressed patients. In the present study, we aim to investigate the alterations in connectivity of whole-brain anatomical networks in those suffering from major depression by using machine learning approaches. Brain anatomical networks were extracted from diffusion magnetic resonance images obtained from both 22 first-episode, treatment-naive adults with major depressive disorder and 26 matched healthy controls. Using machine learning approaches, we differentiated depressed patients from healthy controls based on their whole-brain anatomical connectivity patterns and identified the most discriminating features that represent between-group differences. Classification results showed that 91.7% (patients=86.4%, controls=96.2%; permutation test, p<0.0001 of subjects were correctly classified via leave-one-out cross-validation. Moreover, the strengths of all the most discriminating connections were increased in depressed patients relative to the controls, and these connections were primarily located within the cortical-limbic network, especially the frontal-limbic network. These results not only provide initial steps toward the development of neurobiological diagnostic markers for major depressive disorder, but also suggest that abnormal cortical-limbic anatomical networks may contribute to the anatomical basis of emotional dysregulation and cognitive impairments associated with this disease.

  2. Neuroprotective effect of the endogenous neural peptide apelin in cultured mouse cortical neurons

    International Nuclear Information System (INIS)

    Zeng, Xiang Jun; Yu, Shan Ping; Zhang, Like; Wei, Ling

    2010-01-01

    The adipocytokine apelin and its G protein-coupled APJ receptor were initially isolated from a bovine stomach and have been detected in the brain and cardiovascular system. Recent studies suggest that apelin can protect cardiomyocytes from ischemic injury. Here, we investigated the effect of apelin on apoptosis in mouse primary cultures of cortical neurons. Exposure of the cortical cultures to a serum-free medium for 24 h induced nuclear fragmentation and apoptotic death; apelin-13 (1.0-5.0 nM) markedly prevented the neuronal apoptosis. Apelin neuroprotective effects were mediated by multiple mechanisms. Apelin-13 reduced serum deprivation (SD)-induced ROS generation, mitochondria depolarization, cytochrome c release and activation of caspase-3. Apelin-13 prevented SD-induced changes in phosphorylation status of Akt and ERK1/2. In addition, apelin-13 attenuated NMDA-induced intracellular Ca 2+ accumulation. These results indicate that apelin is an endogenous neuroprotective adipocytokine that may block apoptosis and excitotoxic death via cellular and molecular mechanisms. It is suggested that apelins may be further explored as a potential neuroprotective reagent for ischemia-induced brain damage.

  3. SynGAP regulates protein synthesis and homeostatic synaptic plasticity in developing cortical networks.

    Directory of Open Access Journals (Sweden)

    Chih-Chieh Wang

    Full Text Available Disrupting the balance between excitatory and inhibitory neurotransmission in the developing brain has been causally linked with intellectual disability (ID and autism spectrum disorders (ASD. Excitatory synapse strength is regulated in the central nervous system by controlling the number of postsynaptic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs. De novo genetic mutations of the synaptic GTPase-activating protein (SynGAP are associated with ID and ASD. SynGAP is enriched at excitatory synapses and genetic suppression of SynGAP increases excitatory synaptic strength. However, exactly how SynGAP acts to maintain synaptic AMPAR content is unclear. We show here that SynGAP limits excitatory synaptic strength, in part, by suppressing protein synthesis in cortical neurons. The data presented here from in vitro, rat and mouse cortical networks, demonstrate that regulation of translation by SynGAP involves ERK, mTOR, and the small GTP-binding protein Rheb. Furthermore, these data show that GluN2B-containing NMDARs and the cognitive kinase CaMKII act upstream of SynGAP and that this signaling cascade is required for proper translation-dependent homeostatic synaptic plasticity of excitatory synapses in developing cortical networks.

  4. Safety culture and networks of influence

    International Nuclear Information System (INIS)

    Pereira, Carlos Henrique V.; Barroso, Antonio C.O.; Vieira Neto, Antonio S.

    2011-01-01

    This paper analyzes the social networks that influence the formation and maintenance of the safety culture within the Institute of Energy and Nuclear Research (IPEN-CNEN/SP). From the mapping and analysis of social networks, actors with a significant degree of influence were identified. Later using a questionnaire, the beliefs of the population sample were mapped. Thus, the importance of key actors in the network analysis could be confirmed statistically. Therefore, based on the mentioned methods we could demonstrate our hypothesis, that there are some social networks that are important in the formation of safety culture, as well as the fact that the influence of some distinguished actors plays an essential role in this amalgam. (author)

  5. Safety culture and networks of influence

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Carlos Henrique V.; Barroso, Antonio C.O.; Vieira Neto, Antonio S., E-mail: carloshvp@usp.br, E-mail: barroso@ipen.br, E-mail: asvneto@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    This paper analyzes the social networks that influence the formation and maintenance of the safety culture within the Institute of Energy and Nuclear Research (IPEN-CNEN/SP). From the mapping and analysis of social networks, actors with a significant degree of influence were identified. Later using a questionnaire, the beliefs of the population sample were mapped. Thus, the importance of key actors in the network analysis could be confirmed statistically. Therefore, based on the mentioned methods we could demonstrate our hypothesis, that there are some social networks that are important in the formation of safety culture, as well as the fact that the influence of some distinguished actors plays an essential role in this amalgam. (author)

  6. Slicing, sampling, and distance-dependent effects affect network measures in simulated cortical circuit structures

    Directory of Open Access Journals (Sweden)

    Daniel Carl Miner

    2014-11-01

    Full Text Available The neuroanatomical connectivity of cortical circuits is believed to follow certain rules, the exact origins of which are still poorly understood. In particular, numerous nonrandom features, such as common neighbor clustering, overrepresentation of reciprocal connectivity, and overrepresentation of certain triadic graph motifs have been experimentally observed in cortical slice data. Some of these data, particularly regarding bidirectional connectivity are seemingly contradictory, and the reasons for this are unclear. Here we present a simple static geometric network model with distance-dependent connectivity on a realistic scale that naturally gives rise to certain elements of these observed behaviors, and may provide plausible explanations for some of the conflicting findings. Specifically, investigation of the model shows that experimentally measured nonrandom effects, especially bidirectional connectivity, may depend sensitively on experimental parameters such as slice thickness and sampling area, suggesting potential explanations for the seemingly conflicting experimental results.

  7. Slicing, sampling, and distance-dependent effects affect network measures in simulated cortical circuit structures.

    Science.gov (United States)

    Miner, Daniel C; Triesch, Jochen

    2014-01-01

    The neuroanatomical connectivity of cortical circuits is believed to follow certain rules, the exact origins of which are still poorly understood. In particular, numerous nonrandom features, such as common neighbor clustering, overrepresentation of reciprocal connectivity, and overrepresentation of certain triadic graph motifs have been experimentally observed in cortical slice data. Some of these data, particularly regarding bidirectional connectivity are seemingly contradictory, and the reasons for this are unclear. Here we present a simple static geometric network model with distance-dependent connectivity on a realistic scale that naturally gives rise to certain elements of these observed behaviors, and may provide plausible explanations for some of the conflicting findings. Specifically, investigation of the model shows that experimentally measured nonrandom effects, especially bidirectional connectivity, may depend sensitively on experimental parameters such as slice thickness and sampling area, suggesting potential explanations for the seemingly conflicting experimental results.

  8. Network Supervision of Adult Experience and Learning Dependent Sensory Cortical Plasticity.

    Science.gov (United States)

    Blake, David T

    2017-06-18

    The brain is capable of remodeling throughout life. The sensory cortices provide a useful preparation for studying neuroplasticity both during development and thereafter. In adulthood, sensory cortices change in the cortical area activated by behaviorally relevant stimuli, by the strength of response within that activated area, and by the temporal profiles of those responses. Evidence supports forms of unsupervised, reinforcement, and fully supervised network learning rules. Studies on experience-dependent plasticity have mostly not controlled for learning, and they find support for unsupervised learning mechanisms. Changes occur with greatest ease in neurons containing α-CamKII, which are pyramidal neurons in layers II/III and layers V/VI. These changes use synaptic mechanisms including long term depression. Synaptic strengthening at NMDA-containing synapses does occur, but its weak association with activity suggests other factors also initiate changes. Studies that control learning find support of reinforcement learning rules and limited evidence of other forms of supervised learning. Behaviorally associating a stimulus with reinforcement leads to a strengthening of cortical response strength and enlarging of response area with poor selectivity. Associating a stimulus with omission of reinforcement leads to a selective weakening of responses. In some preparations in which these associations are not as clearly made, neurons with the most informative discharges are relatively stronger after training. Studies analyzing the temporal profile of responses associated with omission of reward, or of plasticity in studies with different discriminanda but statistically matched stimuli, support the existence of limited supervised network learning. © 2017 American Physiological Society. Compr Physiol 7:977-1008, 2017. Copyright © 2017 John Wiley & Sons, Inc.

  9. Initiation of electrographic seizures by neuronal networks in entorhinal and perirhinal cortices in vitro.

    Science.gov (United States)

    de Guzman, P; D'Antuono, M; Avoli, M

    2004-01-01

    The hippocampus is often considered to play a major role in the pathophysiology of mesial temporal lobe epilepsy. However, emerging clinical and experimental evidence suggests that parahippocampal areas may contribute to a greater extent to limbic seizure initiation, and perhaps epileptogenesis. To date, little is known about the participation of entorhinal and perirhinal networks to epileptiform synchronization. Here, we addressed this issue by using simultaneous field potential recordings in horizontal rat brain slices containing interconnected limbic structures that included the hippocampus proper. Epileptiform discharges were disclosed by bath applying the convulsant drug 4-aminopyridine (50 microM) or by superfusing Mg(2+)-free medium. In the presence of 4-aminopyridine, slow interictal- (duration=2.34+/-0.29 s; interval of occurrence=25.75+/-2.11 s, n=16) and ictal-like (duration=31.25+/-3.34 s; interval of occurrence=196.96+/-21.56 s, n=17) discharges were recorded in entorhinal and perirhinal cortices after abating the propagation of CA3-driven interictal activity to these areas following extended hippocampal knife cuts. Simultaneous recordings obtained from the medial and lateral entorhinal cortex, and from the perirhinal cortex revealed that interictal and ictal discharges could initiate from any of these areas and propagate to the neighboring structure with delays of 8-66 ms. However, slow interictal- and ictal-like events more often originated in the medial entorhinal cortex and perirhinal cortex, respectively. Cutting the connections between entorhinal and perirhinal cortices (n=10), or functional inactivation of cortical areas by local application of a glutamatergic receptor antagonist (n=11) made independent epileptiform activity occur in all areas. These procedures also shortened ictal discharge duration in the entorhinal cortices, but not in the perirhinal area. Similar results could be obtained by applying Mg(2+)-free medium (n=7). These findings

  10. Depth-dependent flow and pressure characteristics in cortical microvascular networks.

    Directory of Open Access Journals (Sweden)

    Franca Schmid

    2017-02-01

    Full Text Available A better knowledge of the flow and pressure distribution in realistic microvascular networks is needed for improving our understanding of neurovascular coupling mechanisms and the related measurement techniques. Here, numerical simulations with discrete tracking of red blood cells (RBCs are performed in three realistic microvascular networks from the mouse cerebral cortex. Our analysis is based on trajectories of individual RBCs and focuses on layer-specific flow phenomena until a cortical depth of 1 mm. The individual RBC trajectories reveal that in the capillary bed RBCs preferentially move in plane. Hence, the capillary flow field shows laminar patterns and a layer-specific analysis is valid. We demonstrate that for RBCs entering the capillary bed close to the cortical surface (< 400 μm the largest pressure drop takes place in the capillaries (37%, while for deeper regions arterioles are responsible for 61% of the total pressure drop. Further flow characteristics, such as capillary transit time or RBC velocity, also vary significantly over cortical depth. Comparison of purely topological characteristics with flow-based ones shows that a combined interpretation of topology and flow is indispensable. Our results provide evidence that it is crucial to consider layer-specific differences for all investigations related to the flow and pressure distribution in the cortical vasculature. These findings support the hypothesis that for an efficient oxygen up-regulation at least two regulation mechanisms must be playing hand in hand, namely cerebral blood flow increase and microvascular flow homogenization. However, the contribution of both regulation mechanisms to oxygen up-regulation likely varies over depth.

  11. Early magnetic resonance detection of cortical necrosis and acute network injury associated with neonatal and infantile cerebral infarction

    Energy Technology Data Exchange (ETDEWEB)

    Okabe, Tetsuhiko; Aida, Noriko; Nozawa, Kumiko [Kanagawa Children' s Medical Center, Department of Radiology, Yokohama (Japan); Niwa, Tetsu [Kanagawa Children' s Medical Center, Department of Radiology, Yokohama (Japan); Tokai University School of Medicine, Department of Radiology, Isehara (Japan); Shibasaki, Jun [Kanagawa Children' s Medical Center, Department of Neonatology, Yokohama (Japan); Osaka, Hitoshi [Kanagawa Children' s Medical Center, Department of Neurology, Yokohama (Japan)

    2014-05-15

    Knowledge of MRI findings in pediatric cerebral infarction is limited. To determine whether cortical necrosis and network injury appear in the acute phase in post-stroke children and to identify anatomical location of acute network injury and the ages at which these phenomena are seen. Images from 12 children (age range: 0-9 years; neonates [<1 month], n=5; infants [1 month-12 months], n=3; others [≥1 year], n=4) with acute middle cerebral artery (MCA) cortical infarction were retrospectively analyzed. Cortical necrosis was defined as hyperintense cortical lesions on T1-weighted imaging that lacked evidence of hemorrhage. Acute network injury was defined as hyperintense lesions on diffusion-weighted imaging that were not in the MCA territory and had fiber connections with the affected cerebral cortex. MRI was performed within the first week after disease onset. Cortical necrosis was only found in three neonates. Acute network injury was seen in the corticospinal tract (CST), thalamus and corpus callosum. Acute network injury along the CST was found in five neonates and one 7-month-old infant. Acute network injury was evident in the thalamus of four neonates and two infants (ages 4 and 7 months) and in the corpus callosum of five neonates and two infants (ages 4 and 7 months). The entire thalamus was involved in three children when infarction of MCA was complete. In acute MCA cortical infarction, MRI findings indicating cortical necrosis or acute network injury was frequently found in neonates and early infants. Response to injury in a developing brain may be faster than that in a mature one. (orig.)

  12. Early magnetic resonance detection of cortical necrosis and acute network injury associated with neonatal and infantile cerebral infarction

    International Nuclear Information System (INIS)

    Okabe, Tetsuhiko; Aida, Noriko; Nozawa, Kumiko; Niwa, Tetsu; Shibasaki, Jun; Osaka, Hitoshi

    2014-01-01

    Knowledge of MRI findings in pediatric cerebral infarction is limited. To determine whether cortical necrosis and network injury appear in the acute phase in post-stroke children and to identify anatomical location of acute network injury and the ages at which these phenomena are seen. Images from 12 children (age range: 0-9 years; neonates [<1 month], n=5; infants [1 month-12 months], n=3; others [≥1 year], n=4) with acute middle cerebral artery (MCA) cortical infarction were retrospectively analyzed. Cortical necrosis was defined as hyperintense cortical lesions on T1-weighted imaging that lacked evidence of hemorrhage. Acute network injury was defined as hyperintense lesions on diffusion-weighted imaging that were not in the MCA territory and had fiber connections with the affected cerebral cortex. MRI was performed within the first week after disease onset. Cortical necrosis was only found in three neonates. Acute network injury was seen in the corticospinal tract (CST), thalamus and corpus callosum. Acute network injury along the CST was found in five neonates and one 7-month-old infant. Acute network injury was evident in the thalamus of four neonates and two infants (ages 4 and 7 months) and in the corpus callosum of five neonates and two infants (ages 4 and 7 months). The entire thalamus was involved in three children when infarction of MCA was complete. In acute MCA cortical infarction, MRI findings indicating cortical necrosis or acute network injury was frequently found in neonates and early infants. Response to injury in a developing brain may be faster than that in a mature one. (orig.)

  13. Early magnetic resonance detection of cortical necrosis and acute network injury associated with neonatal and infantile cerebral infarction.

    Science.gov (United States)

    Okabe, Tetsuhiko; Aida, Noriko; Niwa, Tetsu; Nozawa, Kumiko; Shibasaki, Jun; Osaka, Hitoshi

    2014-05-01

    Knowledge of MRI findings in pediatric cerebral infarction is limited. To determine whether cortical necrosis and network injury appear in the acute phase in post-stroke children and to identify anatomical location of acute network injury and the ages at which these phenomena are seen. Images from 12 children (age range: 0-9 years; neonates [acute middle cerebral artery (MCA) cortical infarction were retrospectively analyzed. Cortical necrosis was defined as hyperintense cortical lesions on T1-weighted imaging that lacked evidence of hemorrhage. Acute network injury was defined as hyperintense lesions on diffusion-weighted imaging that were not in the MCA territory and had fiber connections with the affected cerebral cortex. MRI was performed within the first week after disease onset. Cortical necrosis was only found in three neonates. Acute network injury was seen in the corticospinal tract (CST), thalamus and corpus callosum. Acute network injury along the CST was found in five neonates and one 7-month-old infant. Acute network injury was evident in the thalamus of four neonates and two infants (ages 4 and 7 months) and in the corpus callosum of five neonates and two infants (ages 4 and 7 months). The entire thalamus was involved in three children when infarction of MCA was complete. In acute MCA cortical infarction, MRI findings indicating cortical necrosis or acute network injury was frequently found in neonates and early infants. Response to injury in a developing brain may be faster than that in a mature one.

  14. Network Events on Multiple Space and Time Scales in Cultured Neural Networks and in a Stochastic Rate Model.

    Directory of Open Access Journals (Sweden)

    Guido Gigante

    2015-11-01

    Full Text Available Cortical networks, in-vitro as well as in-vivo, can spontaneously generate a variety of collective dynamical events such as network spikes, UP and DOWN states, global oscillations, and avalanches. Though each of them has been variously recognized in previous works as expression of the excitability of the cortical tissue and the associated nonlinear dynamics, a unified picture of the determinant factors (dynamical and architectural is desirable and not yet available. Progress has also been partially hindered by the use of a variety of statistical measures to define the network events of interest. We propose here a common probabilistic definition of network events that, applied to the firing activity of cultured neural networks, highlights the co-occurrence of network spikes, power-law distributed avalanches, and exponentially distributed 'quasi-orbits', which offer a third type of collective behavior. A rate model, including synaptic excitation and inhibition with no imposed topology, synaptic short-term depression, and finite-size noise, accounts for all these different, coexisting phenomena. We find that their emergence is largely regulated by the proximity to an oscillatory instability of the dynamics, where the non-linear excitable behavior leads to a self-amplification of activity fluctuations over a wide range of scales in space and time. In this sense, the cultured network dynamics is compatible with an excitation-inhibition balance corresponding to a slightly sub-critical regime. Finally, we propose and test a method to infer the characteristic time of the fatigue process, from the observed time course of the network's firing rate. Unlike the model, possessing a single fatigue mechanism, the cultured network appears to show multiple time scales, signalling the possible coexistence of different fatigue mechanisms.

  15. Reducing a cortical network to a Potts model yields storage capacity estimates

    Science.gov (United States)

    Naim, Michelangelo; Boboeva, Vezha; Kang, Chol Jun; Treves, Alessandro

    2018-04-01

    An autoassociative network of Potts units, coupled via tensor connections, has been proposed and analysed as an effective model of an extensive cortical network with distinct short- and long-range synaptic connections, but it has not been clarified in what sense it can be regarded as an effective model. We draw here the correspondence between the two, which indicates the need to introduce a local feedback term in the reduced model, i.e. in the Potts network. An effective model allows the study of phase transitions. As an example, we study the storage capacity of the Potts network with this additional term, the local feedback w, which contributes to drive the activity of the network towards one of the stored patterns. The storage capacity calculation, performed using replica tools, is limited to fully connected networks, for which a Hamiltonian can be defined. To extend the results to the case of intermediate partial connectivity, we also derive the self-consistent signal-to-noise analysis for the Potts network; and finally we discuss the implications for semantic memory in humans.

  16. Cortical information flow in Parkinson's disease: a composite network/field model

    Directory of Open Access Journals (Sweden)

    Cliff C. Kerr

    2013-04-01

    Full Text Available The basal ganglia play a crucial role in the execution of movements, as demonstrated by the severe motor deficits that accompany Parkinson's disease (PD. Since motor commands originate in the cortex, an important question is how the basal ganglia influence cortical information flow, and how this influence becomes pathological in PD. To explore this, we developed a composite neuronal network/neural field model. The network model consisted of 4950 spiking neurons, divided into 15 excitatory and inhibitory cell populations in the thalamus and cortex. The field model consisted of the cortex, thalamus, striatum, subthalamic nucleus, and globus pallidus. Both models have been separately validated in previous work. Three field models were used: one with basal ganglia parameters based on data from healthy individuals, one based on data from individuals with PD, and one purely thalamocortical model. Spikes generated by these field models were then used to drive the network model. Compared to the network driven by the healthy model, the PD-driven network had lower firing rates, a shift in spectral power towards lower frequencies, and higher probability of bursting; each of these findings is consistent with empirical data on PD. In the healthy model, we found strong Granger causality in the beta and low gamma bands between cortical layers, but this was largely absent in the PD model. In particular, the reduction in Granger causality from the main "input" layer of the cortex (layer 4 to the main "output" layer (layer 5 was pronounced. This may account for symptoms of PD that seem to reflect deficits in information flow, such as bradykinesia. In general, these results demonstrate that the brain's large-scale oscillatory environment, represented here by the field model, strongly influences the information processing that occurs within its subnetworks. Hence, it may be preferable to drive spiking network models with physiologically realistic inputs rather than

  17. Spatial Topography of Individual-Specific Cortical Networks Predicts Human Cognition, Personality, and Emotion.

    Science.gov (United States)

    Kong, Ru; Li, Jingwei; Orban, Csaba; Sabuncu, Mert R; Liu, Hesheng; Schaefer, Alexander; Sun, Nanbo; Zuo, Xi-Nian; Holmes, Avram J; Eickhoff, Simon B; Yeo, B T Thomas

    2018-06-06

    Resting-state functional magnetic resonance imaging (rs-fMRI) offers the opportunity to delineate individual-specific brain networks. A major question is whether individual-specific network topography (i.e., location and spatial arrangement) is behaviorally relevant. Here, we propose a multi-session hierarchical Bayesian model (MS-HBM) for estimating individual-specific cortical networks and investigate whether individual-specific network topography can predict human behavior. The multiple layers of the MS-HBM explicitly differentiate intra-subject (within-subject) from inter-subject (between-subject) network variability. By ignoring intra-subject variability, previous network mappings might confuse intra-subject variability for inter-subject differences. Compared with other approaches, MS-HBM parcellations generalized better to new rs-fMRI and task-fMRI data from the same subjects. More specifically, MS-HBM parcellations estimated from a single rs-fMRI session (10 min) showed comparable generalizability as parcellations estimated by 2 state-of-the-art methods using 5 sessions (50 min). We also showed that behavioral phenotypes across cognition, personality, and emotion could be predicted by individual-specific network topography with modest accuracy, comparable to previous reports predicting phenotypes based on connectivity strength. Network topography estimated by MS-HBM was more effective for behavioral prediction than network size, as well as network topography estimated by other parcellation approaches. Thus, similar to connectivity strength, individual-specific network topography might also serve as a fingerprint of human behavior.

  18. Differential Motor and Prefrontal Cerebello-Cortical Network Development: Evidence from Multimodal Neuroimaging

    Science.gov (United States)

    Bernard, Jessica A.; Orr, Joseph M.; Mittal, Vijay A.

    2015-01-01

    While our understanding of cerebellar structural development through adolescence and young adulthood has expanded, we still lack knowledge of the developmental patterns of cerebellar networks during this critical portion of the lifespan. Volume in lateral posterior cerebellar regions associated with cognition and the prefrontal cortex develops more slowly, reaching their peak volume in adulthood, particularly as compared to motor Lobule V. We predicted that resting state functional connectivity of the lateral posterior regions would show a similar pattern of development during adolescence and young adulthood. That is, we expected to see changes over time in Crus I and Crus II connectivity with the cortex, but no changes in Lobule V connectivity. Additionally, we were interested in how structural connectivity changes in cerebello-thalamo-cortical white matter are related to changes in functional connectivity. A sample of 23 individuals between 12 and 21 years old underwent neuroimaging scans at baseline and 12-months later. Functional networks of Crus I and Crus II showed significant connectivity decreases over 12-months, though there were no differences in Lobule V. Furthermore, these functional connectivity changes were correlated with increases in white matter structural integrity in the corresponding cerebello-thalamo-cortical white matter tract. We suggest that these functional network changes are due to both later pruning in the prefrontal cortex as well as further development of the white matter tracts linking these brain regions. PMID:26391125

  19. Basal ganglia and cortical networks for sequential ordering and rhythm of complex movements

    Directory of Open Access Journals (Sweden)

    Jeffery G. Bednark

    2015-07-01

    Full Text Available Voluntary actions require the concurrent engagement and coordinated control of complex temporal (e.g. rhythm and ordinal motor processes. Using high-resolution functional magnetic resonance imaging (fMRI and multi-voxel pattern analysis (MVPA, we sought to determine the degree to which these complex motor processes are dissociable in basal ganglia and cortical networks. We employed three different finger-tapping tasks that differed in the demand on the sequential temporal rhythm or sequential ordering of submovements. Our results demonstrate that sequential rhythm and sequential order tasks were partially dissociable based on activation differences. The sequential rhythm task activated a widespread network centered around the SMA and basal-ganglia regions including the dorsomedial putamen and caudate nucleus, while the sequential order task preferentially activated a fronto-parietal network. There was also extensive overlap between sequential rhythm and sequential order tasks, with both tasks commonly activating bilateral premotor, supplementary motor, and superior/inferior parietal cortical regions, as well as regions of the caudate/putamen of the basal ganglia and the ventro-lateral thalamus. Importantly, within the cortical regions that were active for both complex movements, MVPA could accurately classify different patterns of activation for the sequential rhythm and sequential order tasks. In the basal ganglia, however, overlapping activation for the sequential rhythm and sequential order tasks, which was found in classic motor circuits of the putamen and ventro-lateral thalamus, could not be accurately differentiated by MVPA. Overall, our results highlight the convergent architecture of the motor system, where complex motor information that is spatially distributed in the cortex converges into a more compact representation in the basal ganglia.

  20. Structural Covariance Network of Cortical Gyrification in Benign Childhood Epilepsy with Centrotemporal Spikes

    Directory of Open Access Journals (Sweden)

    Lin Jiang

    2018-02-01

    Full Text Available Benign childhood epilepsy with centrotemporal spikes (BECTS is associated with cognitive and language problems. According to recent studies, disruptions in brain structure and function in children with BECTS are beyond a Rolandic focus, suggesting atypical cortical development. However, previous studies utilizing surface-based metrics (e.g., cortical gyrification and their structural covariance networks at high resolution in children with BECTS are limited. Twenty-six children with BECTS (15 males/11 females; 10.35 ± 2.91 years and 26 demographically matched controls (15 males/11 females; 11.35 ± 2.51 years were included in this study and subjected to high-resolution structural brain MRI scans. The gyrification index was calculated, and structural brain networks were reconstructed based on the covariance of the cortical folding. In the BECTS group, significantly increased gyrification was observed in the bilateral Sylvain fissures and the left pars triangularis, temporal, rostral middle frontal, lateral orbitofrontal, and supramarginal areas (cluster-corrected p < 0.05. Global brain network measures were not significantly different between the groups; however, the nodal alterations were most pronounced in the insular, frontal, temporal, and occipital lobes (FDR corrected, p < 0.05. In children with BECTS, brain hubs increased in number and tended to shift to sensorimotor and temporal areas. Furthermore, we observed significantly positive relationships between the gyrification index and age (vertex p < 0.001, cluster-level correction as well as duration of epilepsy (vertex p < 0.001, cluster-level correction. Our results suggest that BECTS may be a condition that features abnormal over-folding of the Sylvian fissures and uncoordinated development of structural wiring, disrupted nodal profiles of centrality, and shifted hub distribution, which potentially represents a neuroanatomical hallmark of BECTS in the

  1. Role of altered cerebello-thalamo-cortical network in the neurobiology of essential tremor

    Energy Technology Data Exchange (ETDEWEB)

    Lenka, Abhishek; Bhalsing, Ketaki Swapnil; Jhunjhunwala, Ketan [National Institute of Mental Health and Neurosciences, Department of Neurology, Bangalore, Karnataka (India); National Institute of Mental Health and Neurosciences, Department of Clinical Neurosciences, Bangalore, Karnataka (India); Panda, Rajanikant; Saini, Jitender; Bharath, Rose Dawn [National Institute of Mental Health and Neurosciences, Department of Neuroimaging and Interventional Radiology, Bangalore, Karnataka (India); Naduthota, Rajini M.; Yadav, Ravi; Pal, Pramod Kumar [National Institute of Mental Health and Neurosciences, Department of Neurology, Bangalore, Karnataka (India)

    2017-02-15

    Essential tremor (ET) is the most common movement disorder among adults. Although ET has been recognized as a mono-symptomatic benign illness, reports of non-motor symptoms and non-tremor motor symptoms have increased its clinical heterogeneity. The neural correlates of ET are not clearly understood. The aim of this study was to understand the neurobiology of ET using resting state fMRI. Resting state functional MR images of 30 patients with ET and 30 age- and gender-matched healthy controls were obtained. The functional connectivity of the two groups was compared using whole-brain seed-to-voxel-based analysis. The ET group had decreased connectivity of several cortical regions especially of the primary motor cortex and the primary somatosensory cortex with several right cerebellar lobules compared to the controls. The thalamus on both hemispheres had increased connectivity with multiple posterior cerebellar lobules and vermis. Connectivity of several right cerebellar seeds with the cortical and thalamic seeds had significant correlation with an overall score of Fahn-Tolosa-Marin tremor rating scale (FTM-TRS) as well as the subscores for head tremor and limb tremor. Seed-to-voxel resting state connectivity analysis revealed significant alterations in the cerebello-thalamo-cortical network in patients with ET. These alterations correlated with the overall FTM scores as well as the subscores for limb tremor and head tremor in patients with ET. These results further support the previous evidence of cerebellar pathology in ET. (orig.)

  2. Role of altered cerebello-thalamo-cortical network in the neurobiology of essential tremor

    International Nuclear Information System (INIS)

    Lenka, Abhishek; Bhalsing, Ketaki Swapnil; Jhunjhunwala, Ketan; Panda, Rajanikant; Saini, Jitender; Bharath, Rose Dawn; Naduthota, Rajini M.; Yadav, Ravi; Pal, Pramod Kumar

    2017-01-01

    Essential tremor (ET) is the most common movement disorder among adults. Although ET has been recognized as a mono-symptomatic benign illness, reports of non-motor symptoms and non-tremor motor symptoms have increased its clinical heterogeneity. The neural correlates of ET are not clearly understood. The aim of this study was to understand the neurobiology of ET using resting state fMRI. Resting state functional MR images of 30 patients with ET and 30 age- and gender-matched healthy controls were obtained. The functional connectivity of the two groups was compared using whole-brain seed-to-voxel-based analysis. The ET group had decreased connectivity of several cortical regions especially of the primary motor cortex and the primary somatosensory cortex with several right cerebellar lobules compared to the controls. The thalamus on both hemispheres had increased connectivity with multiple posterior cerebellar lobules and vermis. Connectivity of several right cerebellar seeds with the cortical and thalamic seeds had significant correlation with an overall score of Fahn-Tolosa-Marin tremor rating scale (FTM-TRS) as well as the subscores for head tremor and limb tremor. Seed-to-voxel resting state connectivity analysis revealed significant alterations in the cerebello-thalamo-cortical network in patients with ET. These alterations correlated with the overall FTM scores as well as the subscores for limb tremor and head tremor in patients with ET. These results further support the previous evidence of cerebellar pathology in ET. (orig.)

  3. Entrepreneurial networks as culturally embedded phenomena

    Directory of Open Access Journals (Sweden)

    Vlatka Skokic

    2015-06-01

    Full Text Available Entrepreneurship research concerning networks has largely focused on network structure, content and governance. We believe that further research is required in order to gain a richer understanding of why specific network forms and types originated. The purpose of this paper is to explore the existence, importance, values and meanings of both the informal and formal networks and networking behaviours of small-scale hotel owner-managers embedded in the socio-economic context of Croatia. In order to gain richer and more detailed understanding of entrepreneurial networks and to understand the influence of socio-economic setting on entrepreneurial networking, we have employed qualitative, in-depth study with small hotel owners. Results suggest that entrepreneurs do not establish strong personal and firm-to-firm ties, but rather focus on formal associations. Reported findings identify socio-cultural factors apparently unique to the context of former socialist economy which have the potential to explain the reported networking behaviour. The adopted research approach brings another dimension to existing theoretical underpinnings, which can encourage researchers to extend or revise theories with new contextual variables.

  4. Glutamate stimulates the formation of N-acylphosphatidylethanolamine in cortical neurons in culture

    DEFF Research Database (Denmark)

    Hansen, Harald S.; Lauritzen, L.; Strand, A.M.

    1995-01-01

    The formation of anandamide (N-arachidonoylethanolamine), N-acylethanolamine, and N-acylphosphatidylethanolamine was studied in primary cultures of rat cortical neurons. The cells were incubated for 22 h with [C]ethanolamine, [U-C]arachidonic acid, [H]arachidonic acid, [P]phosphate, [C]stearic acid......-acylethanolamine. Compound I could be labelled with [C]stearic acid and [H]myristic acid, but not with [H]- or [C]arachidonic acid. Exogenous [H]anandamide was metabolised with a t( 1/2 ) of 2.6 h. The labelling of the two compounds identified as N-acylethanolamine and N-acylphosphatidylethanolamine were more pronounced......, or [H]myristic acid. The lipids from the cells and media were separated by thin layer chromatography. [C]Ethanolamine labelling revealed two compounds (I and II), which on different thin layer chromatography systems migrated as N-acylethanolamine (0.06-0.55% of total radioactivity) and N...

  5. Apoptosis after irradiation of the rat cortical and hippocampal cells in culture

    International Nuclear Information System (INIS)

    Coffigny, H.; Lane, M.C.

    1997-01-01

    During the development of the central nervous system many neurons are generated but over 50% die by natural apoptosis; this phenomenon occurred in neurons without or with wrong connections with their target cells. Children exposed in utero to Hiroshima or Nagasaki bombing presented microcephaly due to cell deaths and mental retardation. In animals, the number of apoptotic cells in the developing central nervous system increased as a function of the dose received. In vitro, we have shown that 1 Gy irradiation induced 50 % decrease of cortical and hippocampal cell survival. Nervous cells when seeded in a plate were round without processes. Neuritis outgrowth increased with culture time and physical contacts were established between cells. Our purpose is to test the importance of these contacts in the radio-induced apoptosis. (authors)

  6. Cortical networks dynamically emerge with the interplay of slow and fast oscillations for memory of a natural scene.

    Science.gov (United States)

    Mizuhara, Hiroaki; Sato, Naoyuki; Yamaguchi, Yoko

    2015-05-01

    Neural oscillations are crucial for revealing dynamic cortical networks and for serving as a possible mechanism of inter-cortical communication, especially in association with mnemonic function. The interplay of the slow and fast oscillations might dynamically coordinate the mnemonic cortical circuits to rehearse stored items during working memory retention. We recorded simultaneous EEG-fMRI during a working memory task involving a natural scene to verify whether the cortical networks emerge with the neural oscillations for memory of the natural scene. The slow EEG power was enhanced in association with the better accuracy of working memory retention, and accompanied cortical activities in the mnemonic circuits for the natural scene. Fast oscillation showed a phase-amplitude coupling to the slow oscillation, and its power was tightly coupled with the cortical activities for representing the visual images of natural scenes. The mnemonic cortical circuit with the slow neural oscillations would rehearse the distributed natural scene representations with the fast oscillation for working memory retention. The coincidence of the natural scene representations could be obtained by the slow oscillation phase to create a coherent whole of the natural scene in the working memory. Copyright © 2015 Elsevier Inc. All rights reserved.

  7. Human brain networks in physiological aging: a graph theoretical analysis of cortical connectivity from EEG data.

    Science.gov (United States)

    Vecchio, Fabrizio; Miraglia, Francesca; Bramanti, Placido; Rossini, Paolo Maria

    2014-01-01

    Modern analysis of electroencephalographic (EEG) rhythms provides information on dynamic brain connectivity. To test the hypothesis that aging processes modulate the brain connectivity network, EEG recording was conducted on 113 healthy volunteers. They were divided into three groups in accordance with their ages: 36 Young (15-45 years), 46 Adult (50-70 years), and 31 Elderly (>70 years). To evaluate the stability of the investigated parameters, a subgroup of 10 subjects underwent a second EEG recording two weeks later. Graph theory functions were applied to the undirected and weighted networks obtained by the lagged linear coherence evaluated by eLORETA on cortical sources. EEG frequency bands of interest were: delta (2-4 Hz), theta (4-8 Hz), alpha1 (8-10.5 Hz), alpha2 (10.5-13 Hz), beta1 (13-20 Hz), beta2 (20-30 Hz), and gamma (30-40 Hz). The spectral connectivity analysis of cortical sources showed that the normalized Characteristic Path Length (λ) presented the pattern Young > Adult>Elderly in the higher alpha band. Elderly also showed a greater increase in delta and theta bands than Young. The correlation between age and λ showed that higher ages corresponded to higher λ in delta and theta and lower in the alpha2 band; this pattern reflects the age-related modulation of higher (alpha) and decreased (delta) connectivity. The Normalized Clustering coefficient (γ) and small-world network modeling (σ) showed non-significant age-modulation. Evidence from the present study suggests that graph theory can aid in the analysis of connectivity patterns estimated from EEG and can facilitate the study of the physiological and pathological brain aging features of functional connectivity networks.

  8. Pragmatics in action: indirect requests engage theory of mind areas and the cortical motor network.

    Science.gov (United States)

    van Ackeren, Markus J; Casasanto, Daniel; Bekkering, Harold; Hagoort, Peter; Rueschemeyer, Shirley-Ann

    2012-11-01

    Research from the past decade has shown that understanding the meaning of words and utterances (i.e., abstracted symbols) engages the same systems we used to perceive and interact with the physical world in a content-specific manner. For example, understanding the word "grasp" elicits activation in the cortical motor network, that is, part of the neural substrate involved in planned and executing a grasping action. In the embodied literature, cortical motor activation during language comprehension is thought to reflect motor simulation underlying conceptual knowledge [note that outside the embodied framework, other explanations for the link between action and language are offered, e.g., Mahon, B. Z., & Caramazza, A. A critical look at the embodied cognition hypothesis and a new proposal for grouding conceptual content. Journal of Physiology, 102, 59-70, 2008; Hagoort, P. On Broca, brain, and binding: A new framework. Trends in Cognitive Sciences, 9, 416-423, 2005]. Previous research has supported the view that the coupling between language and action is flexible, and reading an action-related word form is not sufficient for cortical motor activation [Van Dam, W. O., van Dijk, M., Bekkering, H., & Rueschemeyer, S.-A. Flexibility in embodied lexical-semantic representations. Human Brain Mapping, doi: 10.1002/hbm.21365, 2011]. The current study goes one step further by addressing the necessity of action-related word forms for motor activation during language comprehension. Subjects listened to indirect requests (IRs) for action during an fMRI session. IRs for action are speech acts in which access to an action concept is required, although it is not explicitly encoded in the language. For example, the utterance "It is hot here!" in a room with a window is likely to be interpreted as a request to open the window. However, the same utterance in a desert will be interpreted as a statement. The results indicate (1) that comprehension of IR sentences activates cortical

  9. Hamlet, Performance and Chaotic Cultural Networks

    Directory of Open Access Journals (Sweden)

    Emil Rybczak

    2015-10-01

    Full Text Available Since the 1960s, chaos theory has become an important but controversial tool used by scientists and mathematicians to describe physical or theoretical systems or networks. It explains how the simple can generate the complex. Its central tenets can also provide an alternative language and means of literary interpretation. This article will explore how the principles of chaos theory can be used to close read and systematise various aspects of the language and performance of Shakespeare. The argument is built upon an analysis of Hamlet, in an effort to understand the play and its reproduction as the evolution of interconnected complex networks. Various aspects of the text will be discussed, including its language, structural and character patterning, and its reproduction through performance and cinematic adaptation. Each of these topics, and the characters, devices or ideas they discuss, constitute nodes of the complex network of Hamlet as both text and idea. Responding to the cultural analysis of other scholars, this article uses Hamlet as an ideal example of how the appropriation of scientific language can defamiliarise a particular literary or dramatic artefact. This allows fresh interpretation and understanding of its location within the broader networks of theatre and culture. I suggest the possibilities of close reading literary works through the lens of chaos and suggest how they might be applied and developed in conjunction with other texts, media or performances.

  10. A cortical attractor network with Martinotti cells driven by facilitating synapses.

    Directory of Open Access Journals (Sweden)

    Pradeep Krishnamurthy

    Full Text Available The population of pyramidal cells significantly outnumbers the inhibitory interneurons in the neocortex, while at the same time the diversity of interneuron types is much more pronounced. One acknowledged key role of inhibition is to control the rate and patterning of pyramidal cell firing via negative feedback, but most likely the diversity of inhibitory pathways is matched by a corresponding diversity of functional roles. An important distinguishing feature of cortical interneurons is the variability of the short-term plasticity properties of synapses received from pyramidal cells. The Martinotti cell type has recently come under scrutiny due to the distinctly facilitating nature of the synapses they receive from pyramidal cells. This distinguishes these neurons from basket cells and other inhibitory interneurons typically targeted by depressing synapses. A key aspect of the work reported here has been to pinpoint the role of this variability. We first set out to reproduce quantitatively based on in vitro data the di-synaptic inhibitory microcircuit connecting two pyramidal cells via one or a few Martinotti cells. In a second step, we embedded this microcircuit in a previously developed attractor memory network model of neocortical layers 2/3. This model network demonstrated that basket cells with their characteristic depressing synapses are the first to discharge when the network enters an attractor state and that Martinotti cells respond with a delay, thereby shifting the excitation-inhibition balance and acting to terminate the attractor state. A parameter sensitivity analysis suggested that Martinotti cells might, in fact, play a dominant role in setting the attractor dwell time and thus cortical speed of processing, with cellular adaptation and synaptic depression having a less prominent role than previously thought.

  11. Evoked potentials in large-scale cortical networks elicited by TMS of the visual cortex

    Science.gov (United States)

    Grossman, Emily D.; Srinivasan, Ramesh

    2011-01-01

    Single pulses of transcranial magnetic stimulation (TMS) result in distal and long-lasting oscillations, a finding directly challenging the virtual lesion hypothesis. Previous research supporting this finding has primarily come from stimulation of the motor cortex. We have used single-pulse TMS with simultaneous EEG to target seven brain regions, six of which belong to the visual system [left and right primary visual area V1, motion-sensitive human middle temporal cortex, and a ventral temporal region], as determined with functional MRI-guided neuronavigation, and a vertex “control” site to measure the network effects of the TMS pulse. We found the TMS-evoked potential (TMS-EP) over visual cortex consists mostly of site-dependent theta- and alphaband oscillations. These site-dependent oscillations extended beyond the stimulation site to functionally connected cortical regions and correspond to time windows where the EEG responses maximally diverge (40, 200, and 385 ms). Correlations revealed two site-independent oscillations ∼350 ms after the TMS pulse: a theta-band oscillation carried by the frontal cortex, and an alpha-band oscillation over parietal and frontal cortical regions. A manipulation of stimulation intensity at one stimulation site (right hemisphere V1-V3) revealed sensitivity to the stimulation intensity at different regions of cortex, evidence of intensity tuning in regions distal to the site of stimulation. Together these results suggest that a TMS pulse applied to the visual cortex has a complex effect on brain function, engaging multiple brain networks functionally connected to the visual system with both invariant and site-specific spatiotemporal dynamics. With this characterization of TMS, we propose an alternative to the virtual lesion hypothesis. Rather than a technique that simulates lesions, we propose TMS generates natural brain signals and engages functional networks. PMID:21715670

  12. Early-life exposure to caffeine affects the construction and activity of cortical networks in mice.

    Science.gov (United States)

    Fazeli, Walid; Zappettini, Stefania; Marguet, Stephan Lawrence; Grendel, Jasper; Esclapez, Monique; Bernard, Christophe; Isbrandt, Dirk

    2017-09-01

    The consumption of psychoactive drugs during pregnancy can have deleterious effects on newborns. It remains unclear whether early-life exposure to caffeine, the most widely consumed psychoactive substance, alters brain development. We hypothesized that maternal caffeine ingestion during pregnancy and the early postnatal period in mice affects the construction and activity of cortical networks in offspring. To test this hypothesis, we focused on primary visual cortex (V1) as a model neocortical region. In a study design mimicking the daily consumption of approximately three cups of coffee during pregnancy in humans, caffeine was added to the drinking water of female mice and their offspring were compared to control offspring. Caffeine altered the construction of GABAergic neuronal networks in V1, as reflected by a reduced number of somatostatin-containing GABA neurons at postnatal days 6-7, with the remaining ones showing poorly developed dendritic arbors. These findings were accompanied by increased synaptic activity in vitro and elevated network activity in vivo in V1. Similarly, in vivo hippocampal network activity was altered from the neonatal period until adulthood. Finally, caffeine-exposed offspring showed increased seizure susceptibility in a hyperthermia-induced seizure model. In summary, our results indicate detrimental effects of developmental caffeine exposure on mouse brain development. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Effects of Stress and Task Difficulty on Working Memory and Cortical Networking.

    Science.gov (United States)

    Kim, Yujin; Woo, Jihwan; Woo, Minjung

    2017-12-01

    This study investigated interactive effects of stress and task difficulty on working memory and cortico-cortical communication during memory encoding. Thirty-eight adolescent participants (mean age of 15.7 ± 1.5 years) completed easy and hard working memory tasks under low- and high-stress conditions. We analyzed the accuracy and reaction time (RT) of working memory performance and inter- and intrahemispheric electroencephalogram coherences during memory encoding. Working memory accuracy was higher, and RT shorter, in the easy versus the hard task. RT was shorter under the high-stress (TENS) versus low-stress (no-TENS) condition, while there was no difference in memory accuracy between the two stress conditions. For electroencephalogram coherence, we found higher interhemispheric coherence in all bands but only at frontal electrode sites in the easy versus the hard task. On the other hand, intrahemispheric coherence was higher in the left hemisphere in the easy (versus hard task) and higher in the right hemisphere (with one exception) in the hard (versus easy task). Inter- and intracoherences were higher in the low- versus high-stress condition. Significant interactions between task difficulty and stress condition were observed in coherences of the beta frequency band. The difference in coherence between low- and high-stress conditions was greater in the hard compared with the easy task, with lower coherence under the high-stress condition relative to the low-stress condition. Stress seemed to cause a decrease in cortical network communications between memory-relevant cortical areas as task difficulty increased.

  14. Fast oscillations in cortical-striatal networks switch frequency following rewarding events and stimulant drugs.

    Science.gov (United States)

    Berke, J D

    2009-09-01

    Oscillations may organize communication between components of large-scale brain networks. Although gamma-band oscillations have been repeatedly observed in cortical-basal ganglia circuits, their functional roles are not yet clear. Here I show that, in behaving rats, distinct frequencies of ventral striatal local field potential oscillations show coherence with different cortical inputs. The approximately 50 Hz gamma oscillations that normally predominate in awake ventral striatum are coherent with piriform cortex, whereas approximately 80-100 Hz high-gamma oscillations are coherent with frontal cortex. Within striatum, entrainment to gamma rhythms is selective to fast-spiking interneurons, with distinct fast-spiking interneuron populations entrained to different gamma frequencies. Administration of the psychomotor stimulant amphetamine or the dopamine agonist apomorphine causes a prolonged decrease in approximately 50 Hz power and increase in approximately 80-100 Hz power. The same frequency switch is observed for shorter epochs spontaneously in awake, undrugged animals and is consistently provoked for reward receipt. Individual striatal neurons can participate in these brief high-gamma bursts with, or without, substantial changes in firing rate. Switching between discrete oscillatory states may allow different modes of information processing during decision-making and reinforcement-based learning, and may also be an important systems-level process by which stimulant drugs affect cognition and behavior.

  15. Cortical atrophy and language network reorganization associated with a novel progranulin mutation.

    Science.gov (United States)

    Cruchaga, Carlos; Fernández-Seara, Maria A; Seijo-Martínez, Manuel; Samaranch, Lluis; Lorenzo, Elena; Hinrichs, Anthony; Irigoyen, Jaione; Maestro, Cristina; Prieto, Elena; Martí-Climent, Josep M; Arbizu, Javier; Pastor, Maria A; Pastor, Pau

    2009-08-01

    Progressive nonfluent aphasia (PNFA) is an early stage of frontotemporal degeneration. We identified a novel Cys521Tyr progranulin gene variant in a PNFA family that potentially disrupts disulphide bridging causing protein misfolding. To identify early neurodegeneration changes, we performed neuropsychological and neuroimaging studies in 6 family members (MRI [magnetic resonance imaging], fMRI [functional MRI], and 18f-fluorodeoxygenlucose positron emission tomography, including 4 mutation carriers, and in 9 unrelated controls. Voxel-based morphometry (VBM) of the carriers compared with controls showed significant cortical atrophy in language areas. Grey matter loss was distributed mainly in frontal lobes, being more prominent on the left. Clusters were located in the superior frontal gyri, left inferior frontal gyrus, left middle frontal gyrus, left middle temporal gyri and left posterior parietal areas, concordant with (18)FDG-PET hypometabolic areas. fMRI during semantic and phonemic covert word generation (CWGTs) and word listening tasks (WLTs) showed recruitment of attentional and working memory networks in the carriers indicative of functional reorganization. During CWGTs, activation in left prefrontal cortex and bilateral anterior insulae was present whereas WLT recruited mesial prefrontal and anterior temporal cortex. These findings suggest that Cys521Tyr could be associated with early brain impairment not limited to language areas and compensated by recruitment of bilateral auxiliary cortical areas.

  16. Resveratrol protects primary cortical neuron cultures from transient oxygen-glucose deprivation by inhibiting MMP-9.

    Science.gov (United States)

    Gao, Dakuan; Huang, Tao; Jiang, Xiaofan; Hu, Shijie; Zhang, Lei; Fei, Zhou

    2014-06-01

    It was recently shown that resveratrol exerts neuroprotective effects against cerebral ischemia in mice. The aim of the present study was to further confirm these effects in in vitro primary cortical neuron cultures with transient oxygen-glucose deprivation (OGD), and to investigate whether these effects are due to the inhibition of matrix metalloproteinase-9 (MMP-9) and of cell apoptosis. Neuronal primary cultures of cerebral cortex were prepared from BALB/c mice embryos (13-15 days). Cells from 14- to 16-day cultures were subjected to OGD for 3 h, followed by 21 h of reoxygenation to simulate transient ischemia. Different doses of resveratrol were added into the culture medium during the simulation of transient ischemia. The effect of the extracellular signal-regulated kinase (ERK) inhibitor U0126 was studied by adding U0126 (5 µg/µl, 4 µl) into the culture medium during transient ischemia; as a control, we used treatment of cells with 50 µM of resveratrol. Cell viability was investigated using the 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) reduction assay. Cell apoptosis was assessed by flow cytometry. The effects of resveratrol on the expression of MMP-9 were analyzed by western blotting and reverse transcription-polymerase chain reaction (RT-PCR), while the levels of ERK, phosphorylated (p)-ERK, cleaved caspase-3, Bax and Bcl-2 were measured by western blotting. The results of the MTT assay showed that cell viability is significantly reduced by transient OGD. OGD induced cell apoptosis, the expression of Bax and the activation of caspase-3 and ERK, inhibited the expression of Bcl-2 and increased the expression of MMP-9, while these effects were reversed by treatment with resveratrol. The therapeutic efficacy of resveratrol was shown to be dose-dependent, with the most suitable dose range determined at 50-100 µM. Treatment with U0126 inhibited MMP-9 and Bax expression and caspase-3 activation, while it further promoted the

  17. Methods for parameter identification in oscillatory networks and application to cortical and thalamic 600 Hz activity.

    Science.gov (United States)

    Leistritz, L; Suesse, T; Haueisen, J; Hilgenfeld, B; Witte, H

    2006-01-01

    Directed information transfer in the human brain occurs presumably by oscillations. As of yet, most approaches for the analysis of these oscillations are based on time-frequency or coherence analysis. The present work concerns the modeling of cortical 600 Hz oscillations, localized within the Brodmann Areas 3b and 1 after stimulation of the nervus medianus, by means of coupled differential equations. This approach leads to the so-called parameter identification problem, where based on a given data set, a set of unknown parameters of a system of ordinary differential equations is determined by special optimization procedures. Some suitable algorithms for this task are presented in this paper. Finally an oscillatory network model is optimally fitted to the data taken from ten volunteers.

  18. Synaptic integration of transplanted interneuron progenitor cells into native cortical networks.

    Science.gov (United States)

    Howard, MacKenzie A; Baraban, Scott C

    2016-08-01

    Interneuron-based cell transplantation is a powerful method to modify network function in a variety of neurological disorders, including epilepsy. Whether new interneurons integrate into native neural networks in a subtype-specific manner is not well understood, and the therapeutic mechanisms underlying interneuron-based cell therapy, including the role of synaptic inhibition, are debated. In this study, we tested subtype-specific integration of transplanted interneurons using acute cortical brain slices and visualized patch-clamp recordings to measure excitatory synaptic inputs, intrinsic properties, and inhibitory synaptic outputs. Fluorescently labeled progenitor cells from the embryonic medial ganglionic eminence (MGE) were used for transplantation. At 5 wk after transplantation, MGE-derived parvalbumin-positive (PV+) interneurons received excitatory synaptic inputs, exhibited mature interneuron firing properties, and made functional synaptic inhibitory connections to native pyramidal cells that were comparable to those of native PV+ interneurons. These findings demonstrate that MGE-derived PV+ interneurons functionally integrate into subtype-appropriate physiological niches within host networks following transplantation. Copyright © 2016 the American Physiological Society.

  19. Dynamic brain glucose metabolism identifies anti-correlated cortical-cerebellar networks at rest.

    Science.gov (United States)

    Tomasi, Dardo G; Shokri-Kojori, Ehsan; Wiers, Corinde E; Kim, Sunny W; Demiral, Şukru B; Cabrera, Elizabeth A; Lindgren, Elsa; Miller, Gregg; Wang, Gene-Jack; Volkow, Nora D

    2017-12-01

    It remains unclear whether resting state functional magnetic resonance imaging (rfMRI) networks are associated with underlying synchrony in energy demand, as measured by dynamic 2-deoxy-2-[ 18 F]fluoroglucose (FDG) positron emission tomography (PET). We measured absolute glucose metabolism, temporal metabolic connectivity (t-MC) and rfMRI patterns in 53 healthy participants at rest. Twenty-two rfMRI networks emerged from group independent component analysis (gICA). In contrast, only two anti-correlated t-MC emerged from FDG-PET time series using gICA or seed-voxel correlations; one included frontal, parietal and temporal cortices, the other included the cerebellum and medial temporal regions. Whereas cerebellum, thalamus, globus pallidus and calcarine cortex arose as the strongest t-MC hubs, the precuneus and visual cortex arose as the strongest rfMRI hubs. The strength of the t-MC linearly increased with the metabolic rate of glucose suggesting that t-MC measures are strongly associated with the energy demand of the brain tissue, and could reflect regional differences in glucose metabolism, counterbalanced metabolic network demand, and/or differential time-varying delivery of FDG. The mismatch between metabolic and functional connectivity patterns computed as a function of time could reflect differences in the temporal characteristics of glucose metabolism as measured with PET-FDG and brain activation as measured with rfMRI.

  20. Effects of Increasing Neuromuscular Electrical Stimulation Current Intensity on Cortical Sensorimotor Network Activation: A Time Domain fNIRS Study.

    Directory of Open Access Journals (Sweden)

    Makii Muthalib

    Full Text Available Neuroimaging studies have shown neuromuscular electrical stimulation (NMES-evoked movements activate regions of the cortical sensorimotor network, including the primary sensorimotor cortex (SMC, premotor cortex (PMC, supplementary motor area (SMA, and secondary somatosensory area (S2, as well as regions of the prefrontal cortex (PFC known to be involved in pain processing. The aim of this study, on nine healthy subjects, was to compare the cortical network activation profile and pain ratings during NMES of the right forearm wrist extensor muscles at increasing current intensities up to and slightly over the individual maximal tolerated intensity (MTI, and with reference to voluntary (VOL wrist extension movements. By exploiting the capability of the multi-channel time domain functional near-infrared spectroscopy technique to relate depth information to the photon time-of-flight, the cortical and superficial oxygenated (O2Hb and deoxygenated (HHb hemoglobin concentrations were estimated. The O2Hb and HHb maps obtained using the General Linear Model (NIRS-SPM analysis method, showed that the VOL and NMES-evoked movements significantly increased activation (i.e., increase in O2Hb and corresponding decrease in HHb in the cortical layer of the contralateral sensorimotor network (SMC, PMC/SMA, and S2. However, the level and area of contralateral sensorimotor network (including PFC activation was significantly greater for NMES than VOL. Furthermore, there was greater bilateral sensorimotor network activation with the high NMES current intensities which corresponded with increased pain ratings. In conclusion, our findings suggest that greater bilateral sensorimotor network activation profile with high NMES current intensities could be in part attributable to increased attentional/pain processing and to increased bilateral sensorimotor integration in these cortical regions.

  1. Effects of Increasing Neuromuscular Electrical Stimulation Current Intensity on Cortical Sensorimotor Network Activation: A Time Domain fNIRS Study.

    Science.gov (United States)

    Muthalib, Makii; Re, Rebecca; Zucchelli, Lucia; Perrey, Stephane; Contini, Davide; Caffini, Matteo; Spinelli, Lorenzo; Kerr, Graham; Quaresima, Valentina; Ferrari, Marco; Torricelli, Alessandro

    2015-01-01

    Neuroimaging studies have shown neuromuscular electrical stimulation (NMES)-evoked movements activate regions of the cortical sensorimotor network, including the primary sensorimotor cortex (SMC), premotor cortex (PMC), supplementary motor area (SMA), and secondary somatosensory area (S2), as well as regions of the prefrontal cortex (PFC) known to be involved in pain processing. The aim of this study, on nine healthy subjects, was to compare the cortical network activation profile and pain ratings during NMES of the right forearm wrist extensor muscles at increasing current intensities up to and slightly over the individual maximal tolerated intensity (MTI), and with reference to voluntary (VOL) wrist extension movements. By exploiting the capability of the multi-channel time domain functional near-infrared spectroscopy technique to relate depth information to the photon time-of-flight, the cortical and superficial oxygenated (O2Hb) and deoxygenated (HHb) hemoglobin concentrations were estimated. The O2Hb and HHb maps obtained using the General Linear Model (NIRS-SPM) analysis method, showed that the VOL and NMES-evoked movements significantly increased activation (i.e., increase in O2Hb and corresponding decrease in HHb) in the cortical layer of the contralateral sensorimotor network (SMC, PMC/SMA, and S2). However, the level and area of contralateral sensorimotor network (including PFC) activation was significantly greater for NMES than VOL. Furthermore, there was greater bilateral sensorimotor network activation with the high NMES current intensities which corresponded with increased pain ratings. In conclusion, our findings suggest that greater bilateral sensorimotor network activation profile with high NMES current intensities could be in part attributable to increased attentional/pain processing and to increased bilateral sensorimotor integration in these cortical regions.

  2. MDMA (Ecstasy) Decreases the Number of Neurons and Stem Cells in Embryonic Cortical Cultures

    DEFF Research Database (Denmark)

    Kindlundh-Högberg, Anna M S; Pickering, Chris; Wicher, Grzegorz

    2010-01-01

    Ecstasy, 3,4-methylenedioxymetamphetamine (MDMA), is a recreational drug used among adolescents, including young pregnant women. MDMA passes the placental barrier and may therefore influence fetal development. The aim was to investigate the direct effect of MDMA on cortical cells using dissociated...... CNS cortex of rat embryos, E17. The primary culture was exposed to a single dose of MDMA and collected 5 days later. MDMA caused a dramatic, dose-dependent (100 and 400 muM) decrease in nestin-positive stem cell density, as well as a significant reduction (400 muM) in NeuN-positive cells. By q......PCR, MDMA (200 muM) caused a significant decrease in mRNA expression of the 5HT3 receptor, dopamine D(1) receptor, and glutamate transporter EAAT2-1, as well as an increase in mRNA levels of the NMDA NR1 receptor subunit and the 5HT(1A) receptor. In conclusion, MDMA caused a marked reduction in stem cells...

  3. Lycopene Prevents Amyloid [Beta]-Induced Mitochondrial Oxidative Stress and Dysfunctions in Cultured Rat Cortical Neurons.

    Science.gov (United States)

    Qu, Mingyue; Jiang, Zheng; Liao, Yuanxiang; Song, Zhenyao; Nan, Xinzhong

    2016-06-01

    Brains affected by Alzheimer's disease (AD) show a large spectrum of mitochondrial alterations at both morphological and genetic level. The causal link between β-amyloid (Aβ) and mitochondrial dysfunction has been established in cellular models of AD. We observed previously that lycopene, a member of the carotenoid family of phytochemicals, could counteract neuronal apoptosis and cell damage induced by Aβ and other neurotoxic substances, and that this neuroprotective action somehow involved the mitochondria. The present study aims to investigate the effects of lycopene on mitochondria in cultured rat cortical neurons exposed to Aβ. It was found that lycopene attenuated Aβ-induced oxidative stress, as evidenced by the decreased intracellular reactive oxygen species generation and mitochondria-derived superoxide production. Additionally, lycopene ameliorated Aβ-induced mitochondrial morphological alteration, opening of the mitochondrial permeability transition pores and the consequent cytochrome c release. Lycopene also improved mitochondrial complex activities and restored ATP levels in Aβ-treated neuron. Furthermore, lycopene prevented mitochondrial DNA damages and improved the protein level of mitochondrial transcription factor A in mitochondria. Those results indicate that lycopene protects mitochondria against Aβ-induced damages, at least in part by inhibiting mitochondrial oxidative stress and improving mitochondrial function. These beneficial effects of lycopene may account for its protection against Aβ-induced neurotoxicity.

  4. Cortical neurons and networks are dormant but fully responsive during isoelectric brain state.

    Science.gov (United States)

    Altwegg-Boussac, Tristan; Schramm, Adrien E; Ballestero, Jimena; Grosselin, Fanny; Chavez, Mario; Lecas, Sarah; Baulac, Michel; Naccache, Lionel; Demeret, Sophie; Navarro, Vincent; Mahon, Séverine; Charpier, Stéphane

    2017-09-01

    A continuous isoelectric electroencephalogram reflects an interruption of endogenously-generated activity in cortical networks and systematically results in a complete dissolution of conscious processes. This electro-cerebral inactivity occurs during various brain disorders, including hypothermia, drug intoxication, long-lasting anoxia and brain trauma. It can also be induced in a therapeutic context, following the administration of high doses of barbiturate-derived compounds, to interrupt a hyper-refractory status epilepticus. Although altered sensory responses can be occasionally observed on an isoelectric electroencephalogram, the electrical membrane properties and synaptic responses of individual neurons during this cerebral state remain largely unknown. The aim of the present study was to characterize the intracellular correlates of a barbiturate-induced isoelectric electroencephalogram and to analyse the sensory-evoked synaptic responses that can emerge from a brain deprived of spontaneous electrical activity. We first examined the sensory responsiveness from patients suffering from intractable status epilepticus and treated by administration of thiopental. Multimodal sensory responses could be evoked on the flat electroencephalogram, including visually-evoked potentials that were significantly amplified and delayed, with a high trial-to-trial reproducibility compared to awake healthy subjects. Using an analogous pharmacological procedure to induce prolonged electro-cerebral inactivity in the rat, we could describe its cortical and subcortical intracellular counterparts. Neocortical, hippocampal and thalamo-cortical neurons were all silent during the isoelectric state and displayed a flat membrane potential significantly hyperpolarized compared with spontaneously active control states. Nonetheless, all recorded neurons could fire action potentials in response to intracellularly injected depolarizing current pulses and their specific intrinsic

  5. Nifedipine-activated Ca(2+) permeability in newborn rat cortical collecting duct cells in primary culture.

    Science.gov (United States)

    Valencia, L; Bidet, M; Martial, S; Sanchez, E; Melendez, E; Tauc, M; Poujeol, C; Martin, D; Namorado, M D; Reyes, J L; Poujeol, P

    2001-05-01

    To characterize Ca(2+) transport in newborn rat cortical collecting duct (CCD) cells, we used nifedipine, which in adult rat distal tubules inhibits the intracellular Ca(2+) concentration ([Ca(2+)](i)) increase in response to hormonal activation. We found that the dihydropyridine (DHP) nifedipine (20 microM) produced an increase in [Ca(2+)](i) from 87.6 +/- 3.3 nM to 389.9 +/- 29.0 nM in 65% of the cells. Similar effects of other DHP (BAY K 8644, isradipine) were also observed. Conversely, DHPs did not induce any increase in [Ca(2+)](i) in cells obtained from proximal convoluted tubule. In CCD cells, neither verapamil nor diltiazem induced any rise in [Ca(2+)](i). Experiments in the presence of EGTA showed that external Ca(2+) was required for the nifedipine effect, while lanthanum (20 microM), gadolinium (100 microM), and diltiazem (20 microM) inhibited the effect. Experiments done in the presence of valinomycin resulted in the same nifedipine effect, showing that K(+) channels were not involved in the nifedipine-induced [Ca(2+)](i) rise. H(2)O(2) also triggered [Ca(2+)](i) rise. However, nifedipine-induced [Ca(2+)](i) increase was not affected by protamine. In conclusion, the present results indicate that 1) primary cultures of cells from terminal nephron of newborn rats are a useful tool for investigating Ca(2+) transport mechanisms during growth, and 2) newborn rat CCD cells in primary culture exhibit a new apical nifedipine-activated Ca(2+) channel of capacitive type (either transient receptor potential or leak channel).

  6. Live-Cell, Label-Free Identification of GABAergic and Non-GABAergic Neurons in Primary Cortical Cultures Using Micropatterned Surface

    Science.gov (United States)

    Kono, Sho; Kushida, Takatoshi; Hirano-Iwata, Ayumi; Niwano, Michio; Tanii, Takashi

    2016-01-01

    Excitatory and inhibitory neurons have distinct roles in cortical dynamics. Here we present a novel method for identifying inhibitory GABAergic neurons from non-GABAergic neurons, which are mostly excitatory glutamatergic neurons, in primary cortical cultures. This was achieved using an asymmetrically designed micropattern that directs an axonal process to the longest pathway. In the current work, we first modified the micropattern geometry to improve cell viability and then studied the axon length from 2 to 7 days in vitro (DIV). The cell types of neurons were evaluated retrospectively based on immunoreactivity against GAD67, a marker for inhibitory GABAergic neurons. We found that axons of non-GABAergic neurons grow significantly longer than those of GABAergic neurons in the early stages of development. The optimal threshold for identifying GABAergic and non-GABAergic neurons was evaluated to be 110 μm at 6 DIV. The method does not require any fluorescence labelling and can be carried out on live cells. The accuracy of identification was 98.2%. We confirmed that the high accuracy was due to the use of a micropattern, which standardized the development of cultured neurons. The method promises to be beneficial both for engineering neuronal networks in vitro and for basic cellular neuroscience research. PMID:27513933

  7. Characterization of cortical neuronal and glial alterations during culture of organotypic whole brain slices from neonatal and mature mice.

    Science.gov (United States)

    Staal, Jerome A; Alexander, Samuel R; Liu, Yao; Dickson, Tracey D; Vickers, James C

    2011-01-01

    Organotypic brain slice culturing techniques are extensively used in a wide range of experimental procedures and are particularly useful in providing mechanistic insights into neurological disorders or injury. The cellular and morphological alterations associated with hippocampal brain slice cultures has been well established, however, the neuronal response of mouse cortical neurons to culture is not well documented. In the current study, we compared the cell viability, as well as phenotypic and protein expression changes in cortical neurons, in whole brain slice cultures from mouse neonates (P4-6), adolescent animals (P25-28) and mature adults (P50+). Cultures were prepared using the membrane interface method. Propidium iodide labeling of nuclei (due to compromised cell membrane) and AlamarBlue™ (cell respiration) analysis demonstrated that neonatal tissue was significantly less vulnerable to long-term culture in comparison to the more mature brain tissues. Cultures from P6 animals showed a significant increase in the expression of synaptic markers and a decrease in growth-associated proteins over the entire culture period. However, morphological analysis of organotypic brain slices cultured from neonatal tissue demonstrated that there were substantial changes to neuronal and glial organization within the neocortex, with a distinct loss of cytoarchitectural stratification and increased GFAP expression (pglial limitans and, after 14 DIV, displayed substantial cellular protrusions from slice edges, including cells that expressed both glial and neuronal markers. In summary, we present a substantial evaluation of the viability and morphological changes that occur in the neocortex of whole brain tissue cultures, from different ages, over an extended period of culture.

  8. Spiking in auditory cortex following thalamic stimulation is dominated by cortical network activity

    Science.gov (United States)

    Krause, Bryan M.; Raz, Aeyal; Uhlrich, Daniel J.; Smith, Philip H.; Banks, Matthew I.

    2014-01-01

    The state of the sensory cortical network can have a profound impact on neural responses and perception. In rodent auditory cortex, sensory responses are reported to occur in the context of network events, similar to brief UP states, that produce “packets” of spikes and are associated with synchronized synaptic input (Bathellier et al., 2012; Hromadka et al., 2013; Luczak et al., 2013). However, traditional models based on data from visual and somatosensory cortex predict that ascending sensory thalamocortical (TC) pathways sequentially activate cells in layers 4 (L4), L2/3, and L5. The relationship between these two spatio-temporal activity patterns is unclear. Here, we used calcium imaging and electrophysiological recordings in murine auditory TC brain slices to investigate the laminar response pattern to stimulation of TC afferents. We show that although monosynaptically driven spiking in response to TC afferents occurs, the vast majority of spikes fired following TC stimulation occurs during brief UP states and outside the context of the L4>L2/3>L5 activation sequence. Specifically, monosynaptic subthreshold TC responses with similar latencies were observed throughout layers 2–6, presumably via synapses onto dendritic processes located in L3 and L4. However, monosynaptic spiking was rare, and occurred primarily in L4 and L5 non-pyramidal cells. By contrast, during brief, TC-induced UP states, spiking was dense and occurred primarily in pyramidal cells. These network events always involved infragranular layers, whereas involvement of supragranular layers was variable. During UP states, spike latencies were comparable between infragranular and supragranular cells. These data are consistent with a model in which activation of auditory cortex, especially supragranular layers, depends on internally generated network events that represent a non-linear amplification process, are initiated by infragranular cells and tightly regulated by feed-forward inhibitory

  9. Network-state modulation of power-law frequency-scaling in visual cortical neurons.

    Science.gov (United States)

    El Boustani, Sami; Marre, Olivier; Béhuret, Sébastien; Baudot, Pierre; Yger, Pierre; Bal, Thierry; Destexhe, Alain; Frégnac, Yves

    2009-09-01

    Various types of neural-based signals, such as EEG, local field potentials and intracellular synaptic potentials, integrate multiple sources of activity distributed across large assemblies. They have in common a power-law frequency-scaling structure at high frequencies, but it is still unclear whether this scaling property is dominated by intrinsic neuronal properties or by network activity. The latter case is particularly interesting because if frequency-scaling reflects the network state it could be used to characterize the functional impact of the connectivity. In intracellularly recorded neurons of cat primary visual cortex in vivo, the power spectral density of V(m) activity displays a power-law structure at high frequencies with a fractional scaling exponent. We show that this exponent is not constant, but depends on the visual statistics used to drive the network. To investigate the determinants of this frequency-scaling, we considered a generic recurrent model of cortex receiving a retinotopically organized external input. Similarly to the in vivo case, our in computo simulations show that the scaling exponent reflects the correlation level imposed in the input. This systematic dependence was also replicated at the single cell level, by controlling independently, in a parametric way, the strength and the temporal decay of the pairwise correlation between presynaptic inputs. This last model was implemented in vitro by imposing the correlation control in artificial presynaptic spike trains through dynamic-clamp techniques. These in vitro manipulations induced a modulation of the scaling exponent, similar to that observed in vivo and predicted in computo. We conclude that the frequency-scaling exponent of the V(m) reflects stimulus-driven correlations in the cortical network activity. Therefore, we propose that the scaling exponent could be used to read-out the "effective" connectivity responsible for the dynamical signature of the population signals measured

  10. Network-state modulation of power-law frequency-scaling in visual cortical neurons.

    Directory of Open Access Journals (Sweden)

    Sami El Boustani

    2009-09-01

    Full Text Available Various types of neural-based signals, such as EEG, local field potentials and intracellular synaptic potentials, integrate multiple sources of activity distributed across large assemblies. They have in common a power-law frequency-scaling structure at high frequencies, but it is still unclear whether this scaling property is dominated by intrinsic neuronal properties or by network activity. The latter case is particularly interesting because if frequency-scaling reflects the network state it could be used to characterize the functional impact of the connectivity. In intracellularly recorded neurons of cat primary visual cortex in vivo, the power spectral density of V(m activity displays a power-law structure at high frequencies with a fractional scaling exponent. We show that this exponent is not constant, but depends on the visual statistics used to drive the network. To investigate the determinants of this frequency-scaling, we considered a generic recurrent model of cortex receiving a retinotopically organized external input. Similarly to the in vivo case, our in computo simulations show that the scaling exponent reflects the correlation level imposed in the input. This systematic dependence was also replicated at the single cell level, by controlling independently, in a parametric way, the strength and the temporal decay of the pairwise correlation between presynaptic inputs. This last model was implemented in vitro by imposing the correlation control in artificial presynaptic spike trains through dynamic-clamp techniques. These in vitro manipulations induced a modulation of the scaling exponent, similar to that observed in vivo and predicted in computo. We conclude that the frequency-scaling exponent of the V(m reflects stimulus-driven correlations in the cortical network activity. Therefore, we propose that the scaling exponent could be used to read-out the "effective" connectivity responsible for the dynamical signature of the population

  11. Spike Code Flow in Cultured Neuronal Networks.

    Science.gov (United States)

    Tamura, Shinichi; Nishitani, Yoshi; Hosokawa, Chie; Miyoshi, Tomomitsu; Sawai, Hajime; Kamimura, Takuya; Yagi, Yasushi; Mizuno-Matsumoto, Yuko; Chen, Yen-Wei

    2016-01-01

    We observed spike trains produced by one-shot electrical stimulation with 8 × 8 multielectrodes in cultured neuronal networks. Each electrode accepted spikes from several neurons. We extracted the short codes from spike trains and obtained a code spectrum with a nominal time accuracy of 1%. We then constructed code flow maps as movies of the electrode array to observe the code flow of "1101" and "1011," which are typical pseudorandom sequence such as that we often encountered in a literature and our experiments. They seemed to flow from one electrode to the neighboring one and maintained their shape to some extent. To quantify the flow, we calculated the "maximum cross-correlations" among neighboring electrodes, to find the direction of maximum flow of the codes with lengths less than 8. Normalized maximum cross-correlations were almost constant irrespective of code. Furthermore, if the spike trains were shuffled in interval orders or in electrodes, they became significantly small. Thus, the analysis suggested that local codes of approximately constant shape propagated and conveyed information across the network. Hence, the codes can serve as visible and trackable marks of propagating spike waves as well as evaluating information flow in the neuronal network.

  12. Spike Code Flow in Cultured Neuronal Networks

    Directory of Open Access Journals (Sweden)

    Shinichi Tamura

    2016-01-01

    Full Text Available We observed spike trains produced by one-shot electrical stimulation with 8 × 8 multielectrodes in cultured neuronal networks. Each electrode accepted spikes from several neurons. We extracted the short codes from spike trains and obtained a code spectrum with a nominal time accuracy of 1%. We then constructed code flow maps as movies of the electrode array to observe the code flow of “1101” and “1011,” which are typical pseudorandom sequence such as that we often encountered in a literature and our experiments. They seemed to flow from one electrode to the neighboring one and maintained their shape to some extent. To quantify the flow, we calculated the “maximum cross-correlations” among neighboring electrodes, to find the direction of maximum flow of the codes with lengths less than 8. Normalized maximum cross-correlations were almost constant irrespective of code. Furthermore, if the spike trains were shuffled in interval orders or in electrodes, they became significantly small. Thus, the analysis suggested that local codes of approximately constant shape propagated and conveyed information across the network. Hence, the codes can serve as visible and trackable marks of propagating spike waves as well as evaluating information flow in the neuronal network.

  13. Histological analysis of the alterations on cortical bone channels network after radiotherapy: A rabbit study.

    Science.gov (United States)

    Rabelo, Gustavo Davi; Beletti, Marcelo Emílio; Dechichi, Paula

    2010-10-01

    The aim of this study was to evaluate the effects of radiotherapy in cortical bone channels network. Fourteen rabbits were divided in two groups and test group received single dose of 15 Gy cobalt-60 radiation in tibia, bilaterally. The animals were sacrificed and a segment of tibia was removed and histologically processed. Histological images were taken and had their bone channels segmented and called regions of interest (ROI). Images were analyzed through developed algorithms using the SCILAB mathematical environment, getting percentage of bone matrix, ROI areas, ROI perimeters, their standard deviations and Lacunarity. The osteocytes and empty lacunae were also counted. Data were evaluated using Kolmogorov-Smirnov, Mann Whitney, and Student's t test (P < 0.05). Significant differences in bone matrix percentage, area and perimeters of the channels, their respective standard deviations and lacunarity were found between groups. In conclusion, the radiotherapy causes reduction of bone matrix and modifies the morphology of bone channels network. © 2010 Wiley-Liss, Inc.

  14. Acupuncture analgesia involves modulation of pain-induced gamma oscillations and cortical network connectivity.

    Science.gov (United States)

    Hauck, Michael; Schröder, Sven; Meyer-Hamme, Gesa; Lorenz, Jürgen; Friedrichs, Sunja; Nolte, Guido; Gerloff, Christian; Engel, Andreas K

    2017-11-24

    Recent studies support the view that cortical sensory, limbic and executive networks and the autonomic nervous system might interact in distinct manners under the influence of acupuncture to modulate pain. We performed a double-blind crossover design study to investigate subjective ratings, EEG and ECG following experimental laser pain under the influence of sham and verum acupuncture in 26 healthy volunteers. We analyzed neuronal oscillations and inter-regional coherence in the gamma band of 128-channel-EEG recordings as well as heart rate variability (HRV) on two experimental days. Pain ratings and pain-induced gamma oscillations together with vagally-mediated power in the high-frequency bandwidth (vmHF) of HRV decreased significantly stronger during verum than sham acupuncture. Gamma oscillations were localized in the prefrontal cortex (PFC), mid-cingulate cortex (MCC), primary somatosensory cortex and insula. Reductions of pain ratings and vmHF-power were significantly correlated with increase of connectivity between the insula and MCC. In contrast, connectivity between left and right PFC and between PFC and insula correlated positively with vmHF-power without a relationship to acupuncture analgesia. Overall, these findings highlight the influence of the insula in integrating activity in limbic-saliency networks with vagally mediated homeostatic control to mediate antinociception under the influence of acupuncture.

  15. The slow oscillation in cortical and thalamic networks: mechanisms and functions

    Directory of Open Access Journals (Sweden)

    Garrett T. Neske

    2016-01-01

    Full Text Available During even the most quiescent behavioral periods, the cortex and thalamus express rich spontaneous activity in the form of slow (<1 Hz, synchronous network state transitions. Throughout this so-called slow oscillation, cortical and thalamic neurons fluctuate between periods of intense synaptic activity (Up states and almost complete silence (Down states. The two decades since the original characterization of the slow oscillation in the cortex and thalamus have seen considerable advances in deciphering the cellular and network mechanisms associated with this pervasive phenomenon. There are, nevertheless, many questions regarding the slow oscillation that await more thorough illumination, particularly the mechanisms by which Up states initiate and terminate, the functional role of the rhythmic activity cycles in unconscious or minimally conscious states, and the precise relation between Up states and the activated states associated with waking behavior. Given the substantial advances in multineuronal recording and imaging methods in both in vivo and in vitro preparations, the time is ripe to take stock of our current understanding of the slow oscillation and pave the way for future investigations of its mechanisms and functions. My aim in this Review is to provide a comprehensive account of the mechanisms and functions of the slow oscillation, and to suggest avenues for further exploration.

  16. Exporting embedded in culture and transnational networks around entrepreneurs

    DEFF Research Database (Denmark)

    Ashourizadeh, Shayegheh; Schøtt, Thomas

    2016-01-01

    from networking in the market, professions and work-place, but is impeded by networking for advice in the private sphere. Exporting is embedded in culture in the way that benefits of transnational networking for exporting are higher in secular-rational culture than in traditional culture. This study....... This dynamic unfolds in the context of culture, which expectedly moderates benefit of networks for exporting. Networking for advice was surveyed in the Global Entrepreneurship Monitor in 61 societies with 52,968 entrepreneurs. Exporting greatly benefits from transnational networks around entrepreneurs and also...... generalises to the entrepreneurs in the world, and is a first to account for embedding of exporting in transnational advisory networks in combination with culture....

  17. Feed-Forward Propagation of Temporal and Rate Information between Cortical Populations during Coherent Activation in Engineered In Vitro Networks.

    Science.gov (United States)

    DeMarse, Thomas B; Pan, Liangbin; Alagapan, Sankaraleengam; Brewer, Gregory J; Wheeler, Bruce C

    2016-01-01

    Transient propagation of information across neuronal assembles is thought to underlie many cognitive processes. However, the nature of the neural code that is embedded within these transmissions remains uncertain. Much of our understanding of how information is transmitted among these assemblies has been derived from computational models. While these models have been instrumental in understanding these processes they often make simplifying assumptions about the biophysical properties of neurons that may influence the nature and properties expressed. To address this issue we created an in vitro analog of a feed-forward network composed of two small populations (also referred to as assemblies or layers) of living dissociated rat cortical neurons. The populations were separated by, and communicated through, a microelectromechanical systems (MEMS) device containing a strip of microscale tunnels. Delayed culturing of one population in the first layer followed by the second a few days later induced the unidirectional growth of axons through the microtunnels resulting in a primarily feed-forward communication between these two small neural populations. In this study we systematically manipulated the number of tunnels that connected each layer and hence, the number of axons providing communication between those populations. We then assess the effect of reducing the number of tunnels has upon the properties of between-layer communication capacity and fidelity of neural transmission among spike trains transmitted across and within layers. We show evidence based on Victor-Purpura's and van Rossum's spike train similarity metrics supporting the presence of both rate and temporal information embedded within these transmissions whose fidelity increased during communication both between and within layers when the number of tunnels are increased. We also provide evidence reinforcing the role of synchronized activity upon transmission fidelity during the spontaneous synchronized

  18. Toxicity evaluation of new agricultural fungicides in primary cultured cortical neurons.

    Science.gov (United States)

    Regueiro, Jorge; Olguín, Nair; Simal-Gándara, Jesús; Suñol, Cristina

    2015-07-01

    Fungicides are crucial for food protection as well as for the production of crops of suitable quality and quantity to provide a viable economic return. Like other pesticides, fungicides are widely sprayed on agricultural land, especially in wine-growing areas, from where they can move-off after application. Furthermore, residues of these agrochemicals can remain on crops after harvest and even after some food processing operations, being a major exposure pathway. Although a relatively low toxicity has been claimed for this kind of compounds, information about their neurotoxicity is still scarce. In the present study, nine fungicides recently approved for agricultural uses in the EU - ametoctradin, boscalid, cyazofamid, dimethomorph, fenhexamid, kresoxim-methyl, mepanipyrim, metrafenone and pyraclostrobin - have been evaluated for their toxicity in primary cultured mouse cortical neurons. Exposure to 0.1-100µM for 7 days in vitro resulted in a dose-dependent toxicity in the MTT cell viability assay. Strobilurin fungicides kresoxim-methyl (KR) and pyraclostrobin (PY) were the most neurotoxic compounds (lethal concentration 50 were in the low micromolar and nanomolar levels, respectively) causing a rapid raise in intracellular calcium [Ca(2+)]i and strong depolarization of mitochondrial membrane potential. KR- and PY-induced cell death was reversed by the calcium channels blockers MK-801 and verapamil, suggesting that calcium entry through NMDA receptors and voltage-operated calcium channels are involved in KR- and PY-induced neurotoxicity. These results highlight the need for further evaluation of their neurotoxic effects in vivo. Copyright © 2015 Elsevier Inc. All rights reserved.

  19. Spatiotemporal alterations of cortical network activity by selective loss of NOS-expressing interneurons .

    Directory of Open Access Journals (Sweden)

    Dan eShlosberg

    2012-02-01

    Full Text Available Deciphering the role of GABAergic neurons in large neuronal networks such as the neocortex forms a particularly complex task as they comprise a highly diverse population. The neuronal isoform of the enzyme nitric oxide synthase (nNOS is expressed in the neocortex by specific subsets of GABAergic neurons. These neurons can be identified in live brain slices by the nitric oxide (NO fluorescent indicator DAF-2DA. However, this indicator was found to be highly toxic to the stained neurons. We used this feature to induce acute phototoxic damage to NO-producing neurons in cortical slices, and measured subsequent alterations in parameters of cellular and network activity.Neocortical slices were briefly incubated in DAF-2DA and then illuminated through the 4X objective. Histochemistry for NADPH diaphorase, a marker for nNOS activity, revealed elimination of staining in the illuminated areas following treatment. Whole cell recordings from several neuronal types before, during and after illumination confirmed the selective damage to non fast-spiking interneurons. Treated slices displayed mild disinhibition. The reversal potential of compound synaptic events on pyramidal neurons became more positive, and their decay time constant was elongated, substantiating the removal of an inhibitory conductance. The horizontal decay of local field potentials (LFPs was significantly reduced at distances of 300-400 m from the stimulation, but not when inhibition was non-selectively weakened with the GABAA blocker picrotoxin. Finally, whereas the depression of LFPs along short trains of 40 Hz stimuli was linearly reduced with distance or initial amplitude in control slices, this ordered relationship was disrupted in DAF-treated slices. These results reveal that NO-producing interneurons in the neocortex convey lateral inhibition to neighboring columns, and shape the spatiotemporal dynamics of the network's activity.

  20. Spatiotemporal alterations of cortical network activity by selective loss of NOS-expressing interneurons.

    Science.gov (United States)

    Shlosberg, Dan; Buskila, Yossi; Abu-Ghanem, Yasmin; Amitai, Yael

    2012-01-01

    Deciphering the role of GABAergic neurons in large neuronal networks such as the neocortex forms a particularly complex task as they comprise a highly diverse population. The neuronal isoform of the enzyme nitric oxide synthase (nNOS) is expressed in the neocortex by specific subsets of GABAergic neurons. These neurons can be identified in live brain slices by the nitric oxide (NO) fluorescent indicator diaminofluorescein-2 diacetate (DAF-2DA). However, this indicator was found to be highly toxic to the stained neurons. We used this feature to induce acute phototoxic damage to NO-producing neurons in cortical slices, and measured subsequent alterations in parameters of cellular and network activity. Neocortical slices were briefly incubated in DAF-2DA and then illuminated through the 4× objective. Histochemistry for NADPH-diaphorase (NADPH-d), a marker for nNOS activity, revealed elimination of staining in the illuminated areas following treatment. Whole cell recordings from several neuronal types before, during, and after illumination confirmed the selective damage to non-fast-spiking (FS) interneurons. Treated slices displayed mild disinhibition. The reversal potential of compound synaptic events on pyramidal neurons became more positive, and their decay time constant was elongated, substantiating the removal of an inhibitory conductance. The horizontal decay of local field potentials (LFPs) was significantly reduced at distances of 300-400 μm from the stimulation, but not when inhibition was non-selectively weakened with the GABA(A) blocker picrotoxin. Finally, whereas the depression of LFPs along short trains of 40 Hz stimuli was linearly reduced with distance or initial amplitude in control slices, this ordered relationship was disrupted in DAF-treated slices. These results reveal that NO-producing interneurons in the neocortex convey lateral inhibition to neighboring columns, and shape the spatiotemporal dynamics of the network's activity.

  1. Analysis of organizational culture with social network models

    OpenAIRE

    Titov, S.

    2015-01-01

    Organizational culture is nowadays an object of numerous scientific papers. However, only marginal part of existing research attempts to use the formal models of organizational cultures. The lack of organizational culture models significantly limits the further research in this area and restricts the application of the theory to practice of organizational culture change projects. The article consists of general views on potential application of network models and social network analysis to th...

  2. Cultural Ecosystem of Creative Place: Creative Class, Creative Networks and Participation in Culture

    Directory of Open Access Journals (Sweden)

    Anders-Morawska Justyna

    2017-06-01

    Full Text Available The scope of this paper is to conceptualise a data-based research framework for the role of creative networks in cultural exchange. Participation in culture measured as audience per 1000 residents and expenditures on culture-related activities were analysed in relation to such territorial assets as accessibility to creative infrastructure, the economic status of residents, the governance networks of civil society, and cultural capital. The results indicate how accessibility, governance networks, and cultural capital contribute to participation measured via audience indicators while a low poverty rate has explanatory value with respect to expenditures on culture.

  3. GABA neurons and the mechanisms of network oscillations: implications for understanding cortical dysfunction in schizophrenia.

    Science.gov (United States)

    Gonzalez-Burgos, Guillermo; Lewis, David A

    2008-09-01

    Synchronization of neuronal activity in the neocortex may underlie the coordination of neural representations and thus is critical for optimal cognitive function. Because cognitive deficits are the major determinant of functional outcome in schizophrenia, identifying their neural basis is important for the development of new therapeutic interventions. Here we review the data suggesting that phasic synaptic inhibition mediated by specific subtypes of cortical gamma-aminobutyric acid (GABA) neurons is essential for the production of synchronized network oscillations. We also discuss evidence indicating that GABA neurotransmission is altered in schizophrenia and propose mechanisms by which such alterations can decrease the strength of inhibitory connections in a cell-type-specific manner. We suggest that some alterations observed in the neocortex of schizophrenia subjects may be compensatory responses that partially restore inhibitory synaptic efficacy. The findings of altered neural synchrony and impaired cognitive function in schizophrenia suggest that such compensatory responses are insufficient and that interventions aimed at augmenting the efficacy of GABA neurotransmission might be of therapeutic value.

  4. Neuroglobin overexpression inhibits oxygen-glucose deprivation-induced mitochondrial permeability transition pore opening in primary cultured mouse cortical neurons.

    Science.gov (United States)

    Yu, Zhanyang; Liu, Ning; Li, Yadan; Xu, Jianfeng; Wang, Xiaoying

    2013-08-01

    Neuroglobin (Ngb) is an endogenous neuroprotective molecule against hypoxic/ischemic brain injury, but the underlying mechanisms remain largely undefined. Our recent study revealed that Ngb can bind to voltage-dependent anion channel (VDAC), a regulator of mitochondria permeability transition (MPT). In this study we examined the role of Ngb in MPT pore (mPTP) opening following oxygen-glucose deprivation (OGD) in primary cultured mouse cortical neurons. Co-immunoprecipitation (Co-IP) and immunocytochemistry showed that the binding between Ngb and VDAC was increased after OGD compared to normoxia, indicating the OGD-enhanced Ngb-VDAC interaction. Ngb overexpression protected primary mouse cortical neurons from OGD-induced neuronal death, to an extent comparable to mPTP opening inhibitor, cyclosporine A (CsA) pretreatment. We further measured the role of Ngb in OGD-induced mPTP opening using Ngb overexpression and knockdown approaches in primary cultured neurons, and recombinant Ngb exposure to isolated mitochondria. Same as CsA pretreatment, Ngb overexpression significantly reduced OGD-induced mPTP opening markers including mitochondria swelling, mitochondrial NAD(+) release, and cytochrome c (Cyt c) release in primary cultured neurons. Recombinant Ngb incubation significantly reduced OGD-induced NAD(+) release and Cyt c release from isolated mitochondria. In contrast, Ngb knockdown significantly increased OGD-induced neuron death, and increased OGD-induced mitochondrial NAD(+) release and Cyt c release as well, and these outcomes could be rescued by CsA pretreatment. In summary, our results demonstrated that Ngb overexpression can inhibit OGD-induced mPTP opening in primary cultured mouse cortical neurons, which may be one of the molecular mechanisms of Ngb's neuroprotection. Copyright © 2013 Elsevier Inc. All rights reserved.

  5. Age-related decline in functional connectivity of the vestibular cortical network.

    Science.gov (United States)

    Cyran, Carolin Anna Maria; Boegle, Rainer; Stephan, Thomas; Dieterich, Marianne; Glasauer, Stefan

    2016-04-01

    In the elderly, major complaints include dizziness and an increasing number of falls, possibly related to an altered processing of vestibular sensory input. In this study, we therefore investigate age-related changes induced by processing of vestibular sensory stimulation. While previous functional imaging studies of healthy aging have investigated brain function during task performance or at rest, we used galvanic vestibular stimulation during functional MRI in a task-free sensory stimulation paradigm to study the effect of healthy aging on central vestibular processing, which might only become apparent during stimulation processing. Since aging may affect signatures of brain function beyond the BOLD-signal amplitude-such as functional connectivity or temporal signal variability--we employed independent component analysis and partial least squares analysis of temporal signal variability. We tested for age-associated changes unrelated to vestibular processing, using a motor paradigm, voxel-based morphometry and diffusion tensor imaging. This allows us to control for general age-related modifications, possibly originating from vascular, atrophic or structural connectivity changes. Age-correlated decreases of functional connectivity and increases of BOLD--signal variability were associated with multisensory vestibular networks. In contrast, no age-related functional connectivity changes were detected in somatosensory networks or during the motor paradigm. The functional connectivity decrease was not due to structural changes but to a decrease in response amplitude. In synopsis, our data suggest that both the age-dependent functional connectivity decrease and the variability increase may be due to deteriorating reciprocal cortico-cortical inhibition with age and related to multimodal vestibular integration of sensory inputs.

  6. Functional characterization of GABAA receptor-mediated modulation of cortical neuron network activity in microelectrode array recordings

    DEFF Research Database (Denmark)

    Bader, Benjamin M; Steder, Anne; Klein, Anders Bue

    2017-01-01

    The numerous γ-aminobutyric acid type A receptor (GABAAR) subtypes are differentially expressed and mediate distinct functions at neuronal level. In this study we have investigated GABAAR-mediated modulation of the spontaneous activity patterns of primary neuronal networks from murine frontal...... of the information extractable from the MEA recordings offers interesting insights into the contributions of various GABAAR subtypes/subgroups to cortical network activity and the putative functional interplay between these receptors in these neurons....... cortex by characterizing the effects induced by a wide selection of pharmacological tools at a plethora of activity parameters in microelectrode array (MEA) recordings. The basic characteristics of the primary cortical neurons used in the recordings were studied in some detail, and the expression levels...

  7. Functional clustering in hippocampal cultures: relating network structure and dynamics

    International Nuclear Information System (INIS)

    Feldt, S; Dzakpasu, R; Olariu, E; Żochowski, M; Wang, J X; Shtrahman, E

    2010-01-01

    In this work we investigate the relationship between gross anatomic structural network properties, neuronal dynamics and the resultant functional structure in dissociated rat hippocampal cultures. Specifically, we studied cultures as they developed under two conditions: the first supporting glial cell growth (high glial group), and the second one inhibiting it (low glial group). We then compared structural network properties and the spatio-temporal activity patterns of the neurons. Differences in dynamics between the two groups could be linked to the impact of the glial network on the neuronal network as the cultures developed. We also implemented a recently developed algorithm called the functional clustering algorithm (FCA) to obtain the resulting functional network structure. We show that this new algorithm is useful for capturing changes in functional network structure as the networks evolve over time. The FCA detects changes in functional structure that are consistent with expected dynamical differences due to the impact of the glial network. Cultures in the high glial group show an increase in global synchronization as the cultures age, while those in the low glial group remain locally synchronized. We additionally use the FCA to quantify the amount of synchronization present in the cultures and show that the total level of synchronization in the high glial group is stronger than in the low glial group. These results indicate an interdependence between the glial and neuronal networks present in dissociated cultures

  8. Exploration of Online Culture Through Network Analysis of Wikipedia.

    Science.gov (United States)

    Park, Sung Joo; Kim, Jong Woo; Lee, Hong Joo; Park, Hyunjung; Han, Deugcheon; Gloor, Peter

    2015-11-01

    Understanding online culture is becoming crucial in the global and connected world. Contrary to conventional attitudinal surveys used in cultural research, this study uses the approach of directly observing culture-specific behavior that emerges from online collaboration on the Internet. The editing data of Wikipedia were analyzed in 12 languages. Distinctive cultural dimensions were identified, including collectivism, extraversion, boldness, and egalitarianism. Using network analysis, the language-framed cultural factors were extracted as an emergent phenomenon in the virtual world.

  9. Self-sustained firing activities of the cortical network with plastic rules in weak AC electrical fields

    International Nuclear Information System (INIS)

    Qin Ying-Mei; Wang Jiang; Men Cong; Zhao Jia; Wei Xi-Le; Deng Bin

    2012-01-01

    Both external and endogenous electrical fields widely exist in the environment of cortical neurons. The effects of a weak alternating current (AC) field on a neural network model with synaptic plasticity are studied. It is found that self-sustained rhythmic firing patterns, which are closely correlated with the cognitive functions, are significantly modified due to the self-organizing of the network in the weak AC field. The activities of the neural networks are affected by the synaptic connection strength, the external stimuli, and so on. In the presence of learning rules, the synaptic connections can be modulated by the external stimuli, which will further enhance the sensitivity of the network to the external signal. The properties of the external AC stimuli can serve as control parameters in modulating the evolution of the neural network. (interdisciplinary physics and related areas of science and technology)

  10. Growth dynamics explain the development of spatiotemporal burst activity of young cultured neuronal networks in detail.

    Directory of Open Access Journals (Sweden)

    Taras A Gritsun

    Full Text Available A typical property of isolated cultured neuronal networks of dissociated rat cortical cells is synchronized spiking, called bursting, starting about one week after plating, when the dissociated cells have sufficiently sent out their neurites and formed enough synaptic connections. This paper is the third in a series of three on simulation models of cultured networks. Our two previous studies [26], [27] have shown that random recurrent network activity models generate intra- and inter-bursting patterns similar to experimental data. The networks were noise or pacemaker-driven and had Izhikevich-neuronal elements with only short-term plastic (STP synapses (so, no long-term potentiation, LTP, or depression, LTD, was included. However, elevated pre-phases (burst leaders and after-phases of burst main shapes, that usually arise during the development of the network, were not yet simulated in sufficient detail. This lack of detail may be due to the fact that the random models completely missed network topology .and a growth model. Therefore, the present paper adds, for the first time, a growth model to the activity model, to give the network a time dependent topology and to explain burst shapes in more detail. Again, without LTP or LTD mechanisms. The integrated growth-activity model yielded realistic bursting patterns. The automatic adjustment of various mutually interdependent network parameters is one of the major advantages of our current approach. Spatio-temporal bursting activity was validated against experiment. Depending on network size, wave reverberation mechanisms were seen along the network boundaries, which may explain the generation of phases of elevated firing before and after the main phase of the burst shape.In summary, the results show that adding topology and growth explain burst shapes in great detail and suggest that young networks still lack/do not need LTP or LTD mechanisms.

  11. Cortical Amyloid Beta in Cognitively Normal Elderly Adults is Associated with Decreased Network Efficiency within the Cerebro-Cerebellar System.

    Science.gov (United States)

    Steininger, Stefanie C; Liu, Xinyang; Gietl, Anton; Wyss, Michael; Schreiner, Simon; Gruber, Esmeralda; Treyer, Valerie; Kälin, Andrea; Leh, Sandra; Buck, Alfred; Nitsch, Roger M; Prüssmann, Klaas P; Hock, Christoph; Unschuld, Paul G

    2014-01-01

    Deposition of cortical amyloid beta (Aβ) is a correlate of aging and a risk factor for Alzheimer disease (AD). While several higher order cognitive processes involve functional interactions between cortex and cerebellum, this study aims to investigate effects of cortical Aβ deposition on coupling within the cerebro-cerebellar system. We included 15 healthy elderly subjects with normal cognitive performance as assessed by neuropsychological testing. Cortical Aβ was quantified using (11)carbon-labeled Pittsburgh compound B positron-emission-tomography late frame signals. Volumes of brain structures were assessed by applying an automated parcelation algorithm to three dimensional magnetization-prepared rapid gradient-echo T1-weighted images. Basal functional network activity within the cerebro-cerebellar system was assessed using blood-oxygen-level dependent resting state functional magnetic resonance imaging at the high field strength of 7 T for measuring coupling between cerebellar seeds and cerebral gray matter. A bivariate regression approach was applied for identification of brain regions with significant effects of individual cortical Aβ load on coupling. Consistent with earlier reports, a significant degree of positive and negative coupling could be observed between cerebellar seeds and cerebral voxels. Significant positive effects of cortical Aβ load on cerebro-cerebellar coupling resulted for cerebral brain regions located in inferior temporal lobe, prefrontal cortex, hippocampus, parahippocampal gyrus, and thalamus. Our findings indicate that brain amyloidosis in cognitively normal elderly subjects is associated with decreased network efficiency within the cerebro-cerebellar system. While the identified cerebral regions are consistent with established patterns of increased sensitivity for Aβ-associated neurodegeneration, additional studies are needed to elucidate the relationship between dysfunction of the cerebro-cerebellar system and risk for AD.

  12. Education for a Culture of Peace: The Culture of Peace News Network as a Case Study

    Science.gov (United States)

    Adams, David

    2013-01-01

    The Culture of Peace News Network, an internet news service, is analyzed in the framework of a general approach to education for a culture of peace. Its format reflects the eight program areas for a culture of peace as adopted by the UN General Assembly. Among its other operating principles are universality of news with all cultures and regions of…

  13. Cerebello-thalamo-cortical networks predict positive symptom progression in individuals at ultra-high risk for psychosis

    Directory of Open Access Journals (Sweden)

    Jessica A. Bernard

    2017-01-01

    Full Text Available Prospective longitudinal evaluation of adolescents at ultra-high-risk (UHR for the development of psychosis enables an enriched neurodevelopmental perspective of disease progression in the absence of many of the factors that typically confound research with formally psychotic patients (antipsychotic medications, drug/alcohol dependence. The cerebellum has been linked to cognitive dysfunction and symptom severity in schizophrenia and recent work from our team suggests that it is a promising target for investigation in UHR individuals as well. However, the cerebellum and cerebello-thalamo-cortical networks have not been investigated developmentally or with respect to disease progression in this critical population. Further, to date, the types of longitudinal multimodal connectivity studies that would substantially inform our understanding of this area have not yet been conducted. In the present investigation 26 UHR and 24 healthy control adolescents were administered structured clinical interviews and scanned at baseline and then again at 12-month time points to investigate both functional and structural connectivity development of cerebello-thalamo-cortical networks in conjunction with symptom progression. Our results provide evidence of abnormal functional and structural cerebellar network development in the UHR group. Crucially, we also found that cerebello-thalamo-cortical network development and connectivity at baseline are associated with positive symptom course, suggesting that cerebellar networks may be a biomarker of disease progression. Together, these findings provide support for neurodevelopmental models of psychotic disorders and suggest that the cerebellum and respective networks with the cortex may be especially important for elucidating the pathophysiology of psychosis and highlighting novel treatment targets.

  14. Global Diffusion of Interactive Networks. The Impact of Culture

    OpenAIRE

    Maitland, Carleen

    1998-01-01

    The Internet and other interactive networks are diffusing across the globe at rates that vary from country to country. Typically, economic and market structure variables are used to explain these differences. The addition of culture to these variables will provide a more robust understanding of the differences in Internet and interactive network diffusion. Existing analyses that identify culture as a predictor of diffusion do not adequately specificy the dimensions of culture and their imp...

  15. Levels, Linkages, and Networks in Cross-Cultural Innovation.

    Science.gov (United States)

    Kennedy, Judith; Kennedy, Chris

    1998-01-01

    Individuals belong to different cultural networks, and these networks and connections between them play an important role in success or failure of educational innovation and should be included in any model of the management or evaluation of innovation. Looks at functions of the different networks to which individuals belong at three levels,…

  16. Causal hierarchy within the thalamo-cortical network in spike and wave discharges.

    Directory of Open Access Journals (Sweden)

    Anna E Vaudano

    2009-08-01

    Full Text Available Generalised spike wave (GSW discharges are the electroencephalographic (EEG hallmark of absence seizures, clinically characterised by a transitory interruption of ongoing activities and impaired consciousness, occurring during states of reduced awareness. Several theories have been proposed to explain the pathophysiology of GSW discharges and the role of thalamus and cortex as generators. In this work we extend the existing theories by hypothesizing a role for the precuneus, a brain region neglected in previous works on GSW generation but already known to be linked to consciousness and awareness. We analysed fMRI data using dynamic causal modelling (DCM to investigate the effective connectivity between precuneus, thalamus and prefrontal cortex in patients with GSW discharges.We analysed fMRI data from seven patients affected by Idiopathic Generalized Epilepsy (IGE with frequent GSW discharges and significant GSW-correlated haemodynamic signal changes in the thalamus, the prefrontal cortex and the precuneus. Using DCM we assessed their effective connectivity, i.e. which region drives another region. Three dynamic causal models were constructed: GSW was modelled as autonomous input to the thalamus (model A, ventromedial prefrontal cortex (model B, and precuneus (model C. Bayesian model comparison revealed Model C (GSW as autonomous input to precuneus, to be the best in 5 patients while model A prevailed in two cases. At the group level model C dominated and at the population-level the p value of model C was approximately 1.Our results provide strong evidence that activity in the precuneus gates GSW discharges in the thalamo-(fronto cortical network. This study is the first demonstration of a causal link between haemodynamic changes in the precuneus -- an index of awareness -- and the occurrence of pathological discharges in epilepsy.

  17. IL-10 Promotes Neurite Outgrowth and Synapse Formation in Cultured Cortical Neurons after the Oxygen-Glucose Deprivation via JAK1/STAT3 Pathway.

    Science.gov (United States)

    Chen, Hongbin; Lin, Wei; Zhang, Yixian; Lin, Longzai; Chen, Jianhao; Zeng, Yongping; Zheng, Mouwei; Zhuang, Zezhong; Du, Houwei; Chen, Ronghua; Liu, Nan

    2016-07-26

    As a classic immunoregulatory and anti-inflammatory cytokine, interleukin-10 (IL-10) provides neuroprotection in cerebral ischemia in vivo or oxygen-glucose deprivation (OGD)-induced injury in vitro. However, it remains blurred whether IL-10 promotes neurite outgrowth and synapse formation in cultured primary cortical neurons after OGD injury. In order to evaluate its effect on neuronal apoptosis, neurite outgrowth and synapse formation, we administered IL-10 or IL-10 neutralizing antibody (IL-10NA) to cultured rat primary cortical neurons after OGD injury. We found that IL-10 treatment activated the Janus kinase 1 (JAK1)/signal transducers and activators of transcription 3 (STAT3) signaling pathway. Moreover, IL-10 attenuated OGD-induced neuronal apoptosis by down-regulating the Bax expression and up-regulating the Bcl-2 expression, facilitated neurite outgrowth by increasing the expression of Netrin-1, and promoted synapse formation in cultured primary cortical neurons after OGD injury. These effects were partly abolished by JAK1 inhibitor GLPG0634. Contrarily, IL-10NA produced opposite effects on the cultured cortical neurons after OGD injury. Taken together, our findings suggest that IL-10 not only attenuates neuronal apoptosis, but also promotes neurite outgrowth and synapse formation via the JAK1/STAT3 signaling pathway in cultured primary cortical neurons after OGD injury.

  18. Regional vulnerability of longitudinal cortical association connectivity: Associated with structural network topology alterations in preterm children with cerebral palsy.

    Science.gov (United States)

    Ceschin, Rafael; Lee, Vince K; Schmithorst, Vince; Panigrahy, Ashok

    2015-01-01

    Preterm born children with spastic diplegia type of cerebral palsy and white matter injury or periventricular leukomalacia (PVL), are known to have motor, visual and cognitive impairments. Most diffusion tensor imaging (DTI) studies performed in this group have demonstrated widespread abnormalities using averaged deterministic tractography and voxel-based DTI measurements. Little is known about structural network correlates of white matter topography and reorganization in preterm cerebral palsy, despite the availability of new therapies and the need for brain imaging biomarkers. Here, we combined novel post-processing methodology of probabilistic tractography data in this preterm cohort to improve spatial and regional delineation of longitudinal cortical association tract abnormalities using an along-tract approach, and compared these data to structural DTI cortical network topology analysis. DTI images were acquired on 16 preterm children with cerebral palsy (mean age 5.6 ± 4) and 75 healthy controls (mean age 5.7 ± 3.4). Despite mean tract analysis, Tract-Based Spatial Statistics (TBSS) and voxel-based morphometry (VBM) demonstrating diffusely reduced fractional anisotropy (FA) reduction in all white matter tracts, the along-tract analysis improved the detection of regional tract vulnerability. The along-tract map-structural network topology correlates revealed two associations: (1) reduced regional posterior-anterior gradient in FA of the longitudinal visual cortical association tracts (inferior fronto-occipital fasciculus, inferior longitudinal fasciculus, optic radiation, posterior thalamic radiation) correlated with reduced posterior-anterior gradient of intra-regional (nodal efficiency) metrics with relative sparing of frontal and temporal regions; and (2) reduced regional FA within frontal-thalamic-striatal white matter pathways (anterior limb/anterior thalamic radiation, superior longitudinal fasciculus and cortical spinal tract) correlated with

  19. Crambescidin 816 induces calcium influx though glutamate receptors in primary cultures of cortical neurons

    Directory of Open Access Journals (Sweden)

    Víctor Martín Vázquez

    2014-06-01

    In summary, our data suggest that the cytotoxic effect of 10 μM Cramb816 in cortical neurons may be related to an increase in the cytosolic calcium concentration elicited by the toxin, which is shown to be mediated by glutamate receptor activation. Further studies analyzing the effect of glutamate receptor blockers on the cytotoxic effect of Cramb816 are needed to confirm this hypothesis.

  20. Immunocytochemistry and fluorescence imaging efficiently identify individual neurons with CRISPR/Cas9-mediated gene disruption in primary cortical cultures.

    Science.gov (United States)

    Tsunematsu, Hiroto; Uyeda, Akiko; Yamamoto, Nobuhiko; Sugo, Noriyuki

    2017-08-01

    CRISPR/Cas9 system is a powerful method to investigate the role of genes by introducing a mutation selectively and efficiently to specific genome positions in cell and animal lines. However, in primary neuron cultures, this method is affected by the issue that the effectiveness of CRISPR/Cas9 is different in each neuron. Here, we report an easy, quick and reliable method to identify mutants induced by the CRISPR/Cas9 system at a single neuron level, using immunocytochemistry (ICC) and fluorescence imaging. Dissociated cortical cells were transfected with CRISPR/Cas9 plasmids targeting the transcription factor cAMP-response element binding protein (CREB). Fluorescence ICC with CREB antibody and quantitative analysis of fluorescence intensity demonstrated that CREB expression disappeared in a fraction of the transfected neurons. The downstream FOS expression was also decreased in accordance with suppressed CREB expression. Moreover, dendritic arborization was decreased in the transfected neurons which lacked CREB immunoreactivity. Detection of protein expression is efficient to identify individual postmitotic neurons with CRISPR/Cas9-mediated gene disruption in primary cortical cultures. The present method composed of CRISPR/Cas9 system, ICC and fluorescence imaging is applicable to study the function of various genes at a single-neuron level.

  1. Transcriptomic Analysis of Ciguatoxin-Induced Changes in Gene Expression in Primary Cultures of Mice Cortical Neurons

    Directory of Open Access Journals (Sweden)

    Juan Andrés Rubiolo

    2018-05-01

    Full Text Available Ciguatoxins are polyether marine toxins that act as sodium channel activators. These toxins cause ciguatera, one of the most widespread nonbacterial forms of food poisoning, which presents several symptoms in humans including long-term neurological alterations. Earlier work has shown that both acute and chronic exposure of primary cortical neurons to synthetic ciguatoxin CTX3C have profound impacts on neuronal function. Thus, the present work aimed to identify relevant neuronal genes and metabolic pathways that could be altered by ciguatoxin exposure. To study the effect of ciguatoxins in primary neurons in culture, we performed a transcriptomic analysis using whole mouse genome microarrays, for primary cortical neurons exposed during 6, 24, or 72 h in culture to CTX3C. Here, we have shown that the effects of the toxin on gene expression differ with the exposure time. The results presented here have identified several relevant genes and pathways related to the effect of ciguatoxins on neurons and may assist in future research or even treatment of ciguatera. Moreover, we demonstrated that the effects of the toxin on gene expression were exclusively consequential of its action as a voltage-gated sodium channel activator, since all the effects of CTX3C were avoided by preincubation of the neurons with the sodium channel blocker tetrodotoxin.

  2. Altered Gradients of Glutamate and Gamma-Aminobutyric Acid Transcripts in the Cortical Visuospatial Working Memory Network in Schizophrenia.

    Science.gov (United States)

    Hoftman, Gil D; Dienel, Samuel J; Bazmi, Holly H; Zhang, Yun; Chen, Kehui; Lewis, David A

    2018-04-15

    Visuospatial working memory (vsWM), which is impaired in schizophrenia, requires information transfer across multiple nodes in the cerebral cortex, including visual, posterior parietal, and dorsolateral prefrontal regions. Information is conveyed across these regions via the excitatory projections of glutamatergic pyramidal neurons located in layer 3, whose activity is modulated by local inhibitory gamma-aminobutyric acidergic (GABAergic) neurons. Key properties of these neurons differ across these cortical regions. Consequently, in schizophrenia, alterations in the expression of gene products regulating these properties could disrupt vsWM function in different ways, depending on the region(s) affected. Here, we quantified the expression of markers of glutamate and GABA neurotransmission selectively in layer 3 of four cortical regions in the vsWM network from 20 matched pairs of schizophrenia and unaffected comparison subjects. In comparison subjects, levels of glutamate transcripts tended to increase, whereas GABA transcript levels tended to decrease, from caudal to rostral, across cortical regions of the vsWM network. Composite measures across all transcripts revealed a significant effect of region, with the glutamate measure lowest in the primary visual cortex and highest in the dorsolateral prefrontal cortex, whereas the GABA measure showed the opposite pattern. In schizophrenia subjects, the expression levels of many of these transcripts were altered. However, this disease effect differed across regions, such that the caudal-to-rostral increase in the glutamate measure was blunted and the caudal-to-rostral decline in the GABA measure was enhanced in the illness. Differential alterations in layer 3 glutamate and GABA neurotransmission across cortical regions may contribute to vsWM deficits in schizophrenia. Copyright © 2017 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

  3. Accumulation of pyrethroid compounds in primary cultures of rat cortical neurons

    Science.gov (United States)

    Recent studies have demonstrated that lipophilic compounds (e.g. methylmercury, polychlorinated biphenyls (PCBs) and polybrominated diphenylethers (PBDEs)) rapidly accumulate in cells in culture to concentrations much higher than in the surrounding media. Primary cultures of neur...

  4. Maintenance of cultural diversity: social roles, social networks, and cognitive networks.

    Science.gov (United States)

    Abrams, Marshall

    2014-06-01

    Smaldino suggests that patterns that give rise to group-level cultural traits can also increase individual-level cultural diversity. I distinguish social roles and related social network structures and discuss ways in which each might maintain diversity. I suggest that cognitive analogs of "cohesion," a property of networks that helps maintenance of diversity, might mediate the effects of social roles on diversity.

  5. Dopamine elevates intracellular zinc concentration in cultured rat embryonic cortical neurons through the cAMP-nitric oxide signaling cascade.

    Science.gov (United States)

    Hung, Hui-Hsing; Kao, Lung-Sen; Liu, Pei-Shan; Huang, Chien-Chang; Yang, De-Ming; Pan, Chien-Yuan

    2017-07-01

    Zinc ion (Zn 2+ ), the second most abundant transition metal after iron in the body, is essential for neuronal activity and also induces toxicity if the concentration is abnormally high. Our previous results show that exposure of cultured cortical neurons to dopamine elevates intracellular Zn 2+ concentrations ([Zn 2+ ] i ) and induces autophagosome formation but the mechanism is not clear. In this study, we characterized the signaling pathway responsible for the dopamine-induced elevation of [Zn 2+ ] i and the effect of [Zn 2+ ] i in modulating the autophagy in cultured rat embryonic cortical neurons. N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN), a membrane-permeable Zn 2+ chelator, could rescue the cell death and suppress the autophagosome puncta number induced by dopamine. Dopamine treatment increased the lipidation level of the endogenous microtubule-associated protein 1A/1B-light chain 3 (LC3 II), an autophagosome marker. TPEN added 1h before, but not after, dopamine treatment suppressed the dopamine-induced elevation of LC3 II level. Inhibitors of the dopamine D1-like receptor, protein kinase A (PKA), and NOS suppressed the dopamine-induced elevation of [Zn 2+ ] i . PKA activators and NO generators directly increased [Zn 2+ ] i in cultured neurons. Through cell fractionation, proteins with m.w. values between 5 and 10kD were found to release Zn 2+ following NO stimulation. In addition, TPEN pretreatment and an inhibitor against PKA could suppress the LC3 II level increased by NO and dopamine, respectively. Therefore, our results demonstrate that dopamine-induced elevation of [Zn 2+ ] i is mediated by the D1-like receptor-PKA-NO pathway and is important in modulating the cell death and autophagy. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Fetal brain extracellular matrix boosts neuronal network formation in 3D bioengineered model of cortical brain tissue.

    Science.gov (United States)

    Sood, Disha; Chwalek, Karolina; Stuntz, Emily; Pouli, Dimitra; Du, Chuang; Tang-Schomer, Min; Georgakoudi, Irene; Black, Lauren D; Kaplan, David L

    2016-01-01

    The extracellular matrix (ECM) constituting up to 20% of the organ volume is a significant component of the brain due to its instructive role in the compartmentalization of functional microdomains in every brain structure. The composition, quantity and structure of ECM changes dramatically during the development of an organism greatly contributing to the remarkably sophisticated architecture and function of the brain. Since fetal brain is highly plastic, we hypothesize that the fetal brain ECM may contain cues promoting neural growth and differentiation, highly desired in regenerative medicine. Thus, we studied the effect of brain-derived fetal and adult ECM complemented with matricellular proteins on cortical neurons using in vitro 3D bioengineered model of cortical brain tissue. The tested parameters included neuronal network density, cell viability, calcium signaling and electrophysiology. Both, adult and fetal brain ECM as well as matricellular proteins significantly improved neural network formation as compared to single component, collagen I matrix. Additionally, the brain ECM improved cell viability and lowered glutamate release. The fetal brain ECM induced superior neural network formation, calcium signaling and spontaneous spiking activity over adult brain ECM. This study highlights the difference in the neuroinductive properties of fetal and adult brain ECM and suggests that delineating the basis for this divergence may have implications for regenerative medicine.

  7. Community-centred Networks and Networking among Companies, Educational and Cultural Institutions and Research

    DEFF Research Database (Denmark)

    Konnerup, Ulla; Dirckinck-Holmfeld, Lone

    2010-01-01

    This article presents visions for community-centred networks and networking among companies, educational and cultural institutions and research based on blended on- and off-line collaboration and communication. Our point of departure is the general vision of networking between government, industry...... and research as formulated in the Triple Helix Model (Etzkowitz 2008). The article draws on a case study of NoEL, a network on e-learning among business, educational and cultural institutions and research, all in all 21 partners from all around Denmark. Focus is how networks and networking change character......’ in Networked Learning, Wenger et al. 2009; The analysis concerns the participation structure and how the network activities connect local work practices and research, and how technology and online communication contribute to a change from participation in offline and physical network activities into online...

  8. Thalamo–cortical network underlying deep brain stimulation of centromedian thalamic nuclei in intractable epilepsy: a multimodal imaging analysis

    Directory of Open Access Journals (Sweden)

    Kim SH

    2017-10-01

    Full Text Available Seong Hoon Kim,1 Sung Chul Lim,1 Dong Won Yang,1 Jeong Hee Cho,1 Byung-Chul Son,2 Jiyeon Kim,3 Seung Bong Hong,4 Young-Min Shon4 1Department of Neurology, 2Department of Neurosurgery, Catholic Neuroscience Institute, College of Medicine, The Catholic University of Korea, Seoul, 3Department of Neurology, Korea University Ansan Hospital, College of Medicine, Korea University, Ansan, 4Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea Objective: Deep brain stimulation (DBS of the centromedian thalamic nucleus (CM can be an alternative treatment option for intractable epilepsy patients. Since CM may be involved in widespread cortico-subcortical networks, identification of the cortical sub-networks specific to the target stimuli may provide further understanding on the underlying mechanisms of CM DBS. Several brain structures have distinguishing brain connections that may be related to the pivotal propagation and subsequent clinical effect of DBS.Methods: To explore core structures and their connections relevant to CM DBS, we applied electroencephalogram (EEG and diffusion tensor imaging (DTI to 10 medically intractable patients – three generalized epilepsy (GE and seven multifocal epilepsy (MFE patients unsuitable for resective surgery. Spatiotemporal activation pattern was mapped from scalp EEG by delivering low-frequency stimuli (5 Hz. Structural connections between the CM and the cortical activation spots were assessed using DTI.Results: We confirmed an average 72% seizure reduction after CM DBS and its clinical efficiency remained consistent during the observation period (mean 21 months. EEG data revealed sequential source propagation from the anterior cingulate, followed by the frontotemporal regions bilaterally. In addition, maximal activation was found in the left cingulate gyrus and the right medial frontal cortex during the right and left CM stimulation, respectively

  9. Exposure to high glutamate concentration activates aerobic glycolysis but inhibits ATP-linked respiration in cultured cortical astrocytes.

    Science.gov (United States)

    Shen, Yao; Tian, Yueyang; Shi, Xiaojie; Yang, Jianbo; Ouyang, Li; Gao, Jieqiong; Lu, Jianxin

    2014-08-01

    Astrocytes play a key role in removing the synaptically released glutamate from the extracellular space and maintaining the glutamate below neurotoxic level in the brain. However, high concentration of glutamate leads to toxicity in astrocytes, and the underlying mechanisms are unclear. The purpose of this study was to investigate whether energy metabolism disorder, especially impairment of mitochondrial respiration, is involved in the glutamate-induced gliotoxicity. Exposure to 10-mM glutamate for 48 h stimulated glycolysis and respiration in astrocytes. However, the increased oxygen consumption was used for proton leak and non-mitochondrial respiration, but not for oxidative phosphorylation and ATP generation. When the exposure time extended to 72 h, glycolysis was still activated for ATP generation, but the mitochondrial ATP-linked respiration of astrocytes was reduced. The glutamate-induced astrocyte damage can be mimicked by the non-metabolized substrate d-aspartate but reversed by the non-selective glutamate transporter inhibitor TBOA. In addition, the glutamate toxicity can be partially reversed by vitamin E. These findings demonstrate that changes of bioenergetic profile occur in cultured cortical astrocytes exposed to high concentration of glutamate and highlight the role of mitochondria respiration in glutamate-induced gliotoxicity in cortical astrocytes. Copyright © 2014 John Wiley & Sons, Ltd.

  10. Green Tea Polyphenols Attenuated Glutamate Excitotoxicity via Antioxidative and Antiapoptotic Pathway in the Primary Cultured Cortical Neurons

    Directory of Open Access Journals (Sweden)

    Lin Cong

    2016-01-01

    Full Text Available Green tea polyphenols are a natural product which has antioxidative and antiapoptotic effects. It has been shown that glutamate excitotoxicity induced oxidative stress is linked to neurodegenerative diseases such as Alzheimer’s disease and Parkinson’s disease. In this study we explored the neuroprotective effect of green teen polyphenols against glutamate excitotoxicity in the primary cultured cortical neurons. We found that green tea polyphenols protected against glutamate induced neurotoxicity in the cortical neurons as measured by MTT and TUNEL assays. Green tea polyphenols were then showed to inhibit the glutamate induced ROS release and SOD activity reduction in the neurons. Furthermore, our results demonstrated that green tea polyphenols restored the dysfunction of mitochondrial pro- or antiapoptotic proteins Bax, Bcl-2, and caspase-3 caused by glutamate. Interestingly, the neuroprotective effect of green tea polyphenols was abrogated when the neurons were incubated with siBcl-2. Taken together, these results demonstrated that green tea polyphenols protected against glutamate excitotoxicity through antioxidative and antiapoptotic pathways.

  11. Coevolutionary network approach to cultural dynamics controlled by intolerance

    Science.gov (United States)

    Gracia-Lázaro, Carlos; Quijandría, Fernando; Hernández, Laura; Floría, Luis Mario; Moreno, Yamir

    2011-12-01

    Starting from Axelrod's model of cultural dissemination, we introduce a rewiring probability, enabling agents to cut the links with their unfriendly neighbors if their cultural similarity is below a tolerance parameter. For low values of tolerance, rewiring promotes the convergence to a frozen monocultural state. However, intermediate tolerance values prevent rewiring once the network is fragmented, resulting in a multicultural society even for values of initial cultural diversity in which the original Axelrod model reaches globalization.

  12. NETWORK CULTURE - INTEGRAL PART OF NEW VALUES OF CIVIL SOCIETY

    OpenAIRE

    Vyacheslav Vladimirovich Sukhanov

    2014-01-01

    New technologies not only improve working conditions or communication, they are also bringing new values to  the society. This article discusses the concept of «network culture», which is now perceived by society as an integral part of values that can only exist in a civil society. We can research ( find)   this kind of society in modern time period in Russia. The article analyzes the meaning of communication, how to use it, development processes in network media.  Nowadays network culture an...

  13. Social networks and family violence in cross-cultural perspective.

    Science.gov (United States)

    Korbin, J E

    1995-01-01

    The purpose of this chapter was twofold. First, the chapter put forward a brief cross-cultural perspective indicating that multiple types of intrafamilial violence occur cross-culturally. Second, the chapter placed social networks at the core of a complex etiology of intrafamilial violence. The purpose of giving centrality to social networks is not to suggest that social networks are the sole or primary agent contributing to family violence but to broaden the context in which family violence is viewed beyond that of the perpetrator, the victim/survivor, or the violent dyad.

  14. Learning by Knowledge Networking across Cultures

    DEFF Research Database (Denmark)

    Wangel, Arne; Stærdahl, Jens; Bransholm Pedersen, Kirsten

    2005-01-01

    Engineers and planners working in trans-national production and aid project interventions in Third World countries must be able to 're-invent' technological systems across cultures and plan and build the capacities of their counterparts. A series of joint courses on cleaner production (CP......) and environmental impact assessment (EIA) in Malaysia 1998-2003 has sought to address these needs for new competences. Differences in educational background and the work culture of the participants have presented difficulties during these courses, in particular in terms of achieving a mixed team building to turn...... some of the obstacles into resources for knowledge sharing. However, students have stressed their positive experience of cross-cultural communication. While a joint course of three week duration by itself may involve only limited cross-cultural learning, serving primarily as an introduction to a long...

  15. Cultural competence and social relationships: a social network analysis.

    Science.gov (United States)

    Dauvrin, M; Lorant, V

    2017-06-01

    This study investigated the role of social relationships in the sharing of cultural competence by testing two hypotheses: cultural competence is a socially shared behaviour; and central healthcare professionals are more culturally competent than non-central healthcare professionals. Sustaining cultural competence in healthcare services relies on the assumption that being culturally competent is a socially shared behaviour among health professionals. This assumption has never been tested. Organizational aspects surrounding cultural competence are poorly considered. This therefore leads to a heterogeneous implementation of cultural competence - especially in continental Europe. We carried out a social network analysis in 24 Belgian inpatient and outpatient health services. All healthcare professionals (ego) were requested to fill in a questionnaire (Survey on social relationships of health care professionals) on their level of cultural competence and to identify their professional relationships (alter). We fitted regression models to assess whether (1) at the dyadic level, ego cultural competence was associated with alter cultural competence, and (2) health professionals of greater centrality had greater cultural competence. At the dyadic level, no significant associations were found between ego cultural competence and alter cultural competence, with the exception of subjective exposure to intercultural situations. No significant associations were found between centrality and cultural competence, except for subjective exposure to intercultural situations. Being culturally competent is not a shared behaviour among health professionals. The most central healthcare professionals are not more culturally competent than less central health professionals. Culturally competent health care is not yet a norm in health services. Health care and training authorities should either make cultural competent health care a licensing criteria or reward culturally competent health care

  16. Oscillatory neuronal activity reflects lexical-semantic feature integration within and across sensory modalities in distributed cortical networks.

    Science.gov (United States)

    van Ackeren, Markus J; Schneider, Till R; Müsch, Kathrin; Rueschemeyer, Shirley-Ann

    2014-10-22

    Research from the previous decade suggests that word meaning is partially stored in distributed modality-specific cortical networks. However, little is known about the mechanisms by which semantic content from multiple modalities is integrated into a coherent multisensory representation. Therefore we aimed to characterize differences between integration of lexical-semantic information from a single modality compared with two sensory modalities. We used magnetoencephalography in humans to investigate changes in oscillatory neuronal activity while participants verified two features for a given target word (e.g., "bus"). Feature pairs consisted of either two features from the same modality (visual: "red," "big") or different modalities (auditory and visual: "red," "loud"). The results suggest that integrating modality-specific features of the target word is associated with enhanced high-frequency power (80-120 Hz), while integrating features from different modalities is associated with a sustained increase in low-frequency power (2-8 Hz). Source reconstruction revealed a peak in the anterior temporal lobe for low-frequency and high-frequency effects. These results suggest that integrating lexical-semantic knowledge at different cortical scales is reflected in frequency-specific oscillatory neuronal activity in unisensory and multisensory association networks. Copyright © 2014 the authors 0270-6474/14/3314318-06$15.00/0.

  17. Pyrethroid insecticide accumulation in primary cultures of cortical neurons in vitro

    Science.gov (United States)

    Primary cultures of neurons have been widely utilized to study the actions of pyrethroids and other neurotoxicants, with the presumption that the media concentration accurately reflects the dose received by the cells. However, recent studies have demonstrated that lipophilic comp...

  18. Evidence for a cerebral cortical thickness network anti-correlated with amygdalar volume in healthy youths: implications for the neural substrates of emotion regulation.

    Science.gov (United States)

    Albaugh, Matthew D; Ducharme, Simon; Collins, D Louis; Botteron, Kelly N; Althoff, Robert R; Evans, Alan C; Karama, Sherif; Hudziak, James J

    2013-05-01

    Recent functional connectivity studies have demonstrated that, in resting humans, activity in a dorsally-situated neocortical network is inversely associated with activity in the amygdalae. Similarly, in human neuroimaging studies, aspects of emotion regulation have been associated with increased activity in dorsolateral, dorsomedial, orbital and ventromedial prefrontal regions, as well as concomitant decreases in amygdalar activity. These findings indicate the presence of two countervailing systems in the human brain that are reciprocally related: a dorsally-situated cognitive control network, and a ventrally-situated limbic network. We investigated the extent to which this functional reciprocity between limbic and dorsal neocortical regions is recapitulated from a purely structural standpoint. Specifically, we hypothesized that amygdalar volume would be related to cerebral cortical thickness in cortical regions implicated in aspects of emotion regulation. In 297 typically developing youths (162 females, 135 males; 572 MRIs), the relationship between cortical thickness and amygdalar volume was characterized. Amygdalar volume was found to be inversely associated with thickness in bilateral dorsolateral and dorsomedial prefrontal, inferior parietal, as well as bilateral orbital and ventromedial prefrontal cortices. Our findings are in line with previous work demonstrating that a predominantly dorsally-centered neocortical network is reciprocally related to core limbic structures such as the amygdalae. Future research may benefit from investigating the extent to which such cortical-limbic morphometric relations are qualified by the presence of mood and anxiety psychopathology. Copyright © 2012 Elsevier Inc. All rights reserved.

  19. Switching auditory attention using spatial and non-spatial features recruits different cortical networks.

    Science.gov (United States)

    Larson, Eric; Lee, Adrian K C

    2014-01-01

    Switching attention between different stimuli of interest based on particular task demands is important in many everyday settings. In audition in particular, switching attention between different speakers of interest that are talking concurrently is often necessary for effective communication. Recently, it has been shown by multiple studies that auditory selective attention suppresses the representation of unwanted streams in auditory cortical areas in favor of the target stream of interest. However, the neural processing that guides this selective attention process is not well understood. Here we investigated the cortical mechanisms involved in switching attention based on two different types of auditory features. By combining magneto- and electro-encephalography (M-EEG) with an anatomical MRI constraint, we examined the cortical dynamics involved in switching auditory attention based on either spatial or pitch features. We designed a paradigm where listeners were cued in the beginning of each trial to switch or maintain attention halfway through the presentation of concurrent target and masker streams. By allowing listeners time to switch during a gap in the continuous target and masker stimuli, we were able to isolate the mechanisms involved in endogenous, top-down attention switching. Our results show a double dissociation between the involvement of right temporoparietal junction (RTPJ) and the left inferior parietal supramarginal part (LIPSP) in tasks requiring listeners to switch attention based on space and pitch features, respectively, suggesting that switching attention based on these features involves at least partially separate processes or behavioral strategies. © 2013 Elsevier Inc. All rights reserved.

  20. Vision first? The development of primary visual cortical networks is more rapid than the development of primary motor networks in humans.

    Directory of Open Access Journals (Sweden)

    Patricia Gervan

    Full Text Available The development of cortical functions and the capacity of the mature brain to learn are largely determined by the establishment and maintenance of neocortical networks. Here we address the human development of long-range connectivity in primary visual and motor cortices, using well-established behavioral measures--a Contour Integration test and a Finger-tapping task--that have been shown to be related to these specific primary areas, and the long-range neural connectivity within those. Possible confounding factors, such as different task requirements (complexity, cognitive load are eliminated by using these tasks in a learning paradigm. We find that there is a temporal lag between the developmental timing of primary sensory vs. motor areas with an advantage of visual development; we also confirm that human development is very slow in both cases, and that there is a retained capacity for practice induced plastic changes in adults. This pattern of results seems to point to human-specific development of the "canonical circuits" of primary sensory and motor cortices, probably reflecting the ecological requirements of human life.

  1. Effects of continuous hypoxia on energy metabolism in cultured cerebro-cortical neurons.

    Science.gov (United States)

    Malthankar-Phatak, Gauri H; Patel, Anant B; Xia, Ying; Hong, Soonsun; Chowdhury, Golam M I; Behar, Kevin L; Orina, Isaac A; Lai, James C K

    2008-09-10

    Mechanisms underlying hypoxia-induced neuronal adaptation have not been fully elucidated. In the present study we investigated glucose metabolism and the activities of glycolytic and TCA cycle enzymes in cerebro-cortical neurons exposed to hypoxia (3 days in 1% of O2) or normoxia (room air). Hypoxia led to increased activities of LDH (194%), PK (90%), and HK (24%) and decreased activities of CS (15%) and GDH (34%). Neurons were incubated with [1-(13)C]glucose for 45 and 120 min under normoxic or hypoxic (120 min only) conditions and 13C enrichment determined in the medium and cell extract using 1H-{13C}-NMR. In hypoxia-treated neurons [3-(13)C]lactate release into the medium was 428% greater than in normoxia-treated controls (45-min normoxic incubation) and total flux through lactate was increased by 425%. In contrast glucose oxidation was reduced significantly in hypoxia-treated neurons, even when expressed relative to total cellular protein, which correlated with the reduced activities of the measured mitochondrial enzymes. The results suggest that surviving neurons adapt to prolonged hypoxia by up-regulation of glycolysis and down-regulation of oxidative energy metabolism, similar to certain other cell types. The factors leading to adaptation and survival for some neurons but not others remain to be determined.

  2. Networking - concepts and dimensions of the cross-cultural comparative study

    DEFF Research Database (Denmark)

    Rasmussen, Lauge Baungaard

    2000-01-01

    The litarature about networking is weak regarding precise definitions of networking and methodologies to analyse how networking is carried out in practice. Besides, the croos cultural dimension is often underestimated.......The litarature about networking is weak regarding precise definitions of networking and methodologies to analyse how networking is carried out in practice. Besides, the croos cultural dimension is often underestimated....

  3. Hidden neuronal correlations in cultured networks

    International Nuclear Information System (INIS)

    Segev, Ronen; Baruchi, Itay; Hulata, Eyal; Ben-Jacob, Eshel

    2004-01-01

    Utilization of a clustering algorithm on neuronal spatiotemporal correlation matrices recorded during a spontaneous activity of in vitro networks revealed the existence of hidden correlations: the sequence of synchronized bursting events (SBEs) is composed of statistically distinguishable subgroups each with its own distinct pattern of interneuron spatiotemporal correlations. These findings hint that each of the SBE subgroups can serve as a template for coding, storage, and retrieval of a specific information

  4. Decomposing neural synchrony: toward an explanation for near-zero phase-lag in cortical oscillatory networks.

    Directory of Open Access Journals (Sweden)

    Rajasimhan Rajagovindan

    Full Text Available BACKGROUND: Synchronized oscillation in cortical networks has been suggested as a mechanism for diverse functions ranging from perceptual binding to memory formation to sensorimotor integration. Concomitant with synchronization is the occurrence of near-zero phase-lag often observed between network components. Recent theories have considered the importance of this phenomenon in establishing an effective communication framework among neuronal ensembles. METHODOLOGY/PRINCIPAL FINDINGS: Two factors, among possibly others, can be hypothesized to contribute to the near-zero phase-lag relationship: (1 positively correlated common input with no significant relative time delay and (2 bidirectional interaction. Thus far, no empirical test of these hypotheses has been possible for lack of means to tease apart the specific causes underlying the observed synchrony. In this work simulation examples were first used to illustrate the ideas. A quantitative method that decomposes the statistical interdependence between two cortical areas into a feed-forward, a feed-back and a common-input component was then introduced and applied to test the hypotheses on multichannel local field potential recordings from two behaving monkeys. CONCLUSION/SIGNIFICANCE: The near-zero phase-lag phenomenon is important in the study of large-scale oscillatory networks. A rigorous mathematical theorem is used for the first time to empirically examine the factors that contribute to this phenomenon. Given the critical role that oscillatory activity is likely to play in the regulation of biological processes at all levels, the significance of the proposed method may extend beyond systems neuroscience, the level at which the present analysis is conceived and performed.

  5. Networked Cultures in the Collaborative Economy

    DEFF Research Database (Denmark)

    Gyimóthy, Szilvia

    2017-01-01

    , and together open up for multidimensional interpretations of social exchange in the collaborative economy. The chapter concludes with a critical reflection on the challenges of understanding the collaborative economy in tourism, particularly when discourses are dominated by a communitarian logic......This chapter charts diverse approaches to conceptualizing the cultures of connection characterizing the collaborative economy. To decode the “we-conomy”, we revisit classic notions of coexistence, collaboration and bonding in communities. Informed by a multidisciplinary review (touching upon human...... ecology, sociology, anthropology and cultural theory), the chapter identifies distinct theoretical frameworks to describe the constitution of communities and discusses their relevance to the collaborative economy. These frameworks explain the drivers of communitarian behavior and resource circulation...

  6. Recapitulating cortical development with organoid culture in vitro and modeling abnormal spindle-like (ASPM related primary) microcephaly disease

    Institute of Scientific and Technical Information of China (English)

    Rui Li; Le Sun; Ai Fang; Peng Li; Qian Wu; Xiaoqun Wang

    2017-01-01

    The development of a cerebral organoid culture in vitro offers an opportunity to generate human brain-like organs to investigate mechanisms of human disease that are specific to the neurogenesis of radial glial (RG) and outer radial glial (oRG) cells in the ventricular zone (VZ) and subventricular zone (SVZ) of the developing neocortex.Modeling neuronal progenitors and the organization that produces mature subcortical neuron subtypes during early stages of development is essential for studying human brain developmental diseases.Several previous efforts have shown to grow neural organoid in culture dishes successfully,however we demonstrate a new paradigm that recapitulates neocortical development process with VZ,OSVZ formation and the lamination organization of cortical layer structure.In addition,using patient-specific induced pluripotent stem cells (iPSCs) with dysfunction of the Aspm gene from a primary microcephaly patient,we demonstrate neurogenesis defects result in defective neuronal activity in patient organoids,suggesting a new strategy to study human developmental diseases in central nerve system.

  7. Temporal Genetic Modifications after Controlled Cortical Impact—Understanding Traumatic Brain Injury through a Systematic Network Approach

    Directory of Open Access Journals (Sweden)

    Yung-Hao Wong

    2016-02-01

    Full Text Available Traumatic brain injury (TBI is a primary injury caused by external physical force and also a secondary injury caused by biological processes such as metabolic, cellular, and other molecular events that eventually lead to brain cell death, tissue and nerve damage, and atrophy. It is a common disease process (as opposed to an event that causes disabilities and high death rates. In order to treat all the repercussions of this injury, treatment becomes increasingly complex and difficult throughout the evolution of a TBI. Using high-throughput microarray data, we developed a systems biology approach to explore potential molecular mechanisms at four time points post-TBI (4, 8, 24, and 72 h, using a controlled cortical impact (CCI model. We identified 27, 50, 48, and 59 significant proteins as network biomarkers at these four time points, respectively. We present their network structures to illustrate the protein–protein interactions (PPIs. We also identified UBC (Ubiquitin C, SUMO1, CDKN1A (cyclindependent kinase inhibitor 1A, and MYC as the core network biomarkers at the four time points, respectively. Using the functional analytical tool MetaCore™, we explored regulatory mechanisms and biological processes and conducted a statistical analysis of the four networks. The analytical results support some recent findings regarding TBI and provide additional guidance and directions for future research.

  8. Multiscale approach including microfibril scale to assess elastic constants of cortical bone based on neural network computation and homogenization method.

    Science.gov (United States)

    Barkaoui, Abdelwahed; Chamekh, Abdessalem; Merzouki, Tarek; Hambli, Ridha; Mkaddem, Ali

    2014-03-01

    The complexity and heterogeneity of bone tissue require a multiscale modeling to understand its mechanical behavior and its remodeling mechanisms. In this paper, a novel multiscale hierarchical approach including microfibril scale based on hybrid neural network (NN) computation and homogenization equations was developed to link nanoscopic and macroscopic scales to estimate the elastic properties of human cortical bone. The multiscale model is divided into three main phases: (i) in step 0, the elastic constants of collagen-water and mineral-water composites are calculated by averaging the upper and lower Hill bounds; (ii) in step 1, the elastic properties of the collagen microfibril are computed using a trained NN simulation. Finite element calculation is performed at nanoscopic levels to provide a database to train an in-house NN program; and (iii) in steps 2-10 from fibril to continuum cortical bone tissue, homogenization equations are used to perform the computation at the higher scales. The NN outputs (elastic properties of the microfibril) are used as inputs for the homogenization computation to determine the properties of mineralized collagen fibril. The mechanical and geometrical properties of bone constituents (mineral, collagen, and cross-links) as well as the porosity were taken in consideration. This paper aims to predict analytically the effective elastic constants of cortical bone by modeling its elastic response at these different scales, ranging from the nanostructural to mesostructural levels. Our findings of the lowest scale's output were well integrated with the other higher levels and serve as inputs for the next higher scale modeling. Good agreement was obtained between our predicted results and literature data. Copyright © 2013 John Wiley & Sons, Ltd.

  9. Analysis of Amygdalar-Cortical Network Covariance During Pre- versus Post-menopausal Estrogen Levels: Potential Relevance to Resting State Networks, Mood, and Cognition

    Science.gov (United States)

    Ottowitz, William E.; Derro, David; Dougherty, Darin D.; Lindquist, Martin A.; Fischman, Alan J.; Hall, Janet E.

    2014-01-01

    Objectives 1.) Expand the scope of neuroendocrine applications of functional neuroimaging techniques. 2.) Compare the covariance of amygdalar activity with that of the rest of the brain during pre- and post-menopausal levels of estrogen (E2). Based on the distribution of cortical E2 receptors and the neocortical regions where E2 has been shown to preferentially accumulate, we predict that E2 infusion will increase covariance of amygdalar activity with that of the temporal and frontal cortices. Design This basic physiology study employed a within-subject design. All participants were post-menopausal women (n =7). Analysis of covariance between whole brain and amygdalar regional cerebral glucose consumption (CMRglc) was conducted in a voxel-wise manner by means of the basic regression option in SPM2 and was applied to FDG-PET scans acquired at baseline and after a 24 hour graded E2 infusion. Setting an academic medical center; Massachusetts General Hospital, Boston, Massachusetts. Results E2 levels (mean ± sem) were significantly greater at 24 hours (257.9 pg/mL ± 29.7) than at 0 hours (28.1 pg/mL ± 3.4). Right amygdalar CMRglc showed a significant covariance with activity of three different regions of the temporal cortex during E2 infusion, but none at baseline. In addition, right amygdalar CMRglc covaried with that of the right medial and superior frontal gyri only during E2 infusion. Conclusions In addition to suggesting changes in amygdalar-cortical network connectivity as a result of short-term E2 exposure, these analyses provide evidence that basic neuroendocrine research may benefit from further use of FDG-PET and other functional neuroimaging modalities for network level analyses. PMID:18766152

  10. Differential effects of ciguatoxin and maitotoxin in primary cultures of cortical neurons.

    Science.gov (United States)

    Martin, Victor; Vale, Carmen; Antelo, Alvaro; Hirama, Masahiro; Yamashita, Shuji; Vieytes, Mercedes R; Botana, Luis M

    2014-08-18

    Ciguatoxins (CTXs) and maitotoxins (MTXs) are polyether ladder shaped toxins derived from the dinoflagellate Gambierdiscus toxicus. Despite the fact that MTXs are 3 times larger than CTXs, part of the structure of MTXs resembles that of CTXs. To date, the synthetic ciguatoxin, CTX 3C has been reported to activate voltage-gated sodium channels, whereas the main effect of MTX is inducing calcium influx into the cell leading to cell death. However, there is a lack of information regarding the effects of these toxins in a common cellular model. Here, in order to have an overview of the main effects of these toxins in mice cortical neurons, we examined the effects of MTX and the synthetic ciguatoxin CTX 3C on the main voltage dependent ion channels in neurons, sodium, potassium, and calcium channels as well as on membrane potential, cytosolic calcium concentration ([Ca(2+)]c), intracellular pH (pHi), and neuronal viability. Regarding voltage-gated ion channels, neither CTX 3C nor MTX affected voltage-gated calcium or potassium channels, but while CTX 3C had a large effect on voltage-gated sodium channels (VGSC) by shifting the activation and inactivation curves to more hyperpolarized potentials and decreasing peak sodium channel amplitude, MTX, at 5 nM, had no effect on VGSC activation and inactivation but decreased peak sodium current amplitude. Other major differences between both toxins were the massive calcium influx and intracellular acidification produced by MTX but not by CTX 3C. Indeed, the novel finding that MTX produces acidosis supports a pathway recently described in which MTX produces calcium influx via the sodium-hydrogen exchanger (NHX). For the first time, we found that VGSC blockers partially blocked the MTX-induced calcium influx, intracellular acidification, and protected against the short-term MTX-induced cytotoxicity. The results presented here provide the first report that shows the comparative effects of two prototypical ciguatera toxins, CTX 3C

  11. Enriched encoding: reward motivation organizes cortical networks for hippocampal detection of unexpected events.

    Science.gov (United States)

    Murty, Vishnu P; Adcock, R Alison

    2014-08-01

    Learning how to obtain rewards requires learning about their contexts and likely causes. How do long-term memory mechanisms balance the need to represent potential determinants of reward outcomes with the computational burden of an over-inclusive memory? One solution would be to enhance memory for salient events that occur during reward anticipation, because all such events are potential determinants of reward. We tested whether reward motivation enhances encoding of salient events like expectancy violations. During functional magnetic resonance imaging, participants performed a reaction-time task in which goal-irrelevant expectancy violations were encountered during states of high- or low-reward motivation. Motivation amplified hippocampal activation to and declarative memory for expectancy violations. Connectivity of the ventral tegmental area (VTA) with medial prefrontal, ventrolateral prefrontal, and visual cortices preceded and predicted this increase in hippocampal sensitivity. These findings elucidate a novel mechanism whereby reward motivation can enhance hippocampus-dependent memory: anticipatory VTA-cortical-hippocampal interactions. Further, the findings integrate literatures on dopaminergic neuromodulation of prefrontal function and hippocampus-dependent memory. We conclude that during reward motivation, VTA modulation induces distributed neural changes that amplify hippocampal signals and records of expectancy violations to improve predictions-a potentially unique contribution of the hippocampus to reward learning. © The Author 2013. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  12. Biophysical network modeling of the dLGN circuit: Effects of cortical feedback on spatial response properties of relay cells.

    Directory of Open Access Journals (Sweden)

    Pablo Martínez-Cañada

    2018-01-01

    Full Text Available Despite half-a-century of research since the seminal work of Hubel and Wiesel, the role of the dorsal lateral geniculate nucleus (dLGN in shaping the visual signals is not properly understood. Placed on route from retina to primary visual cortex in the early visual pathway, a striking feature of the dLGN circuit is that both the relay cells (RCs and interneurons (INs not only receive feedforward input from retinal ganglion cells, but also a prominent feedback from cells in layer 6 of visual cortex. This feedback has been proposed to affect synchronicity and other temporal properties of the RC firing. It has also been seen to affect spatial properties such as the center-surround antagonism of thalamic receptive fields, i.e., the suppression of the response to very large stimuli compared to smaller, more optimal stimuli. Here we explore the spatial effects of cortical feedback on the RC response by means of a a comprehensive network model with biophysically detailed, single-compartment and multicompartment neuron models of RCs, INs and a population of orientation-selective layer 6 simple cells, consisting of pyramidal cells (PY. We have considered two different arrangements of synaptic feedback from the ON and OFF zones in the visual cortex to the dLGN: phase-reversed ('push-pull' and phase-matched ('push-push', as well as different spatial extents of the corticothalamic projection pattern. Our simulation results support that a phase-reversed arrangement provides a more effective way for cortical feedback to provide the increased center-surround antagonism seen in experiments both for flashing spots and, even more prominently, for patch gratings. This implies that ON-center RCs receive direct excitation from OFF-dominated cortical cells and indirect inhibitory feedback from ON-dominated cortical cells. The increased center-surround antagonism in the model is accompanied by spatial focusing, i.e., the maximum RC response occurs for smaller stimuli

  13. Biophysical network modeling of the dLGN circuit: Effects of cortical feedback on spatial response properties of relay cells

    Science.gov (United States)

    Martínez-Cañada, Pablo; Halnes, Geir; Fyhn, Marianne

    2018-01-01

    Despite half-a-century of research since the seminal work of Hubel and Wiesel, the role of the dorsal lateral geniculate nucleus (dLGN) in shaping the visual signals is not properly understood. Placed on route from retina to primary visual cortex in the early visual pathway, a striking feature of the dLGN circuit is that both the relay cells (RCs) and interneurons (INs) not only receive feedforward input from retinal ganglion cells, but also a prominent feedback from cells in layer 6 of visual cortex. This feedback has been proposed to affect synchronicity and other temporal properties of the RC firing. It has also been seen to affect spatial properties such as the center-surround antagonism of thalamic receptive fields, i.e., the suppression of the response to very large stimuli compared to smaller, more optimal stimuli. Here we explore the spatial effects of cortical feedback on the RC response by means of a a comprehensive network model with biophysically detailed, single-compartment and multicompartment neuron models of RCs, INs and a population of orientation-selective layer 6 simple cells, consisting of pyramidal cells (PY). We have considered two different arrangements of synaptic feedback from the ON and OFF zones in the visual cortex to the dLGN: phase-reversed (‘push-pull’) and phase-matched (‘push-push’), as well as different spatial extents of the corticothalamic projection pattern. Our simulation results support that a phase-reversed arrangement provides a more effective way for cortical feedback to provide the increased center-surround antagonism seen in experiments both for flashing spots and, even more prominently, for patch gratings. This implies that ON-center RCs receive direct excitation from OFF-dominated cortical cells and indirect inhibitory feedback from ON-dominated cortical cells. The increased center-surround antagonism in the model is accompanied by spatial focusing, i.e., the maximum RC response occurs for smaller stimuli when

  14. The United States Culture Collection Network (USCCN): Enhancing Microbial Genomics Research through Living Microbe Culture Collections

    Science.gov (United States)

    Boundy-Mills, Kyria; Hess, Matthias; Bennett, A. Rick; Ryan, Matthew; Kang, Seogchan; Nobles, David; Eisen, Jonathan A.; Inderbitzin, Patrik; Sitepu, Irnayuli R.; Torok, Tamas; Brown, Daniel R.; Cho, Juliana; Wertz, John E.; Mukherjee, Supratim; Cady, Sherry L.

    2015-01-01

    The mission of the United States Culture Collection Network (USCCN; http://usccn.org) is “to facilitate the safe and responsible utilization of microbial resources for research, education, industry, medicine, and agriculture for the betterment of human kind.” Microbial culture collections are a key component of life science research, biotechnology, and emerging global biobased economies. Representatives and users of several microbial culture collections from the United States and Europe gathered at the University of California, Davis, to discuss how collections of microorganisms can better serve users and stakeholders and to showcase existing resources available in public culture collections. PMID:26092453

  15. Inter-individual variability in cortical excitability and motor network connectivity following multiple blocks of rTMS.

    Science.gov (United States)

    Nettekoven, Charlotte; Volz, Lukas J; Leimbach, Martha; Pool, Eva-Maria; Rehme, Anne K; Eickhoff, Simon B; Fink, Gereon R; Grefkes, Christian

    2015-09-01

    The responsiveness to non-invasive neuromodulation protocols shows high inter-individual variability, the reasons of which remain poorly understood. We here tested whether the response to intermittent theta-burst stimulation (iTBS) - an effective repetitive transcranial magnetic stimulation (rTMS) protocol for increasing cortical excitability - depends on network properties of the cortical motor system. We furthermore investigated whether the responsiveness to iTBS is dose-dependent. To this end, we used a sham-stimulation controlled, single-blinded within-subject design testing for the relationship between iTBS aftereffects and (i) motor-evoked potentials (MEPs) as well as (ii) resting-state functional connectivity (rsFC) in 16 healthy subjects. In each session, three blocks of iTBS were applied, separated by 15min. We found that non-responders (subjects not showing an MEP increase of ≥10% after one iTBS block) featured stronger rsFC between the stimulated primary motor cortex (M1) and premotor areas before stimulation compared to responders. However, only the group of responders showed increases in rsFC and MEPs, while most non-responders remained close to baseline levels after all three blocks of iTBS. Importantly, there was still a large amount of variability in both groups. Our data suggest that responsiveness to iTBS at the local level (i.e., M1 excitability) depends upon the pre-interventional network connectivity of the stimulated region. Of note, increasing iTBS dose did not turn non-responders into responders. The finding that higher levels of pre-interventional connectivity precluded a response to iTBS could reflect a ceiling effect underlying non-responsiveness to iTBS at the systems level. Copyright © 2015 Elsevier Inc. All rights reserved.

  16. Quality of Service in Networks Supporting Cultural Multimedia Applications

    Science.gov (United States)

    Kanellopoulos, Dimitris N.

    2011-01-01

    Purpose: This paper aims to provide an overview of representative multimedia applications in the cultural heritage sector, as well as research results on quality of service (QoS) mechanisms in internet protocol (IP) networks that support such applications. Design/methodology/approach: The paper's approach is a literature review. Findings: Cultural…

  17. Consumer culture theory (re)visits actor-network theory

    DEFF Research Database (Denmark)

    Bajde, Domen

    2013-01-01

    The vocabulary and tactics developed by actor-network theory (ANT) can shed light on several ontological and epistemological challenges faced by consumer culture theory. Rather than providing ready-made theories or methods, our translation of ANT puts forward a series of questions and propositions...

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

    Science.gov (United States)

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

    2016-09-01

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

  19. Displacement of the mitotic apparatuses by centrifugation reveals cortical actin organization during cytokinesis in cultured tobacco BY-2 cells.

    Science.gov (United States)

    Arima, Kengo; Tamaoki, Daisuke; Mineyuki, Yoshinobu; Yasuhara, Hiroki; Nakai, Tomonori; Shimmen, Teruo; Yoshihisa, Tohru; Sonobe, Seiji

    2018-06-19

    In plant cytokinesis, actin is thought to be crucial in cell plate guidance to the cortical division zone (CDZ), but its organization and function are not fully understood. To elucidate actin organization during cytokinesis, we employed an experimental system, in which the mitotic apparatus is displaced and separated from the CDZ by centrifugation and observed using a global-local live imaging microscope that enabled us to record behavior of actin filaments in the CDZ and the whole cell division process in parallel. In this system, returning movement of the cytokinetic apparatus in cultured-tobacco BY-2 cells occurs, and there is an advantage to observe actin organization clearly during the cytokinetic phase because more space was available between the CDZ and the distantly formed phragmoplast. Actin cables were clearly observed between the CDZ and the phragmoplast in BY-2 cells expressing GFP-fimbrin after centrifugation. Both the CDZ and the edge of the expanding phragmoplast had actin bulges. Using live-cell imaging including the global-local live imaging microscopy, we found actin filaments started to accumulate at the actin-depleted zone when cell plate expansion started even in the cell whose cell plate failed to reach the CDZ. These results suggest that specific accumulation of actin filaments at the CDZ and the appearance of actin cables between the CDZ and the phragmoplast during cell plate formation play important roles in the guidance of cell plate edges to the CDZ.

  20. Low and High-Frequency Field Potentials of Cortical Networks Exhibit Distinct Responses to Chemicals

    Science.gov (United States)

    Neural networks grown on microelectrode arrays (MEAs) have become an important, high content in vitro assay for assessing neuronal function. MEA experiments typically examine high- frequency (HF) (>200 Hz) spikes, and bursts which can be used to discriminate between differ...

  1. Low Frequency Activity of Cortical Networks on Microelectrode Arrays is Differentially Altered by Bicuculline and Carbaryl

    Science.gov (United States)

    Thousands of chemicals need to be characterized for their neurotoxicity potential. Neurons grown on microelectrode arrays (MEAs) are an in vitro model used to screen chemicals for functional effects on neuronal networks. Typically, after removal of low frequency components, effec...

  2. Effect of acute stretch injury on action potential and network activity of rat neocortical neurons in culture.

    Science.gov (United States)

    Magou, George C; Pfister, Bryan J; Berlin, Joshua R

    2015-10-22

    The basis for acute seizures following traumatic brain injury (TBI) remains unclear. Animal models of TBI have revealed acute hyperexcitablility in cortical neurons that could underlie seizure activity, but studying initiating events causing hyperexcitability is difficult in these models. In vitro models of stretch injury with cultured cortical neurons, a surrogate for TBI, allow facile investigation of cellular changes after injury but they have only demonstrated post-injury hypoexcitability. The goal of this study was to determine if neuronal hyperexcitability could be triggered by in vitro stretch injury. Controlled uniaxial stretch injury was delivered to a spatially delimited region of a spontaneously active network of cultured rat cortical neurons, yielding a region of stretch-injured neurons and adjacent regions of non-stretched neurons that did not directly experience stretch injury. Spontaneous electrical activity was measured in non-stretched and stretch-injured neurons, and in control neuronal networks not subjected to stretch injury. Non-stretched neurons in stretch-injured cultures displayed a three-fold increase in action potential firing rate and bursting activity 30-60 min post-injury. Stretch-injured neurons, however, displayed dramatically lower rates of action potential firing and bursting. These results demonstrate that acute hyperexcitability can be observed in non-stretched neurons located in regions adjacent to the site of stretch injury, consistent with reports that seizure activity can arise from regions surrounding the site of localized brain injury. Thus, this in vitro procedure for localized neuronal stretch injury may provide a model to study the earliest cellular changes in neuronal function associated with acute post-traumatic seizures. Copyright © 2015. Published by Elsevier B.V.

  3. Enhancement of cortical network activity in vitro and promotion of GABAergic neurogenesis by stimulation with an electromagnetic field with a 150 MHz carrier wave pulsed with an alternating 10 and 16 Hz modulation.

    Directory of Open Access Journals (Sweden)

    Alexandra eGramowski-Voss

    2015-07-01

    Full Text Available In recent years, various stimuli were identified capable of enhancing neurogenesis, a process which is dysfunctional in the senescent brain and in neurodegenerative and certain neuropsychiatric diseases. Applications of electromagnetic fields to brain tissue have been shown to affect cellular properties and their importance for therapies in medicine is recognized.In this study, differentiating murine cortical networks on multiwell microelectrode arrays were repeatedly exposed to an extremely low electromagnetic field (ELEMF with alternating 10 and 16 Hz frequencies piggy-backed onto a 150 MHz carrier frequency. The ELEMF exposure stimulated the electrical network activity and intensified the structure of bursts. Further, the exposure with an electromagnetic field within the first 28 days of the differentiation the network activity induced also reorganization within the burst structure. This effect was already most pronounced at 14 days in vitro after 10 days of exposure. Overall, the development of cortical activity under these conditions was accelerated. These functional electrophysiological changes were accompanied by morphological ones. The percentage of neurons in the neuron glia co-culture was increased without affecting the total number of cells, indicating an enhancement of neurogenesis. The ELEMF exposure selectively promoted the proliferation of a particular population of neurons, evidenced by the increased proportion of GABAergic neurons. The results support the initial hypothesis that this kind of ELEMF stimulation is a treatment option for specific indications with promising potential for CNS applications, especially for degenerative diseases such as Alzheimer’s disease and other dementias.

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

    Directory of Open Access Journals (Sweden)

    Jennifer C Whitman

    2013-03-01

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

  5. Exogenous α-synuclein hinders synaptic communication in cultured cortical primary rat neurons.

    Science.gov (United States)

    Hassink, G C; Raiss, C C; Segers-Nolten, I M J; van Wezel, R J A; Subramaniam, V; le Feber, J; Claessens, M M A E

    2018-01-01

    Amyloid aggregates of the protein α-synuclein (αS) called Lewy Bodies (LB) and Lewy Neurites (LN) are the pathological hallmark of Parkinson's disease (PD) and other synucleinopathies. We have previously shown that high extracellular αS concentrations can be toxic to cells and that neurons take up αS. Here we aimed to get more insight into the toxicity mechanism associated with high extracellular αS concentrations (50-100 μM). High extracellular αS concentrations resulted in a reduction of the firing rate of the neuronal network by disrupting synaptic transmission, while the neuronal ability to fire action potentials was still intact. Furthermore, many cells developed αS deposits larger than 500 nm within five days, but otherwise appeared healthy. Synaptic dysfunction clearly occurred before the establishment of large intracellular deposits and neuronal death, suggesting that an excessive extracellular αS concentration caused synaptic failure and which later possibly contributed to neuronal death.

  6. Humanin rescues cultured rat cortical neurons from NMDA-induced toxicity through the alleviation of mitochondrial dysfunction

    Directory of Open Access Journals (Sweden)

    Cui A

    2017-04-01

    Full Text Available Ai-Ling Cui,1 Ying-Hua Zhang,2 Jian-Zhong Li,3 Tianbin Song,4 Xue-Min Liu,1 Hui Wang,2 Ce Zhang,5 Guo-Lin Ma,6 Hui Zhang,7 Kefeng Li8 1Anatomy Department, Changzhi Medical College, Changzhi, Shanxi, 2Key Laboratory of Tissue Regeneration of Henan Province, Xinxiang Medical University, Xinxiang, Henan, 3Clinical Laboratory of Heji Hospital Affiliated to Changzhi Medical College, Changzhi, Shanxi, 4Department of Nuclear Medicine, Xuanwu Hospital, Capital Medical University, Beijing, 5Department of Physiology, Shanxi Medical University, Taiyuan, Shanxi, 6Department of Radiology, China-Japan Friendship Hospital, Beijing, 7Department of Radiology, First Clinical Medical College, Shanxi Medical University, Taiyuan, Shanxi, People’s Republic of China; 8School of Medicine, University of California – San Diego, San Diego, CA, USA Abstract: N-methyl-D-aspartate (NDMA receptor-mediated excitotoxicity has been implicated in a variety of pathological situations such as Alzheimer’s disease (AD and Parkinson’s disease. However, no effective treatments for the same have been developed so far. Humanin (HN is a 24-amino acid peptide originally cloned from the brain of patients with AD and it prevents stress-induced cell death in many cells/tissues. In our previous study, HN was found to effectively rescue rat cortical neurons. It is still not clear whether HN protects the neurons through the attenuation of mitochondrial dysfunction. In this study, excitatory toxicity was induced by NMDA, which binds the NMDA receptor in primarily cultured rat cortical neurons. We found that NMDA (100 µmol/L dramatically induced the decrease of cell viability and caused mitochondrial dysfunction. Pretreatment of the neurons with HN (1 µmol/L led to significant increases of mitochondrial succinate dehydrogenase (SDH activity and membrane potential. In addition, HN pretreatment significantly reduced the excessive production of both reactive oxygen species (ROS and nitric

  7. Glycine Receptor Activation Impairs ATP-Induced Calcium Transients in Cultured Cortical Astrocytes

    Directory of Open Access Journals (Sweden)

    Tatiana P. Morais

    2018-01-01

    Full Text Available In central nervous system, glycine receptor (GlyR is mostly expressed in the spinal cord and brainstem, but glycinergic transmission related elements have also been identified in the brain. Astrocytes are active elements at the tripartite synapse, being responsible for the maintenance of brain homeostasis and for the fine-tuning of synaptic activity. These cells communicate, spontaneously or in response to a stimulus, by elevations in their cytosolic calcium (calcium transients, Ca2+T that can be propagated to other cells. How these Ca2+T are negatively modulated is yet poorly understood. In this work, we evaluated GlyR expression and its role on calcium signaling modulation in rat brain astrocytes. We first proved that GlyR, predominantly subunits α2 and β, was expressed in brain astrocytes and its localization was confirmed in the cytoplasm and astrocytic processes by immunohistochemistry assays. Calcium imaging experiments in cultured astrocytes showed that glycine (500 μM, a GlyR agonist, caused a concentration-dependent reduction in ATP-induced Ca2+T, an effect abolished by the GlyR antagonist, strychnine (0.8 μM, as well as by nocodazole (1 μM, known to impair GlyR anchorage to the plasma membrane. This effect was mimicked by activation of GABAAR, another Cl--permeable channel. In summary, we demonstrated that GlyR activation in astrocytes mediates an inhibitory effect upon ATP induced Ca2+T, which most probably involves changes in membrane permeability to Cl- and requires GlyR anchorage at the plasma membrane. GlyR in astrocytes may thus be part of a mechanism to modulate astrocyte-to-neuron communication.

  8. NETWORK CULTURE - INTEGRAL PART OF NEW VALUES OF CIVIL SOCIETY

    Directory of Open Access Journals (Sweden)

    Vyacheslav Vladimirovich Sukhanov

    2014-06-01

    Full Text Available New technologies not only improve working conditions or communication, they are also bringing new values to  the society. This article discusses the concept of «network culture», which is now perceived by society as an integral part of values that can only exist in a civil society. We can research ( find   this kind of society in modern time period in Russia. The article analyzes the meaning of communication, how to use it, development processes in network media.  Nowadays network culture and its influence on society are almost in all spheres of state and society, as well as changes in perception of information and content generation process. Development of the Internet and Internet technologies largely set the tone for  the development of popular culture and allows you to store or to influence the national culture. Internet press today is and example which shows us, how this kind of tool can be used to influence on citizens.DOI: http://dx.doi.org/10.12731/2218-7405-2014-3-6

  9. The brain's router: a cortical network model of serial processing in the primate brain

    NARCIS (Netherlands)

    Zylberberg, Ariel; Fernández Slezak, Diego; Roelfsema, Pieter R.; Dehaene, Stanislas; Sigman, Mariano

    2010-01-01

    The human brain efficiently solves certain operations such as object recognition and categorization through a massively parallel network of dedicated processors. However, human cognition also relies on the ability to perform an arbitrarily large set of tasks by flexibly recombining different

  10. Automatic Detection of Cortical Arousals in Sleep using Bi-direction LSTM Networks

    DEFF Research Database (Denmark)

    Brink-Kjaer, A.; Olesen, Alexander Neergaard; Jespersen, C. A.

    2018-01-01

    ) and chin electromyography (EMG) to compute a probability of arousals through a bi-directional long short-term memory neural network. The study used a dataset of 233 nocturnal PSGs of population-based samples from Wisconsin Sleep Cohort (WSC) and 30 nocturnal PSGs of clinical samples from the Stanford Sleep...

  11. Resting-state functional under-connectivity within and between large-scale cortical networks across three low-frequency bands in adolescents with autism.

    Science.gov (United States)

    Duan, Xujun; Chen, Heng; He, Changchun; Long, Zhiliang; Guo, Xiaonan; Zhou, Yuanyue; Uddin, Lucina Q; Chen, Huafu

    2017-10-03

    Although evidence is accumulating that autism spectrum disorder (ASD) is associated with disruption of functional connections between and within brain networks, it remains largely unknown whether these abnormalities are related to specific frequency bands. To address this question, network contingency analysis was performed on brain functional connectomes obtained from 213 adolescent participants across nine sites in the Autism Brain Imaging Data Exchange (ABIDE) multisite sample, to determine the disrupted connections between and within seven major cortical networks in adolescents with ASD at Slow-5, Slow-4 and Slow-3 frequency bands and further assess whether the aberrant intra- and inter-network connectivity varied as a function of ASD symptoms. Overall under-connectivity within and between large-scale intrinsic networks in ASD was revealed across the three frequency bands. Specifically, decreased connectivity strength within the default mode network (DMN), between DMN and visual network (VN), ventral attention network (VAN), and between dorsal attention network (DAN) and VAN was observed in the lower frequency band (slow-5, slow-4), while decreased connectivity between limbic network (LN) and frontal-parietal network (FPN) was observed in the higher frequency band (slow-3). Furthermore, weaker connectivity within and between specific networks correlated with poorer communication and social interaction skills in the slow-5 band, uniquely. These results demonstrate intrinsic under-connectivity within and between multiple brain networks within predefined frequency bands in ASD, suggesting that frequency-related properties underlie abnormal brain network organization in the disorder. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Effects of an environmentally-relevant mixture of pyrethroid insecticides on spontaneous activity in primary cortical networks on microelectrode arrays.

    Science.gov (United States)

    Johnstone, Andrew F M; Strickland, Jenna D; Crofton, Kevin M; Gennings, Chris; Shafer, Timothy J

    2017-05-01

    Pyrethroid insecticides exert their insecticidal and toxicological effects primarily by disrupting voltage-gated sodium channel (VGSC) function, resulting in altered neuronal excitability. Numerous studies of individual pyrethroids have characterized effects on mammalian VGSC function and neuronal excitability, yet studies examining effects of complex pyrethroid mixtures in mammalian neurons, especially in environmentally relevant mixture ratios, are limited. In the present study, concentration-response functions were characterized for five pyrethroids (permethrin, deltamethrin, cypermethrin, β-cyfluthrin and esfenvalerate) in an in vitro preparation containing cortical neurons and glia. As a metric of neuronal network activity, spontaneous mean network firing rates (MFR) were measured using microelectorde arrays (MEAs). In addition, the effect of a complex and exposure relevant mixture of the five pyrethroids (containing 52% permethrin, 28.8% cypermethrin, 12.9% β-cyfluthrin, 3.4% deltamethrin and 2.7% esfenvalerate) was also measured. Data were modeled to determine whether effects of the pyrethroid mixture were predicted by dose-addition. At concentrations up to 10μM, all compounds except permethrin reduced MFR. Deltamethrin and β-cyfluthrin were the most potent and reduced MFR by as much as 60 and 50%, respectively, while cypermethrin and esfenvalerate were of approximately equal potency and reduced MFR by only ∼20% at the highest concentration. Permethrin caused small (∼24% maximum), concentration-dependent increases in MFR. Effects of the environmentally relevant mixture did not depart from the prediction of dose-addition. These data demonstrate that an environmentally relevant mixture caused dose-additive effects on spontaneous neuronal network activity in vitro, and is consistent with other in vitro and in vivo assessments of pyrethroid mixtures. Published by Elsevier B.V.

  13. Epileptic Networks in Focal Cortical Dysplasia Revealed Using Electroencephalography–Functional Magnetic Resonance Imaging

    Science.gov (United States)

    Thornton, Rachel; Vulliemoz, Serge; Rodionov, Roman; Carmichael, David W; Chaudhary, Umair J; Diehl, Beate; Laufs, Helmut; Vollmar, Christian; McEvoy, Andrew W; Walker, Matthew C; Bartolomei, Fabrice; Guye, Maxime; Chauvel, Patrick; Duncan, John S; Lemieux, Louis

    2011-01-01

    Objective Surgical treatment of focal epilepsy in patients with focal cortical dysplasia (FCD) is most successful if all epileptogenic tissue is resected. This may not be evident on structural magnetic resonance imaging (MRI), so intracranial electroencephalography (icEEG) is needed to delineate the seizure onset zone (SOZ). EEG-functional MRI (fMRI) can reveal interictal discharge (IED)-related hemodynamic changes in the irritative zone (IZ). We assessed the value of EEG-fMRI in patients with FCD-associated focal epilepsy by examining the relationship between IED-related hemodynamic changes, icEEG findings, and postoperative outcome. Methods Twenty-three patients with FCD-associated focal epilepsy undergoing presurgical evaluation including icEEG underwent simultaneous EEG-fMRI at 3T. IED-related hemodynamic changes were modeled, and results were overlaid on coregistered T1-weighted MRI scans fused with computed tomography scans showing the intracranial electrodes. IED-related hemodynamic changes were compared with the SOZ on icEEG and postoperative outcome at 1 year. Results Twelve of 23 patients had IEDs during recording, and 11 of 12 had significant IED-related hemodynamic changes. The fMRI results were concordant with the SOZ in 5 of 11 patients, all of whom had a solitary SOZ on icEEG. Four of 5 had >50% reduction in seizure frequency following resective surgery. The remaining 6 of 11 patients had widespread or discordant regions of IED-related fMRI signal change. Five of 6 had either a poor surgical outcome (<50% reduction in seizure frequency) or widespread SOZ precluding surgery. Interpretation Comparison of EEG-fMRI with icEEG suggests that EEG-fMRI may provide useful additional information about the SOZ in FCD. Widely distributed discordant regions of IED-related hemodynamic change appear to be associated with a widespread SOZ and poor postsurgical outcome. ANN NEUROL 2011 PMID:22162063

  14. Spreadable media: Creating value and meaning in a networked culture

    Directory of Open Access Journals (Sweden)

    Moderated by Louisa Stein

    2014-09-01

    Full Text Available Online Roundtable on Spreadable Media, by Henry Jenkins, Sam Ford, and Joshua Green, with participants Paul Booth, Kristina Busse, Melissa Click, Sam Ford, Henry Jenkins, Xiaochang Li, and Sharon Ross. Section 1 first published as the article "Spreadable Media: Creating Value and Meaning in a Networked Culture", by Louisa Stein, from Cinema Journal Volume 53 Issue 3, pp152-177. Copyright 2014 by The University of Texas Press. All rights reserved.

  15. Autophagy activation is involved in 3,4-methylenedioxymethamphetamine ('ecstasy'--induced neurotoxicity in cultured cortical neurons.

    Directory of Open Access Journals (Sweden)

    I-Hsun Li

    Full Text Available Autophagic (type II cell death, characterized by the massive accumulation of autophagic vacuoles in the cytoplasm of cells, has been suggested to play pathogenetic roles in cerebral ischemia, brain trauma, and neurodegenerative disorders. 3,4-Methylenedioxymethamphetamine (MDMA or ecstasy is an illicit drug causing long-term neurotoxicity in the brain. Apoptotic (type I and necrotic (type III cell death have been implicated in MDMA-induced neurotoxicity, while the role of autophagy in MDMA-elicited neurotoxicity has not been investigated. The present study aimed to evaluate the occurrence and contribution of autophagy to neurotoxicity in cultured rat cortical neurons challenged with MDMA. Autophagy activation was monitored by expression of microtubule-associated protein 1 light chain 3 (LC3; an autophagic marker using immunofluorescence and western blot analysis. Here, we demonstrate that MDMA exposure induced monodansylcadaverine (MDC- and LC3B-densely stained autophagosome formation and increased conversion of LC3B-I to LC3B-II, coinciding with the neurodegenerative phase of MDMA challenge. Autophagy inhibitor 3-methyladenine (3-MA pretreatment significantly attenuated MDMA-induced autophagosome accumulation, LC3B-II expression, and ameliorated MDMA-triggered neurite damage and neuronal death. In contrast, enhanced autophagy flux by rapamycin or impaired autophagosome clearance by bafilomycin A1 led to more autophagosome accumulation in neurons and aggravated neurite degeneration, indicating that excessive autophagosome accumulation contributes to MDMA-induced neurotoxicity. Furthermore, MDMA induced phosphorylation of AMP-activated protein kinase (AMPK and its downstream unc-51-like kinase 1 (ULK1, suggesting the AMPK/ULK1 signaling pathway might be involved in MDMA-induced autophagy activation.

  16. Segmentation of nanotomographic cortical bone images for quantitative characterization of the osteoctyte lacuno-canalicular network

    Energy Technology Data Exchange (ETDEWEB)

    Ciani, A.; Kewish, C. M. [Synchrotron Soleil, L’Orme des Merisiers, 91192 Saint-Aubin (France); Guizar-Sicairos, M.; Diaz, A.; Holler, M. [Paul Scherrer Institut, 5232 Villigen PSI (Switzerland); Pallu, S.; Achiou, Z.; Jennane, R.; Toumi, H.; Lespessailles, E. [Univ Orléans, I3MTO, Ea 4708, 45000 Orléans (France)

    2016-01-28

    A newly developed data processing method able to characterize the osteocytes lacuno-canalicular network (LCN) is presented. Osteocytes are the most abundant cells in the bone, living in spaces called lacunae embedded inside the bone matrix and connected to each other with an extensive network of canals that allows for the exchange of nutrients and for mechanotransduction functions. The geometrical three-dimensional (3D) architecture is increasingly thought to be related to the macroscopic strength or failure of the bone and it is becoming the focus for investigating widely spread diseases such as osteoporosis. To obtain 3D LCN images non-destructively has been out of reach until recently, since tens-of-nanometers scale resolution is required. Ptychographic tomography was validated for bone imaging in [1], showing clearly the LCN. The method presented here was applied to 3D ptychographic tomographic images in order to extract morphological and geometrical parameters of the lacuno-canalicular structures.

  17. Modulation of cortical-subcortical networks in Parkinson’s disease by applied field effects

    OpenAIRE

    Hess, Christopher W.

    2013-01-01

    Studies suggest that endogenous field effects may play a role in neuronal oscillations and communication. Non-invasive transcranial electrical stimulation with low-intensity currents can also have direct effects on the underlying cortex as well as distant network effects. While Parkinson’s disease (PD) is amenable to invasive neuromodulation in the basal ganglia by deep brain stimulation (DBS), techniques of non-invasive neuromodulation like transcranial direct current stimulation (tDCS) and ...

  18. Motor Cortical Networks for Skilled Movements Have Dynamic Properties That Are Related to Accurate Reaching

    Directory of Open Access Journals (Sweden)

    David F. Putrino

    2011-01-01

    Full Text Available Neurons in the Primary Motor Cortex (MI are known to form functional ensembles with one another in order to produce voluntary movement. Neural network changes during skill learning are thought to be involved in improved fluency and accuracy of motor tasks. Unforced errors during skilled tasks provide an avenue to study network connections related to motor learning. In order to investigate network activity in MI, microwires were implanted in the MI of cats trained to perform a reaching task. Spike trains from eight groups of simultaneously recorded cells (95 neurons in total were acquired. A point process generalized linear model (GLM was developed to assess simultaneously recorded cells for functional connectivity during reaching attempts where unforced errors or no errors were made. Whilst the same groups of neurons were often functionally connected regardless of trial success, functional connectivity between neurons was significantly different at fine time scales when the outcome of task performance changed. Furthermore, connections were shown to be significantly more robust across multiple latencies during successful trials of task performance. The results of this study indicate that reach-related neurons in MI form dynamic spiking dependencies whose temporal features are highly sensitive to unforced movement errors.

  19. Cultured Neural Networks: Optimization of Patterned Network Adhesiveness and Characterization of their Neural Activity

    Directory of Open Access Journals (Sweden)

    W. L. C. Rutten

    2006-01-01

    Full Text Available One type of future, improved neural interface is the “cultured probe”. It is a hybrid type of neural information transducer or prosthesis, for stimulation and/or recording of neural activity. It would consist of a microelectrode array (MEA on a planar substrate, each electrode being covered and surrounded by a local circularly confined network (“island” of cultured neurons. The main purpose of the local networks is that they act as biofriendly intermediates for collateral sprouts from the in vivo system, thus allowing for an effective and selective neuron–electrode interface. As a secondary purpose, one may envisage future information processing applications of these intermediary networks. In this paper, first, progress is shown on how substrates can be chemically modified to confine developing networks, cultured from dissociated rat cortex cells, to “islands” surrounding an electrode site. Additional coating of neurophobic, polyimide-coated substrate by triblock-copolymer coating enhances neurophilic-neurophobic adhesion contrast. Secondly, results are given on neuronal activity in patterned, unconnected and connected, circular “island” networks. For connected islands, the larger the island diameter (50, 100 or 150 μm, the more spontaneous activity is seen. Also, activity may show a very high degree of synchronization between two islands. For unconnected islands, activity may start at 22 days in vitro (DIV, which is two weeks later than in unpatterned networks.

  20. Preparing hearts and minds: cardiac slowing and a cortical inhibitory network.

    Science.gov (United States)

    Jennings, J R; van der Molen, M W; Tanase, C

    2009-11-01

    Preparing for a cued, speeded response induces a set of physiological changes. A review of the psychophysiology of preparation suggested that inhibition of action was an important process among the constellation of changes constituting attentive preparation. The current experiment combined event-related functional magnetic resonance imaging and cardiac inter-beat interval measures in an experiment that compared preparing for a response, watching stimuli without responding, and responding in the absence of preparation. Ten college-aged participants were tested in an initial psychophysiological experiment followed by two scanning sessions during which reverse spiral imaging was performed concurrent with inter-beat interval measurement. Two analytic approaches were used to confirm blood oxygenation level dependent responses during preparation, and these converged to show inferior prefrontal and related subthalamic nuclei activity in the context of other known changes related to brain attentional networks. Subthalamic nuclei changes were related to the depth of preparatory cardiac deceleration. This pattern of findings suggests that preparation involves the activation of a complex inhibitory neural network implicating brain and autonomic nervous systems.

  1. The pairwise phase consistency in cortical network and its relationship with neuronal activation

    Directory of Open Access Journals (Sweden)

    Wang Daming

    2017-01-01

    Full Text Available Gamma-band neuronal oscillation and synchronization with the range of 30-90 Hz are ubiquitous phenomenon across numerous brain areas and various species, and correlated with plenty of cognitive functions. The phase of the oscillation, as one aspect of CTC (Communication through Coherence hypothesis, underlies various functions for feature coding, memory processing and behaviour performing. The PPC (Pairwise Phase Consistency, an improved coherence measure, statistically quantifies the strength of phase synchronization. In order to evaluate the PPC and its relationships with input stimulus, neuronal activation and firing rate, a simplified spiking neuronal network is constructed to simulate orientation columns in primary visual cortex. If the input orientation stimulus is preferred for a certain orientation column, neurons within this corresponding column will obtain higher firing rate and stronger neuronal activation, which consequently engender higher PPC values, with higher PPC corresponding to higher firing rate. In addition, we investigate the PPC in time resolved analysis with a sliding window.

  2. From Spinal Central Pattern Generators to Cortical Network: Integrated BCI for Walking Rehabilitation

    Directory of Open Access Journals (Sweden)

    G. Cheron

    2012-01-01

    Full Text Available Success in locomotor rehabilitation programs can be improved with the use of brain-computer interfaces (BCIs. Although a wealth of research has demonstrated that locomotion is largely controlled by spinal mechanisms, the brain is of utmost importance in monitoring locomotor patterns and therefore contains information regarding central pattern generation functioning. In addition, there is also a tight coordination between the upper and lower limbs, which can also be useful in controlling locomotion. The current paper critically investigates different approaches that are applicable to this field: the use of electroencephalogram (EEG, upper limb electromyogram (EMG, or a hybrid of the two neurophysiological signals to control assistive exoskeletons used in locomotion based on programmable central pattern generators (PCPGs or dynamic recurrent neural networks (DRNNs. Plantar surface tactile stimulation devices combined with virtual reality may provide the sensation of walking while in a supine position for use of training brain signals generated during locomotion. These methods may exploit mechanisms of brain plasticity and assist in the neurorehabilitation of gait in a variety of clinical conditions, including stroke, spinal trauma, multiple sclerosis, and cerebral palsy.

  3. A cortical network model of cognitive and emotional influences in human decision making.

    Science.gov (United States)

    Nazir, Azadeh Hassannejad; Liljenström, Hans

    2015-10-01

    Decision making (DM)(2) is a complex process that appears to involve several brain structures. In particular, amygdala, orbitofrontal cortex (OFC) and lateral prefrontal cortex (LPFC) seem to be essential in human decision making, where both emotional and cognitive aspects are taken into account. In this paper, we present a computational network model representing the neural information processing of DM, from perception to behavior. We model the population dynamics of the three neural structures (amygdala, OFC and LPFC), as well as their interaction. In our model, the neurodynamic activity of amygdala and OFC represents the neural correlates of secondary emotion, while the activity of certain neural populations in OFC alone represents the outcome expectancy of different options. The cognitive/rational aspect of DM is associated with LPFC. Our model is intended to give insights on the emotional and cognitive processes involved in DM under various internal and external contexts. Different options for actions are represented by the oscillatory activity of cell assemblies, which may change due to experience and learning. Knowledge and experience of the outcome of our decisions and actions can eventually result in changes in our neural structures, attitudes and behaviors. Simulation results may have implications for how we make decisions for our individual actions, as well as for societal choices, where we take examples from transport and its impact on CO2 emissions and climate change. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  4. Ghrelin stimulates synaptic formation in cultured cortical networks in a dose-dependent manner

    NARCIS (Netherlands)

    Herzig, K.H.; Stoyanova, Irina; le Feber, Jakob; Rutten, Wim

    2013-01-01

    Ghrelin was initially related to appetite stimulation and growth hormone secretion. These findings suggest that ghrelin may provide a novel therapeutic strategy for the treatment of disorders related to synaptic impairment.

  5. Effect of ghrelin on the network development and activity in cultured cortical neurons of newborn rats

    NARCIS (Netherlands)

    Stoyanova, Irina; le Feber, Jakob; Rutten, Wim; Stett, A

    2010-01-01

    Ghrelin is a gastric hormone and a neuropeptide, initially related to the appetite stimulation and growth hormone secretation. Ghrelin has also an important role in regulation of many other processes, including higher brain funtions like memory performance, sleep and wakefulness. Previous studies on

  6. Ghrelin accelerates synapse formation and activity development in cultured cortical networks

    NARCIS (Netherlands)

    Stoyanova, Irina; le Feber, Joost

    2014-01-01

    Background: While ghrelin was initially related to appetite stimulation and growth hormone secretion, it also has a neuroprotective effect in neurodegenerative diseases and regulates cognitive function. The cellular basis of those processes is related to synaptic efficacy and plasticity. Previous

  7. Folate and S-adenosylmethionine modulate synaptic activity in cultured cortical neurons: acute differential impact on normal and apolipoprotein-deficient mice

    International Nuclear Information System (INIS)

    Serra, Michael; Chan, Amy; Dubey, Maya; Shea, Thomas B; Gilman, Vladimir

    2008-01-01

    Folate deficiency is accompanied by a decline in the cognitive neurotransmitter acetylcholine and a decline in cognitive performance in mice lacking apolipoprotein E (ApoE−/− mice), a low-density lipoprotein that regulates aspects of lipid metabolism. One direct consequence of folate deficiency is a decline in S-adenosylmethionine (SAM). Since dietary SAM supplementation maintains acetylcholine levels and cognitive performance in the absence of folate, we examined herein the impact of folate and SAM on neuronal synaptic activity. Embryonic cortical neurons from mice expressing or lacking ApoE (ApoE+/+ or −/−, respectively) were cultured for 1 month on multi-electrode arrays, and signaling was recorded. ApoE+/+ cultures displayed significantly more frequent spontaneous signals than ApoE−/− cultures. Supplementation with 166 µm SAM (not normally present in culture medium) increased signal frequency and decreased signal amplitude in ApoE+/+ cultures. SAM also increased the frequency of tightly clustered signal bursts. Folate deprivation reversibly reduced signal frequency in ApoE+/+ cultures; SAM supplementation maintained signal frequency despite folate deprivation. These findings support the importance of dietary supplementation with folate and SAM on neuronal health. Supplementation with 166 µm SAM did not alter signaling in ApoE−/− cultures, which may be a reflection of the reduced SAM levels in ApoE−/− mice. The differential impact of SAM on ApoE+/+ and −/− neurons underscores the combined impact of nutritional and genetic deficiencies on neuronal homeostasis. (communication)

  8. Integrating microRNA and mRNA expression profiles of neuronal progenitors to identify regulatory networks underlying the onset of cortical neurogenesis

    Directory of Open Access Journals (Sweden)

    Barker Jeffery L

    2009-08-01

    Full Text Available Abstract Background Cortical development is a complex process that includes sequential generation of neuronal progenitors, which proliferate and migrate to form the stratified layers of the developing cortex. To identify the individual microRNAs (miRNAs and mRNAs that may regulate the genetic network guiding the earliest phase of cortical development, the expression profiles of rat neuronal progenitors obtained at embryonic day 11 (E11, E12 and E13 were analyzed. Results Neuronal progenitors were purified from telencephalic dissociates by a positive-selection strategy featuring surface labeling with tetanus-toxin and cholera-toxin followed by fluorescence-activated cell sorting. Microarray analyses revealed the fractions of miRNAs and mRNAs that were up-regulated or down-regulated in these neuronal progenitors at the beginning of cortical development. Nearly half of the dynamically expressed miRNAs were negatively correlated with the expression of their predicted target mRNAs. Conclusion These data support a regulatory role for miRNAs during the transition from neuronal progenitors into the earliest differentiating cortical neurons. In addition, by supplying a robust data set in which miRNA and mRNA profiles originate from the same purified cell type, this empirical study may facilitate the development of new algorithms to integrate various "-omics" data sets.

  9. Localization of the kinesin adaptor proteins trafficking kinesin proteins 1 and 2 in primary cultures of hippocampal pyramidal and cortical neurons.

    Science.gov (United States)

    Loss, Omar; Stephenson, F Anne

    2015-07-01

    Neuronal function requires regulated anterograde and retrograde trafficking of mitochondria along microtubules by using the molecular motors kinesin and dynein. Previous work has established that trafficking kinesin proteins (TRAKs),TRAK1 and TRAK2, are kinesin adaptor proteins that link mitochondria to kinesin motor proteins via an acceptor protein in the mitochondrial outer membrane, etc. the Rho GTPase Miro. Recent studies have shown that TRAK1 preferentially controls mitochondrial transport in axons of hippocampal neurons by virtue of its binding to both kinesin and dynein motor proteins, whereas TRAK2 controls mitochondrial transport in dendrites resulting from its binding to dynein. This study further investigates the subcellular localization of TRAK1 and TRAK2 in primary cultures of hippocampal and cortical neurons by using both commercial antibodies and anti-TRAK1 and anti-TRAK2 antibodies raised in our own laboratory (in-house). Whereas TRAK1 was prevalently localized in axons of hippocampal and cortical neurons, TRAK2 was more prevalent in dendrites of hippocampal neurons. In cortical neurons, TRAK2 was equally distributed between axons and dendrites. Some qualitative differences were observed between commercial and in-house-generated antibody immunostaining. © 2015 Wiley Periodicals, Inc.

  10. Effect of extracellular generation of the reactive oxygen species, singlet oxygen (1O2), on the electrophysiological properties of cultured cortical neurons

    DEFF Research Database (Denmark)

    Breitenbach, Thomas; Sinks, Louise, E.; Vionogradov, Sergej A.

    (ABM) were made from cultured rat cortical neurons to provide insight into the events following extracellular generation of 1O2. Membrane resistance (Rm), capacitance (Cm), holding current (Ihold), and firing properties were monitored throughout. The V/I relationship was investigated with 1 s duration...... current steps of 0.1 nA (-0.4 - 1 nA). The PS, dissolved in ABM (10 µM), was administered by local application directly to the neuron monitored. The intensity of the applied light at 455 nm was adjusted by neutral density filters. Phosphorescence at 700 nm proved the presence of the PS, which was absent...

  11. Age- and function-related regional changes in cortical folding of the default mode network in older adults.

    Science.gov (United States)

    Jockwitz, Christiane; Caspers, Svenja; Lux, Silke; Jütten, Kerstin; Schleicher, Axel; Eickhoff, Simon B; Amunts, Katrin; Zilles, Karl

    2017-01-01

    Healthy aging is accompanied by changes in the functional architecture of the default mode network (DMN), e.g. a posterior to anterior shift (PASA) of activations. The putative structural correlate for this functional reorganization, however, is largely unknown. Changes in gyrification, i.e. decreases of cortical folding were found to be a marker of atrophy of the brain in later decades of life. Therefore, the present study assessed local gyrification indices of the DMN in relation to age and cognitive performance in 749 older adults aged 55-85 years. Age-related decreases in local gyrification indices were found in the anterior part of the DMN [particularly; medial prefrontal cortex (mPFC)] of the right hemisphere, and the medial posterior parts of the DMN [particularly; posterior cingulate cortex (PCC)/precuneus] of both hemispheres. Positive correlations between cognitive performance and local gyrification indices were found for (1) selective attention and left PCC/precuneus, (2) visual/visual-spatial working memory and bilateral PCC/precuneus and right angular gyrus (AG), and (3) semantic verbal fluency and right AG and right mPFC. The more pronounced age-related decrease in local gyrification indices of the posterior parts of the DMN supports the functionally motivated PASA theory by correlated structural changes. Surprisingly, the prominent age-related decrease in local gyrification indices in right hemispheric ROIs provides evidence for a structural underpinning of the right hemi-aging hypothesis. Noticeably, the performance-related changes in local gyrification largely involved the same parts of the DMN that were subject to age-related local gyrification decreases. Thus, the present study lends support for a combined structural and functional theory of aging, in that the functional changes in the DMN during aging are accompanied by comparably localized structural alterations.

  12. Cortical networks for vision and language in dyslexic and normal children of variable socio-economic status.

    Science.gov (United States)

    Monzalvo, Karla; Fluss, Joel; Billard, Catherine; Dehaene, Stanislas; Dehaene-Lambertz, Ghislaine

    2012-05-15

    In dyslexia, anomalous activations have been described in both left temporo-parietal language cortices and in left ventral visual occipito-temporal cortex. However, the reproducibility, task-dependency, and presence of these brain anomalies in childhood rather than adulthood remain debated. We probed the large-scale organization of ventral visual and spoken language areas in dyslexic children using minimal target-detection tasks that were performed equally well by all groups. In 23 normal and 23 dyslexic 10-year-old children from two different socio-economic status (SES) backgrounds, we compared fMRI activity to visually presented houses, faces, and written strings, and to spoken sentences in the native or in a foreign language. Our results confirm a disorganization of both ventral visual and spoken language areas in dyslexic children. Visually, dyslexic children showed a normal lateral-to-medial mosaic of preferences, as well as normal responses to houses and checkerboards, but a reduced activation to words in the visual word form area (VWFA) and to faces in the right fusiform face area (FFA). Auditorily, dyslexic children exhibited reduced responses to speech in posterior temporal cortex, left insula and supplementary motor area, as well as reduced responses to maternal language in subparts of the planum temporale, left basal language area and VWFA. By correlating these two findings, we identify spoken-language predictors of VWFA activation to written words, which differ for dyslexic and normal readers. Similarities in fMRI deficits in both SES groups emphasize the existence of a core set of brain activation anomalies in dyslexia, regardless of culture, language and SES, without however resolving whether these anomalies are a cause or a consequence of impaired reading. Copyright © 2012 Elsevier Inc. All rights reserved.

  13. 77 FR 37730 - Culturally Significant Objects Imported for Exhibition Determinations: “Nomads and Networks: The...

    Science.gov (United States)

    2012-06-22

    ... DEPARTMENT OF STATE [Public Notice 7928] Culturally Significant Objects Imported for Exhibition Determinations: ``Nomads and Networks: The Ancient Art and Culture of Kazakhstan'' SUMMARY: Notice is hereby... objects to be included in the exhibition ``Nomads and Networks: The Ancient Art and Culture of Kazakhstan...

  14. 77 FR 7229 - Culturally Significant Objects Imported for Exhibition Determinations: “Nomads and Networks: The...

    Science.gov (United States)

    2012-02-10

    ... DEPARTMENT OF STATE [Public Notice 7794] Culturally Significant Objects Imported for Exhibition Determinations: ``Nomads and Networks: The Ancient Art and Culture of Kazakhstan'' SUMMARY: Notice is hereby... objects to be included in the exhibition ``Nomads and Networks: The Ancient Art and Culture of Kazakhstan...

  15. The Marine Guanidine Alkaloid Crambescidin 816 Induces Calcium Influx and Cytotoxicity in Primary Cultures of Cortical Neurons through Glutamate Receptors.

    Science.gov (United States)

    Mendez, Aida G; Juncal, Andrea Boente; Silva, Siguara B L; Thomas, Olivier P; Martín Vázquez, Víctor; Alfonso, Amparo; Vieytes, Mercedes R; Vale, Carmen; Botana, Luís M

    2017-07-19

    Crambescidin 816 is a guanidine alkaloid produced by the sponge Crambe crambe with known antitumoral activity. While the information describing the effects of this alkaloid in central neurons is scarce, Cramb816 is known to block voltage dependent calcium channels being selective for L-type channels. Moreover, Cramb816 reduced neuronal viability through an unknown mechanism. Here, we aimed to describe the toxic activity of Cramb816 in cortical neurons. Since calcium influx is considered the main mechanism responsible for neuronal cell death, the effects of Cramb816 in the cytosolic calcium concentration of cortical neurons were studied. The alkaloid decreased neuronal viability and induced a dose-dependent increase in cytosolic calcium that was also related to the presence of calcium in the extracellular media. The increase in calcium influx was age dependent, being higher in younger neurons. Moreover, this effect was prevented by glutamate receptor antagonists, which did not fully block the cytotoxic effect of Cramb816 after 24 h of treatment but completely prevented Cramb816 cytotoxicity after 10 min exposure. Therefore, the findings presented herein provide new insights into the cytotoxic effect of Cramb816 in cortical neurons.

  16. Three-dimensional neural cultures produce networks that mimic native brain activity.

    Science.gov (United States)

    Bourke, Justin L; Quigley, Anita F; Duchi, Serena; O'Connell, Cathal D; Crook, Jeremy M; Wallace, Gordon G; Cook, Mark J; Kapsa, Robert M I

    2018-02-01

    Development of brain function is critically dependent on neuronal networks organized through three dimensions. Culture of central nervous system neurons has traditionally been limited to two dimensions, restricting growth patterns and network formation to a single plane. Here, with the use of multichannel extracellular microelectrode arrays, we demonstrate that neurons cultured in a true three-dimensional environment recapitulate native neuronal network formation and produce functional outcomes more akin to in vivo neuronal network activity. Copyright © 2017 John Wiley & Sons, Ltd.

  17. The interplay between social networks and culture: theoretically and among whales and dolphins

    OpenAIRE

    Cantor, Mauricio; Whitehead, Hal

    2013-01-01

    Culture is increasingly being understood as a driver of mammalian phenotypes. Defined as group-specific behaviour transmitted by social learning, culture is shaped by social structure. However, culture can itself affect social structure if individuals preferentially interact with others whose behaviour is similar, or cultural symbols are used to mark groups. Using network formalism, this interplay can be depicted by the coevolution of nodes and edges together with the coevolution of network t...

  18. Improved diagnostic accuracy of Alzheimer's disease by combining regional cortical thickness and default mode network functional connectivity: Validated in the Alzheimer's disease neuroimaging initiative set

    International Nuclear Information System (INIS)

    Park, Ji Eun; Park, Bum Woo; Kim, Sang Joon; Kim, Ho Sung; Choi, Choong Gon; Jung, Seung Jung; Oh, Joo Young; Shim, Woo Hyun; Lee, Jae Hong; Roh, Jee Hoon

    2017-01-01

    To identify potential imaging biomarkers of Alzheimer's disease by combining brain cortical thickness (CThk) and functional connectivity and to validate this model's diagnostic accuracy in a validation set. Data from 98 subjects was retrospectively reviewed, including a study set (n = 63) and a validation set from the Alzheimer's Disease Neuroimaging Initiative (n = 35). From each subject, data for CThk and functional connectivity of the default mode network was extracted from structural T1-weighted and resting-state functional magnetic resonance imaging. Cortical regions with significant differences between patients and healthy controls in the correlation of CThk and functional connectivity were identified in the study set. The diagnostic accuracy of functional connectivity measures combined with CThk in the identified regions was evaluated against that in the medial temporal lobes using the validation set and application of a support vector machine. Group-wise differences in the correlation of CThk and default mode network functional connectivity were identified in the superior temporal (p < 0.001) and supramarginal gyrus (p = 0.007) of the left cerebral hemisphere. Default mode network functional connectivity combined with the CThk of those two regions were more accurate than that combined with the CThk of both medial temporal lobes (91.7% vs. 75%). Combining functional information with CThk of the superior temporal and supramarginal gyri in the left cerebral hemisphere improves diagnostic accuracy, making it a potential imaging biomarker for Alzheimer's disease

  19. Neuroprotective effects of orientin on oxygen-glucose deprivation/reperfusion-induced cell injury in primary culture of rat cortical neurons.

    Science.gov (United States)

    Tian, Tian; Zeng, Junan; Zhao, Guangyu; Zhao, Wenjing; Gao, Songyi; Liu, Li

    2018-01-01

    Orientin (luteolin-8-C-glucoside) is a phenolic compound found abundantly in millet, juice, and peel of passion fruit and has been shown to have antioxidant properties. In the present study, we explored the effects of orientin on oxygen-glucose deprivation/reperfusion (OGD/RP)-induced cell injury in primary culture of rat cortical neurons using an in vitro model of neonatal ischemic brain injury. The reduced cell viability and elevated lactate dehydrogenase leakage were observed after OGD/RP exposure, which were then reversed by orientin (10, 20, and 30 µM) pretreatment in a dose-dependent manner. Additionally, OGD/RP treatment resulted in significant oxidative stress, accompanied by enhanced intracellular reactive oxygen species (ROS) generation, and obvious depletion in the activities of intracellular Mn-superoxide dismutase, catalase, and glutathione peroxidase antioxidases. However, these effects were dose dependently restored by orientin pretreatment. We also found that orientin pretreatment dose dependently suppressed [Ca 2+ ] i increase and mitochondrial membrane potential dissipation caused by OGD/RP in primary culture of rat cortical neurons. Western blot analysis showed that OGD/RP exposure induced a distinct decrease of Bcl-2 protein and a marked elevation of Bax, caspase-3, and cleaved caspase-3 proteins; whereas these effects were dose dependently reversed by orientin incubation. Both the caspase-3 activity and the apoptosis rate were increased under OGD/RP treatment, but was then dose dependently down-regulated by orientin (10, 20, and 30 µM) incubation. Moreover, orientin pretreatment dose dependently inhibited OGD/RP-induced phosphorylation of JNK and ERK1/2. Notably, JNK inhibitor SP600125 and ERK1/2 inhibitor PD98059 also dramatically attenuated OGD/RP-induced cell viability loss and ROS generation, and further, orientin failed to protect cortical neurons with the interference of JNK activator anisomycin or ERK1/2 activator FGF-2. Taken

  20. Growth and structural discrimination of cortical neurons on randomly oriented and vertically aligned dense carbon nanotube networks

    Directory of Open Access Journals (Sweden)

    Christoph Nick

    2014-09-01

    Full Text Available The growth of cortical neurons on three dimensional structures of spatially defined (structured randomly oriented, as well as on vertically aligned, carbon nanotubes (CNT is studied. Cortical neurons are attracted towards both types of CNT nano-architectures. For both, neurons form clusters in close vicinity to the CNT structures whereupon the randomly oriented CNTs are more closely colonised than the CNT pillars. Neurons develop communication paths via neurites on both nanoarchitectures. These neuron cells attach preferentially on the CNT sidewalls of the vertically aligned CNT architecture instead than onto the tips of the individual CNT pillars.

  1. Amitriptyline up-regulates connexin43-gap junction in rat cultured cortical astrocytes via activation of the p38 and c-Fos/AP-1 signalling pathway.

    Science.gov (United States)

    Morioka, N; Suekama, K; Zhang, F F; Kajitani, N; Hisaoka-Nakashima, K; Takebayashi, M; Nakata, Y

    2014-06-01

    Intercellular communication via gap junctions, comprised of connexin (Cx) proteins, allow for communication between astrocytes, which in turn is crucial for maintaining CNS homeostasis. The expression of Cx43 is decreased in post-mortem brains from patients with major depression. A potentially novel mechanism of tricyclic antidepressants is to increase the expression and functioning of gap junctions in astrocytes. The effect of amitriptyline on the expression of Cx43 and gap junction intercellular communication (GJIC) in rat primary cultured cortical astrocytes was investigated. We also investigated the role of p38 MAPK intracellular signalling pathway in the amitriptyline-induced expression of Cx43 and GJIC. Treatment with amitriptyline for 48 h significantly up-regulated Cx43 mRNA, protein and GJIC. The up-regulation of Cx43 was not monoamine-related since noradrenaline, 5-HT and dopamine did not induce Cx43 expression and pretreatment with α- and β-adrenoceptor antagonists had no effect. Intracellular signalling involved p38 MAPK, as amitriptyline significantly increased p38 MAPK phosphorylation and Cx43 expression and GJIC were significantly blocked by the p38 inhibitor SB 202190. Furthermore, amitriptyline-induced Cx43 expression and GJIC were markedly reduced by transcription factor AP-1 inhibitors (curcumin and tanshinone IIA). The translocation of c-Fos from the cytosol and the nucleus of cortical astrocytes was increased by amitriptyline, and this response was dependent on p38 activity. These findings indicate a novel mechanism of action of amitriptyline through cortical astrocytes, and further suggest that targeting this mechanism could lead to the development of a new class of antidepressants. © 2014 The British Pharmacological Society.

  2. Neuroprotection by biodegradable PAMAM ester (e-PAM-R)-mediated HMGB1 siRNA delivery in primary cortical cultures and in the postischemic brain.

    Science.gov (United States)

    Kim, Il-Doo; Lim, Chae-Moon; Kim, Jung-Bin; Nam, Hye Yeong; Nam, Kihoon; Kim, Seung-Woo; Park, Jong-Sang; Lee, Ja-Kyeong

    2010-03-19

    Although RNA interference (RNAi)-mediated gene silencing provides a powerful strategy for modulating specific gene functions, difficulties associated with siRNA delivery have impeded the development of efficient therapeutic applications. In particular, the efficacy of siRNA delivery into neurons has been limited by extremely low transfection efficiencies. e-PAM-R is a biodegradable arginine ester of PAMAM dendrimer, which is readily degradable under physiological conditions (pH 7.4, 37 degrees C). In the present study, we investigated the efficiency of siRNA delivery by e-PAM-R in primary cortical cultures and in rat brain. e-PAM-R/siRNA complexes showed high transfection efficiencies and low cytotoxicities in primary cortical cultures. Localization of fluorescence-tagged siRNA revealed that siRNA was delivered not only into the nucleus and cytoplasm, but also along the processes of the neuron. e-PAM-R/siRNA complex-mediated target gene reduction was observed in over 40% of cells and it was persistent for over 48 h. The potential use of e-PAM-R was demonstrated by gene knockdown after transfecting High mobility group box-1 (HMGB1, a novel cytokine-like molecule) siRNA into H(2)O(2)- or NMDA-treated primary cortical cultures. In these cells, HMGB1 siRNA delivery successfully reduced both basal and H(2)O(2)- or NMDA-induced HMGB1 levels, and as a result of that, neuronal cell death was significantly suppressed in both cases. Furthermore, we showed that e-PAM-R successfully delivered HMGB1 siRNA into the rat brain, wherein HMGB1 expression was depleted in over 40% of neurons and astrocytes of the normal brain. Moreover, e-PAM-R-mediated HMGB1 siRNA delivery notably reduced infarct volume in the postischemic rat brain, which is generated by occluding the middle cerebral artery for 60 min. These results indicate that e-PAM-R, a novel biodegradable nonviral gene carrier, offers an efficient means of transfecting siRNA into primary neuronal cells and in the brain and of

  3. Regulation of the fear network by mediators of stress: Norepinephrine alters the balance between Cortical and Subcortical afferent excitation of the Lateral Amygdala

    Directory of Open Access Journals (Sweden)

    Luke R Johnson

    2011-05-01

    Full Text Available Pavlovian auditory fear conditioning crucially involves the integration of information about and acoustic conditioned stimulus (CS and an aversive unconditioned stimulus (US in the lateral nucleus of the amygdala (LA. The auditory CS reaches the LA subcortically via a direct connection from the auditory thalamus and also from the auditory association cortex itself. How neural modulators, especially those activated during stress, such as norepinephrine (NE, regulate synaptic transmission and plasticity in this network is poorly understood. Here we show that NE inhibits synaptic transmission in both the subcortical and cortical input pathway but that sensory processing is biased towards the subcortical pathway. In addition binding of NE to β-adrenergic receptors further dissociates sensory processing in the LA. These findings suggest a network mechanism that shifts sensory balance towards the faster but more primitive subcortical input.

  4. Brainlab: A Python Toolkit to Aid in the Design, Simulation, and Analysis of Spiking Neural Networks with the NeoCortical Simulator.

    Science.gov (United States)

    Drewes, Rich; Zou, Quan; Goodman, Philip H

    2009-01-01

    Neuroscience modeling experiments often involve multiple complex neural network and cell model variants, complex input stimuli and input protocols, followed by complex data analysis. Coordinating all this complexity becomes a central difficulty for the experimenter. The Python programming language, along with its extensive library packages, has emerged as a leading "glue" tool for managing all sorts of complex programmatic tasks. This paper describes a toolkit called Brainlab, written in Python, that leverages Python's strengths for the task of managing the general complexity of neuroscience modeling experiments. Brainlab was also designed to overcome the major difficulties of working with the NCS (NeoCortical Simulator) environment in particular. Brainlab is an integrated model-building, experimentation, and data analysis environment for the powerful parallel spiking neural network simulator system NCS.

  5. Brainlab: a Python toolkit to aid in the design, simulation, and analysis of spiking neural networks with the NeoCortical Simulator

    Directory of Open Access Journals (Sweden)

    Richard P Drewes

    2009-05-01

    Full Text Available Neuroscience modeling experiments often involve multiple complex neural network and cell model variants, complex input stimuli and input protocols, followed by complex data analysis. Coordinating all this complexity becomes a central difficulty for the experimenter. The Python programming language, along with its extensive library packages, has emerged as a leading ``glue'' tool for managing all sorts of complex programmatictasks. This paper describes a toolkit called Brainlab, written in Python, that leverages Python's strengths for the task of managing the general complexity of neuroscience modeling experiments. Brainlab was also designed to overcome the major difficulties of working with the NCS environment in particular. Brainlab is an integrated model building, experimentation, and data analysis environment for the powerful parallel spiking neural network simulator system NCS (the NeoCortical Simulator.

  6. Functional connectivity of motor cortical network in patients with brachial plexus avulsion injury after contralateral cervical nerve transfer: a resting-state fMRI study

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Aihong; Cheng, Xiaoguang; Liang, Wei; Bai, Rongjie [The 4th Medical College of Peking University, Department of Radiology, Beijing Jishuitan Hospital, Xicheng Qu, Beijing (China); Wang, Shufeng; Xue, Yunhao; Li, Wenjun [The 4th Medical College of Peking University, Department of Hand Surgery, Beijing Jishuitan Hospital, Beijing (China)

    2017-03-15

    The purpose of this study is to assess the functional connectivity of the motor cortical network in patients with brachial plexus avulsion injury (BPAI) after contralateral C7 nerve transfer, using resting-state functional magnetic resonance imaging (RS-fMRI). Twelve patients with total brachial plexus root avulsion underwent RS-fMRI after contralateral C7 nerve transfer. Seventeen healthy volunteers were also included in this fMRI study as controls. The hand motor seed regions were defined as region of interests in the bilateral hemispheres. The seed-based functional connectivity was calculated in all the subjects. Differences in functional connectivity of the motor cortical network between patients and healthy controls were compared. The inter-hemispheric functional connectivity of the M1 areas was increased in patients with BPAI compared with the controls. The inter-hemispheric functional connectivity between the supplementary motor areas was reduced bilaterally. The resting-state inter-hemispheric functional connectivity of the bilateral M1 areas is altered in patients after contralateral C7 nerve transfer, suggesting a functional reorganization of cerebral cortex. (orig.)

  7. Functional connectivity of motor cortical network in patients with brachial plexus avulsion injury after contralateral cervical nerve transfer: a resting-state fMRI study

    International Nuclear Information System (INIS)

    Yu, Aihong; Cheng, Xiaoguang; Liang, Wei; Bai, Rongjie; Wang, Shufeng; Xue, Yunhao; Li, Wenjun

    2017-01-01

    The purpose of this study is to assess the functional connectivity of the motor cortical network in patients with brachial plexus avulsion injury (BPAI) after contralateral C7 nerve transfer, using resting-state functional magnetic resonance imaging (RS-fMRI). Twelve patients with total brachial plexus root avulsion underwent RS-fMRI after contralateral C7 nerve transfer. Seventeen healthy volunteers were also included in this fMRI study as controls. The hand motor seed regions were defined as region of interests in the bilateral hemispheres. The seed-based functional connectivity was calculated in all the subjects. Differences in functional connectivity of the motor cortical network between patients and healthy controls were compared. The inter-hemispheric functional connectivity of the M1 areas was increased in patients with BPAI compared with the controls. The inter-hemispheric functional connectivity between the supplementary motor areas was reduced bilaterally. The resting-state inter-hemispheric functional connectivity of the bilateral M1 areas is altered in patients after contralateral C7 nerve transfer, suggesting a functional reorganization of cerebral cortex. (orig.)

  8. Synergy by secretory phospholipase A2 and glutamate on inducing cell death and sustained arachidonic acid metabolic changes in primary cortical neuronal cultures

    DEFF Research Database (Denmark)

    Kolko, M; DeCoster, M A; de Turco, E B

    1996-01-01

    glutamate and sPLA2 from bee venom. sPLA2, at concentrations eliciting low neurotoxicity (acid into triacylglycerols. Free [3H]arachidonic acid accumulated at higher enzyme concentrations......, from Taipan snake venom. The NMDA receptor antagonist MK-801 blocked glutamate effects and partially inhibited sPLA2 OS2 but not sPLA2 from bee venom-induced arachidonic acid release. Thus, the synergy with glutamate and very low concentrations of exogenously added sPLA2 suggests a potential role......Secretory and cytosolic phospholipases A2 (sPLA2 and cPLA2) may contribute to the release of arachidonic acid and other bioactive lipids, which are modulators of synaptic function. In primary cortical neuron cultures, neurotoxic cell death and [3H]arachidonate metabolism was studied after adding...

  9. Animal social networks as substrate for cultural behavioural diversity.

    Science.gov (United States)

    Whitehead, Hal; Lusseau, David

    2012-02-07

    We used individual-based stochastic models to examine how social structure influences the diversity of socially learned behaviour within a non-human population. For continuous behavioural variables we modelled three forms of dyadic social learning, averaging the behavioural value of the two individuals, random transfer of information from one individual to the other, and directional transfer from the individual with highest behavioural value to the other. Learning had potential error. We also examined the transfer of categorical behaviour between individuals with random directionality and two forms of error, the adoption of a randomly chosen existing behavioural category or the innovation of a new type of behaviour. In populations without social structuring the diversity of culturally transmitted behaviour increased with learning error and population size. When the populations were structured socially either by making individuals members of permanent social units or by giving them overlapping ranges, behavioural diversity increased with network modularity under all scenarios, although the proportional increase varied considerably between continuous and categorical behaviour, with transmission mechanism, and population size. Although functions of the form e(c)¹(m)⁻(c)² + (c)³(Log(N)) predicted the mean increase in diversity with modularity (m) and population size (N), behavioural diversity could be highly unpredictable both between simulations with the same set of parameters, and within runs. Errors in social learning and social structuring generally promote behavioural diversity. Consequently, social learning may be considered to produce culture in populations whose social structure is sufficiently modular. Copyright © 2011 Elsevier Ltd. All rights reserved.

  10. Top-down feedback in an HMAX-like cortical model of object perception based on hierarchical Bayesian networks and belief propagation.

    Directory of Open Access Journals (Sweden)

    Salvador Dura-Bernal

    Full Text Available Hierarchical generative models, such as Bayesian networks, and belief propagation have been shown to provide a theoretical framework that can account for perceptual processes, including feedforward recognition and feedback modulation. The framework explains both psychophysical and physiological experimental data and maps well onto the hierarchical distributed cortical anatomy. However, the complexity required to model cortical processes makes inference, even using approximate methods, very computationally expensive. Thus, existing object perception models based on this approach are typically limited to tree-structured networks with no loops, use small toy examples or fail to account for certain perceptual aspects such as invariance to transformations or feedback reconstruction. In this study we develop a Bayesian network with an architecture similar to that of HMAX, a biologically-inspired hierarchical model of object recognition, and use loopy belief propagation to approximate the model operations (selectivity and invariance. Crucially, the resulting Bayesian network extends the functionality of HMAX by including top-down recursive feedback. Thus, the proposed model not only achieves successful feedforward recognition invariant to noise, occlusions, and changes in position and size, but is also able to reproduce modulatory effects such as illusory contour completion and attention. Our novel and rigorous methodology covers key aspects such as learning using a layerwise greedy algorithm, combining feedback information from multiple parents and reducing the number of operations required. Overall, this work extends an established model of object recognition to include high-level feedback modulation, based on state-of-the-art probabilistic approaches. The methodology employed, consistent with evidence from the visual cortex, can be potentially generalized to build models of hierarchical perceptual organization that include top-down and bottom

  11. Cultural intelligence and network organizations in society: Case of Tehran neighborhood councils

    Directory of Open Access Journals (Sweden)

    Salamzadeh Yashar

    2016-01-01

    Full Text Available Network communications is one of the modern ideas in the field of organizational behavior. On the other hand, the ability to communicate with employees and understand the cultural differences between them in a multicultural environment is one of the key skills that managers and employees need them in the nowadays organizations. These skills are introduced as cultural intelligence in organizations that have ability to respond to many challenges in multicultural environments. This article was aimed to analysis the relationship between cultural intelligence and network communication. These questionnaires were distributed between 134 members at the Tehran neighborhood councils. In order to analyzing data and concluding results, SPSS, and then Pearson correlation test were used. The research was done based on structural equation modeling (SEM. The result indicated that there was significant positive relationship between cultural intelligence and network communication. Also there was significant positive relationship between each dimension of cultural intelligence and network communication. Findings show that cultural intelligence is a basic factor in network communication and confirm the main hypothesis of this study which represents the existence of a positive and meaningful relation between cultural intelligence and network communication. Furthermore, the results show that considering this kind of intelligence, especially in network organizations which has a high ethnic and cultural variety, could be very useful for improve employees and managers communications.

  12. Understanding and Influencing Teaching and Learning Cultures at University: A Network Approach

    Science.gov (United States)

    Roxa, Torgny; Martensson, Katarina; Alveteg, Mattias

    2011-01-01

    Academic cultures might be perceived as conservative, at least in terms of development of teaching and learning. Through a lens of network theory this conceptual article analyses the pattern of pathways in which culture is constructed through negotiation of meaning. The perspective contributes to an understanding of culture construction and…

  13. Exploring Educational and Cultural Adaptation through Social Networking Sites

    Science.gov (United States)

    Ryan, Sherry D.; Magro, Michael J.; Sharp, Jason H.

    2011-01-01

    Social networking sites have seen tremendous growth and are widely used around the world. Nevertheless, the use of social networking sites in educational contexts is an under explored area. This paper uses a qualitative methodology, autoethnography, to investigate how social networking sites, specifically Facebook[TM], can help first semester…

  14. Role of GluR2 expression in AMPA-induced toxicity in cultured murine cerebral cortical neurons

    DEFF Research Database (Denmark)

    Jensen, Jette Bisgaard; Lund, Trine Meldgaard; Timmermann, Daniel B.

    2001-01-01

    of the Mg(2+) block of the NMDA receptor on AMPA-R stimulation. The involvement of Ca(2+) influx through AMPA-R was also examined. The number of neurons possessing Ca(2+)-permeable AMPA-R increased during culture development, concurrently with an increasing susceptibility for AMPA-induced toxicity during...

  15. The Ketone Body, β-Hydroxybutyrate Stimulates the Autophagic Flux and Prevents Neuronal Death Induced by Glucose Deprivation in Cortical Cultured Neurons.

    Science.gov (United States)

    Camberos-Luna, Lucy; Gerónimo-Olvera, Cristian; Montiel, Teresa; Rincon-Heredia, Ruth; Massieu, Lourdes

    2016-03-01

    Glucose is the major energy substrate in brain, however, during ketogenesis induced by starvation or prolonged hypoglycemia, the ketone bodies (KB), acetoacetate and β-hydroxybutyrate (BHB) can substitute for glucose. KB improve neuronal survival in diverse injury models, but the mechanisms by which KB prevent neuronal damage are still not well understood. In the present study we have investigated whether protection by the D isomer of BHB (D-BHB) against neuronal death induced by glucose deprivation (GD), is related to autophagy. Autophagy is a lysosomal-dependent degradation process activated during nutritional stress, which leads to the digestion of damaged proteins and organelles providing energy for cell survival. Results show that autophagy is activated in cortical cultured neurons during GD, as indicated by the increase in the levels of the lipidated form of the microtubule associated protein light chain 3 (LC3-II), and the number of autophagic vesicles. At early phases of glucose reintroduction (GR), the levels of p62 declined suggesting that the degradation of the autophagolysosomal content takes place at this time. In cultures exposed to GD and GR in the presence of D-BHB, the levels of LC3-II and p62 rapidly declined and remained low during GR, suggesting that the KB stimulates the autophagic flux preventing autophagosome accumulation and improving neuronal survival.

  16. Social Networking Sites Use and Cross Cultural Adaptation of Muslim Indonesian Students in Australian Universities: Valuing Cultural Diversity

    OpenAIRE

    Nuraryo, Imam

    2016-01-01

    Muslim Asian students have diverse specific needs when undertaking education in western country universities. Many international students use social networking sites as media for distance communication and helping in their adjustment.This study attempts to investigate the impact of using new social networking sites on the cross cultural adaptation process. Qualitative methodology was used for the study. Individual in-depth interviews were conducted for data collection. The study investigates ...

  17. Persistence and storage of activity patterns in spiking recurrent cortical networks: modulation of sigmoid signals by after-hyperpolarization currents and acetylcholine.

    Science.gov (United States)

    Palma, Jesse; Grossberg, Stephen; Versace, Massimiliano

    2012-01-01

    Many cortical networks contain recurrent architectures that transform input patterns before storing them in short-term memory (STM). Theorems in the 1970's showed how feedback signal functions in rate-based recurrent on-center off-surround networks control this process. A sigmoid signal function induces a quenching threshold below which inputs are suppressed as noise and above which they are contrast-enhanced before pattern storage. This article describes how changes in feedback signaling, neuromodulation, and recurrent connectivity may alter pattern processing in recurrent on-center off-surround networks of spiking neurons. In spiking neurons, fast, medium, and slow after-hyperpolarization (AHP) currents control sigmoid signal threshold and slope. Modulation of AHP currents by acetylcholine (ACh) can change sigmoid shape and, with it, network dynamics. For example, decreasing signal function threshold and increasing slope can lengthen the persistence of a partially contrast-enhanced pattern, increase the number of active cells stored in STM, or, if connectivity is distance-dependent, cause cell activities to cluster. These results clarify how cholinergic modulation by the basal forebrain may alter the vigilance of category learning circuits, and thus their sensitivity to predictive mismatches, thereby controlling whether learned categories code concrete or abstract features, as predicted by Adaptive Resonance Theory. The analysis includes global, distance-dependent, and interneuron-mediated circuits. With an appropriate degree of recurrent excitation and inhibition, spiking networks maintain a partially contrast-enhanced pattern for 800 ms or longer after stimuli offset, then resolve to no stored pattern, or to winner-take-all (WTA) stored patterns with one or multiple winners. Strengthening inhibition prolongs a partially contrast-enhanced pattern by slowing the transition to stability, while strengthening excitation causes more winners when the network

  18. Persistence and storage of activity patterns in spiking recurrent cortical networks:Modulation of sigmoid signals by after-hyperpolarization currents and acetylcholine

    Directory of Open Access Journals (Sweden)

    Jesse ePalma

    2012-06-01

    Full Text Available Many cortical networks contain recurrent architectures that transform input patterns before storing them in short-term memory (STM. Theorems in the 1970’s showed how feedback signal functions in rate-based recurrent on-center off-surround networks control this process. A sigmoid signal function induces a quenching threshold below which inputs are suppressed as noise and above which they are contrast-enhanced before pattern storage. This article describes how changes in feedback signaling, neuromodulation, and recurrent connectivity may alter pattern processing in recurrent on-center off-surround networks of spiking neurons. In spiking neurons, fast, medium, and slow after-hyperpolarization (AHP currents control sigmoid signal threshold and slope. Modulation of AHP currents by acetylcholine (ACh can change sigmoid shape and, with it, network dynamics. For example, decreasing signal function threshold and increasing slope can lengthen the persistence of a partially contrast-enhanced pattern, increase the number of active cells stored in STM, or, if connectivity is distance-dependent, cause cell activities to cluster. These results clarify how cholinergic modulation by the basal forebrain may alter the vigilance of category learning circuits, and thus their sensitivity to predictive mismatches, thereby controlling whether learned categories code concrete or abstract features, as predicted by Adaptive Resonance Theory. The analysis includes global, distance-dependent, and interneuron-mediated circuits. With an appropriate degree of recurrent excitation and inhibition, spiking networks maintain a partially contrast-enhanced pattern for 800 milliseconds or longer after stimuli offset, then resolve to no stored pattern, or to winner-take-all stored patterns with one or multiple winners. Strengthening inhibition prolongs a partially contrast-enhanced pattern by slowing the transition to stability, while strengthening excitation causes more winners

  19. Predicting workload profiles of brain-robot interface and electromygraphic neurofeedback with cortical resting-state networks: personal trait or task-specific challenge?

    Science.gov (United States)

    Fels, Meike; Bauer, Robert; Gharabaghi, Alireza

    2015-08-01

    Objective. Novel rehabilitation strategies apply robot-assisted exercises and neurofeedback tasks to facilitate intensive motor training. We aimed to disentangle task-specific and subject-related contributions to the perceived workload of these interventions and the related cortical activation patterns. Approach. We assessed the perceived workload with the NASA Task Load Index in twenty-one subjects who were exposed to two different feedback tasks in a cross-over design: (i) brain-robot interface (BRI) with haptic/proprioceptive feedback of sensorimotor oscillations related to motor imagery, and (ii) control of neuromuscular activity with feedback of the electromyography (EMG) of the same hand. We also used electroencephalography to examine the cortical activation patterns beforehand in resting state and during the training session of each task. Main results. The workload profile of BRI feedback differed from EMG feedback and was particularly characterized by the experience of frustration. The frustration level was highly correlated across tasks, suggesting subject-related relevance of this workload component. Those subjects who were specifically challenged by the respective tasks could be detected by an interhemispheric alpha-band network in resting state before the training and by their sensorimotor theta-band activation pattern during the exercise. Significance. Neurophysiological profiles in resting state and during the exercise may provide task-independent workload markers for monitoring and matching participants’ ability and task difficulty of neurofeedback interventions.

  20. Cultural Routes and Networks of Knowledge: the Identity and Promotion of Cultural Heritage. The Case Study of Piedmont

    OpenAIRE

    Silvia Beltramo

    2013-01-01

    The European project called “PER VIAM Pilgrims’ Routes In Action”, funded by the European Commission in 2012, is a significant opportunity of cultural and economic development for the whole Europe and also for the territory of Piedmont Region. The certainty of the need for transnational cooperation, which should create a network amongst the different territories in a perspective of working together and exchange of traveling, economic and cultural experiences – as well as best practices - nowa...

  1. Identification of neuronal network properties from the spectral analysis of calcium imaging signals in neuronal cultures.

    Science.gov (United States)

    Tibau, Elisenda; Valencia, Miguel; Soriano, Jordi

    2013-01-01

    Neuronal networks in vitro are prominent systems to study the development of connections in living neuronal networks and the interplay between connectivity, activity and function. These cultured networks show a rich spontaneous activity that evolves concurrently with the connectivity of the underlying network. In this work we monitor the development of neuronal cultures, and record their activity using calcium fluorescence imaging. We use spectral analysis to characterize global dynamical and structural traits of the neuronal cultures. We first observe that the power spectrum can be used as a signature of the state of the network, for instance when inhibition is active or silent, as well as a measure of the network's connectivity strength. Second, the power spectrum identifies prominent developmental changes in the network such as GABAA switch. And third, the analysis of the spatial distribution of the spectral density, in experiments with a controlled disintegration of the network through CNQX, an AMPA-glutamate receptor antagonist in excitatory neurons, reveals the existence of communities of strongly connected, highly active neurons that display synchronous oscillations. Our work illustrates the interest of spectral analysis for the study of in vitro networks, and its potential use as a network-state indicator, for instance to compare healthy and diseased neuronal networks.

  2. Distribution and Network of Basal Temporal Language Areas: A Study of the Combination of Electric Cortical Stimulation and Diffusion Tensor Imaging.

    Science.gov (United States)

    Enatsu, Rei; Kanno, Aya; Ookawa, Satoshi; Ochi, Satoko; Ishiai, Sumio; Nagamine, Takashi; Mikuni, Nobuhiro

    2017-10-01

    The basal temporal language area (BTLA) is considered to have several functions in language processing; however, its brain network is still unknown. This study investigated the distribution and networks of the BTLA using a combination of electric cortical stimulation and diffusion tensor imaging (DTI). 10 patients with intractable focal epilepsy who underwent presurgical evaluation with subdural electrodes were enrolled in this study (language dominant side: 6 patients, language nondominant side: 4 patients). Electric stimulation at 50 Hz was applied to the electrodes during Japanese sentence reading, morphograms (kanji) reading, and syllabograms (kana) reading tasks to identify the BTLA. DTI was used to identify the subcortical fibers originating from the BTLA found by electric stimulation. The BTLA was found in 6 patients who underwent implantation of the subdural electrodes in the dominant hemisphere. The BTLA was located anywhere between 20 mm and 56 mm posterior to the temporal tips. In 3 patients, electric stimulation of some or all areas within the BTLA induced disturbance in reading of kanji words only. DTI detected the inferior longitudinal fasciculus (ILF) in all patients and the uncinate fasciculus (UF) in 1 patient, originating from the BTLA. ILF was detected from both kanji-specific areas and kanji-nonspecific areas. This study indicates that the network of the BTLA is a part of a ventral stream and is mainly composed of the ILF, which acts as a critical structure for lexical retrieval. ILF is also associated with the specific processing of kanji words. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. Organizational Culture and Firms’ Internationalization, Innovativeness and Networking Behaviour: Hofstede Approach

    OpenAIRE

    Maja Szymura-Tyc; Michał Kucia

    2016-01-01

    Objective: The objective of this paper is to describe the features of firms’ organizational culture within four of Hofstede’s national culture dimensions and their potential relationships with internationalization, innovativeness and networking behaviour of firms. Research Design & Methods: This explorative quantitative research refers to results of an earlier study on internationalization, innovativeness and networking of firms in Poland. Descriptive statistics are used to depict the...

  4. Safety culture and subcontractor network governance in a complex safety critical project

    International Nuclear Information System (INIS)

    Oedewald, Pia; Gotcheva, Nadezhda

    2015-01-01

    In safety critical industries many activities are currently carried out by subcontractor networks. Nevertheless, there are few studies where the core dimensions of resilience would have been studied in safety critical network activities. This paper claims that engineering resilience into a system is largely about steering the development of culture of the system towards better ability to anticipate, monitor, respond and learn. Thus, safety culture literature has relevance in resilience engineering field. This paper analyzes practical and theoretical challenges in applying the concept of safety culture in a complex, dynamic network of subcontractors involved in the construction of a new nuclear power plant in Finland, Olkiluoto 3. The concept of safety culture is in focus since it is widely used in nuclear industry and bridges the scientific and practical interests. This paper approaches subcontractor networks as complex systems. However, the management model of the Olkiluoto 3 project is to a large degree a traditional top-down hierarchy, which creates a mismatch between the management approach and the characteristics of the system to be managed. New insights were drawn from network governance studies. - Highlights: • We studied a relevant topical subject safety culture in nuclear new build project. • We integrated safety science challenges and network governance studies. • We produced practicable insights in managing safety of subcontractor networks

  5. Effects of an Environmentally-relevant Mixture of Pyrethroid Insecticides on Spontaneous Activity in Primary Cortical Networks on Microelectrode Arrays

    Data.gov (United States)

    U.S. Environmental Protection Agency — This manuscript tests the hypothesis of dose additivity of an environmental mixture of pyrethriod insecticides at the level of network function, in vitro. The...

  6. Culture, agency and power: Theoretical reflections on informal economic networks and political process

    OpenAIRE

    Meagher, Kate

    2009-01-01

    Do network theory really offer a suitable concept for the theorization of informal processes of economic regulation and institutional change? This working paper challenges both essentialist and skeptical attitudes to networks through an examination of the positive and negative effects of network governance in contemporary societies in a range of regional contexts. The analysis focuses on three broad principles of non-state organization - culture, agency and power - and their role in shaping p...

  7. A Cross-Cultural Comparison of Korean and American Social Network Sites: Exploring Cultural Differences in Social Relationships and Self-Presentation

    Science.gov (United States)

    Cho, Seong Eun

    2010-01-01

    National culture is being challenged as societies evolve from their homogeneous origins. The theoretical base of this study uses two cultural dimensions, individualism-collectivism (Hofstede, 2001) and high-and low-context cultures (Hall, 1976), to unpack the effects of national culture on social network sites (SNSs). This study explores cultural…

  8. Differential regulation of synaptic and extrasynaptic α4 GABA(A) receptor populations by protein kinase A and protein kinase C in cultured cortical neurons.

    Science.gov (United States)

    Bohnsack, John Peyton; Carlson, Stephen L; Morrow, A Leslie

    2016-06-01

    The GABAA α4 subunit exists in two distinct populations of GABAA receptors. Synaptic GABAA α4 receptors are localized at the synapse and mediate phasic inhibitory neurotransmission, while extrasynaptic GABAA receptors are located outside of the synapse and mediate tonic inhibitory transmission. These receptors have distinct pharmacological and biophysical properties that contribute to interest in how these different subtypes are regulated under physiological and pathological states. We utilized subcellular fractionation procedures to separate these populations of receptors in order to investigate their regulation by protein kinases in cortical cultured neurons. Protein kinase A (PKA) activation decreases synaptic α4 expression while protein kinase C (PKC) activation increases α4 subunit expression, and these effects are associated with increased β3 S408/409 or γ2 S327 phosphorylation respectively. In contrast, PKA activation increases extrasynaptic α4 and δ subunit expression, while PKC activation has no effect. Our findings suggest synaptic and extrasynaptic GABAA α4 subunit expression can be modulated by PKA to inform the development of more specific therapeutics for neurological diseases that involve deficits in GABAergic transmission. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Targeted disruption of the Mast syndrome gene SPG21 in mice impairs hind limb function and alters axon branching in cultured cortical neurons

    Science.gov (United States)

    Soderblom, Cynthia; Stadler, Julia; Jupille, Henri; Blackstone, Craig; Shupliakov, Oleg

    2017-01-01

    Mast syndrome (SPG21) is a childhood-onset, autosomal recessive, complicated form of hereditary spastic paraplegia (HSP) characterized by dementia, thin corpus callosum, white matter abnormalities, and cerebellar and extrapyramidal signs in addition to spastic paraparesis. A nucleotide insertion resulting in premature truncation of the SPG21 gene product maspardin underlies this disorder, likely leading to loss of protein function. In this study, we generated SPG21−/− knockout mice by homologous recombination as a possible animal model for SPG21. Though SPG21−/− mice appeared normal at birth, within several months they developed gradually progressive hind limb dysfunction. Cerebral cortical neurons cultured from SPG21−/− mice exhibited significantly more axonal branching than neurons from wild-type animals, while comprehensive neuropathological analysis of SPG21−/− mice did not reveal definitive abnormalities. Since alterations in axon branching have been seen in neurons derived from animal models of other forms of HSP as well as motor neuron diseases, this may represent a common cellular pathogenic theme. PMID:20661613

  10. Quantitative immuno-electron microscopic analysis of depolarization-induced expression of PGC-1alpha in cultured rat visual cortical neurons.

    Science.gov (United States)

    Meng, Hui; Liang, Huan Ling; Wong-Riley, Margaret

    2007-10-17

    Peroxisome proliferator-activated receptor-gamma coactivator 1alpha (PGC- 1alpha) is a coactivator of nuclear receptors and other transcription factors that regulate several metabolic processes, including mitochondrial biogenesis, energy homeostasis, respiration, and gluconeogenesis. PGC-1alpha plays a vital role in stimulating genes that are important to oxidative metabolism and other mitochondrial functions in brown adipose tissue and skeleton muscles, but the significance of PGC-1alpha in the brain remains elusive. The goal of our present study was to determine by means of quantitative immuno-electron microscopy the expression of PGC-1alpha in cultured rat visual cortical neurons under normal conditions as well as after depolarizing stimulation for varying periods of time. Our results showed that: (a) PGC-1alpha was normally located in both the nucleus and the cytoplasm. In the nucleus, PGC-1alpha was associated mainly with euchromatin rather than heterochromatin, consistent with active involvement in transcription. In the cytoplasm, it was associated mainly with free ribosomes. (b) Neuronal depolarization by KCl for 0.5 h induced a significant increase in PGC-1alpha labeling density in both the nucleus and the cytoplasm (Pneuronal activity by synthesizing more proteins in the cytoplasm and translocating them to the nucleus for gene activation. PGC-1alpha level in neurons is, therefore, tightly regulated by neuronal activity.

  11. Fast, Na+ /K+ pump driven, steady-state transcytolemmal water exchange in neuronal tissue: A study of rat brain cortical cultures.

    Science.gov (United States)

    Bai, Ruiliang; Springer, Charles S; Plenz, Dietmar; Basser, Peter J

    2018-06-01

    Water homeostasis and transport play important roles in brain function (e.g., ion homeostasis, neuronal excitability, cell volume regulation, etc.). However, specific mechanisms of water transport across cell membranes in neuronal tissue have not been completely elaborated. The kinetics of transcytolemmal water exchange were measured in neuronal tissue using simultaneous, real-time fluorescence and nuclear magnetic resonance (NMR) measurements of perfused, active brain organotypic cortical cultures. Perfusion with a paramagnetic MRI contrast agent, gadoteridol, allows NMR determination of the unidirectional rate constant for steady-state cellular water efflux (k io ), and the mole fraction of intracellular water ( pi), related to the average cell volume (V). Changes in intracellular calcium concentration [Cai2+] were used as a proxy for neuronal activity and were monitored by fluorescence imaging. The k io value, averaged over all cultures (N = 99) at baseline, was 2.02 (±1.72) s -1 , indicating that on average, the equivalent of the entire intracellular water volume turns over twice each second. To probe possible molecular pathways, the specific Na + -K + -ATPase (NKA) inhibitor, ouabain (1 mM), was transiently introduced into the perfusate. This caused significant transient changes (N = 8): [Cai2+] rose ∼250%, V rose ∼89%, and k io fell ∼45%, with a metabolically active k io contribution probably eliminated by ouabain saturation. These results suggest that transcytolemmal water exchange in neuronal tissue involves mechanisms affected by NKA activity as well as passive pathways. The active pathway may account for half of the basal homeostatic water flux. Magn Reson Med 79:3207-3217, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  12. Social Network Culture Needs the Lens of Critical Trust Research

    OpenAIRE

    Dwyer , Natasha; Marsh , Stephen

    2015-01-01

    Part 2: Full Papers; International audience; Trust is essential to the success of the social networks that are aggregating and applying masses of information about us. In this position paper, we argue that a critical approach to exploring trust and social networks is required; this entails genuinely working in the interests of users and acknowledging the power relations and wider social context of this form of technology that is impacting more and more of our everyday life. Without a critical...

  13. Dynamic causal modeling revealed dysfunctional effective connectivity in both, the cortico-basal-ganglia and the cerebello-cortical motor network in writers' cramp

    Directory of Open Access Journals (Sweden)

    Inken Rothkirch

    demonstrates abnormal reciprocal excitatory connectivity in the cortico-cerebellar circuitry. These results highlight the dysfunctional cerebello-cortical as well as basalganglio-cortical interaction in WC. Keywords: Dynamic causal modeling, Focal hand dystonia, Writer's cramp, Network disorder, Cerebellum

  14. The interplay between social networks and culture: theoretically and among whales and dolphins.

    Science.gov (United States)

    Cantor, Mauricio; Whitehead, Hal

    2013-05-19

    Culture is increasingly being understood as a driver of mammalian phenotypes. Defined as group-specific behaviour transmitted by social learning, culture is shaped by social structure. However, culture can itself affect social structure if individuals preferentially interact with others whose behaviour is similar, or cultural symbols are used to mark groups. Using network formalism, this interplay can be depicted by the coevolution of nodes and edges together with the coevolution of network topology and transmission patterns. We review attempts to model the links between the spread, persistence and diversity of culture and the network topology of non-human societies. We illustrate these processes using cetaceans. The spread of socially learned begging behaviour within a population of bottlenose dolphins followed the topology of the social network, as did the evolution of the song of the humpback whale between breeding areas. In three bottlenose dolphin populations, individuals preferentially associated with animals using the same socially learned foraging behaviour. Homogeneous behaviour within the tight, nearly permanent social structures of the large matrilineal whales seems to result from transmission bias, with cultural symbols marking social structures. We recommend the integration of studies of culture and society in species for which social learning is an important determinant of behaviour.

  15. Recently learned foreign abstract and concrete nouns are represented in distinct cortical networks similar to the native language.

    Science.gov (United States)

    Mayer, Katja M; Macedonia, Manuela; von Kriegstein, Katharina

    2017-09-01

    In the native language, abstract and concrete nouns are represented in distinct areas of the cerebral cortex. Currently, it is unknown whether this is also the case for abstract and concrete nouns of a foreign language. Here, we taught adult native speakers of German 45 abstract and 45 concrete nouns of a foreign language. After learning the nouns for 5 days, participants performed a vocabulary translation task during functional magnetic resonance imaging. Translating abstract nouns in contrast to concrete nouns elicited responses in regions that are also responsive to abstract nouns in the native language: the left inferior frontal gyrus and the left middle and superior temporal gyri. Concrete nouns elicited larger responses in the angular gyri bilaterally and the left parahippocampal gyrus than abstract nouns. The cluster in the left angular gyrus showed psychophysiological interaction (PPI) with the left lingual gyrus. The left parahippocampal gyrus showed PPI with the posterior cingulate cortex. Similar regions have been previously found for concrete nouns in the native language. The results reveal similarities in the cortical representation of foreign language nouns with the representation of native language nouns that already occur after 5 days of vocabulary learning. Furthermore, we showed that verbal and enriched learning methods were equally suitable to teach foreign abstract and concrete nouns. Hum Brain Mapp 38:4398-4412, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  16. Neurophysiology of the cortical pain network: revisiting the role of S1 in subjective pain perception via standardized low-resolution brain electromagnetic tomography (sLORETA).

    Science.gov (United States)

    Nir, Rony-Reuven; Lev, Rina; Moont, Ruth; Granovsky, Yelena; Sprecher, Elliot; Yarnitsky, David

    2008-11-01

    Multiple studies have supported the usefulness of standardized low-resolution brain electromagnetic tomography (sLORETA) in localizing generators of scalp-recorded potentials. The current study implemented sLORETA on pain event-related potentials, primarily aiming at validating this technique for pain research by identifying well-known pain-related regions. Subsequently, we pointed at investigating the still-debated and ambiguous topic of pain intensity coding at these regions, focusing on their relative impact on subjective pain perception. sLORETA revealed significant activations of the bilateral primary somatosensory (SI) and anterior cingulate cortices and of the contralateral operculoinsular and dorsolateral prefrontal (DLPFC) cortices (P < .05 for each). Activity of these regions, excluding DLPFC, correlated with subjective numerical pain scores (P < .05 for each). However, a multivariate regression analysis (R = .80; P = .024) distinguished the contralateral SI as the only region whose activation magnitude significantly predicted the subjective perception of noxious stimuli (P = .020), further substantiated by a reduced regression model (R = .75, P = .008). Based on (1) correspondence of the pain-activated regions identified by sLORETA with the acknowledged imaging-based pain-network and (2) the contralateral SI proving to be the most contributing region in pain intensity coding, we found sLORETA to be an appropriate tool for relevant pain research and further substantiated the role of SI in pain perception. Because the literature of pain intensity coding offers inconsistent findings, the current article used a novel tool for revisiting this controversial issue. Results suggest that it is the activation magnitude of SI, which solely establishes the significant correlation with subjective pain ratings, in accordance with the classical clinical thinking, relating SI lesions to diminished perception of pain. Although this study cannot support a causal relation

  17. Lacunar-canalicular network in femoral cortical bone is reduced in aged women and is predominantly due to a loss of canalicular porosity

    Directory of Open Access Journals (Sweden)

    A.M. Ashique

    2017-12-01

    Full Text Available The lacunar-canalicular network (LCN of bone contains osteocytes and their dendritic extensions, which allow for intercellular communication, and are believed to serve as the mechanosensors that coordinate the processes of bone modeling and remodeling. Imbalances in remodeling, for example, are linked to bone disease, including fragility associated with aging. We have reported that there is a reduction in scale for one component of the LCN, osteocyte lacunar volume, across the human lifespan in females. In the present study, we explore the hypothesis that canalicular porosity also declines with age. To visualize the LCN and to determine how its components are altered with aging, we examined samples from young (age: 20–23 y; n = 5 and aged (age: 70–86 y; n = 6 healthy women donors utilizing a fluorescent labelling technique in combination with confocal laser scanning microscopy. A large cross-sectional area of cortical bone spanning the endosteal to periosteal surfaces from the anterior proximal femoral shaft was examined in order to account for potential trans-cortical variation in the LCN. Overall, we found that LCN areal fraction was reduced by 40.6% in the samples from aged women. This reduction was due, in part, to a reduction in lacunar density (21.4% decline in lacunae number per given area of bone, but much more so due to a 44.6% decline in canalicular areal fraction. While the areal fraction of larger vascular canals was higher in endosteal vs. periosteal regions for both age groups, no regional differences were observed in the areal fractions of the LCN and its components for either age group. Our data indicate that the LCN is diminished in aged women, and is largely due to a decline in the canalicular areal fraction, and that, unlike vascular canal porosity, this diminished LCN is uniform across the cortex.

  18. Drugs for stroke: action of nitrone (Z)-N-(2-bromo-5-hydroxy-4-methoxybenzylidene)-2-methylpropan-2-amine oxide on rat cortical neurons in culture subjected to oxygen-glucose-deprivation.

    Science.gov (United States)

    Arce, Carmen; Diaz-Castroverde, Sabela; Canales, María J; Marco-Contelles, José; Samadi, Abdelouahid; Oset-Gasque, María J; González, María P

    2012-09-01

    The action of (Z)-N-(2-bromo-5-hydroxy-4-methoxybenzylidene)-2-methylpropan-2-amine oxide (RP6) on rat cortical neurons in culture, under oxygen-glucose-deprivation conditions, is reported. Cortical neurons in culture were treated during 1 h with OGD. After, they were placed under normal conditions during 24 h (reperfusion) in absence and presence of RP6. Different parameters were measured under each condition (control, 1 h OGD and 1 h OGD + reperfusion in absence and presence of RP6). RP6 protects neurons against ROS generation, lipid peroxidation levels, LDH release and mitochondrial membrane potential alteration, when administered during reperfusion after the OGD damage. Consequently, these results show that nitrone RP6 protects cells against ischemia injury produced during the reoxygenation, and could be a potential drug for the ictus therapy. Copyright © 2012. Published by Elsevier Masson SAS.

  19. Transcranial Direct Current Stimulation Targeting Primary Motor Versus Dorsolateral Prefrontal Cortices: Proof-of-Concept Study Investigating Functional Connectivity of Thalamocortical Networks Specific to Sensory-Affective Information Processing.

    Science.gov (United States)

    Sankarasubramanian, Vishwanath; Cunningham, David A; Potter-Baker, Kelsey A; Beall, Erik B; Roelle, Sarah M; Varnerin, Nicole M; Machado, Andre G; Jones, Stephen E; Lowe, Mark J; Plow, Ela B

    2017-04-01

    The pain matrix is comprised of an extensive network of brain structures involved in sensory and/or affective information processing. The thalamus is a key structure constituting the pain matrix. The thalamus serves as a relay center receiving information from multiple ascending pathways and relating information to and from multiple cortical areas. However, it is unknown how thalamocortical networks specific to sensory-affective information processing are functionally integrated. Here, in a proof-of-concept study in healthy humans, we aimed to understand this connectivity using transcranial direct current stimulation (tDCS) targeting primary motor (M1) or dorsolateral prefrontal cortices (DLPFC). We compared changes in functional connectivity (FC) with DLPFC tDCS to changes in FC with M1 tDCS. FC changes were also compared to further investigate its relation with individual's baseline experience of pain. We hypothesized that resting-state FC would change based on tDCS location and would represent known thalamocortical networks. Ten right-handed individuals received a single application of anodal tDCS (1 mA, 20 min) to right M1 and DLPFC in a single-blind, sham-controlled crossover study. FC changes were studied between ventroposterolateral (VPL), the sensory nucleus of thalamus, and cortical areas involved in sensory information processing and between medial dorsal (MD), the affective nucleus, and cortical areas involved in affective information processing. Individual's perception of pain at baseline was assessed using cutaneous heat pain stimuli. We found that anodal M1 tDCS and anodal DLPFC tDCS both increased FC between VPL and sensorimotor cortices, although FC effects were greater with M1 tDCS. Similarly, anodal M1 tDCS and anodal DLPFC tDCS both increased FC between MD and motor cortices, but only DLPFC tDCS modulated FC between MD and affective cortices, like DLPFC. Our findings suggest that M1 stimulation primarily modulates FC of sensory networks

  20. Reduced topological efficiency in cortical-basal Ganglia motor network of Parkinson's disease: a resting state fMRI study.

    Science.gov (United States)

    Wei, Luqing; Zhang, Jiuquan; Long, Zhiliang; Wu, Guo-Rong; Hu, Xiaofei; Zhang, Yanling; Wang, Jian

    2014-01-01

    Parkinson's disease (PD) is mainly characterized by dopamine depletion of the cortico-basal ganglia (CBG) motor circuit. Given that dopamine dysfunction could affect functional brain network efficiency, the present study utilized resting-state fMRI (rs-fMRI) and graph theoretical approach to investigate the topological efficiency changes of the CBG motor network in patients with PD during a relatively hypodopaminergic state (12 hours after a last dose of dopamimetic treatment). We found that PD compared with controls had remarkable decreased efficiency in the CBG motor network, with the most pronounced changes observed in rostral supplementary motor area (pre-SMA), caudal SMA (SMA-proper), primary motor cortex (M1), primary somatosensory cortex (S1), thalamus (THA), globus pallidus (GP), and putamen (PUT). Furthermore, reduced efficiency in pre-SMA, M1, THA and GP was significantly correlated with Unified Parkinson's Disease Rating Scale (UPDRS) motor scores in PD patients. Together, our results demonstrate that individuals with PD appear to be less effective at information transfer within the CBG motor pathway, which provides a novel perspective on neurobiological explanation for the motor symptoms in patients. These findings are in line with the pathophysiology of PD, suggesting that network efficiency metrics may be used to identify and track the pathology of PD.

  1. Horizontal integration and cortical dynamics.

    Science.gov (United States)

    Gilbert, C D

    1992-07-01

    We have discussed several results that lead to a view that cells in the visual system are endowed with dynamic properties, influenced by context, expectation, and long-term modifications of the cortical network. These observations will be important for understanding how neuronal ensembles produce a system that perceives, remembers, and adapts to injury. The advantage to being able to observe changes at early stages in a sensory pathway is that one may be able to understand the way in which neuronal ensembles encode and represent images at the level of their receptive field properties, of cortical topographies, and of the patterns of connections between cells participating in a network.

  2. Not only … but also: REM sleep creates and NREM Stage 2 instantiates landmark junctions in cortical memory networks.

    Science.gov (United States)

    Llewellyn, Sue; Hobson, J Allan

    2015-07-01

    This article argues both rapid eye movement (REM) and non-rapid eye movement (NREM) sleep contribute to overnight episodic memory processes but their roles differ. Episodic memory may have evolved from memory for spatial navigation in animals and humans. Equally, mnemonic navigation in world and mental space may rely on fundamentally equivalent processes. Consequently, the basic spatial network characteristics of pathways which meet at omnidirectional nodes or junctions may be conserved in episodic brain networks. A pathway is formally identified with the unidirectional, sequential phases of an episodic memory. In contrast, the function of omnidirectional junctions is not well understood. In evolutionary terms, both animals and early humans undertook tours to a series of landmark junctions, to take advantage of resources (food, water and shelter), whilst trying to avoid predators. Such tours required memory for emotionally significant landmark resource-place-danger associations and the spatial relationships amongst these landmarks. In consequence, these tours may have driven the evolution of both spatial and episodic memory. The environment is dynamic. Resource-place associations are liable to shift and new resource-rich landmarks may be discovered, these changes may require re-wiring in neural networks. To realise these changes, REM may perform an associative, emotional encoding function between memory networks, engendering an omnidirectional landmark junction which is instantiated in the cortex during NREM Stage 2. In sum, REM may preplay associated elements of past episodes (rather than replay individual episodes), to engender an unconscious representation which can be used by the animal on approach to a landmark junction in wake. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Practice and Learning: Spatiotemporal Differences in Thalamo-Cortical-Cerebellar Networks Engagement across Learning Phases in Schizophrenia.

    Science.gov (United States)

    Korostil, Michele; Remington, Gary; McIntosh, Anthony Randal

    2016-01-01

    Understanding how practice mediates the transition of brain-behavior networks between early and later stages of learning is constrained by the common approach to analysis of fMRI data. Prior imaging studies have mostly relied on a single scan, and parametric, task-related analyses. Our experiment incorporates a multisession fMRI lexicon-learning experiment with multivariate, whole-brain analysis to further knowledge of the distributed networks supporting practice-related learning in schizophrenia (SZ). Participants with SZ were compared with healthy control (HC) participants as they learned a novel lexicon during two fMRI scans over a several day period. All participants were trained to equal task proficiency prior to scanning. Behavioral-Partial Least Squares, a multivariate analytic approach, was used to analyze the imaging data. Permutation testing was used to determine statistical significance and bootstrap resampling to determine the reliability of the findings. With practice, HC participants transitioned to a brain-accuracy network incorporating dorsostriatal regions in late-learning stages. The SZ participants did not transition to this pattern despite comparable behavioral results. Instead, successful learners with SZ were differentiated primarily on the basis of greater engagement of perceptual and perceptual-integration brain regions. There is a different spatiotemporal unfolding of brain-learning relationships in SZ. In SZ, given the same amount of practice, the movement from networks suggestive of effortful learning toward subcortically driven procedural one differs from HC participants. Learning performance in SZ is driven by varying levels of engagement in perceptual regions, which suggests perception itself is impaired and may impact downstream, "higher level" cognition.

  4. Activity patterns of cultured neural networks on micro electrode arrays

    NARCIS (Netherlands)

    Rutten, Wim; van Pelt, J.

    2001-01-01

    A hybrid neuro-electronic interface is a cell-cultured micro electrode array, acting as a neural information transducer for stimulation and/or recording of neural activity in the brain or the spinal cord (ventral motor region or dorsal sensory region). It consists of an array of micro electrodes on

  5. The co-evolution of cultures, social network communities, and agent locations in an extension of Axelrod’s model of cultural dissemination

    Science.gov (United States)

    Pfau, Jens; Kirley, Michael; Kashima, Yoshihisa

    2013-01-01

    We introduce a variant of the Axelrod model of cultural dissemination in which agents change their physical locations, social links, and cultures. Numerical simulations are used to investigate the evolution of social network communities and the cultural diversity within and between these communities. An analysis of the simulation results shows that an initial peak in the cultural diversity within network communities is evident before agents segregate into a final configuration of culturally homogeneous communities. Larger long-range interaction probabilities facilitate the initial emergence of culturally diverse network communities, which leads to a more pronounced initial peak in cultural diversity within communities. At equilibrium, the number of communities, and hence cultures, increases when the initial cultural diversity increases. However, the number of communities decreases when the lattice size or population density increases. A phase transition between two regimes of initial cultural diversity is evident. For initial diversities below a critical value, a single network community and culture emerges that dominates the population. For initial diversities above the critical value, multiple culturally homogeneous communities emerge. The critical value of initial diversity at which this transition occurs increases with increasing lattice size and population density and generally with increasing absolute population size. We conclude that larger initial diversities promote cultural heterogenization, while larger lattice sizes, population densities, and in fact absolute population sizes promote homogenization.

  6. Are the users of social networking sites homogeneous? A cross-cultural study.

    Science.gov (United States)

    Alarcón-Del-Amo, María-Del-Carmen; Gómez-Borja, Miguel-Ángel; Lorenzo-Romero, Carlota

    2015-01-01

    The growing use of Social Networking Sites (SNS) around the world has made it necessary to understand individuals' behaviors within these sites according to different cultures. Based on a comparative study between two different European countries (The Netherlands versus Spain), a comparison of typologies of networked Internet users has been obtained through a latent segmentation approach. These typologies are based on the frequency with which users perform different activities, their socio-demographic variables, and experience in social networking and interaction patterns. The findings show new insights regarding international segmentation in order to analyse SNS user behaviors in both countries. These results are relevant for marketing strategists eager to use the communication potential of networked individuals and for marketers willing to explore the potential of online networking as a low cost and a highly efficient alternative to traditional networking approaches. For most businesses, expert users could be valuable opinion leaders and potential brand influencers.

  7. Are the users of social networking sites homogeneous? A cross-cultural study

    Science.gov (United States)

    Alarcón-del-Amo, María-del-Carmen; Gómez-Borja, Miguel-Ángel; Lorenzo-Romero, Carlota

    2015-01-01

    The growing use of Social Networking Sites (SNS) around the world has made it necessary to understand individuals' behaviors within these sites according to different cultures. Based on a comparative study between two different European countries (The Netherlands versus Spain), a comparison of typologies of networked Internet users has been obtained through a latent segmentation approach. These typologies are based on the frequency with which users perform different activities, their socio-demographic variables, and experience in social networking and interaction patterns. The findings show new insights regarding international segmentation in order to analyse SNS user behaviors in both countries. These results are relevant for marketing strategists eager to use the communication potential of networked individuals and for marketers willing to explore the potential of online networking as a low cost and a highly efficient alternative to traditional networking approaches. For most businesses, expert users could be valuable opinion leaders and potential brand influencers. PMID:26321971

  8. Are the users of Social Networking Sites homogeneous? A cross-cultural study

    Directory of Open Access Journals (Sweden)

    MARÍA-DEL-CARMEN eALARCÓN-DEL-AMO

    2015-08-01

    Full Text Available The growing use of Social Networking Sites (SNS around the world has made it necessary to understand individuals’ behaviours within these sites according to different cultures. Based on a comparative study between two different European countries (The Netherlands versus Spain, a comparison of typologies of networked Internet users has been obtained through a latent segmentation approach. These typologies are based on the frequency with which users perform different activities, their socio-demographic variables, and experience in social networking and interaction patterns. The findings show new insights regarding international segmentation in order to analyse SNS user behaviours in both countries. These results are relevant for marketing strategists eager to use the communication potential of networked individuals and for marketers willing to explore the potential of online networking as a low cost and a highly efficient alternative to traditional networking approaches. For most businesses, expert users could be valuable opinion leaders and potential brand influencers.

  9. Rich-Club Organization in Effective Connectivity among Cortical Neurons.

    Science.gov (United States)

    Nigam, Sunny; Shimono, Masanori; Ito, Shinya; Yeh, Fang-Chin; Timme, Nicholas; Myroshnychenko, Maxym; Lapish, Christopher C; Tosi, Zachary; Hottowy, Pawel; Smith, Wesley C; Masmanidis, Sotiris C; Litke, Alan M; Sporns, Olaf; Beggs, John M

    2016-01-20

    The performance of complex networks, like the brain, depends on how effectively their elements communicate. Despite the importance of communication, it is virtually unknown how information is transferred in local cortical networks, consisting of hundreds of closely spaced neurons. To address this, it is important to record simultaneously from hundreds of neurons at a spacing that matches typical axonal connection distances, and at a temporal resolution that matches synaptic delays. We used a 512-electrode array (60 μm spacing) to record spontaneous activity at 20 kHz from up to 500 neurons simultaneously in slice cultures of mouse somatosensory cortex for 1 h at a time. We applied a previously validated version of transfer entropy to quantify information transfer. Similar to in vivo reports, we found an approximately lognormal distribution of firing rates. Pairwise information transfer strengths also were nearly lognormally distributed, similar to reports of synaptic strengths. Some neurons transferred and received much more information than others, which is consistent with previous predictions. Neurons with the highest outgoing and incoming information transfer were more strongly connected to each other than chance, thus forming a "rich club." We found similar results in networks recorded in vivo from rodent cortex, suggesting the generality of these findings. A rich-club structure has been found previously in large-scale human brain networks and is thought to facilitate communication between cortical regions. The discovery of a small, but information-rich, subset of neurons within cortical regions suggests that this population will play a vital role in communication, learning, and memory. Significance statement: Many studies have focused on communication networks between cortical brain regions. In contrast, very few studies have examined communication networks within a cortical region. This is the first study to combine such a large number of neurons (several

  10. Rich-Club Organization in Effective Connectivity among Cortical Neurons

    Science.gov (United States)

    Shimono, Masanori; Ito, Shinya; Yeh, Fang-Chin; Timme, Nicholas; Myroshnychenko, Maxym; Lapish, Christopher C.; Tosi, Zachary; Hottowy, Pawel; Smith, Wesley C.; Masmanidis, Sotiris C.; Litke, Alan M.; Sporns, Olaf; Beggs, John M.

    2016-01-01

    The performance of complex networks, like the brain, depends on how effectively their elements communicate. Despite the importance of communication, it is virtually unknown how information is transferred in local cortical networks, consisting of hundreds of closely spaced neurons. To address this, it is important to record simultaneously from hundreds of neurons at a spacing that matches typical axonal connection distances, and at a temporal resolution that matches synaptic delays. We used a 512-electrode array (60 μm spacing) to record spontaneous activity at 20 kHz from up to 500 neurons simultaneously in slice cultures of mouse somatosensory cortex for 1 h at a time. We applied a previously validated version of transfer entropy to quantify information transfer. Similar to in vivo reports, we found an approximately lognormal distribution of firing rates. Pairwise information transfer strengths also were nearly lognormally distributed, similar to reports of synaptic strengths. Some neurons transferred and received much more information than others, which is consistent with previous predictions. Neurons with the highest outgoing and incoming information transfer were more strongly connected to each other than chance, thus forming a “rich club.” We found similar results in networks recorded in vivo from rodent cortex, suggesting the generality of these findings. A rich-club structure has been found previously in large-scale human brain networks and is thought to facilitate communication between cortical regions. The discovery of a small, but information-rich, subset of neurons within cortical regions suggests that this population will play a vital role in communication, learning, and memory. SIGNIFICANCE STATEMENT Many studies have focused on communication networks between cortical brain regions. In contrast, very few studies have examined communication networks within a cortical region. This is the first study to combine such a large number of neurons (several

  11. Ethanol affects network activity in cultured rat hippocampus: mediation by potassium channels.

    Directory of Open Access Journals (Sweden)

    Eduard Korkotian

    Full Text Available The effects of ethanol on neuronal network activity were studied in dissociated cultures of rat hippocampus. Exposure to low (0.25-0.5% ethanol concentrations caused an increase in synchronized network spikes, and a decrease in the duration of individual spikes. Ethanol also caused an increase in rate of miniature spontaneous excitatory postsynaptic currents. Higher concentrations of ethanol eliminated network spikes. These effects were reversible upon wash. The effects of the high, but not the low ethanol were blocked by the GABA antagonist bicuculline. The enhancing action of low ethanol was blocked by apamin, an SK potassium channel antagonist, and mimicked by 1-EBIO, an SK channel opener. It is proposed that in cultured hippocampal networks low concentration of ethanol is associated with SK channel activity, rather than the GABAergic receptor.

  12. THE PREPARATION OF A SPECIALIST IN NETWORKING CULTURAL-EDUCATIONAL SPACE OF UNIVERSITY

    Directory of Open Access Journals (Sweden)

    Zinaida Kekeeva

    2015-12-01

    Full Text Available The article deals with specialist preparation problems in networking cultural-educational space of the University. The authors consider the role of networking technologies in quality improvement of educational services in the conditions of the international cooperation. They also substantiate the process of entering the future experts in the working environment, the formation of their professional and personal competencies. The article reveals priority areas of training new generation specialists in the cultural and educational space of the university taking into account modern educational trends in the world.

  13. A combined Bodian-Nissl stain for improved network analysis in neuronal cell culture.

    Science.gov (United States)

    Hightower, M; Gross, G W

    1985-11-01

    Bodian and Nissl procedures were combined to stain dissociated mouse spinal cord cells cultured on coverslips. The Bodian technique stains fine neuronal processes in great detail as well as an intracellular fibrillar network concentrated around the nucleus and in proximal neurites. The Nissl stain clearly delimits neuronal cytoplasm in somata and in large dendrites. A combination of these techniques allows the simultaneous depiction of neuronal perikarya and all afferent and efferent processes. Costaining with little background staining by either procedure suggests high specificity for neurons. This procedure could be exploited for routine network analysis of cultured neurons.

  14. How the human brain goes virtual: distinct cortical regions of the person-processing network are involved in self-identification with virtual agents.

    Science.gov (United States)

    Ganesh, Shanti; van Schie, Hein T; de Lange, Floris P; Thompson, Evan; Wigboldus, Daniël H J

    2012-07-01

    Millions of people worldwide engage in online role-playing with their avatar, a virtual agent that represents the self. Previous behavioral studies have indicated that many gamers identify more strongly with their avatar than with their biological self. Through their avatar, gamers develop social networks and learn new social-cognitive skills. The cognitive neurosciences have yet to identify the neural processes that underlie self-identification with these virtual agents. We applied functional neuroimaging to 22 long-term online gamers and 21 nongaming controls, while they rated personality traits of self, avatar, and familiar others. Strikingly, neuroimaging data revealed greater avatar-referential cortical activity in the left inferior parietal lobe, a region associated with self-identification from a third-person perspective. The magnitude of this brain activity correlated positively with the propensity to incorporate external body enhancements into one's bodily identity. Avatar-referencing furthermore recruited greater activity in the rostral anterior cingulate gyrus, suggesting relatively greater emotional self-involvement with one's avatar. Post-scanning behavioral data revealed superior recognition memory for avatar relative to others. Interestingly, memory for avatar positively covaried with play duration. These findings significantly advance our knowledge about the brain's plasticity to self-identify with virtual agents and the human cognitive-affective potential to live and learn in virtual worlds.

  15. Networking and cultural differences in Human Resource Management: The Case of Kazakhstan

    OpenAIRE

    Altynbekov, Mardan

    2014-01-01

    The new emerging markets are becoming significant players in global market in recent decade. This study follows current pace in employing institutional theory to explore the specific pressures and factors makes networking essential in Human Resource Management in different countries. The study is a detailed qualitative analysis of networking and cultural differences in Kazakhstan, a country with very different value and government structure. Contrary to simplistic expectations, Kazakhstan sho...

  16. Low and then high frequency oscillations of distinct right cortical networks are progressively enhanced by medium and long term Satyananda Yoga meditation practice

    Directory of Open Access Journals (Sweden)

    John eThomas

    2014-06-01

    Full Text Available Meditation proficiency is related to trait-like (learned effects on brain function, developed over time. Previous studies show increases in EEG power in lower frequency bands (theta, alpha in experienced meditators in both meditation states and baseline conditions. Higher gamma band power has been found in advanced Buddhist meditators, yet it is not known if this occurs in Yoga meditation practices. This study used eLORETA to compare differences in cortical source activity underlying scalp EEG from intermediate (mean experience 4 years and advanced (mean experience 30 years Australian meditators from the Satyananda Yoga tradition during a body-steadiness meditation, mantra meditation and non-meditation mental calculation condition. Intermediate Yoga meditators showed greater source activity in low frequencies (particularly theta and alpha1 during mental calculation, body-steadiness and mantra meditation. A similar spatial pattern of significant differences was found in all conditions but the number of significant voxels was double during body-steadiness and mantra meditation than in the non-meditation (calculation condition. These differences were greatest in right (R superior frontal and R precentral gyri and extended back to include the R parietal and occipital lobes. Advanced Yoga meditators showed greater activity in high frequencies (beta and especially gamma in all conditions but greatly expanded during meditation practice. Across all conditions (meditation and non-meditation differences were greatest in the same regions; R insula, R inferior frontal gyrus and R anterior temporal lobe. Distinct R core networks were identified in alpha1 (8-10 Hz and gamma (25-42 Hz bands respectively. The voxels recruited to these networks greatly expanded during meditation practice to include homologous regions of the left hemisphere. Functional interpretation parallels traditionally described stages of development in Yoga proficiency.

  17. Monitoring Different Phonological Parameters of Sign Language Engages the Same Cortical Language Network but Distinctive Perceptual Ones.

    Science.gov (United States)

    Cardin, Velia; Orfanidou, Eleni; Kästner, Lena; Rönnberg, Jerker; Woll, Bencie; Capek, Cheryl M; Rudner, Mary

    2016-01-01

    The study of signed languages allows the dissociation of sensorimotor and cognitive neural components of the language signal. Here we investigated the neurocognitive processes underlying the monitoring of two phonological parameters of sign languages: handshape and location. Our goal was to determine if brain regions processing sensorimotor characteristics of different phonological parameters of sign languages were also involved in phonological processing, with their activity being modulated by the linguistic content of manual actions. We conducted an fMRI experiment using manual actions varying in phonological structure and semantics: (1) signs of a familiar sign language (British Sign Language), (2) signs of an unfamiliar sign language (Swedish Sign Language), and (3) invented nonsigns that violate the phonological rules of British Sign Language and Swedish Sign Language or consist of nonoccurring combinations of phonological parameters. Three groups of participants were tested: deaf native signers, deaf nonsigners, and hearing nonsigners. Results show that the linguistic processing of different phonological parameters of sign language is independent of the sensorimotor characteristics of the language signal. Handshape and location were processed by different perceptual and task-related brain networks but recruited the same language areas. The semantic content of the stimuli did not influence this process, but phonological structure did, with nonsigns being associated with longer RTs and stronger activations in an action observation network in all participants and in the supramarginal gyrus exclusively in deaf signers. These results suggest higher processing demands for stimuli that contravene the phonological rules of a signed language, independently of previous knowledge of signed languages. We suggest that the phonological characteristics of a language may arise as a consequence of more efficient neural processing for its perception and production.

  18. Inferring cultural regions from correlation networks of given baby names

    Science.gov (United States)

    Pomorski, Mateusz; Krawczyk, Małgorzata J.; Kułakowski, Krzysztof; Kwapień, Jarosław; Ausloos, Marcel

    2016-03-01

    We report investigations on the statistical characteristics of the baby names given between 1910 and 2010 in the United States of America. For each year, the 100 most frequent names in the USA are sorted out. For these names, the correlations between the names profiles are calculated for all pairs of states (minus Hawaii and Alaska). The correlations are used to form a weighted network which is found to vary mildly in time. In fact, the structure of communities in the network remains quite stable till about 1980. The goal is that the calculated structure approximately reproduces the usually accepted geopolitical regions: the Northeast, the South, and the "Midwest + West" as the third one. Furthermore, the dataset reveals that the name distribution satisfies the Zipf law, separately for each state and each year, i.e. the name frequency f ∝r-α, where r is the name rank. Between 1920 and 1980, the exponent α is the largest one for the set of states classified as 'the South', but the smallest one for the set of states classified as "Midwest + West". Our interpretation is that the pool of selected names was quite narrow in the Southern states. The data is compared with some related statistics of names in Belgium, a country also with different regions, but having quite a different scale than the USA. There, the Zipf exponent is low for young people and for the Brussels citizens.

  19. The role of “network of cities” in construction of global urban culture

    OpenAIRE

    Baycan-Levent, Tüzin; Kundak, Seda; Gülümser, Aliye Ahu

    2004-01-01

    The globalization process has led to an increased interaction between cities and to a new urban system/network in which they need to be competitive and complementary at the same time. “Network of cities”, such as World Cities, Eurocities or Sister Cities are among the well known examples of interaction and cooperation of the cities at the regional and global level. The cities of different regions and countries tend to share their experiences and their cultures within these networks in order t...

  20. Insular networks for emotional processing and social cognition: comparison of two case reports with either cortical or subcortical involvement.

    Science.gov (United States)

    Couto, Blas; Sedeño, Lucas; Sposato, Luciano A; Sigman, Mariano; Riccio, Patricia M; Salles, Alejo; Lopez, Vladimir; Schroeder, Johannes; Manes, Facundo; Ibanez, Agustin

    2013-05-01

    The processing of the emotion of disgust is attributed to the insular cortex (IC), which is also responsible for social emotions and higher-cognitive functions. We distinguish the role of the IC from its connections in regard to these functions through the assessment of emotions and social cognition in a double case report. These subjects were very rare cases that included a focal IC lesion and a subcortical focal stroke affecting the connections of the IC with frontotemporal areas. Both patients and a sample of 10 matched controls underwent neuropsychological and affective screening questionnaires, a battery of multimodal basic emotion recognition tests, an emotional inference disambiguation task using social contextual clues, an empathy task and a theory of mind task. The insular lesion (IL) patient showed no impairments in emotion recognition and social emotions and presented with a pattern of delayed reaction times (RTs) in a subset of both groups of tasks. The subcortical lesion (SL) patient was impaired in multimodal aversive emotion recognition, including disgust, and exhibited delayed RTs and a heterogeneous pattern of impairments in subtasks of empathy and in the contextual inference of emotions. Our results suggest that IC related networks, and not the IC itself, are related to negative emotional processing and social emotions. We discuss these results with respect to theoretical approaches of insular involvement in emotional and social processing and propose that IC connectivity with frontotemporal and subcortical regions might be relevant for contextual emotional processing and social cognition. Copyright © 2012 Elsevier Ltd. All rights reserved.

  1. Multiple Regions of a Cortical Network Commonly Encode the Meaning of Words in Multiple Grammatical Positions of Read Sentences.

    Science.gov (United States)

    Anderson, Andrew James; Lalor, Edmund C; Lin, Feng; Binder, Jeffrey R; Fernandino, Leonardo; Humphries, Colin J; Conant, Lisa L; Raizada, Rajeev D S; Grimm, Scott; Wang, Xixi

    2018-05-16

    Deciphering how sentence meaning is represented in the brain remains a major challenge to science. Semantically related neural activity has recently been shown to arise concurrently in distributed brain regions as successive words in a sentence are read. However, what semantic content is represented by different regions, what is common across them, and how this relates to words in different grammatical positions of sentences is weakly understood. To address these questions, we apply a semantic model of word meaning to interpret brain activation patterns elicited in sentence reading. The model is based on human ratings of 65 sensory/motor/emotional and cognitive features of experience with words (and their referents). Through a process of mapping functional Magnetic Resonance Imaging activation back into model space we test: which brain regions semantically encode content words in different grammatical positions (e.g., subject/verb/object); and what semantic features are encoded by different regions. In left temporal, inferior parietal, and inferior/superior frontal regions we detect the semantic encoding of words in all grammatical positions tested and reveal multiple common components of semantic representation. This suggests that sentence comprehension involves a common core representation of multiple words' meaning being encoded in a network of regions distributed across the brain.

  2. The Effect of Facebook Social Network on Cultural Identity of Youth in Isfahan

    Directory of Open Access Journals (Sweden)

    Samad Alipour

    2014-06-01

    Full Text Available By expanding the access to the Internet and the Internet social networks and increasing use which the youth represents of different types of issues and the content of these modern media, the cultural identity has transformed into one of the main concerns related to social coherence and national unity. Therefore, the present study investigates the relationship between the presence and interaction in Facebook social network and the youth's cultural identity. The main question of this study is what influence using Facebook has on cultural identity of users? Is Facebook as one of the tools of globalization attenuator of cultural identity? The present study is in the form of a survey one and is conducted using the method ofvolunteer and available sampling and employing the internet researcher-made questionnaire by focusing Giddens' Cultivation and Strucration theories. The population of the present study includes young users of Facebook in Isfahan in 2012 and the sample is equal 424 participants. The results of the present study indicate that there is a significant and reverse correlation between the length of membership, users' amount of se and participation and activities in Facebook and their cultural identities and also there is a significant and positive correlation between considering Facebook contents as real and users' cultural identities. It means that the more the length of membership is, the more the users' amount of use and participation and activity in Facebook and the weaker users' cultural identities.

  3. Intra-burst firing characteristics as network state parameters

    NARCIS (Netherlands)

    Stegenga, J.; le Feber, Jakob; Rutten, Wim; Marani, Enrico; Stett, A

    Introduction In our group we are aiming to demonstrate learning and memory capabilities of cultured networks of cortical neurons. A first step is to identify parameters that accurately describe changes in the network due to learning. Usually, such parameters are calculated from the responses to

  4. Young Diplomats' Socialization to the Networked Professional Cultures of Their Workplace Communities

    Science.gov (United States)

    Hytönen, Kaisa; Hakkarainen, Kai; Palonen, Tuire

    2011-01-01

    The purpose of the present investigation was to examine young diplomats' socialization to the professional expert culture of the Ministry for Foreign Affairs of Finland over a six-month on-job training period, as part of their preparation for service in the diplomatic corps. Using social network analysis, we analyzed departments' internal social…

  5. A methodology for a quantitative assessment of safety culture in NPPs based on Bayesian networks

    International Nuclear Information System (INIS)

    Kim, Young Gab; Lee, Seung Min; Seong, Poong Hyun

    2017-01-01

    Highlights: • A safety culture framework and a quantitative methodology to assess safety culture were proposed. • The relation among Norm system, Safety Management System and worker's awareness was established. • Safety culture probability at NPPs was updated by collecting actual organizational data. • Vulnerable areas and the relationship between safety culture and human error were confirmed. - Abstract: For a long time, safety has been recognized as a top priority in high-reliability industries such as aviation and nuclear power plants (NPPs). Establishing a safety culture requires a number of actions to enhance safety, one of which is changing the safety culture awareness of workers. The concept of safety culture in the nuclear power domain was established in the International Atomic Energy Agency (IAEA) safety series, wherein the importance of employee attitudes for maintaining organizational safety was emphasized. Safety culture assessment is a critical step in the process of enhancing safety culture. In this respect, assessment is focused on measuring the level of safety culture in an organization, and improving any weakness in the organization. However, many continue to think that the concept of safety culture is abstract and unclear. In addition, the results of safety culture assessments are mostly subjective and qualitative. Given the current situation, this paper suggests a quantitative methodology for safety culture assessments based on a Bayesian network. A proposed safety culture framework for NPPs would include the following: (1) a norm system, (2) a safety management system, (3) safety culture awareness of worker, and (4) Worker behavior. The level of safety culture awareness of workers at NPPs was reasoned through the proposed methodology. Then, areas of the organization that were vulnerable in terms of safety culture were derived by analyzing observational evidence. We also confirmed that the frequency of events involving human error

  6. Collectivism culture, HIV stigma and social network support in Anhui, China: a path analytic model.

    Science.gov (United States)

    Zang, Chunpeng; Guida, Jennifer; Sun, Yehuan; Liu, Hongjie

    2014-08-01

    HIV stigma is rooted in culture and, therefore, it is essential to investigate it within the context of culture. The objective of this study was to examine the interrelationships among individualism-collectivism, HIV stigma, and social network support. A social network study was conducted among 118 people living with HIVAIDS in China, who were infected by commercial plasma donation, a nonstigmatized behavior. The Individualism-Collectivism Interpersonal Assessment Inventory (ICIAI) was used to measure cultural norms and values in the context of three social groups, family members, friends, and neighbors. Path analyses revealed (1) a higher level of family ICIAI was significantly associated with a higher level of HIV self-stigma (β=0.32); (2) a higher level of friend ICIAI was associated with a lower level of self-stigma (β=-035); (3) neighbor ICIAI was associated with public stigma (β=-0.61); (4) self-stigman was associated with social support from neighbors (β=-0.27); and (5) public stigma was associated with social support from neighbors (β=-0.24). This study documents that HIV stigma may mediate the relationship between collectivist culture and social network support, providing an empirical basis for interventions to include aspects of culture into HIV intervention strategies.

  7. Dearfield Dream Project: Developing an Interdisciplinary Historical/Cultural Research Network

    Directory of Open Access Journals (Sweden)

    Robert Brunswig

    2013-08-01

    Full Text Available The Dearfield Dream Project is a collaborative research initiative to conduct historical, cultural, archaeological, and environmental studies on the early 20th Century African-American colony site of Dearfield, Colorado, USA. Because the breadth and significance of the Dearfield Project requires an interdisciplinary research team, a network of research collaborators has been assembled. This research network seeks to discover, preserve, and disseminate knowledge of the site and its surrounding farmsteads’ economic, social, political, and environmental history for better understanding and interpretation of its contributions to Colorado and U.S. history. Herein, we detail progress that has been made on this important historical/cultural research project. Further, we outline the future of the Dearfield research network along with our current and anticipated subjects of inquiry.

  8. A study of epileptogenic network structures in rat hippocampal cultures using first spike latencies during synchronization events

    International Nuclear Information System (INIS)

    Raghavan, Mohan; Amrutur, Bharadwaj; Srinivas, Kalyan V; Sikdar, Sujit K

    2012-01-01

    Study of hypersynchronous activity is of prime importance for combating epilepsy. Studies on network structure typically reconstruct the network by measuring various aspects of the interaction between neurons and subsequently measure the properties of the reconstructed network. In sub-sampled networks such methods lead to significant errors in reconstruction. Using rat hippocampal neurons cultured on a multi-electrode array dish and a glutamate injury model of epilepsy in vitro, we studied synchronous activity in neuronal networks. Using the first spike latencies in various neurons during a network burst, we extract various recurring spatio-temporal onset patterns in the networks. Comparing the patterns seen in control and injured networks, we observe that injured networks express a wide diversity in their foci (origin) and activation pattern, while control networks show limited diversity. Furthermore, we note that onset patterns in glutamate injured networks show a positive correlation between synchronization delay and physical distance between neurons, while control networks do not. (paper)

  9. Voltage-sensitive dye recording from networks of cultured neurons

    Science.gov (United States)

    Chien, Chi-Bin

    This thesis describes the development and testing of a sensitive apparatus for recording electrical activity from microcultures of rat superior cervical ganglion (SCG) neurons by using voltage-sensitive fluorescent dyes.The apparatus comprises a feedback-regulated mercury arc light source, an inverted epifluorescence microscope, a novel fiber-optic camera with discrete photodiode detectors, and low-noise preamplifiers. Using an NA 0.75 objective and illuminating at 10 W/cm2 with the 546 nm mercury line, a typical SCG neuron stained with the styryl dye RH423 gives a detected photocurrent of 1 nA; the light source and optical detectors are quiet enough that the shot noise in this photocurrent--about.03% rms--dominates. The design, theory, and performance of this dye-recording apparatus are discussed in detail.Styryl dyes such as RH423 typically give signals of 1%/100 mV on these cells; the signals are linear in membrane potential, but do not appear to arise from a purely electrochromic mechanism. Given this voltage sensitivity and the noise level of the apparatus, it should be possible to detect both action potentials and subthreshold synaptic potentials from SCG cell bodies. In practice, dye recording can easily detect action potentials from every neuron in an SCG microculture, but small synaptic potentials are obscured by dye signals from the dense network of axons.In another microculture system that does not have such long and complex axons, this dye-recording apparatus should be able to detect synaptic potentials, making it possible to noninvasively map the synaptic connections in a microculture, and thus to study long-term synaptic plasticity.

  10. Dynamic Causal Modeling of the Cortical Responses to Wrist Perturbations

    Directory of Open Access Journals (Sweden)

    Yuan Yang

    2017-09-01

    Full Text Available Mechanical perturbations applied to the wrist joint typically evoke a stereotypical sequence of cortical and muscle responses. The early cortical responses (<100 ms are thought be involved in the “rapid” transcortical reaction to the perturbation while the late cortical responses (>100 ms are related to the “slow” transcortical reaction. Although previous studies indicated that both responses involve the primary motor cortex, it remains unclear if both responses are engaged by the same effective connectivity in the cortical network. To answer this question, we investigated the effective connectivity cortical network after a “ramp-and-hold” mechanical perturbation, in both the early (<100 ms and late (>100 ms periods, using dynamic causal modeling. Ramp-and-hold perturbations were applied to the wrist joint while the subject maintained an isometric wrist flexion. Cortical activity was recorded using a 128-channel electroencephalogram (EEG. We investigated how the perturbation modulated the effective connectivity for the early and late periods. Bayesian model comparisons suggested that different effective connectivity networks are engaged in these two periods. For the early period, we found that only a few cortico-cortical connections were modulated, while more complicated connectivity was identified in the cortical network during the late period with multiple modulated cortico-cortical connections. The limited early cortical network likely allows for a rapid muscle response without involving high-level cognitive processes, while the complexity of the late network may facilitate coordinated responses.

  11. Assessing the permeability of engineered capillary networks in a 3D culture.

    Directory of Open Access Journals (Sweden)

    Stephanie J Grainger

    Full Text Available Many pathologies are characterized by poor blood vessel growth and reduced nutrient delivery to the surrounding tissue, introducing a need for tissue engineered blood vessels. Our lab has developed a 3D co-culture method to grow interconnected networks of pericyte-invested capillaries, which can anastamose with host vasculature following implantation to restore blood flow to ischemic tissues. However, if the engineered vessels contain endothelial cells (ECs that are misaligned or contain wide junctional gaps, they may function improperly and behave more like the pathologic vessels that nourish tumors. The purpose of this study was to test the resistance to permeability of these networks in vitro, grown with different stromal cell types, as a metric of vessel functionality. A fluorescent dextran tracer was used to visualize transport across the endothelium and the pixel intensity was quantified using a customized MATLAB algorithm. In fibroblast-EC co-cultures, the dextran tracer easily penetrated through the vessel wall and permeability was high through the first 5 days of culture, indicative of vessel immaturity. Beyond day 5, dextran accumulated at the periphery of the vessel, with very little transported across the endothelium. Quantitatively, permeability dropped from initial levels of 61% to 39% after 7 days, and to 7% after 2 weeks. When ECs were co-cultured with bone marrow-derived mesenchymal stem cells (MSCs or adipose-derived stem cells (AdSCs, much tighter control of permeability was achieved. Relative to the EC-fibroblast co-cultures, permeabilities were reduced 41% for the EC-MSC co-cultures and 50% for the EC-AdSC co-cultures after 3 days of culture. By day 14, these permeabilities decreased by 68% and 77% over the EC-fibroblast cultures. Co-cultures containing stem cells exhibit elevated VE-cadherin levels and more prominent EC-EC junctional complexes when compared to cultures containing fibroblasts. These data suggest the stromal

  12. Acceptance and Quality Perceptions of Social Network Services in Cultural Context: Vkontakte as a Case Study

    Directory of Open Access Journals (Sweden)

    Katsiaryna S. Baran

    2015-06-01

    Full Text Available In terms of network economics, as well as other information services, a social network service (SNS has two chances–either it gains acceptance ("success breeds success" and will become standard or it slowly dies. Nowadays, Facebook is the standard in the social network world, however, not in Russia's and the neighboring countries' social network communities. Here, Vkontakte, the domestic SNS, dominates. What are the reasons for this success of the regional SNS and the failure of the global giant? We answer this research question while we empirically studied both SNSs, Facebook as well as Vkontakte, among Russian users. In the evaluation, based on the Information Service Evaluation (ISE Model, we found out that Vkontakte is perceived as more useful than Facebook, is much more trustworthy, and more enjoyable to use. The cultural environment of the Russian community plays an important role as well.

  13. Negotiating Intra-Asian Games Networks: On Cultural Proximity, East Asian Games Design, and Chinese Farmers

    Directory of Open Access Journals (Sweden)

    Dean Chan

    2006-01-01

    Full Text Available A key feature of networked games in East Asia is the relationship between the adaptation of regional Asian aesthetic and narrative forms in game content, and the parallel growth in more regionally-focused marketing and distribution initiatives. This essay offers a contextual analysis of intra-Asian games networks, with reference to the production, marketing and circulation of Asian MMORPGs. My discussion locates these networks as part of broader discourses on regionalism, East Asian cultural production and Asian modernity. At the same time, I consider how these networks highlight structural asymmetry and uneven power relations within the region; and I examine the emergent use of gamer-workers known as Chinese farmers in the digital game-items trade.

  14. Undergraduate students' development of social, cultural, and human capital in a networked research experience

    Science.gov (United States)

    Thompson, Jennifer Jo; Conaway, Evan; Dolan, Erin L.

    2016-12-01

    Recent calls for reform in undergraduate biology education have emphasized integrating research experiences into the learning experiences of all undergraduates. Contemporary science research increasingly demands collaboration across disciplines and institutions to investigate complex research questions, providing new contexts and models for involving undergraduates in research. In this study, we examined the experiences of undergraduates participating in a multi-institution and interdisciplinary biology research network. Unlike the traditional apprenticeship model of research, in which a student participates in research under the guidance of a single faculty member, students participating in networked research have the opportunity to develop relationships with additional faculty and students working in other areas of the project, at their own and at other institutions. We examined how students in this network develop social ties and to what extent a networked research experience affords opportunities for students to develop social, cultural, and human capital. Most studies of undergraduate involvement in science research have focused on documenting student outcomes rather than elucidating how students gain access to research experiences or how elements of research participation lead to desired student outcomes. By taking a qualitative approach framed by capital theories, we have identified ways that undergraduates utilize and further develop various forms of capital important for success in science research. In our study of the first 16 months of a biology research network, we found that undergraduates drew upon a combination of human, cultural, and social capital to gain access to the network. Within their immediate research groups, students built multidimensional social ties with faculty, peers, and others, yielding social capital that can be drawn upon for information, resources, and support. They reported developing cultural capital in the form of learning to

  15. New Challenges for Urban History: Culture, Networks, Globalization

    Directory of Open Access Journals (Sweden)

    Hietala, Marjatta

    2012-12-01

    Full Text Available Urban history is a very lively and dynamic research field, showing strict parallelism with the fast increasing of the urban population. Today, competitiveness is one of the key aims for cities in the globalized world. Factors such as accessibility and infrastructure, industry, human capital, innovation, and investment, green spaces, affordable housing, business support and quality of education are necessaries. However, the OECD recognizes three dilemmas in this strategic vision, concerning the spill over of metro-regions, the public strategic vision, and the relationship between economic dynamism and the liveable city. Today urban historians are facing some general challenges: comparative aspects are needed; also interdisciplinarity to develop cooperation between disciplines; and for maintaining the professional status of academic urban history. The expanding networks between towns and cities, and the meeting places as conferences and exhibitions are considered, as they are the multitudinous challenges and threats, especially for those cities suffering continuously of major natural and man-made disasters. Moreover, new amalgams of hazard are being created in metropolitan areas with overlapping natural, technological, biological and social risks, exposing more people and places, needing safety and security.

    La historia urbana es un campo de investigación muy vivo y dinámico, mostrando un paralelismo estricto con el rápido incremento de la población urbana. La competencia es hoy uno de los objetivos claves para las ciudades en el mundo globalizado. Factores tales como la accesibilidad y las infraestructuras, la industria, el capital humano, la innovación y la inversión, los espacios verdes, la vivienda accesible, el apoyo a los negocios y la calidad de la educación son necesarios. Sin embargo, la OCDE reconoce tres dilemas en esa visión estratégica, el desarrollo de las metrópolis, la visión estratégica pública y la relaci

  16. Cortical visual impairment

    OpenAIRE

    Koželj, Urša

    2013-01-01

    In this thesis we discuss cortical visual impairment, diagnosis that is in the developed world in first place, since 20 percent of children with blindness or low vision are diagnosed with it. The objectives of the thesis are to define cortical visual impairment and the definition of characters suggestive of the cortical visual impairment as well as to search for causes that affect the growing diagnosis of cortical visual impairment. There are a lot of signs of cortical visual impairment. ...

  17. Word-of-Mouth of Cultural Products through Institutional Social Networks

    Directory of Open Access Journals (Sweden)

    Eun Ea Lee

    2017-05-01

    Full Text Available Recently, a number of cultural institutions such as museums, galleries, art auctions, events, and performance centers have been utilizing social network sites (SNS for promoting and marketing their culture, art content, and events. The online social space is appropriate for cultural products to be viral, since users of SNS mainly share personal interest and spread hedonic consumption with close friends and acquaintances. If viral content drives strong emotions such as joy, arousal, pleasure, sorrow, or horror, it will be transmitted to more people, and rapidly. This study investigates how a certain type of motivation for using a social network service such as Facebook influences trust in art and culture exhibition information providers and the content of the information itself. Results show that people who have an informational motivation for using social media expressed a higher degree of trust in exhibition information provided by institutions such as museums. On the contrary, those who have relational motivation for using social media credited acquaintances such as friends, families, and colleagues more. Trust in the information provider resulted in trust in the content itself, and hence, increased the possibility of word-of-mouth for the corresponding information. An empirical survey was implemented, using followers of the Facebook page of a national museum and users who clicked “Like” on postings of exhibitions. Finally, the potential applications of the result for promotion and marketing of exhibitions of art and culture for public will be discussed.

  18. Communication and Wiring in the Cortical Connectome

    Directory of Open Access Journals (Sweden)

    Julian eBudd

    2012-10-01

    Full Text Available In cerebral cortex, the huge mass of axonal wiring that carries information between near and distant neurons is thought to provide the neural substrate for cognitive and perceptual function. The goal of mapping the connectivity of cortical axons at different spatial scales, the cortical connectome, is to trace the paths of information flow in cerebral cortex. To appreciate the relationship between the connectome and cortical function, we need to discover the nature and purpose of the wiring principles underlying cortical connectivity. A popular explanation has been that axonal length is strictly minimized both within and between cortical regions. In contrast, we have hypothesized the existence of a multi-scale principle of cortical wiring where to optimise communication there is a trade-off between spatial (construction and temporal (routing costs. Here, using recent evidence concerning cortical spatial networks we critically evaluate this hypothesis at neuron, local circuit, and pathway scales. We report three main conclusions. First, the axonal and dendritic arbor morphology of single neocortical neurons may be governed by a similar wiring principle, one that balances the conservation of cellular material and conduction delay. Second, the same principle may be observed for fibre tracts connecting cortical regions. Third, the absence of sufficient local circuit data currently prohibits any meaningful assessment of the hypothesis at this scale of cortical organization. To avoid neglecting neuron and microcircuit levels of cortical organization, the connectome framework should incorporate more morphological description. In addition, structural analyses of temporal cost for cortical circuits should take account of both axonal conduction and neuronal integration delays, which appear mostly of the same order of magnitude. We conclude the hypothesized trade-off between spatial and temporal costs may potentially offer a powerful explanation for

  19. Minimal Camera Networks for 3D Image Based Modeling of Cultural Heritage Objects

    Science.gov (United States)

    Alsadik, Bashar; Gerke, Markus; Vosselman, George; Daham, Afrah; Jasim, Luma

    2014-01-01

    3D modeling of cultural heritage objects like artifacts, statues and buildings is nowadays an important tool for virtual museums, preservation and restoration. In this paper, we introduce a method to automatically design a minimal imaging network for the 3D modeling of cultural heritage objects. This becomes important for reducing the image capture time and processing when documenting large and complex sites. Moreover, such a minimal camera network design is desirable for imaging non-digitally documented artifacts in museums and other archeological sites to avoid disturbing the visitors for a long time and/or moving delicate precious objects to complete the documentation task. The developed method is tested on the Iraqi famous statue “Lamassu”. Lamassu is a human-headed winged bull of over 4.25 m in height from the era of Ashurnasirpal II (883–859 BC). Close-range photogrammetry is used for the 3D modeling task where a dense ordered imaging network of 45 high resolution images were captured around Lamassu with an object sample distance of 1 mm. These images constitute a dense network and the aim of our study was to apply our method to reduce the number of images for the 3D modeling and at the same time preserve pre-defined point accuracy. Temporary control points were fixed evenly on the body of Lamassu and measured by using a total station for the external validation and scaling purpose. Two network filtering methods are implemented and three different software packages are used to investigate the efficiency of the image orientation and modeling of the statue in the filtered (reduced) image networks. Internal and external validation results prove that minimal image networks can provide highly accurate records and efficiency in terms of visualization, completeness, processing time (>60% reduction) and the final accuracy of 1 mm. PMID:24670718

  20. Minimal camera networks for 3D image based modeling of cultural heritage objects.

    Science.gov (United States)

    Alsadik, Bashar; Gerke, Markus; Vosselman, George; Daham, Afrah; Jasim, Luma

    2014-03-25

    3D modeling of cultural heritage objects like artifacts, statues and buildings is nowadays an important tool for virtual museums, preservation and restoration. In this paper, we introduce a method to automatically design a minimal imaging network for the 3D modeling of cultural heritage objects. This becomes important for reducing the image capture time and processing when documenting large and complex sites. Moreover, such a minimal camera network design is desirable for imaging non-digitally documented artifacts in museums and other archeological sites to avoid disturbing the visitors for a long time and/or moving delicate precious objects to complete the documentation task. The developed method is tested on the Iraqi famous statue "Lamassu". Lamassu is a human-headed winged bull of over 4.25 m in height from the era of Ashurnasirpal II (883-859 BC). Close-range photogrammetry is used for the 3D modeling task where a dense ordered imaging network of 45 high resolution images were captured around Lamassu with an object sample distance of 1 mm. These images constitute a dense network and the aim of our study was to apply our method to reduce the number of images for the 3D modeling and at the same time preserve pre-defined point accuracy. Temporary control points were fixed evenly on the body of Lamassu and measured by using a total station for the external validation and scaling purpose. Two network filtering methods are implemented and three different software packages are used to investigate the efficiency of the image orientation and modeling of the statue in the filtered (reduced) image networks. Internal and external validation results prove that minimal image networks can provide highly accurate records and efficiency in terms of visualization, completeness, processing time (>60% reduction) and the final accuracy of 1 mm.

  1. Barriers of Culture, Networks, and Language in International Migration: A Review

    Directory of Open Access Journals (Sweden)

    Zhiling Wang

    2018-05-01

    Full Text Available Along with the increasing pace of globalization, recent decades faced a dramatically increase in international migrant flows as well. Compared to the flows of trade, capital and knowledge, we observe that contemporaneous complex institutional differences, historical backgrounds, and individuals' diverse socio-demographic characteristics make the migrant workers' choice of destination arguably much more uncontrollable. This study shows that migration is in a complex way intertwined with culture, networks and language, (i by reviewing related studies on the barriers of culture, networks and language in international labor mobility, and (ii by exploring missing gaps and prospective avenues for research. Nowadays, the migration pressure on Europe and the United states has created substantial challenges, leading to an urgent need to address the economic assimilation and social integration of migrants. Against this background, we emphasize that these non-economic factors have played an increasingly critical role in shaping international migration and its future socio-economic consequences for destination countries.

  2. The role of learning analytics in networking for business and leisure: A study of culture and gender differences in social platform users

    OpenAIRE

    Benson, Vladlena; Filippaios, Fragkiskos

    2018-01-01

    Engagement with social networking sites is influenced by the cognitive and learning processes which in turn is influenced by culture. This paper aims at unbundling the effect of culture on the use of social network sites and thus contributes to our understanding on the way cognitive and learning processes influence the engagement with social networks. The study of over 600 social networking users addresses how professional and leisure use of social networks differs across cultures, gender and...

  3. Cultural Routes and Networks of Knowledge: the Identity and Promotion of Cultural Heritage. The Case Study of Piedmont

    Directory of Open Access Journals (Sweden)

    Silvia Beltramo

    2013-07-01

    Full Text Available The European project called “PER VIAM Pilgrims’ Routes In Action”, funded by the European Commission in 2012, is a significant opportunity of cultural and economic development for the whole Europe and also for the territory of Piedmont Region. The certainty of the need for transnational cooperation, which should create a network amongst the different territories in a perspective of working together and exchange of traveling, economic and cultural experiences – as well as best practices - nowadays calls for implementation tools such as European projects supported and sought for by the local authorities.The Piedmont is nowadays crossed by various cultural itineraries, many of which are certificated by the European Council: Via Francigena, the Route of the Cistercian Abbeys, the Transromanica, the itinerary of the historical thermal cities and the Saint Michael's way. Starting from a survey on the meaning of "cultural itinerary" expressed by the different European institutions (i.e. ICOMOS, UNESCO, Council of Europe and European Commission, this essay is proposing an analysis of the current status of such territory, highlighting the public policies in progress, the role and activities of the local associations and the valorisation of implemented projects as related to those itineraries which have already been recognized by the Council of Europe.This paper presents some significant experiences and best practices in the study of religious tourism, as they have been defined on the regional territory throughout the last few years, which can contribute to the debate and to the overall awareness on management and valorization of sustainable tourism. 

  4. A moveable feast: Contemporary relational food cultures emerging from local food networks.

    Science.gov (United States)

    O'Kane, Gabrielle

    2016-10-01

    Although the globalised food system delivers unparalleled food variety and quantity to most in the developed world it also disconnects consumers from where, how and by whom food is grown. This change in the food system has resulted in an acceptance of an anonymous and homogeneous food supply, which has contributed to over-consumption and the rise in diet-related diseases. 'Nutritionism' responds to this issue by maintaining that a 'healthy diet' can be achieved by consuming the correct balance of energy and nutrients, but with limited success. Yet, some food cultures can moderate the effects of the environmental drivers of increasing global obesity rates. This paper draws on this premise and presents an alternative eco-dietetic response, exploring people's meaning-making of food and food culture through local food networks. This research used narrative inquiry methodology and purposive sampling to gather stories through focus group conversations. Twenty people attended focus groups comprised of food procurers from one of three local food networks in the Canberra region: community gardens, a modified Community Supported Agriculture (CSA) and farmers' markets. The findings showed that those using local food networks enjoyed a 'contemporary relational food culture' that highlighted the importance of people, place and time, in their visceral experiences of food. The community gardeners made meaning of food through their connections to the earth and to others. The farmers' market and CSA food procurers valued the seasonal, local and ethical food produced by their beloved farmer(s). This paper provides qualitative evidence that local food networks enable people to enjoy multi-dimensional relationships to food. Further research is required to examine whether experiencing a contemporary relational food culture can lead to improved health outcomes for people and the planet. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Adaptive enhancement of learning protocol in hippocampal cultured networks grown on multielectrode arrays

    Science.gov (United States)

    Pimashkin, Alexey; Gladkov, Arseniy; Mukhina, Irina; Kazantsev, Victor

    2013-01-01

    Learning in neuronal networks can be investigated using dissociated cultures on multielectrode arrays supplied with appropriate closed-loop stimulation. It was shown in previous studies that weakly respondent neurons on the electrodes can be trained to increase their evoked spiking rate within a predefined time window after the stimulus. Such neurons can be associated with weak synaptic connections in nearby culture network. The stimulation leads to the increase in the connectivity and in the response. However, it was not possible to perform the learning protocol for the neurons on electrodes with relatively strong synaptic inputs and responding at higher rates. We proposed an adaptive closed-loop stimulation protocol capable to achieve learning even for the highly respondent electrodes. It means that the culture network can reorganize appropriately its synaptic connectivity to generate a desired response. We introduced an adaptive reinforcement condition accounting for the response variability in control stimulation. It significantly enhanced the learning protocol to a large number of responding electrodes independently on its base response level. We also found that learning effect preserved after 4–6 h after training. PMID:23745105

  6. Graph-based unsupervised segmentation algorithm for cultured neuronal networks' structure characterization and modeling.

    Science.gov (United States)

    de Santos-Sierra, Daniel; Sendiña-Nadal, Irene; Leyva, Inmaculada; Almendral, Juan A; Ayali, Amir; Anava, Sarit; Sánchez-Ávila, Carmen; Boccaletti, Stefano

    2015-06-01

    Large scale phase-contrast images taken at high resolution through the life of a cultured neuronal network are analyzed by a graph-based unsupervised segmentation algorithm with a very low computational cost, scaling linearly with the image size. The processing automatically retrieves the whole network structure, an object whose mathematical representation is a matrix in which nodes are identified neurons or neurons' clusters, and links are the reconstructed connections between them. The algorithm is also able to extract any other relevant morphological information characterizing neurons and neurites. More importantly, and at variance with other segmentation methods that require fluorescence imaging from immunocytochemistry techniques, our non invasive measures entitle us to perform a longitudinal analysis during the maturation of a single culture. Such an analysis furnishes the way of individuating the main physical processes underlying the self-organization of the neurons' ensemble into a complex network, and drives the formulation of a phenomenological model yet able to describe qualitatively the overall scenario observed during the culture growth. © 2014 International Society for Advancement of Cytometry.

  7. Accuracy of typical photogrammetric networks in cultural heritage 3D modeling projects

    Directory of Open Access Journals (Sweden)

    E. Nocerino

    2014-06-01

    Full Text Available The easy generation of 3D geometries (point clouds or polygonal models with fully automated image-based methods poses nontrivial problems on how to check a posteriori the quality of the achieved results. Clear statements and procedures on how to plan the camera network, execute the survey and use automatic tools to achieve the prefixed requirements are still an open issue. Although such issues had been discussed and solved some years ago, the importance of camera network geometry is today often underestimated or neglected in the cultural heritage field. In this paper different camera network geometries, with normal and convergent images, are analyzed and the accuracy of the produced results are compared to ground truth measurements.

  8. The neural correlates of persuasion: a common network across cultures and media.

    Science.gov (United States)

    Falk, Emily B; Rameson, Lian; Berkman, Elliot T; Liao, Betty; Kang, Yoona; Inagaki, Tristen K; Lieberman, Matthew D

    2010-11-01

    Persuasion is at the root of countless social exchanges in which one person or group is motivated to have another share its beliefs, desires, or behavioral intentions. Here, we report the first three functional magnetic resonance imaging studies to investigate the neurocognitive networks associated with feeling persuaded by an argument. In the first two studies, American and Korean participants, respectively, were exposed to a number of text-based persuasive messages. In both Study 1 and Study 2, feeling persuaded was associated with increased activity in posterior superior temporal sulcus bilaterally, temporal pole bilaterally, and dorsomedial prefrontal cortex. The findings suggest a discrete set of underlying mechanisms in the moment that the persuasion process occurs, and are strengthened by the fact that the results replicated across two diverse linguistic and cultural groups. Additionally, a third study using region-of-interest analyses demonstrated that neural activity in this network was also associated with persuasion when a sample of American participants viewed video-based messages. In sum, across three studies, including two different cultural groups and two types of media, persuasion was associated with a consistent network of regions in the brain. Activity in this network has been associated with social cognition and mentalizing and is consistent with models of persuasion that emphasize the importance of social cognitive processing in determining the efficacy of persuasive communication.

  9. Developing a culturally competent health network: a planning framework and guide.

    Science.gov (United States)

    Gertner, Eric J; Sabino, Judith N; Mahady, Erica; Deitrich, Lynn M; Patton, Jarret R; Grim, Mary Kay; Geiger, James F; Salas-Lopez, Debbie

    2010-01-01

    The number of cultural competency initiatives in healthcare is increasing due to many factors, including changing demographics, quality improvement and regulatory requirements, equitable care missions, and accreditation standards. To facilitate organization-wide transformation, a hospital or healthcare system must establish strategic goals, objectives, and implementation tasks for culturally competent provision of care. This article reports the largely successful results of a cultural competency program instituted at a large system in eastern Pennsylvania. Prior to the development of its cultural competency initiative, Lehigh Valley Health Network, Allentown, Pennsylvania, saw isolated activities producing innovative solutions to diversity and culture issues in the provision of equitable care. But it took a transformational event to support an organization-wide program in cultural competency by strengthening leadership buy-in and providing a sense of urgency, excitement, and shared vision among multiple stakeholders. A multidisciplinary task force, including senior leaders and a diverse group of employees, was created with the authority and responsibility to enact changes. Through a well-organized strategic planning process, existing patient and community demographic data were reviewed to describe existing disparities, a baseline assessment was completed, a mission statement was created, and clear metrics were developed. The strategic plan, which focused on five key areas (demographics, language-appropriate services, employees, training, and education/communication), was approved by the network's chief executive officer and senior managers to demonstrate commitment prior to implementation. Strategic plan implementation proceeded through a project structure consisting of subproject teams charged with achieving the following specific objectives: develop a cultural material repository, enhance employee recruitment/retention, establish a baseline assessment

  10. Relations, interactions and networks of cultural tourism stakeholders in rural areas of Vojvodina

    Directory of Open Access Journals (Sweden)

    Pavlović Nataša

    2015-01-01

    Full Text Available Contemporary trends, which are characterized by a very strong level of competition and the maturity of the market, become more than ever essential for success of tourist destinations. Rural areas in Vojvodina, because of its authentic atmosphere and multiculturalism, have significant advantages for cultural tourism. Each participant who creates a tourism product in toda y's competitive environment aims to have a strong focus on customer satisfaction, which indicates the necessity of adopting the concept of total relationship marketing. The aim of this paper is to show how cultural institutions, souvenir craftsmen, tourism organizations, travel agencies and other stakeholders achieve cooperation and apply modern concept of total relationship marketing for the purposes of satisfying the needs of tourists. The paper will explore the fundamental postulates of relationship marketing applied by key stakeholders of cultural tourism in rural areas, and will get reference results on relations, interactions and networks.

  11. Functional roles of 10 Hz alpha-band power modulating engagement and disengagement of cortical networks in a complex visual motion task.

    Directory of Open Access Journals (Sweden)

    Kunjan D Rana

    Full Text Available Alpha band power, particularly at the 10 Hz frequency, is significantly involved in sensory inhibition, attention modulation, and working memory. However, the interactions between cortical areas and their relationship to the different functional roles of the alpha band oscillations are still poorly understood. Here we examined alpha band power and the cortico-cortical interregional phase synchrony in a psychophysical task involving the detection of an object moving in depth by an observer in forward self-motion. Wavelet filtering at the 10 Hz frequency revealed differences in the profile of cortical activation in the visual processing regions (occipital and parietal lobes and in the frontoparietal regions. The alpha rhythm driving the visual processing areas was found to be asynchronous with the frontoparietal regions. These findings suggest a decoupling of the 10 Hz frequency into separate functional roles: sensory inhibition in the visual processing regions and spatial attention in the frontoparietal regions.

  12. Improved diagnostic accuracy of Alzheimer's disease by combining regional cortical thickness and default mode network functional connectivity: Validated in the Alzheimer's disease neuroimaging initiative set

    Energy Technology Data Exchange (ETDEWEB)

    Park, Ji Eun; Park, Bum Woo; Kim, Sang Joon; Kim, Ho Sung; Choi, Choong Gon; Jung, Seung Jung; Oh, Joo Young; Shim, Woo Hyun [Dept. of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul (Korea, Republic of); Lee, Jae Hong; Roh, Jee Hoon [University of Ulsan College of Medicine, Asan Medical Center, Seoul (Korea, Republic of)

    2017-11-15

    To identify potential imaging biomarkers of Alzheimer's disease by combining brain cortical thickness (CThk) and functional connectivity and to validate this model's diagnostic accuracy in a validation set. Data from 98 subjects was retrospectively reviewed, including a study set (n = 63) and a validation set from the Alzheimer's Disease Neuroimaging Initiative (n = 35). From each subject, data for CThk and functional connectivity of the default mode network was extracted from structural T1-weighted and resting-state functional magnetic resonance imaging. Cortical regions with significant differences between patients and healthy controls in the correlation of CThk and functional connectivity were identified in the study set. The diagnostic accuracy of functional connectivity measures combined with CThk in the identified regions was evaluated against that in the medial temporal lobes using the validation set and application of a support vector machine. Group-wise differences in the correlation of CThk and default mode network functional connectivity were identified in the superior temporal (p < 0.001) and supramarginal gyrus (p = 0.007) of the left cerebral hemisphere. Default mode network functional connectivity combined with the CThk of those two regions were more accurate than that combined with the CThk of both medial temporal lobes (91.7% vs. 75%). Combining functional information with CThk of the superior temporal and supramarginal gyri in the left cerebral hemisphere improves diagnostic accuracy, making it a potential imaging biomarker for Alzheimer's disease.

  13. Characterizing steady states of genome-scale metabolic networks in continuous cell cultures.

    Directory of Open Access Journals (Sweden)

    Jorge Fernandez-de-Cossio-Diaz

    2017-11-01

    Full Text Available In the continuous mode of cell culture, a constant flow carrying fresh media replaces culture fluid, cells, nutrients and secreted metabolites. Here we present a model for continuous cell culture coupling intra-cellular metabolism to extracellular variables describing the state of the bioreactor, taking into account the growth capacity of the cell and the impact of toxic byproduct accumulation. We provide a method to determine the steady states of this system that is tractable for metabolic networks of arbitrary complexity. We demonstrate our approach in a toy model first, and then in a genome-scale metabolic network of the Chinese hamster ovary cell line, obtaining results that are in qualitative agreement with experimental observations. We derive a number of consequences from the model that are independent of parameter values. The ratio between cell density and dilution rate is an ideal control parameter to fix a steady state with desired metabolic properties. This conclusion is robust even in the presence of multi-stability, which is explained in our model by a negative feedback loop due to toxic byproduct accumulation. A complex landscape of steady states emerges from our simulations, including multiple metabolic switches, which also explain why cell-line and media benchmarks carried out in batch culture cannot be extrapolated to perfusion. On the other hand, we predict invariance laws between continuous cell cultures with different parameters. A practical consequence is that the chemostat is an ideal experimental model for large-scale high-density perfusion cultures, where the complex landscape of metabolic transitions is faithfully reproduced.

  14. Cortical Visual Impairment

    Science.gov (United States)

    ... resolves by one year of life. Is “cortical blindness” the same thing as CVI? Cortical blindness is ... What visual characteristics are associated with CVI? • Distinct color preferences • Variable level of vision loss, often demonstrating ...

  15. Investigation of global and local network properties of music perception with culturally different styles of music.

    Science.gov (United States)

    Li, Yan; Rui, Xue; Li, Shuyu; Pu, Fang

    2014-11-01

    Graph theoretical analysis has recently become a popular research tool in neuroscience, however, there have been very few studies on brain responses to music perception, especially when culturally different styles of music are involved. Electroencephalograms were recorded from ten subjects listening to Chinese traditional music, light music and western classical music. For event-related potentials, phase coherence was calculated in the alpha band and then constructed into correlation matrices. Clustering coefficients and characteristic path lengths were evaluated for global properties, while clustering coefficients and efficiency were assessed for local network properties. Perception of light music and western classical music manifested small-world network properties, especially with a relatively low proportion of weights of correlation matrices. For local analysis, efficiency was more discernible than clustering coefficient. Nevertheless, there was no significant discrimination between Chinese traditional and western classical music perception. Perception of different styles of music introduces different network properties, both globally and locally. Research into both global and local network properties has been carried out in other areas; however, this is a preliminary investigation aimed at suggesting a possible new approach to brain network properties in music perception. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. Amitriptyline induces brain-derived neurotrophic factor (BDNF) mRNA expression through ERK-dependent modulation of multiple BDNF mRNA variants in primary cultured rat cortical astrocytes and microglia.

    Science.gov (United States)

    Hisaoka-Nakashima, Kazue; Kajitani, Naoto; Kaneko, Masahiro; Shigetou, Takahiro; Kasai, Miho; Matsumoto, Chie; Yokoe, Toshiki; Azuma, Honami; Takebayashi, Minoru; Morioka, Norimitsu; Nakata, Yoshihiro

    2016-03-01

    A significant role of brain-derived neurotrophic factor (BDNF) has been previously implicated in the therapeutic effect of antidepressants. To ascertain the contribution of specific cell types in the brain that produce BDNF following antidepressant treatment, the effects of the tricyclic antidepressant amitriptyline on rat primary neuronal, astrocytic and microglial cortical cultures were examined. Amitriptyline increased the expression of BDNF mRNA in astrocytic and microglial cultures but not neuronal cultures. Antidepressants with distinct mechanisms of action, such as clomipramine, duloxetine and fluvoxamine, also increased BDNF mRNA expression in astrocytic and microglial cultures. There are multiple BDNF mRNA variants (exon I, IIA, IV and VI) expressed in astrocytes and microglia and the variant induced by antidepressants has yet to be elaborated. Treatment with antidepressants increased the expression of exon I, IV and VI in astrocyte and microglia. Clomipramine alone significantly upregulated expression of exon IIA. The amitriptyline-induced expression of both total and individual BDNF mRNA variants (exon I, IV and VI) were blocked by MEK inhibitor U0126, indicating MEK/ERK signaling is required in the expression of BDNF. These findings indicate that non-neural cells are a significant target of antidepressants and further support the contention that glial production of BDNF is crucial role in the therapeutic effect of antidepressants. The current data suggest that targeting of glial function could lead to the development of antidepressants with a truly novel mechanism of action. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Functional Stem Cell Integration into Neural Networks Assessed by Organotypic Slice Cultures.

    Science.gov (United States)

    Forsberg, David; Thonabulsombat, Charoensri; Jäderstad, Johan; Jäderstad, Linda Maria; Olivius, Petri; Herlenius, Eric

    2017-08-14

    Re-formation or preservation of functional, electrically active neural networks has been proffered as one of the goals of stem cell-mediated neural therapeutics. A primary issue for a cell therapy approach is the formation of functional contacts between the implanted cells and the host tissue. Therefore, it is of fundamental interest to establish protocols that allow us to delineate a detailed time course of grafted stem cell survival, migration, differentiation, integration, and functional interaction with the host. One option for in vitro studies is to examine the integration of exogenous stem cells into an existing active neural network in ex vivo organotypic cultures. Organotypic cultures leave the structural integrity essentially intact while still allowing the microenvironment to be carefully controlled. This allows detailed studies over time of cellular responses and cell-cell interactions, which are not readily performed in vivo. This unit describes procedures for using organotypic slice cultures as ex vivo model systems for studying neural stem cell and embryonic stem cell engraftment and communication with CNS host tissue. © 2017 by John Wiley & Sons, Inc. Copyright © 2017 John Wiley & Sons, Inc.

  18. Culture-related differences in default network activity during visuo-spatial judgments.

    Science.gov (United States)

    Goh, Joshua O S; Hebrank, Andrew C; Sutton, Bradley P; Chee, Michael W L; Sim, Sam K Y; Park, Denise C

    2013-02-01

    Studies on culture-related differences in cognition have shown that Westerners attend more to object-related information, whereas East Asians attend more to contextual information. Neural correlates of these different culture-related visual processing styles have been reported in the ventral-visual and fronto-parietal regions. We conducted an fMRI study of East Asians and Westerners on a visuospatial judgment task that involved relative, contextual judgments, which are typically more challenging for Westerners. Participants judged the relative distances between a dot and a line in visual stimuli during task blocks and alternated finger presses during control blocks. Behaviorally, East Asians responded faster than Westerners, reflecting greater ease of the task for East Asians. In response to the greater task difficulty, Westerners showed greater neural engagement compared to East Asians in frontal, parietal, and occipital areas. Moreover, Westerners also showed greater suppression of the default network-a brain network that is suppressed under condition of high cognitive challenge. This study demonstrates for the first time that cultural differences in visual attention during a cognitive task are manifested both by differences in activation in fronto-parietal regions as well as suppression in default regions.

  19. Democratization or else vulgarization of cultural capital? The role of social networks in theater’s audience behavior

    OpenAIRE

    Carmela Milano

    2015-01-01

    This paper investigates the participation in social networks of theater's audiences. Our purpose is to observe, describe and understand the role of social networks in the consumption behavior of the theater field. In particular, we put the accent on the concept of cultural capital with its social dimension. We realize an exploratory study that consists in a dozen of qualitative semi-structured interviews with theater’s audiences that participate in social networks. We provide an analytical fr...

  20. Networking: a study in planning and developing cross-cultural collaboration

    Directory of Open Access Journals (Sweden)

    Sanjeev Singh

    2002-12-01

    Full Text Available This paper reports on a collaboration between the authors at the University of Brighton (UK and the University of Delhi, South Campus. The collaboration came about as a result of the EU-India Cross-Cultural Innovation Network collaboration programme, a project involving several universities and organizations across Europe and India. The authors of this paper both lecture in the area of computer networking. Following meetings in Delhi, they agreed to work together to produce a Web-based networking resource to be generated by the students of both institutions. The first phase of development involved the mounting of Web-based tutorials and documents produced by the students. The second phase will centre on the development of a knowledge base generated by the interaction of the students within an asynchronous forum. Running alongside these phases will be a collaborative bookmarking system, a database in which the students will post URLs of Web-based resources that they find useful in their studies. This system incorporates a form of collaborative filtering, an evolutionary mechanism which seeks to embody the qualities that students value in resources to provide a dynamic set of ratings to assist in the selection of those of most use. The planning of such a system raises some unusual issues, not least in the process of collaboration itself, with concerns as diverse as technical compatibility, institutional and cultural differences, timezones and the reliability of email. Limited bandwidth between our institutions causes special problems with the interactive elements of the resource. We present the methods we are investigating to reduce the impact of this. The fact that the students share an intellectual discipline but are otherwise separated by a cultural and geographical divide is expected to lead to fruitful diversity in thinking and approaches to problem-solving.

  1. Modulation of cultured neural networks using neurotrophin release from hydrogel-coated microelectrode arrays

    Science.gov (United States)

    Jun, Sang Beom; Hynd, Matthew R.; Dowell-Mesfin, Natalie M.; Al-Kofahi, Yousef; Roysam, Badrinath; Shain, William; Kim, Sung June

    2008-06-01

    Polyacrylamide and poly(ethylene glycol) diacrylate hydrogels were synthesized and characterized for use as drug release and substrates for neuron cell culture. Protein release kinetics was determined by incorporating bovine serum albumin (BSA) into hydrogels during polymerization. To determine if hydrogel incorporation and release affect bioactivity, alkaline phosphatase was incorporated into hydrogels and a released enzyme activity determined using the fluorescence-based ELF-97 assay. Hydrogels were then used to deliver a brain-derived neurotrophic factor (BDNF) from hydrogels polymerized over planar microelectrode arrays (MEAs). Primary hippocampal neurons were cultured on both control and neurotrophin-containing hydrogel-coated MEAs. The effect of released BDNF on neurite length and process arborization was investigated using automated image analysis. An increased spontaneous activity as a response to the released BDNF was recorded from the neurons cultured on the top of hydrogel layers. These results demonstrate that proteins of biological interest can be incorporated into hydrogels to modulate development and function of cultured neural networks. These results also set the stage for development of hydrogel-coated neural prosthetic devices for local delivery of various biologically active molecules.

  2. High-Degree Neurons Feed Cortical Computations.

    Directory of Open Access Journals (Sweden)

    Nicholas M Timme

    2016-05-01

    Full Text Available Recent work has shown that functional connectivity among cortical neurons is highly varied, with a small percentage of neurons having many more connections than others. Also, recent theoretical developments now make it possible to quantify how neurons modify information from the connections they receive. Therefore, it is now possible to investigate how information modification, or computation, depends on the number of connections a neuron receives (in-degree or sends out (out-degree. To do this, we recorded the simultaneous spiking activity of hundreds of neurons in cortico-hippocampal slice cultures using a high-density 512-electrode array. This preparation and recording method combination produced large numbers of neurons recorded at temporal and spatial resolutions that are not currently available in any in vivo recording system. We utilized transfer entropy (a well-established method for detecting linear and nonlinear interactions in time series and the partial information decomposition (a powerful, recently developed tool for dissecting multivariate information processing into distinct parts to quantify computation between neurons where information flows converged. We found that computations did not occur equally in all neurons throughout the networks. Surprisingly, neurons that computed large amounts of information tended to receive connections from high out-degree neurons. However, the in-degree of a neuron was not related to the amount of information it computed. To gain insight into these findings, we developed a simple feedforward network model. We found that a degree-modified Hebbian wiring rule best reproduced the pattern of computation and degree correlation results seen in the real data. Interestingly, this rule also maximized signal propagation in the presence of network-wide correlations, suggesting a mechanism by which cortex could deal with common random background input. These are the first results to show that the extent to

  3. Firing-rate based network modeling of the dLGN circuit: Effects of cortical feedback on spatiotemporal response properties of relay cells.

    Science.gov (United States)

    Mobarhan, Milad Hobbi; Halnes, Geir; Martínez-Cañada, Pablo; Hafting, Torkel; Fyhn, Marianne; Einevoll, Gaute T

    2018-05-01

    Visually evoked signals in the retina pass through the dorsal geniculate nucleus (dLGN) on the way to the visual cortex. This is however not a simple feedforward flow of information: there is a significant feedback from cortical cells back to both relay cells and interneurons in the dLGN. Despite four decades of experimental and theoretical studies, the functional role of this feedback is still debated. Here we use a firing-rate model, the extended difference-of-Gaussians (eDOG) model, to explore cortical feedback effects on visual responses of dLGN relay cells. For this model the responses are found by direct evaluation of two- or three-dimensional integrals allowing for fast and comprehensive studies of putative effects of different candidate organizations of the cortical feedback. Our analysis identifies a special mixed configuration of excitatory and inhibitory cortical feedback which seems to best account for available experimental data. This configuration consists of (i) a slow (long-delay) and spatially widespread inhibitory feedback, combined with (ii) a fast (short-delayed) and spatially narrow excitatory feedback, where (iii) the excitatory/inhibitory ON-ON connections are accompanied respectively by inhibitory/excitatory OFF-ON connections, i.e. following a phase-reversed arrangement. The recent development of optogenetic and pharmacogenetic methods has provided new tools for more precise manipulation and investigation of the thalamocortical circuit, in particular for mice. Such data will expectedly allow the eDOG model to be better constrained by data from specific animal model systems than has been possible until now for cat. We have therefore made the Python tool pyLGN which allows for easy adaptation of the eDOG model to new situations.

  4. Growth-expectations among women entrepreneurs: embedded in networks and culture in Algeria, Morocco, Tunisia and in Belgium and France

    DEFF Research Database (Denmark)

    Cheraghi, Maryam; Setti, Zakia; Schøtt, Thomas

    2014-01-01

    Entrepreneurship Monitor, randomly sampling 39,336 women, including 2,306 entrepreneurs. Analyses show that women entrepreneurs have growth-expectations based on their background and increased by their competence and opportunity-motive, which also promote business networks around their firms. Formation......An entrepreneur usually has an expectation for the firm, expecting expansion, stability or contraction. Expectation is influenced by the entrepreneur's attributes, but expectation is also embedded in the micro-environment of networking and the macro-environment of culture. Traditional culture...... and secular-rational culture differ in roles for women, which influence women entrepreneurs' networking and expectations. The design compares cultures, with data from three traditional societies, Algeria, Morocco and Tunisia and two secular-rational societies, France and Belgium, surveyed in the Global...

  5. Cortical actin networks induce spatio-temporal confinement of phospholipids in the plasma membrane--a minimally invasive investigation by STED-FCS.

    Science.gov (United States)

    Andrade, Débora M; Clausen, Mathias P; Keller, Jan; Mueller, Veronika; Wu, Congying; Bear, James E; Hell, Stefan W; Lagerholm, B Christoffer; Eggeling, Christian

    2015-06-29

    Important discoveries in the last decades have changed our view of the plasma membrane organisation. Specifically, the cortical cytoskeleton has emerged as a key modulator of the lateral diffusion of membrane proteins. Cytoskeleton-dependent compartmentalised lipid diffusion has been proposed, but this concept remains controversial because this phenomenon has thus far only been observed with artefact-prone probes in combination with a single technique: single particle tracking. In this paper, we report the first direct observation of compartmentalised phospholipid diffusion in the plasma membrane of living cells using a minimally invasive, fluorescent dye labelled lipid analogue. These observations were made using optical STED nanoscopy in combination with fluorescence correlation spectroscopy (STED-FCS), a technique which allows the study of membrane dynamics on a sub-millisecond time-scale and with a spatial resolution of down to 40 nm. Specifically, we find that compartmentalised phospholipid diffusion depends on the cortical actin cytoskeleton, and that this constrained diffusion is directly dependent on the F-actin branching nucleator Arp2/3. These findings provide solid evidence that the Arp2/3-dependent cortical actin cytoskeleton plays a pivotal role in the dynamic organisation of the plasma membrane, potentially regulating fundamental cellular processes.

  6. OPTIMAL CAMERA NETWORK DESIGN FOR 3D MODELING OF CULTURAL HERITAGE

    Directory of Open Access Journals (Sweden)

    B. S. Alsadik

    2012-07-01

    Full Text Available Digital cultural heritage documentation in 3D is subject to research and practical applications nowadays. Image-based modeling is a technique to create 3D models, which starts with the basic task of designing the camera network. This task is – however – quite crucial in practical applications because it needs a thorough planning and a certain level of expertise and experience. Bearing in mind todays computational (mobile power we think that the optimal camera network should be designed in the field, and, therefore, making the preprocessing and planning dispensable. The optimal camera network is designed when certain accuracy demands are fulfilled with a reasonable effort, namely keeping the number of camera shots at a minimum. In this study, we report on the development of an automatic method to design the optimum camera network for a given object of interest, focusing currently on buildings and statues. Starting from a rough point cloud derived from a video stream of object images, the initial configuration of the camera network assuming a high-resolution state-of-the-art non-metric camera is designed. To improve the image coverage and accuracy, we use a mathematical penalty method of optimization with constraints. From the experimental test, we found that, after optimization, the maximum coverage is attained beside a significant improvement of positional accuracy. Currently, we are working on a guiding system, to ensure, that the operator actually takes the desired images. Further next steps will include a reliable and detailed modeling of the object applying sophisticated dense matching techniques.

  7. The challenges of cross-cultural research and teaching in family medicine: How can professional networks help?

    Directory of Open Access Journals (Sweden)

    Amanda Caroline Howe

    2016-05-01

    Full Text Available Modern medical training emphasizes the value of understanding the patient’s ideas, concerns and expectations, and the use of their personal perspective to assist communication, diagnosis, and uptake of all appropriate health and treatment options. This requires doctors to be ‘culturally sensitive’, which “… involves an awareness and acceptance of cultural differences, self-awareness, knowledge of a patient’s culture, and adaptation of skills”. Yet most of us work in one country, and often one community, for much of our professional careers. Those who enter into academic pursuits will similarly be constrained by our own backgrounds and experiences, even though universities and medical schools often attract a multicultural membership. We therefore rely on our professional training and networks to extend our scope and understanding of how cultural issues impact upon our research and its relevance to our discipline and curricula. This article uses a reflexive narrative approach to examine the role and value of international networks through the lens of one individual and one organisation. It explores the extent to which such networks assist cross cultural sensitivity, using examples from its networks, and how these can (and have impacted on greater cross-culturalism in our teaching and research outputs.

  8. Palmitoylethanolamide Blunts Amyloid-β42-Induced Astrocyte Activation and Improves Neuronal Survival in Primary Mouse Cortical Astrocyte-Neuron Co-Cultures.

    Science.gov (United States)

    Beggiato, Sarah; Borelli, Andrea Celeste; Ferraro, Luca; Tanganelli, Sergio; Antonelli, Tiziana; Tomasini, Maria Cristina

    2018-01-01

    Based on the pivotal role of astrocytes in brain homeostasis and the strong metabolic cooperation existing between neurons and astrocytes, it has been suggested that astrocytic dysfunctions might cause and/or contribute to neuroinflammation and neurodegenerative processes. Therapeutic approaches aimed at both neuroprotection and neuroinflammation reduction may prove particularly effective in slowing the progression of these diseases. The endogenous lipid mediator palmitoylethanolamide (PEA) displayed neuroprotective and anti(neuro)inflammatory properties, and demonstrated interesting potential as a novel treatment for Alzheimer's disease. We firstly evaluated whether astrocytes could participate in regulating the Aβ42-induced neuronal damage, by using primary mouse astrocytes cell cultures and mixed astrocytes-neurons cultures. Furthermore, the possible protective effects of PEA against Aβ42-induced neuronal toxicity have also been investigated by evaluating neuronal viability, apoptosis, and morphometric parameters. The presence of astrocytes pre-exposed to Aβ42 (0.5μM; 24 h) induced a reduction of neuronal viability in primary mouse astrocytes-neurons co-cultures. Furthermore, under these experimental conditions, an increase in the number of neuronal apoptotic nuclei and a decrease in the number of MAP-2 positive neurons were observed. Finally, astrocytic Aβ42 pre-exposure induced an increase in the number of neurite aggregations/100μm as compared to control (i.e., untreated) astrocytes-neurons co-cultures. These effects were not observed in neurons cultured in the presence of astrocytes pre-exposed to PEA (0.1μM), applied 1 h before and maintained during Aβ42 treatment. Astrocytes contribute to Aβ42-induced neurotoxicity and PEA, by blunting Aβ42-induced astrocyte activation, improved neuronal survival in mouse astrocyte-neuron co-cultures.

  9. Micropit: a new cell culturing approach for characterization of solitary astrocytes and small networks of these glial cells

    Directory of Open Access Journals (Sweden)

    William Lee

    2008-12-01

    Full Text Available Astrocytes play an important role in cell-cell signaling in the mammalian central nervous system. The ability of astrocytes to communicate with surrounding cells through gap-junctional coupling or signaling via the release of transmitters makes characterization of these cells difficult in vitro and even more so in vivo. To simplify the complexity of common in vitro systems, introduced by intercellular communication between astrocytes, we developed a novel cell culturing method, in which purified rat visual cortical astrocytes were grown in spatially defined cell-adhesion wells which we termed micropits. We showed that astrocytes cultured in micropit regions were viable and exhibited similar characteristics of Ca2+ dynamics and astrocytic marker expression to those of cells cultured in non-micropit regions. Examination of intracellular Ca2+ oscillations in solitary astrocytes cultured in micropits revealed less variable oscillations than those of non-micropit grouped astrocytes, which were in contact with their neighbors. Solitary cells in micropit regions can undergo ATP-mediated astrocyte-microglia signaling, demonstrating that this culturing method can also be used to investigate glial-glial interactions in a spatially well-defined microenvironment.

  10. Osteogenic stimulatory conditions enhance growth and maturation of endothelial cell microvascular networks in culture with mesenchymal stem cells

    Directory of Open Access Journals (Sweden)

    Torbjorn O Pedersen

    2012-12-01

    Full Text Available To optimize culture conditions for in vitro prevascularization of tissue-engineered bone constructs, the development of organotypic blood vessels under osteogenic stimulatory conditions (OM was investigated. Coculture of endothelial cells and mesenchymal stem cells was used to assess proangiogenic effects of mesenchymal stem cells on endothelial cells. Four different culture conditions were evaluated for their effect on development of microvascular endothelial cell networks. Mineralization, deposition of extracellular matrix, and perivascular gene expression were studied in OM. After 3 days, endothelial cells established elongated capillary-like networks, and upregulated expression of vascular markers was seen. After 15 days, all parameters evaluated were significantly increased for cultures in OM. Mature networks developed in OM presented lumens enveloped by basement membrane-like collagen IV, with obvious mineralization and upregulated perivascular gene expression from mesenchymal stem cells. Our results suggest osteogenic stimulatory conditions to be appropriate for in vitro development of vascularized bone implants for tissue engineering.

  11. The Use of Social Networking Sites in Job Related Activities: A Cross-cultural Comparison

    Directory of Open Access Journals (Sweden)

    Małgorzata Bartosik-Purgat

    2017-06-01

    Full Text Available Objective: The main objective of the paper is to identify the use of Social Networking Sites (SNSs in job related activities and indicate the interdependencies between these activities and age, gender, as well as education in culturally diversified markets (China, Poland, Turkey, the United States. Research Design & Methods: In the exploratory empirical study the authors used two research methods: PAPI (Paper and Pen Personal Interview and CAWI (Computer Assisted Web Interview. The empirical data were collected in 2016 and the total number of respondents from four culturally diversified countries was 1246. Findings: The analysis with the use of Kruskal-Wallis and Dunn post-hoc tests showed that the Turkish respondents most often use SNSs for job related activities, while it is the least often done by the studied Americans. Moreover, from among the studied factors (gender, age and education level that differentiate the SNSs usage for job related activities in a statistically significant way age is of greatest importance. Implications & Recommendations: The results of the research provide implications for the recruitment policy of multinational enterprises (MNEs. Since more and more enterprises use SNSs in order to look for new employees and advertise themselves as employers (employer branding, the identified interdependencies between the SNSs activities and the analysed factors can support firm attempts to develop the proper recruitment policy taking into account the cultural diversity of potential workers. Contribution & Value Added: There are not many studies in the literature which present the usage of SNSs for job related activities from the perspective of individual users in the cross-cultural approach. The majority of studies are related to the usage of SNSs by enterprises in the recruitment process.

  12. Memantine, a Low-Affinity NMDA Receptor Antagonist, Protects against Methylmercury-Induced Cytotoxicity of Rat Primary Cultured Cortical Neurons, Involvement of Ca2+ Dyshomeostasis Antagonism, and Indirect Antioxidation Effects.

    Science.gov (United States)

    Liu, Wei; Xu, Zhaofa; Yang, Tianyao; Xu, Bin; Deng, Yu; Feng, Shu

    2017-09-01

    Methylmercury (MeHg) is an extremely dangerous environmental pollutant that induces severe toxic effects in the central nervous system. Neuronal damage plays critical roles mediating MeHg-induced loss of brain function and neurotoxicity. The molecular mechanisms of MeHg neurotoxicity are incompletely understood. The objective of the study is to explore mechanisms that contribute to MeHg-induced neurocyte injuries focusing on neuronal Ca 2+ dyshomeostasis and alteration of N-methyl-D-aspartate receptors (NMDARs) expression, as well as oxidative stress in primary cultured cortical neurons. In addition, the neuroprotective effects of memantine against MeHg cytotoxicity were also investigated. The cortical neurons were exposed to 0, 0.01, 0.1, 1, or 2 μM methylmercury chloride (MeHgCl) for 0.5-12 h, or pre-treated with 2.5, 5, 10, or 20 μM memantine for 0.5-6 h, respectively; cell viability and LDH release were then quantified. For further experiments, 2.5, 5, and 10 μM of memantine pre-treatment for 3 h followed by 1 μM MeHgCl for 6 h were performed for evaluation of neuronal injuries, specifically addressing apoptosis; intracellular free Ca 2+ concentrations; ATPase activities; calpain activities; expressions of NMDAR subunits (NR1, NR2A, NR2B); NPSH levels; and ROS formation. Exposure of MeHgCl resulted in toxicity of cortical neurons, which were shown as a loss of cell viability, high levels of LDH release, morphological changes, and cell apoptosis. Moreover, intracellular Ca 2+ dyshomeostasis, ATPase activities inhibition, calpain activities, and NMDARs expression alteration were observed with 1 μM MeHgCl administration. Last but not least, NPSH depletion and reactive oxygen species (ROS) overproduction showed an obvious oxidative stress in neurons. However, memantine pre-treatment dose-dependently antagonized MeHg-induced neuronal toxic effects, apoptosis, Ca 2+ dyshomeostasis, NMDARs expression alteration, and oxidative stress. In conclusion, the

  13. Co-induction of p75NTR and p75NTR-associated death executor in neurons after zinc exposure in cortical culture or transient ischemia in the rat.

    Science.gov (United States)

    Park, J A; Lee, J Y; Sato, T A; Koh, J Y

    2000-12-15

    Recently, a 22 kDa protein termed p75(NTR)-associated death executor (NADE) was discovered to be a necessary factor for p75(NTR)-mediated apoptosis in certain cells. However, the possible role for p75(NTR)/NADE in pathological neuronal death has yet been undetermined. In the present study, we have examined this possibility in vivo and in vitro. Exposure of cortical cultures to zinc induced both p75(NTR) and NADE in neurons, whereas exposure to NMDA, ionomycin, iron, or H(2)O(2) induced neither. In addition, zinc exposure increased neuronal NGF expression and its release into the medium. A function-blocking antibody of p75(NTR) (REX) inhibited association between p75(NTR) and NADE as well as neuronal death induced by zinc. Conversely, NGF augmented zinc-induced neuronal death. Caspase inhibitors reduced zinc-induced neuronal death, indicating that caspases were involved. Because reduction of NADE expression with cycloheximide or NADE antisense oligonucleotides attenuated zinc-induced neuronal death, NADE appears to contribute to p75(NTR)-induced cortical neuronal death as shown in other cells. Because zinc neurotoxicity may be a key mechanism of neuronal death after transient forebrain ischemia, we next examined this model. After ischemia, p75(NTR) and NADE were induced in degenerating rat hippocampal CA1 neurons. There was a close correlation between zinc accumulation and p75(NTR)/NADE induction. Suggesting the role of zinc here, injection of a metal chelator, CaEDTA, into the lateral ventricle completely blocked the induction of p75(NTR) and NADE. Our results suggest that co-induction of p75(NTR) and NADE plays a role in zinc-triggered neuronal death in vitro and in vivo.

  14. Designing 3ERP to meet use and users - methods to handle cultural diversity and collaborative networking in SMEs

    DEFF Research Database (Denmark)

    Dirckinck-Holmfeld, Lone; Nielsen, Janni

    2007-01-01

    The purpose is to describe a project the aim of which is to develop and validate the scientific methodological foundation for design of user friendly and usable, flexible and configurable global Enterprise Resource Planning system for Small and Medium sized Enterprises (SMEs) which are adoptable ...... to cultural diversity and support the collaborative networking tasks embedded in 3gERP. Focus is on Human Centered Design methods and tools which must be developed to handle cultural diversity....

  15. CULTURAL ISSUES OF SOCIAL NETWORKS, THEIR PRINCIPLES AND VALUES IN SOCIAL INCLUSION

    Directory of Open Access Journals (Sweden)

    Alessandro Marco Rosini

    2015-09-01

    Full Text Available This article aims to show the importance of a samba school for the local community (in relation to social inclusion and redemption of human values, reflect on the application of this learning created at community to a (organization and discuss the role of people in organizational and cultural strengthening in a social networking environment. It also shows how the use of information technology and communication (ITC can contribute to the evolution of educational scenario of those communities. The scientific method for this is case study, using Delphi technique, where the main community stakeholders are interviewed. Care, respect and consideration for the people who are part of the community are important factors in these social communities. The learning generated by the community and their leaders’ effort are determining for them. ITC can help this learning.

  16. Culture.

    Science.gov (United States)

    Smith, Timothy B; Rodríguez, Melanie Domenech; Bernal, Guillermo

    2011-02-01

    This article summarizes the definitions, means, and research of adapting psychotherapy to clients' cultural backgrounds. We begin by reviewing the prevailing definitions of cultural adaptation and providing a clinical example. We present an original meta-analysis of 65 experimental and quasi-experimental studies involving 8,620 participants. The omnibus effect size of d = .46 indicates that treatments specifically adapted for clients of color were moderately more effective with that clientele than traditional treatments. The most effective treatments tended to be those with greater numbers of cultural adaptations. Mental health services targeted to a specific cultural group were several times more effective than those provided to clients from a variety of cultural backgrounds. We recommend a series of research-supported therapeutic practices that account for clients' culture, with culture-specific treatments being more effective than generally culture-sensitive treatments. © 2010 Wiley Periodicals, Inc.

  17. Women Favour Dyadic Relationships, but Men Prefer Clubs: Cross-Cultural Evidence from Social Networking

    Science.gov (United States)

    David-Barrett, Tamas; Rotkirch, Anna; Carney, James; Behncke Izquierdo, Isabel; Krems, Jaimie A.; Townley, Dylan; McDaniell, Elinor; Byrne-Smith, Anna; Dunbar, Robin I. M.

    2015-01-01

    The ability to create lasting, trust-based friendships makes it possible for humans to form large and coherent groups. The recent literature on the evolution of sociality and on the network dynamics of human societies suggests that large human groups have a layered structure generated by emotionally supported social relationships. There are also gender differences in adult social style which may involve different trade-offs between the quantity and quality of friendships. Although many have suggested that females tend to focus on intimate relations with a few other females, while males build larger, more hierarchical coalitions, the existence of such gender differences is disputed and data from adults is scarce. Here, we present cross-cultural evidence for gender differences in the preference for close friendships. We use a sample of ∼112,000 profile pictures from nine world regions posted on a popular social networking site to show that, in self-selected displays of social relationships, women favour dyadic relations, whereas men favour larger, all-male cliques. These apparently different solutions to quality-quantity trade-offs suggest a universal and fundamental difference in the function of close friendships for the two sexes. PMID:25775258

  18. Women favour dyadic relationships, but men prefer clubs: cross-cultural evidence from social networking.

    Directory of Open Access Journals (Sweden)

    Tamas David-Barrett

    Full Text Available The ability to create lasting, trust-based friendships makes it possible for humans to form large and coherent groups. The recent literature on the evolution of sociality and on the network dynamics of human societies suggests that large human groups have a layered structure generated by emotionally supported social relationships. There are also gender differences in adult social style which may involve different trade-offs between the quantity and quality of friendships. Although many have suggested that females tend to focus on intimate relations with a few other females, while males build larger, more hierarchical coalitions, the existence of such gender differences is disputed and data from adults is scarce. Here, we present cross-cultural evidence for gender differences in the preference for close friendships. We use a sample of ∼112,000 profile pictures from nine world regions posted on a popular social networking site to show that, in self-selected displays of social relationships, women favour dyadic relations, whereas men favour larger, all-male cliques. These apparently different solutions to quality-quantity trade-offs suggest a universal and fundamental difference in the function of close friendships for the two sexes.

  19. Simultaneous stability and sensitivity in model cortical networks is achieved through anti-correlations between the in- and out-degree of connectivity

    Directory of Open Access Journals (Sweden)

    Juan Carlos Vasquez

    2013-11-01

    Full Text Available Neuronal networks in rodent barrel cortex are characterized by stable low baseline firing rates. However, they are sensitive to the action potentials of single neurons as suggested by recent single-cell stimulation experiments that report quantifiable behavioral responses in response to short spike trains elicited in single neurons. Hence, these networks are stable against internally generated fluctuations in firing rate but at the same time remain sensitive to similarly-sized externally induced perturbations. We investigated stability and sensitivity in a simple recurrent network of stochastic binary neurons and determined numerically the effects of correlation between the number of afferent (‘in-degree’ and efferent (‘out-degree’ connections in neurons. The key advance reported in this work is that anti-correlation between in-/out-degree distributions increased the stability of the network in comparison to networks with no correlation or positive correlations, while being able to achieve the same level of sensitivity. The experimental characterization of degree distributions is difficult because all presynaptic and postsynaptic neurons have to be identified and counted. We explored whether the statistics of network motifs, which requires the characterization of connections between small subsets of neurons, could be used to detect evidence for degree anti-correlations. We find that the sample frequency of the 3-neuron ‘ring’ motif (1→2→3→1, can be used to detect degree anti-correlation for sub-networks of size 30 using about 50 samples, which is of significance because the necessary measurements are achievable experimentally in the near future.Taken together, we hypothesize that barrel cortex networks exhibit degree anti-correlations and specific network motif statistics.

  20. Barbed channels enhance unidirectional connectivity between neuronal networks cultured on multi electrode arrays

    Science.gov (United States)

    le Feber, Joost; Postma, Wybren; de Weerd, Eddy; Weusthof, Marcel; Rutten, Wim L. C.

    2015-01-01

    Cultured neurons on multi electrode arrays (MEAs) have been widely used to study various aspects of neuronal (network) functioning. A possible drawback of this approach is the lack of structure in these networks. At the single cell level, several solutions have been proposed to enable directed connectivity, and promising results were obtained. At the level of connected sub-populations, a few attempts have been made with promising results. First assessment of the designs' functionality, however, suggested room for further improvement. We designed a two chamber MEA aiming to create a unidirectional connection between the networks in both chambers (“emitting” and “receiving”). To achieve this unidirectionality, all interconnecting channels contained barbs that hindered axon growth in the opposite direction (from receiving to emitting chamber). Visual inspection showed that axons predominantly grew through the channels in the promoted direction. This observation was confirmed by spontaneous activity recordings. Cross-correlation between the signals from two electrodes inside the channels suggested signal propagation at ≈2 m/s from emitting to receiving chamber. Cross-correlation between the firing patterns in both chambers indicated that most correlated activity was initiated in the emitting chamber, which was also reflected by a significantly lower fraction of partial bursts (i.e., a one-chamber-only burst) in the emitting chamber. Finally, electrical stimulation in the emitting chamber induced a fast response in that chamber, and a slower response in the receiving chamber. Stimulation in the receiving chamber evoked a fast response in that chamber, but no response in the emitting chamber. These results confirm the predominantly unidirectional nature of the connecting channels from emitting to receiving chamber. PMID:26578869

  1. Barbed channels enhance unidirectional connectivity between neuronal networks cultured on multi electrode arrays.

    Directory of Open Access Journals (Sweden)

    Joost eLe Feber

    2015-11-01

    Full Text Available Cultured neurons on multi electrode arrays (MEAs have been widely used to study various as-pects of neuronal (network functioning. A possible drawback of this approach is the lack of structure in these networks. At the single cell level, several solutions have been proposed to ena-ble directed connectivity, and promising results were obtained. At the level of connected sub-populations, a few attempts have been made with promising results. First assessment of the de-signs’ functionality, however, suggested room for further improvement.We designed a two chamber MEA aiming to create a unidirectional connection between the net-works in both chambers (‘emitting’ and ‘receiving’. To achieve this unidirectionality, all inter-connecting channels contained barbs that hindered axon growth in the opposite direction (from receiving to emitting chamber. Visual inspection showed that axons predominantly grew through the channels in the promoted direction . This observation was confirmed by spontaneous activity recordings. Cross-correlation between the signals from two electrodes inside the channels suggested signal propagation at ≈2 m/s from emitting to receiving chamber. Cross-correlation between the firing patterns in both chambers indicated that most correlated activity was initiated in the emitting chamber, which was also reflected by a significantly lower fraction of partial bursts (e. a one-chamber-only burst in the emitting chamber. Finally, electrical stimulation in the emitting chamber induced a fast response in that chamber, and a slower response in the receiving chamber. Stimulation in the receiving chamber evoked a fast response in that chamber, but no response in the emitting chamber. These results confirm the predominantly unidirectional nature of the connecting channels from emitting to receiving chamber.

  2. Cortical bone metastases

    International Nuclear Information System (INIS)

    Davis, T.M. Jr.; Rogers, L.F.; Hendrix, R.W.

    1986-01-01

    Twenty-five cases of bone metastases involving the cortex alone are reviewed. Seven patients had primary lung carcinoma, while 18 had primary tumors not previously reported to produce cortical bone metastases (tumors of the breast, kidney, pancreas, adenocarcinoma of unknown origin, multiple myeloma). Radiographically, these cortical lesions were well circumscribed, osteolytic, and produced soft-tissue swelling and occasional periosteal reaction. A recurrent pattern of metadiaphyseal involvement of the long bones of the lower extremity (particularly the femur) was noted, and is discussed. Findings reported in the literature, review, pathophysiology, and the role of skeletal radiographs, bone scans, and CT scans in evaluating cortical bone metastases are addressed

  3. Detoxification of ammonia in mouse cortical GABAergic cell cultures increases neuronal oxidative metabolism and reveals an emerging role for release of glucose-derived alanine

    DEFF Research Database (Denmark)

    Leke, Renata; Bak, Lasse Kristoffer; Anker, Malene

    2011-01-01

    Cerebral hyperammonemia is believed to play a pivotal role in the development of hepatic encephalopathy (HE), a debilitating condition arising due to acute or chronic liver disease. In the brain, ammonia is thought to be detoxified via the activity of glutamine synthetase, an astrocytic enzyme....... Moreover, it has been suggested that cerebral tricarboxylic acid (TCA) cycle metabolism is inhibited and glycolysis enhanced during hyperammonemia. The aim of this study was to characterize the ammonia-detoxifying mechanisms as well as the effects of ammonia on energy-generating metabolic pathways...... in a mouse neuronal-astrocytic co-culture model of the GABAergic system. We found that 5 mM ammonium chloride affected energy metabolism by increasing the neuronal TCA cycle activity and switching the astrocytic TCA cycle toward synthesis of substrate for glutamine synthesis. Furthermore, ammonia exposure...

  4. [Schizophrenia and cortical GABA neurotransmission].

    Science.gov (United States)

    Hashimoto, Takanori; Matsubara, Takuro; Lewis, David A

    2010-01-01

    -synaptic GABA-A receptors. Our recent analyses demonstrated that this pattern exists across diverse cortical areas including the prefrontal, anterior cingulate, primary motor, and primary visual cortices. GABA neurotransmission by PV-containing and SST-containing neurons is important for the generation of cortical oscillatory activities in the gamma (30-100 Hz) and theta (4-7 Hz) bands, respectively. These oscillatory activities have been proposed to play critical roles in regulating the efficiency of information transfer between neurons and neuronal networks in the cortex. Altered cortical GABA neurotransmission appears to contribute to disturbances in diverse functions through affecting the generation of cortical oscillations in schizophrenia.

  5. Cultural specificity of socioemotional selectivity: age differences in social network composition among Germans and Hong Kong Chinese.

    Science.gov (United States)

    Fung, Helene H; Stoeber, Franziska S; Yeung, Dannii Yuen-lan; Lang, Frieder R

    2008-05-01

    We examined age differences in social network composition among 330 Germans and 330 Hong Kong Chinese, aged 20 to 91 years. We measured social network composition with the Social Convoy Questionnaire. In both cultures, older age was associated with the same number of close social partners and fewer peripheral social partners than was younger age. However, the patterns of age differences in specific relationships differed across cultures: Age was negatively associated with the proportion of nuclear family members among Germans but the association was positive among Hong Kong Chinese. Age was positively associated with the proportion of acquaintances among Germans but the association was negative among Hong Kong Chinese. We discuss the findings in terms of whether the socioemotional selectivity theory holds in both cultures.

  6. Networks, narratives and territory in anthropological race classification: towards a more comprehensive historical geography of Europe's culture.

    Science.gov (United States)

    McMahon, Richard

    2011-01-01

    This article aims to integrate discourse analysis of politically instrumental imagined identity geographies with the relational and territorial geography of the communities of praxis and interpretation that produce them. My case study is the international community of nationalist scientists who classified Europe's biological races in the 1820s-1940s. I draw on network analysis, relational geography, historical sociology and the historical turn to problematize empirically how spatial patterns of this community's shifting disciplinary and political coalitions, communication networks and power relations emerged, were structured, persisted, changed, interacted and disappeared. I focus especially on core-periphery relations. I argue that if local historical spatial patterns affect those of later phenomena, geographies like that of European integration should be understood in the context of Europe's complex historical cultural geography. Unlike discourse deconstruction alone, this complementary relational de-essentialization of geography can identify large-scale, enduring associations of cultural patterns as well as cultural flux and ambiguity.

  7. Detoxification of ammonia in mouse cortical GABAergic cell cultures increases neuronal oxidative metabolism and reveals an emerging role for release of glucose-derived alanine.

    Science.gov (United States)

    Leke, Renata; Bak, Lasse K; Anker, Malene; Melø, Torun M; Sørensen, Michael; Keiding, Susanne; Vilstrup, Hendrik; Ott, Peter; Portela, Luis V; Sonnewald, Ursula; Schousboe, Arne; Waagepetersen, Helle S

    2011-04-01

    Cerebral hyperammonemia is believed to play a pivotal role in the development of hepatic encephalopathy (HE), a debilitating condition arising due to acute or chronic liver disease. In the brain, ammonia is thought to be detoxified via the activity of glutamine synthetase, an astrocytic enzyme. Moreover, it has been suggested that cerebral tricarboxylic acid (TCA) cycle metabolism is inhibited and glycolysis enhanced during hyperammonemia. The aim of this study was to characterize the ammonia-detoxifying mechanisms as well as the effects of ammonia on energy-generating metabolic pathways in a mouse neuronal-astrocytic co-culture model of the GABAergic system. We found that 5 mM ammonium chloride affected energy metabolism by increasing the neuronal TCA cycle activity and switching the astrocytic TCA cycle toward synthesis of substrate for glutamine synthesis. Furthermore, ammonia exposure enhanced the synthesis and release of alanine. Collectively, our results demonstrate that (1) formation of glutamine is seminal for detoxification of ammonia; (2) neuronal oxidative metabolism is increased in the presence of ammonia; and (3) synthesis and release of alanine is likely to be important for ammonia detoxification as a supplement to formation of glutamine.

  8. Response of Cultured Neuronal Network Activity After High-Intensity Power Frequency Magnetic Field Exposure

    Directory of Open Access Journals (Sweden)

    Atsushi Saito

    2018-03-01

    Full Text Available High-intensity and low frequency (1–100 kHz time-varying electromagnetic fields stimulate the human body through excitation of the nervous system. In power frequency range (50/60 Hz, a frequency-dependent threshold of the external electric field-induced neuronal modulation in cultured neuronal networks was used as one of the biological indicator in international guidelines; however, the threshold of the magnetic field-induced neuronal modulation has not been elucidated. In this study, we exposed rat brain-derived neuronal networks to a high-intensity power frequency magnetic field (hPF-MF, and evaluated the modulation of synchronized bursting activity using a multi-electrode array (MEA-based extracellular recording technique. As a result of short-term hPF-MF exposure (50–400 mT root-mean-square (rms, 50 Hz, sinusoidal wave, 6 s, the synchronized bursting activity was increased in the 400 mT-exposed group. On the other hand, no change was observed in the 50–200 mT-exposed groups. In order to clarify the mechanisms of the 400 mT hPF-MF exposure-induced neuronal response, we evaluated it after blocking inhibitory synapses using bicuculline methiodide (BMI; subsequently, increase in bursting activity was observed with BMI application, and the response of 400 mT hPF-MF exposure disappeared. Therefore, it was suggested that the response of hPF-MF exposure was involved in the inhibitory input. Next, we screened the inhibitory pacemaker-like neuronal activity which showed autonomous 4–10 Hz firing with CNQX and D-AP5 application, and it was confirmed that the activity was reduced after 400 mT hPF-MF exposure. Comparison of these experimental results with estimated values of the induced electric field (E-field in the culture medium revealed that the change in synchronized bursting activity occurred over 0.3 V/m, which was equivalent to the findings of a previous study that used the external electric fields. In addition, the results suggested that

  9. Automated Interpretation of Blood Culture Gram Stains by Use of a Deep Convolutional Neural Network.

    Science.gov (United States)

    Smith, Kenneth P; Kang, Anthony D; Kirby, James E

    2018-03-01

    Microscopic interpretation of stained smears is one of the most operator-dependent and time-intensive activities in the clinical microbiology laboratory. Here, we investigated application of an automated image acquisition and convolutional neural network (CNN)-based approach for automated Gram stain classification. Using an automated microscopy platform, uncoverslipped slides were scanned with a 40× dry objective, generating images of sufficient resolution for interpretation. We collected 25,488 images from positive blood culture Gram stains prepared during routine clinical workup. These images were used to generate 100,213 crops containing Gram-positive cocci in clusters, Gram-positive cocci in chains/pairs, Gram-negative rods, or background (no cells). These categories were targeted for proof-of-concept development as they are associated with the majority of bloodstream infections. Our CNN model achieved a classification accuracy of 94.9% on a test set of image crops. Receiver operating characteristic (ROC) curve analysis indicated a robust ability to differentiate between categories with an area under the curve of >0.98 for each. After training and validation, we applied the classification algorithm to new images collected from 189 whole slides without human intervention. Sensitivity and specificity were 98.4% and 75.0% for Gram-positive cocci in chains and pairs, 93.2% and 97.2% for Gram-positive cocci in clusters, and 96.3% and 98.1% for Gram-negative rods. Taken together, our data support a proof of concept for a fully automated classification methodology for blood-culture Gram stains. Importantly, the algorithm was highly adept at identifying image crops with organisms and could be used to present prescreened, classified crops to technologists to accelerate smear review. This concept could potentially be extended to all Gram stain interpretive activities in the clinical laboratory. Copyright © 2018 American Society for Microbiology.

  10. Early and phasic cortical metabolic changes in vestibular neuritis onset.

    Directory of Open Access Journals (Sweden)

    Marco Alessandrini

    Full Text Available Functional brain activation studies described the presence of separate cortical areas responsible for central processing of peripheral vestibular information and reported their activation and interactions with other sensory modalities and the changes of this network associated to strategic peripheral or central vestibular lesions. It is already known that cortical changes induced by acute unilateral vestibular failure (UVF are various and undergo variations over time, revealing different cortical involved areas at the onset and recovery from symptoms. The present study aimed at reporting the earliest change in cortical metabolic activity during a paradigmatic form of UVF such as vestibular neuritis (VN, that is, a purely peripheral lesion of the vestibular system, that offers the opportunity to study the cortical response to altered vestibular processing. This research reports [(18F]fluorodeoxyglucose positron emission tomography brain scan data concerning the early cortical metabolic activity associated to symptoms onset in a group of eight patients suffering from VN. VN patients' cortical metabolic activity during the first two days from symptoms onset was compared to that recorded one month later and to a control healthy group. Beside the known cortical response in the sensorimotor network associated to vestibular deafferentation, we show for the first time the involvement of Entorhinal (BAs 28, 34 and Temporal (BA 38 cortices in early phases of symptomatology onset. We interpret these findings as the cortical counterparts of the attempt to reorient oneself in space counteracting the vertigo symptom (Bas 28, 34 and of the emotional response to the new pathologic condition (BA 38 respectively. These interpretations were further supported by changes in patients' subjective ratings in balance, anxiety, and depersonalization/derealization scores when tested at illness onset and one month later. The present findings contribute in expanding

  11. Identifying socio-ecological networks in rural-urban gradients: Diagnosis of a changing cultural landscape.

    Science.gov (United States)

    Arnaiz-Schmitz, C; Schmitz, M F; Herrero-Jáuregui, C; Gutiérrez-Angonese, J; Pineda, F D; Montes, C

    2018-01-15

    Socio-ecological systems maintain reciprocal interactions between biophysical and socioeconomic structures. As a result of these interactions key essential services for society emerge. Urban expansion is a direct driver of land change and cause serious shifts in socio-ecological relationships and the associated lifestyles. The framework of rural-urban gradients has proved to be a powerful tool for ecological research about urban influences on ecosystems and on sociological issues related to social welfare. However, to date there has not been an attempt to achieve a classification of municipalities in rural-urban gradients based on socio-ecological interactions. In this paper, we developed a methodological approach that allows identifying and classifying a set of socio-ecological network configurations in the Region of Madrid, a highly dynamic cultural landscape considered one of the European hotspots in urban development. According to their socio-ecological links, the integrated model detects four groups of municipalities, ordered along a rural-urban gradient, characterized by their degree of biophysical and socioeconomic coupling and different indicators of landscape structure and social welfare. We propose the developed model as a useful tool to improve environmental management schemes and land planning from a socio-ecological perspective, especially in territories subject to intense urban transformations and loss of rurality. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Digital media sport technology, power and culture in the network society

    CERN Document Server

    Hutchins, Brett; Morris, Peter; Therivel, Riki

    2013-01-01

    Live broadband streaming of the 2008 Beijing Olympics accounted for 2,200 of the estimated 3,600 total hours shown by the American NBC-Universal networks. At the 2012 London Olympics, unprecedented multi-platforming embraced online, mobile devices, game consoles and broadcast television, with the BBC providing 2,500 hours of live coverage, including every competitive event, much in high definition and some in 3D. The BBC also had 12 million requests for video on mobile phones and 9.2 million browsers on its mobile Olympics website and app. This pattern will only intensify at future sport mega events like the 2014 FIFA World Cup and 2016 Summer Olympics, both of which will take place in Brazil. Increasingly, when people talk of the screen that delivers footage of their favorite professional sport, they are describing desktop, laptop, and tablet computer screens as well as television and mobile handsets. Digital Media Sport analyzes the intersecting issues of technological change, market power, and cultural pra...

  13. THE PAN AFRICAN E-NETWORK PROJECT: A New Learning Culture

    Directory of Open Access Journals (Sweden)

    Nundoo-Ghoorah SUNITI

    2012-07-01

    Full Text Available This paper sets out to explore the paradigm shift in learning culture brought about by the advent of online learning in the mostly print-based ODL system at the Mauritius College of the Air (MCA. It delves into the perceptions of learners and MCA staff involved in a range of undergraduate to Master’s programmes forming part of the Pan African e- Network Project that wires 23 African countries with top-ranking Indian universities through synchronous and interactive state of the art technology. Learners across five of the disciplines offered through tele-learning and a team of MCA staff participating in programme delivery were surveyed through questionnaires and interviews to collect both quantitative and qualitative data. For most of the respondents this new learning ethos has induced an acculturation process requiring radical reconceptualisation of prior notions about teaching/learning. MCA staff, too, have had to learn conducive behavior patterns to consolidate existing support services. Survival in this new learning environment where the tutor is a remote on-screen entity, where e-books replace printed material, where connectivity can be a daily struggle, demands another mindset, another set of values enabling learning and fine-tuned ICT skills. Socialisation with tutors and fellow learners is possible through links in Facebook and Twitter. However, learners still tend to feel somewhat isolated. It is proposed that an e-platform be set up to link up learners as a mutually supportive learning community engaged in the construction of knowledge.

  14. The Influence of Culture on the Expression of Emotions in Online Social Networks

    Directory of Open Access Journals (Sweden)

    Cathia PAPI

    2016-12-01

    Full Text Available Seeking to understand the influence of culture on the expression of emotions in online social networks, we analyzed four Facebook groups – two from Quebec, Canada and two from Colombia – created following unexpected deaths. Comparison of the messages posted in these groups reveals a stronger tendency to maintain a virtual relationship with the deceased by Canadians than by Columbians. Among the former, the deceased is more often asked to and thanked for watching over the living, and testimonies of love addressed to the deceased are more numerous than among the latter. Among the latter, the strength of the links maintained with the deceased justifying the present pain and evocation of the mourners’ Catholic beliefs are relatively more frequent. Finally, while the Canadian Quebecers’ messages would presumably be written in French and those of Colombians in Spanish, it is interesting to observe a certain presence of English to express feelings of loss and love in the four groups, as well as a certain affinity between North American virtual bereavement practices and those seemingly more characteristic of women, the main contributors in all four groups.

  15. The cortical signature of impaired gesturing: Findings from schizophrenia

    Directory of Open Access Journals (Sweden)

    Petra Verena Viher

    2018-01-01

    Full Text Available Schizophrenia is characterized by deficits in gesturing that is important for nonverbal communication. Research in healthy participants and brain-damaged patients revealed a left-lateralized fronto-parieto-temporal network underlying gesture performance. First evidence from structural imaging studies in schizophrenia corroborates these results. However, as of yet, it is unclear if cortical thickness abnormalities contribute to impairments in gesture performance. We hypothesized that patients with deficits in gesture production show cortical thinning in 12 regions of interest (ROIs of a gesture network relevant for gesture performance and recognition. Forty patients with schizophrenia and 41 healthy controls performed hand and finger gestures as either imitation or pantomime. Group differences in cortical thickness between patients with deficits, patients without deficits, and controls were explored using a multivariate analysis of covariance. In addition, the relationship between gesture recognition and cortical thickness was investigated. Patients with deficits in gesture production had reduced cortical thickness in eight ROIs, including the pars opercularis of the inferior frontal gyrus, the superior and inferior parietal lobes, and the superior and middle temporal gyri. Gesture recognition correlated with cortical thickness in fewer, but mainly the same, ROIs within the patient sample. In conclusion, our results show that impaired gesture production and recognition in schizophrenia is associated with cortical thinning in distinct areas of the gesture network.

  16. Effects of Cultural Tightness-Looseness and Social Network Density on Expression of Positive and Negative Emotions: A Large-Scale Study of Impression Management by Facebook Users.

    Science.gov (United States)

    Liu, Pan; Chan, David; Qiu, Lin; Tov, William; Tong, Victor Joo Chuan

    2018-05-01

    Using data from 13,789 Facebook users across U.S. states, this study examined the main effects of societal-level cultural tightness-looseness and its interaction effects with individuals' social network density on impression management (IM) in terms of online emotional expression. Results showed that individuals from culturally tight (vs. loose) states were more likely to express positive emotions and less likely to express negative emotions. Meanwhile, for positive emotional expression, there was a tightness-looseness by social network density interaction effect. In culturally tight states, individuals with dense (vs. sparse) networks were more likely to express positive emotions, while in culturally loose states this pattern was reversed. For negative emotional expression, however, no such interaction was observed. Our findings highlight the influence of cultural norms and social network structure on emotional expressions as IM strategies.

  17. Thyroid hormone-dependent development of early cortical networks: Temporal specificity and the contribution of trkB and mTOR pathways

    Directory of Open Access Journals (Sweden)

    Sören eWesterholz

    2013-08-01

    Full Text Available Early in neocortical network development, triiodothyronine (T3 promotes GABAergic neurons’ population increase, their somatic growth and the formation of GABAergic synapses. In the presence of T3, GABAergic interneurons form longer axons and conspicuous axonal arborizations, with an increased number of putative synaptic boutons. Here we show that the increased GABAergic axonal growth is positively correlated with the proximity to non-GABAergic neurons. A differential innervation emerges from a T3-dependent decrease of axonal length in fields with low density of neuronal cell bodies, combined with an increased bouton formation in fields with high density of neuronal somata. T3 addition to deprived networks after the first two weeks of development did not rescue deficits in the GABAergic synaptic bouton distribution, or in the frequency and duration of spontaneous bursts. During the critical two-week-period, GABAergic signaling is depolarizing as revealed by calcium imaging experiments. Interestingly, T3 enhanced the expression of the potassium-chloride cotransporter 2 (KCC2, and accelerated the developmental shift from depolarizing to hyperpolarizing GABAergic signaling in non-GABAergic neurons.The T3-related increase of spontaneous network activity was remarkably reduced after blockade of either tropomyosin-receptor kinase B (trkB or mammalian target of rapamycin (mTOR pathways. T3-dependent increase in GABAergic neurons’ soma size was mediated mainly by mTOR signaling. Conversely, the T3-dependent selective increase of GABAergic boutons near non-GABAergic cell bodies is mediated by trkB signaling only. Both trkB and mTOR signaling mediate T3-dependent reduction of the GABAergic axon extension. The circuitry context is relevant for the interaction between T3 and trkB signaling, but not for the interactions between T3 and mTOR signaling.

  18. Artificial neural network-based model for the prediction of optimal growth and culture conditions for maximum biomass accumulation in multiple shoot cultures of Centella asiatica.

    Science.gov (United States)

    Prasad, Archana; Prakash, Om; Mehrotra, Shakti; Khan, Feroz; Mathur, Ajay Kumar; Mathur, Archana

    2017-01-01

    An artificial neural network (ANN)-based modelling approach is used to determine the synergistic effect of five major components of growth medium (Mg, Cu, Zn, nitrate and sucrose) on improved in vitro biomass yield in multiple shoot cultures of Centella asiatica. The back propagation neural network (BPNN) was employed to predict optimal biomass accumulation in terms of growth index over a defined culture duration of 35 days. The four variable concentrations of five media components, i.e. MgSO 4 (0, 0.75, 1.5, 3.0 mM), ZnSO 4 (0, 15, 30, 60 μM), CuSO 4 (0, 0.05, 0.1, 0.2 μM), NO 3 (20, 30, 40, 60 mM) and sucrose (1, 3, 5, 7 %, w/v) were taken as inputs for the ANN model. The designed model was evaluated by performing three different sets of validation experiments that indicated a greater similarity between the target and predicted dataset. The results of the modelling experiment suggested that 1.5 mM Mg, 30 μM Zn, 0.1 μM Cu, 40 mM NO 3 and 6 % (w/v) sucrose were the respective optimal concentrations of the tested medium components for achieving maximum growth index of 1654.46 with high centelloside yield (62.37 mg DW/culture) in the cultured multiple shoots. This study can facilitate the generation of higher biomass of uniform, clean, good quality C. asiatica herb that can efficiently be utilized by pharmaceutical industries.

  19. How the Internet Facilitates the Activity within a Consumer Culture : - A Study of the Online Vinyl Record Network

    OpenAIRE

    Söderlindh, Stefan; Broman, David

    2009-01-01

    The purpose of this thesis is to describe and analyze how the online vinyl record network functions from both a consumer and retailer perspective, in order to gain an understanding of how the Internet facilitates the activity within a consumer culture. The vinyl record industry is experiencing a revival, with an upswing in sales and media attention and a significant increase in the amount of online trading. This inductive study contains data from qualitative interviews with ten vinyl record c...

  20. The Power of Social Networks: A Model for Weaving the Scholarship of Teaching and Learning into Institutional Culture

    Directory of Open Access Journals (Sweden)

    Andrea L. Williams

    2013-09-01

    micro, the meso, and the macro. The authors argue that for SoTL to take root in organizational cultures, there must be 1 effective communication and dissemination of SoTL activity across all levels, 2 well established social networks and links between these levels (nodes, and 3 sustained support by senior administrationThe authors conclude by suggesting ways their model could be tested.

  1. Development of an Evaluation Method for Team Safety Culture Competencies using Social Network Analysis

    International Nuclear Information System (INIS)

    Han, Sang Min; Kim, Ar Ryum; Seong, Poong Hyun

    2016-01-01

    In this study, team safety culture competency of a team was estimated through SNA, as a team safety culture index. To overcome the limit of existing safety culture evaluation methods, the concept of competency and SNA were adopted. To estimate team safety culture competency, we defined the definition, range and goal of team safety culture competencies. Derivation of core team safety culture competencies is performed and its behavioral characteristics were derived for each safety culture competency, from the procedures used in NPPs and existing criteria to assess safety culture. Then observation was chosen as a method to provide the input data for the SNA matrix of team members versus insufficient team safety culture competencies. Then through matrix operation, the matrix was converted into the two meaningful values, which are density of team members and degree centralities of each team safety culture competency. Density of tem members and degree centrality of each team safety culture competency represent the team safety culture index and the priority of team safety culture competency to be improved

  2. Development of an Evaluation Method for Team Safety Culture Competencies using Social Network Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Han, Sang Min; Kim, Ar Ryum; Seong, Poong Hyun [KAIST, Daejeon (Korea, Republic of)

    2016-05-15

    In this study, team safety culture competency of a team was estimated through SNA, as a team safety culture index. To overcome the limit of existing safety culture evaluation methods, the concept of competency and SNA were adopted. To estimate team safety culture competency, we defined the definition, range and goal of team safety culture competencies. Derivation of core team safety culture competencies is performed and its behavioral characteristics were derived for each safety culture competency, from the procedures used in NPPs and existing criteria to assess safety culture. Then observation was chosen as a method to provide the input data for the SNA matrix of team members versus insufficient team safety culture competencies. Then through matrix operation, the matrix was converted into the two meaningful values, which are density of team members and degree centralities of each team safety culture competency. Density of tem members and degree centrality of each team safety culture competency represent the team safety culture index and the priority of team safety culture competency to be improved.

  3. A spatially resolved network spike in model neuronal cultures reveals nucleation centers, circular traveling waves and drifting spiral waves.

    Science.gov (United States)

    Paraskevov, A V; Zendrikov, D K

    2017-03-23

    We show that in model neuronal cultures, where the probability of interneuronal connection formation decreases exponentially with increasing distance between the neurons, there exists a small number of spatial nucleation centers of a network spike, from where the synchronous spiking activity starts propagating in the network typically in the form of circular traveling waves. The number of nucleation centers and their spatial locations are unique and unchanged for a given realization of neuronal network but are different for different networks. In contrast, if the probability of interneuronal connection formation is independent of the distance between neurons, then the nucleation centers do not arise and the synchronization of spiking activity during a network spike occurs spatially uniform throughout the network. Therefore one can conclude that spatial proximity of connections between neurons is important for the formation of nucleation centers. It is also shown that fluctuations of the spatial density of neurons at their random homogeneous distribution typical for the experiments in vitro do not determine the locations of the nucleation centers. The simulation results are qualitatively consistent with the experimental observations.

  4. Development and function of human cerebral cortex neural networks from pluripotent stem cells in vitro.

    Science.gov (United States)

    Kirwan, Peter; Turner-Bridger, Benita; Peter, Manuel; Momoh, Ayiba; Arambepola, Devika; Robinson, Hugh P C; Livesey, Frederick J

    2015-09-15

    A key aspect of nervous system development, including that of the cerebral cortex, is the formation of higher-order neural networks. Developing neural networks undergo several phases with distinct activity patterns in vivo, which are thought to prune and fine-tune network connectivity. We report here that human pluripotent stem cell (hPSC)-derived cerebral cortex neurons form large-scale networks that reflect those found in the developing cerebral cortex in vivo. Synchronised oscillatory networks develop in a highly stereotyped pattern over several weeks in culture. An initial phase of increasing frequency of oscillations is followed by a phase of decreasing frequency, before giving rise to non-synchronous, ordered activity patterns. hPSC-derived cortical neural networks are excitatory, driven by activation of AMPA- and NMDA-type glutamate receptors, and can undergo NMDA-receptor-mediated plasticity. Investigating single neuron connectivity within PSC-derived cultures, using rabies-based trans-synaptic tracing, we found two broad classes of neuronal connectivity: most neurons have small numbers (40). These data demonstrate that the formation of hPSC-derived cortical networks mimics in vivo cortical network development and function, demonstrating the utility of in vitro systems for mechanistic studies of human forebrain neural network biology. © 2015. Published by The Company of Biologists Ltd.

  5. Early development of synchrony in cortical activations in the human.

    Science.gov (United States)

    Koolen, N; Dereymaeker, A; Räsänen, O; Jansen, K; Vervisch, J; Matic, V; Naulaers, G; De Vos, M; Van Huffel, S; Vanhatalo, S

    2016-05-13

    Early intermittent cortical activity is thought to play a crucial role in the growth of neuronal network development, and large scale brain networks are known to provide the basis for higher brain functions. Yet, the early development of the large scale synchrony in cortical activations is unknown. Here, we tested the hypothesis that the early intermittent cortical activations seen in the human scalp EEG show a clear developmental course during the last trimester of pregnancy, the period of intensive growth of cortico-cortical connections. We recorded scalp EEG from altogether 22 premature infants at post-menstrual age between 30 and 44 weeks, and the early cortical synchrony was quantified using recently introduced activation synchrony index (ASI). The developmental correlations of ASI were computed for individual EEG signals as well as anatomically and mathematically defined spatial subgroups. We report two main findings. First, we observed a robust and statistically significant increase in ASI in all cortical areas. Second, there were significant spatial gradients in the synchrony in fronto-occipital and left-to-right directions. These findings provide evidence that early cortical activity is increasingly synchronized across the neocortex. The ASI-based metrics introduced in our work allow direct translational comparison to in vivo animal models, as well as hold promise for implementation as a functional developmental biomarker in future research on human neonates. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  6. Cortical myoclonus and cerebellar pathology

    NARCIS (Netherlands)

    Tijssen, MAJ; Thom, M; Ellison, DW; Wilkins, P; Barnes, D; Thompson, PD; Brown, P

    2000-01-01

    Objective To study the electrophysiologic and pathologic findings in three patients with cortical myoclonus. In two patients the myoclonic ataxic syndrome was associated with proven celiac disease. Background: The pathologic findings in conditions associated with cortical myoclonus commonly involve

  7. Cortical myoclonus and cerebellar pathology

    NARCIS (Netherlands)

    Tijssen, M. A.; Thom, M.; Ellison, D. W.; Wilkins, P.; Barnes, D.; Thompson, P. D.; Brown, P.

    2000-01-01

    OBJECTIVE: To study the electrophysiologic and pathologic findings in three patients with cortical myoclonus. In two patients the myoclonic ataxic syndrome was associated with proven celiac disease. BACKGROUND: The pathologic findings in conditions associated with cortical myoclonus commonly involve

  8. Study on team characteristics influencing on nuclear safety culture in Korea based on Bayesian networks

    Energy Technology Data Exchange (ETDEWEB)

    Young-gab, K.; Chan-ho, S.; Jeong-jin, P., E-mail: iamkyg@khnp.co.kr, E-mail: chsung@khnp.co.kr, E-mail: jjpark82@khnp.co.kr [Korea Hydro & Nuclear Power Co., Central Research Inst., Yuseong-gu, Daejeon (Korea, Republic of)

    2014-07-01

    The safety culture of Korean nuclear power plants has been settled down as an organizational culture since the Chernobyl accident in 1986. Reason (1997) proposed that safety culture is a sub-culture of corporate culture and sub-culture is a term that can be used interchangeably to a sub-group of people (i.e., department, workgroup). Therefore, the safety culture of organization comprised of various teams can be told as a culture to reflect team characteristics and interact with each other. Team characteristics have something to do with a successful task performance and task efficiency. However, the team characteristics in nuclear power plant have to consider safety preferentially rather than performance. Team characteristics for a safety are necessary to ensure and enhance the safety of safety-critical system. This paper proposed team characteristics for a safety which influence on the strong and vulnerable area of safety culture. These characteristics were analyzed on the basis of the safety culture evaluation which was performed to measure the level of plant workers' safety culture in 2013. The model of team characteristics was constructed considering Bayesian inference and the result was proposed according to workers' awareness. Safety team characteristics have a direct or indirect effect on the safety of nuclear power plants. Therefore, if they are improved and trained continuously, the safety of nuclear power plants might be enhanced. (author)

  9. Study on team characteristics influencing on nuclear safety culture in Korea based on Bayesian networks

    International Nuclear Information System (INIS)

    Young-gab, K.; Chan-ho, S.; Jeong-jin, P.

    2014-01-01

    The safety culture of Korean nuclear power plants has been settled down as an organizational culture since the Chernobyl accident in 1986. Reason (1997) proposed that safety culture is a sub-culture of corporate culture and sub-culture is a term that can be used interchangeably to a sub-group of people (i.e., department, workgroup). Therefore, the safety culture of organization comprised of various teams can be told as a culture to reflect team characteristics and interact with each other. Team characteristics have something to do with a successful task performance and task efficiency. However, the team characteristics in nuclear power plant have to consider safety preferentially rather than performance. Team characteristics for a safety are necessary to ensure and enhance the safety of safety-critical system. This paper proposed team characteristics for a safety which influence on the strong and vulnerable area of safety culture. These characteristics were analyzed on the basis of the safety culture evaluation which was performed to measure the level of plant workers' safety culture in 2013. The model of team characteristics was constructed considering Bayesian inference and the result was proposed according to workers' awareness. Safety team characteristics have a direct or indirect effect on the safety of nuclear power plants. Therefore, if they are improved and trained continuously, the safety of nuclear power plants might be enhanced. (author)

  10. Flow of cortical activity underlying a tactile decision in mice

    OpenAIRE

    Guo, Zengcai V.; Li, Nuo; Huber, Daniel; Ophir, Eran; Gutnisky, Diego; Ting, Jonathan T.; Feng, Guoping; Svoboda, Karel

    2013-01-01

    Perceptual decisions involve distributed cortical activity. Does information flow sequentially from one cortical area to another, or do networks of interconnected areas contribute at the same time? Here we delineate when and how activity in specific areas drives a whisker-based decision in mice. A short-term memory component temporally separated tactile “sensation” and “action” (licking). Using optogenetic inhibition (spatial resolution, 2 mm; temporal resolution, 100 ms), we surveyed the neo...

  11. Preparing culture change agents for academic medicine in a multi-institutional consortium: the C - change learning action network.

    Science.gov (United States)

    Pololi, Linda H; Krupat, Edward; Schnell, Eugene R; Kern, David E

    2013-01-01

    Research suggests an ongoing need for change in the culture of academic medicine. This article describes the structure, activities and evaluation of a culture change project: the C - Change Learning Action Network (LAN) and its impact on participants. The LAN was developed to create the experience of a culture that would prepare participants to facilitate a culture in academic medicine that would be more collaborative, inclusive, relational, and that supports the humanity and vitality of faculty. Purposefully diverse faculty, leaders, and deans from 5 US medical schools convened in 2 1/2-day meetings biannually over 4 years. LAN meetings employed experiential, cognitive, and affective learning modes; innovative dialogue strategies; and reflective practice aimed at facilitating deep dialogue, relationship formation, collaboration, authenticity, and transformative learning to help members experience the desired culture. Robust aggregated qualitative and quantitative data collected from the 5 schools were used to inform and stimulate culture-change plans. Quantitative and qualitative evaluation methods were used. Participants indicated that a safe, supportive, inclusive, collaborative culture was established in LAN and highly valued. LAN members reported a deepened understanding of organizational change, new and valued interpersonal connections, increased motivation and resilience, new skills and approaches, increased self-awareness and personal growth, emotional connection to the issues of diversity and inclusion, and application of new learnings in their work. A carefully designed multi-institutional learning community can transform the way participants experience and view institutional culture. It can motivate and prepare them to be change agents in their own institutions. Copyright © 2013 The Alliance for Continuing Education in the Health Professions, the Society for Academic Continuing Medical Education, and the Council on CME, Association for Hospital Medical

  12. Culture, social networks, and information sharing: An exploratory study of Japanese aerospace engineers' information-seeking processes and habits in light of cultural factors

    Science.gov (United States)

    Sato, Yuko

    The purpose of this study was to investigate the effects of culture and language on Japanese aerospace engineers' information-seeking processes by both quantitative and qualitative approaches. The Japanese sample consisted of 162 members of the Japan Society for Aeronautical and Space Sciences (JSASS). U.S. aerospace engineers served as a reference point, consisting of 213 members of the American Institute of Aeronautics and Astronautics (AIAA). The survey method was utilized in gathering data using self-administered mail questionnaires in order to explore the following eight areas: (1) the content and use of information resources; (2) production and use of information products; (3) methods of accessing information service providers; (4) foreign language skills; (5) studying/researching/collaborating abroad as a tool in expanding information resources; (6) scientific and technical societies as networking tools; (7) alumni associations (school/class reunions) as networking tools; and (8) social, corporate, civic and health/fitness clubs as networking tools. Nine Japanese cultural factors expressed as statements about Japanese society are as follows: (1) information is neither autonomous, objective, nor independent of the subject of cognition; (2) information and knowledge are not readily accessible to the public; (3) emphasis on groups is reinforced in a hierarchical society; (4) social networks thrive as information-sharing vehicles; (5) high context is a predominant form of communication in which most of the information is already in the person, while very little is in the coded, transmitted part of the message; (6) obligations based on mutual trust dictate social behaviors instead of contractual agreements; (7) a surface message is what is presented while a bottom-line message is true feeling privately held; (8) various religious beliefs uphold a work ethic based on harmony; (9) ideas from outside are readily assimilated into its own society. The result of the

  13. cultural

    Directory of Open Access Journals (Sweden)

    Irene Kreutz

    2006-01-01

    Full Text Available Es un estudio cualitativo que adoptó como referencial teorico-motodológico la antropología y la etnografía. Presenta las experiencias vivenciadas por mujeres de una comunidad en el proceso salud-enfermedad, con el objetivo de comprender los determinantes sócio-culturales e históricos de las prácticas de prevención y tratamiento adoptados por el grupo cultural por medio de la entrevista semi-estructurada. Los temas que emergieron fueron: la relación entre la alimentación y lo proceso salud-enfermedad, las relaciones con el sistema de salud oficial y el proceso salud-enfermedad y lo sobrenatural. Los dados revelaron que los moradores de la comunidad investigada tienen un modo particular de explicar sus procedimientos terapéuticos. Consideramos que es papel de los profesionales de la salud en sus prácticas, la adopción de abordajes o enfoques que consideren al individuo en su dimensión sócio-cultural e histórica, considerando la enorme diversidad cultural en nuestro país.

  14. Stroke rehabilitation using noninvasive cortical stimulation: aphasia.

    Science.gov (United States)

    Mylius, Veit; Zouari, Hela G; Ayache, Samar S; Farhat, Wassim H; Lefaucheur, Jean-Pascal

    2012-08-01

    Poststroke aphasia results from the lesion of cortical areas involved in the motor production of speech (Broca's aphasia) or in the semantic aspects of language comprehension (Wernicke's aphasia). Such lesions produce an important reorganization of speech/language-specific brain networks due to an imbalance between cortical facilitation and inhibition. In fact, functional recovery is associated with changes in the excitability of the damaged neural structures and their connections. Two main mechanisms are involved in poststroke aphasia recovery: the recruitment of perilesional regions of the left hemisphere in case of small lesion and the acquisition of language processing ability in homotopic areas of the nondominant right hemisphere when left hemispheric language abilities are permanently lost. There is some evidence that noninvasive cortical stimulation, especially when combined with language therapy or other therapeutic approaches, can promote aphasia recovery. Cortical stimulation was mainly used to either increase perilesional excitability or reduce contralesional activity based on the concept of reciprocal inhibition and maladaptive plasticity. However, recent studies also showed some positive effects of the reinforcement of neural activities in the contralateral right hemisphere, based on the potential compensatory role of the nondominant hemisphere in stroke recovery.

  15. Productive Tensions in a Cross-Cultural Peer Mentoring Women's Network: A Social Capital Perspective

    Science.gov (United States)

    Esnard, Talia; Cobb-Roberts, Deirdre; Agosto, Vonzell; Karanxha, Zorka; Beck, Makini; Wu, Ke; Unterreiner, Ann

    2015-01-01

    A growing body of researchers documents the unique barriers women face in their academic career progression and the significance of mentoring networks for advancement of their academic trajectories as faculty. However, few researchers explore the embedded tensions and conflicts in the social processes and relations of mentoring networks, and the…

  16. The neuroprotective efficacy of cell-penetrating peptides TAT, penetratin, Arg-9, and Pep-1 in glutamic acid, kainic acid, and in vitro ischemia injury models using primary cortical neuronal cultures.

    Science.gov (United States)

    Meloni, Bruno P; Craig, Amanda J; Milech, Nadia; Hopkins, Richard M; Watt, Paul M; Knuckey, Neville W

    2014-03-01

    Cell-penetrating peptides (CPPs) are small peptides (typically 5-25 amino acids), which are used to facilitate the delivery of normally non-permeable cargos such as other peptides, proteins, nucleic acids, or drugs into cells. However, several recent studies have demonstrated that the TAT CPP has neuroprotective properties. Therefore, in this study, we assessed the TAT and three other CPPs (penetratin, Arg-9, Pep-1) for their neuroprotective properties in cortical neuronal cultures following exposure to glutamic acid, kainic acid, or in vitro ischemia (oxygen-glucose deprivation). Arg-9, penetratin, and TAT-D displayed consistent and high level neuroprotective activity in both the glutamic acid (IC50: 0.78, 3.4, 13.9 μM) and kainic acid (IC50: 0.81, 2.0, 6.2 μM) injury models, while Pep-1 was ineffective. The TAT-D isoform displayed similar efficacy to the TAT-L isoform in the glutamic acid model. Interestingly, Arg-9 was the only CPP that displayed efficacy when washed-out prior to glutamic acid exposure. Neuroprotection following in vitro ischemia was more variable with all peptides providing some level of neuroprotection (IC50; Arg-9: 6.0 μM, TAT-D: 7.1 μM, penetratin/Pep-1: >10 μM). The positive control peptides JNKI-1D-TAT (JNK inhibitory peptide) and/or PYC36L-TAT (AP-1 inhibitory peptide) were neuroprotective in all models. Finally, in a post-glutamic acid treatment experiment, Arg-9 was highly effective when added immediately after, and mildly effective when added 15 min post-insult, while the JNKI-1D-TAT control peptide was ineffective when added post-insult. These findings demonstrate that different CPPs have the ability to inhibit neurodamaging events/pathways associated with excitotoxic and ischemic injuries. More importantly, they highlight the need to interpret neuroprotection studies when using CPPs as delivery agents with caution. On a positive note, the cytoprotective properties of CPPs suggests they are ideal carrier molecules to

  17. Visual social network analysis: effective approach to model complex human social, behaviour & culture.

    Science.gov (United States)

    Ahram, Tareq Z; Karwowski, Waldemar

    2012-01-01

    The advent and adoption of internet-based social networking has significantly altered our daily lives. The educational community has taken notice of the positive aspects of social networking such as creation of blogs and to support groups of system designers going through the same challenges and difficulties. This paper introduces a social networking framework for collaborative education, design and modeling of the next generation of smarter products and services. Human behaviour modeling in social networking application aims to ensure that human considerations for learners and designers have a prominent place in the integrated design and development of sustainable, smarter products throughout the total system lifecycle. Social networks blend self-directed learning and prescribed, existing information. The self-directed element creates interest within a learner and the ability to access existing information facilitates its transfer, and eventual retention of knowledge acquired.

  18. The Spirit in the Network: Models for Spirituality in a Technological Culture.

    NARCIS (Netherlands)

    Coeckelbergh, Mark

    2010-01-01

    Can a technological culture accommodate spiritual experience and spiritual thinking? If so, what kind of spirituality? I explore the relation between technology and spirituality by constructing and discussing several models for spirituality in a technological culture. I show that although gnostic

  19. Impedance Spectroscopic Characterisation of Porosity in 3D Cell Culture Scaffolds with Different Channel Networks

    DEFF Research Database (Denmark)

    Canali, Chiara; Mohanty, Soumyaranjan; Heiskanen, Arto

    2015-01-01

    We present the application of electrochemical impedance spectroscopy (EIS) as a method for discriminating between different polydimethylsiloxane (PDMS) scaffolds for three-dimensional (3D) cell cultures. The validity of EIS characterisation for scaffolds having different degree of porosity...... serve as means of single-frequency measurements for fast scaffold characterization combined with in vitro monitoring of 3D cell cultures....

  20. Using Cultural Historical Activity Theory (CHAT) to Frame `SuperclubsPLUS', an Online Social Network for Children

    Science.gov (United States)

    Masters, Jennifer

    This paper uses a Cultural Historical Activity Theory framework to describe a social-networking online community project, “SuperclubsPLUS”, for children aged 6-12. The use of the CHAT frame enables a detailed description of connections within the project as participants work together to achieve individual and common goals. Application of this structure to the SuperclubsPLUS environment supports the concept that the community is continually changing, shaped by the interactions of the participants. It is anticipated that this snapshot of the project will provide a tangible base in order to further develop and map ongoing patterns of interaction for research.

  1. Regional vulnerability of longitudinal cortical association connectivity

    Directory of Open Access Journals (Sweden)

    Rafael Ceschin

    2015-01-01

    Full Text Available Preterm born children with spastic diplegia type of cerebral palsy and white matter injury or periventricular leukomalacia (PVL, are known to have motor, visual and cognitive impairments. Most diffusion tensor imaging (DTI studies performed in this group have demonstrated widespread abnormalities using averaged deterministic tractography and voxel-based DTI measurements. Little is known about structural network correlates of white matter topography and reorganization in preterm cerebral palsy, despite the availability of new therapies and the need for brain imaging biomarkers. Here, we combined novel post-processing methodology of probabilistic tractography data in this preterm cohort to improve spatial and regional delineation of longitudinal cortical association tract abnormalities using an along-tract approach, and compared these data to structural DTI cortical network topology analysis. DTI images were acquired on 16 preterm children with cerebral palsy (mean age 5.6 ± 4 and 75 healthy controls (mean age 5.7 ± 3.4. Despite mean tract analysis, Tract-Based Spatial Statistics (TBSS and voxel-based morphometry (VBM demonstrating diffusely reduced fractional anisotropy (FA reduction in all white matter tracts, the along-tract analysis improved the detection of regional tract vulnerability. The along-tract map-structural network topology correlates revealed two associations: (1 reduced regional posterior–anterior gradient in FA of the longitudinal visual cortical association tracts (inferior fronto-occipital fasciculus, inferior longitudinal fasciculus, optic radiation, posterior thalamic radiation correlated with reduced posterior–anterior gradient of intra-regional (nodal efficiency metrics with relative sparing of frontal and temporal regions; and (2 reduced regional FA within frontal–thalamic–striatal white matter pathways (anterior limb/anterior thalamic radiation, superior longitudinal fasciculus and cortical spinal tract

  2. The U.S. Culture Collection Network Responding to the Requirements of the Nagoya Protocol on Access and Benefit Sharing

    Directory of Open Access Journals (Sweden)

    Kevin McCluskey

    2017-08-01

    Full Text Available The U.S. Culture Collection Network held a meeting to share information about how culture collections are responding to the requirements of the recently enacted Nagoya Protocol on Access to Genetic Resources and the Fair and Equitable Sharing of Benefits Arising from their Utilization to the Convention on Biological Diversity (CBD. The meeting included representatives of many culture collections and other biological collections, the U.S. Department of State, U.S. Department of Agriculture, Secretariat of the CBD, interested scientific societies, and collection groups, including Scientific Collections International and the Global Genome Biodiversity Network. The participants learned about the policies of the United States and other countries regarding access to genetic resources, the definition of genetic resources, and the status of historical materials and genetic sequence information. Key topics included what constitutes access and how the CBD Access and Benefit-Sharing Clearing-House can help guide researchers through the process of obtaining Prior Informed Consent on Mutually Agreed Terms. U.S. scientists and their international collaborators are required to follow the regulations of other countries when working with microbes originally isolated outside the United States, and the local regulations required by the Nagoya Protocol vary by the country of origin of the genetic resource. Managers of diverse living collections in the United States described their holdings and their efforts to provide access to genetic resources. This meeting laid the foundation for cooperation in establishing a set of standard operating procedures for U.S. and international culture collections in response to the Nagoya Protocol.

  3. Effect of correlating adjacent neurons for identifying communications: Feasibility experiment in a cultured neuronal network

    OpenAIRE

    Yoshi Nishitani; Chie Hosokawa; Yuko Mizuno-Matsumoto; Tomomitsu Miyoshi; Shinichi Tamura

    2017-01-01

    Neuronal networks have fluctuating characteristics, unlike the stable characteristics seen in computers. The underlying mechanisms that drive reliable communication among neuronal networks and their ability to perform intelligible tasks remain unknown. Recently, in an attempt to resolve this issue, we showed that stimulated neurons communicate via spikes that propagate temporally, in the form of spike trains. We named this phenomenon “spike wave propagation”. In these previous studies, using ...

  4. Basal Forebrain Gating by Somatostatin Neurons Drives Prefrontal Cortical Activity.

    Science.gov (United States)

    Espinosa, Nelson; Alonso, Alejandra; Morales, Cristian; Espinosa, Pedro; Chávez, Andrés E; Fuentealba, Pablo

    2017-11-17

    The basal forebrain provides modulatory input to the cortex regulating brain states and cognitive processing. Somatostatin-expressing neurons constitute a heterogeneous GABAergic population known to functionally inhibit basal forebrain cortically projecting cells thus favoring sleep and cortical synchronization. However, it remains unclear if somatostatin cells can regulate population activity patterns in the basal forebrain and modulate cortical dynamics. Here, we demonstrate that somatostatin neurons regulate the corticopetal synaptic output of the basal forebrain impinging on cortical activity and behavior. Optogenetic inactivation of somatostatin neurons in vivo rapidly modified neural activity in the basal forebrain, with the consequent enhancement and desynchronization of activity in the prefrontal cortex, reflected in both neuronal spiking and network oscillations. Cortical activation was partially dependent on cholinergic transmission, suppressing slow waves and potentiating gamma oscillations. In addition, recruitment dynamics was cell type-specific, with interneurons showing similar temporal profiles, but stronger responses than pyramidal cells. Finally, optogenetic stimulation of quiescent animals during resting periods prompted locomotor activity, suggesting generalized cortical activation and increased arousal. Altogether, we provide physiological and behavioral evidence indicating that somatostatin neurons are pivotal in gating the synaptic output of the basal forebrain, thus indirectly controlling cortical operations via both cholinergic and non-cholinergic mechanisms. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  5. Motor cortical plasticity in Parkinson's disease.

    Science.gov (United States)

    Udupa, Kaviraja; Chen, Robert

    2013-09-04

    In Parkinson's disease (PD), there are alterations of the basal ganglia (BG) thalamocortical networks, primarily due to degeneration of nigrostriatal dopaminergic neurons. These changes in subcortical networks lead to plastic changes in primary motor cortex (M1), which mediates cortical motor output and is a potential target for treatment of PD. Studies investigating the motor cortical plasticity using non-invasive transcranial magnetic stimulation (TMS) have found altered plasticity in PD, but there are inconsistencies among these studies. This is likely because plasticity depends on many factors such as the extent of dopaminergic loss and disease severity, response to dopaminergic replacement therapies, development of l-DOPA-induced dyskinesias (LID), the plasticity protocol used, medication, and stimulation status in patients treated with deep brain stimulation (DBS). The influences of LID and DBS on BG and M1 plasticity have been explored in animal models and in PD patients. In addition, many other factors such age, genetic factors (e.g., brain derived neurotropic factor and other neurotransmitters or receptors polymorphism), emotional state, time of the day, physical fitness have been documented to play role in the extent of plasticity induced by TMS in human studies. In this review, we summarize the studies that investigated M1 plasticity in PD and demonstrate how these afore-mentioned factors affect motor cortical plasticity in PD. We conclude that it is important to consider the clinical, demographic, and technical factors that influence various plasticity protocols while developing these protocols as diagnostic or prognostic tools in PD. We also discuss how the modulation of cortical excitability and the plasticity with these non-invasive brain stimulation techniques facilitate the understanding of the pathophysiology of PD and help design potential therapeutic possibilities in this disorder.

  6. Changing the culture of academic medicine: the C-Change learning action network and its impact at participating medical schools.

    Science.gov (United States)

    Krupat, Edward; Pololi, Linda; Schnell, Eugene R; Kern, David E

    2013-09-01

    The culture of academic medicine has been described as hierarchical, competitive, and not highly supportive of female or minority faculty. In response to this, the authors designed the Learning Action Network (LAN), which was part of the National Initiative on Gender, Culture and Leadership in Medicine (C-Change). The LAN is a five-school consortium aimed at changing the organizational culture of its constituent institutions. The authors selected LAN schools to be geographically diverse and representative of U.S. medical schools. Institutional leaders and faculty representatives from constituent schools met twice yearly for four years (2006-2010), forming a cross-institutional learning community. Through their quarterly listing of institutional activities, schools reported a wide array of actions. Most common were increased faculty development and/or mentoring, new approaches to communication, and adoption of new policies and procedures. Other categories included data collection/management, engagement of key stakeholders, education regarding gender/diversity, and new/expanded leadership positions. Through exit interviews, most participants reported feeling optimistic about maintaining the momentum of change. However, some, especially in schools with leadership changes, expressed uncertainty. Participants reported that they felt that the LAN enabled, empowered, facilitated, and/or caused the reported actions.For others who might want to work toward changing the culture of academic medicine, the authors offer several lessons learned from their experiences with C-Change. Most notably, people, structures, policies, and reward systems must be put into place to support cultural values, and broad-based support should be created in order for changes to persist when inevitable transitions in leadership occur.

  7. Rapid learning in visual cortical networks.

    Science.gov (United States)

    Wang, Ye; Dragoi, Valentin

    2015-08-26

    Although changes in brain activity during learning have been extensively examined at the single neuron level, the coding strategies employed by cell populations remain mysterious. We examined cell populations in macaque area V4 during a rapid form of perceptual learning that emerges within tens of minutes. Multiple single units and LFP responses were recorded as monkeys improved their performance in an image discrimination task. We show that the increase in behavioral performance during learning is predicted by a tight coordination of spike timing with local population activity. More spike-LFP theta synchronization is correlated with higher learning performance, while high-frequency synchronization is unrelated with changes in performance, but these changes were absent once learning had stabilized and stimuli became familiar, or in the absence of learning. These findings reveal a novel mechanism of plasticity in visual cortex by which elevated low-frequency synchronization between individual neurons and local population activity accompanies the improvement in performance during learning.

  8. The changing roles of neurons in the cortical subplate

    Directory of Open Access Journals (Sweden)

    Michael J Friedlander

    2009-08-01

    Full Text Available Neurons may serve different functions over the course of an organism’s life. Recent evidence suggests that cortical subplate neurons including those that reside in the white matter may perform longitudinal multi-tasking at different stages of development. These cells play a key role in early cortical development in coordinating thalamocortical reciprocal innervation. At later stages of development, they become integrated within the cortical microcircuitry. This type of longitudinal multi-tasking can enhance the capacity for information processing by populations of cells serving different functions over the lifespan. Subplate cells are initially derived when cells from the ventricular zone underlying the cortex migrate to the cortical preplate that is subsequently split by the differentiating neurons of the cortical plate with some neurons locating in the marginal zone and others settling below in the subplate (SP. While the cortical plate neurons form most of the cortical layers (layers 2-6, the marginal zone neurons form layer 1 and the SP neurons become interstitial cells of the white matter as well as forming a compact sublayer along the bottom of layer 6. After serving as transient innervation targets for thalamocortical axons, most of these cells die and layer 4 neurons become innervated by thalamic axons. However, 10-20% survives, remaining into adulthood along the bottom of layer 6 and as a scattered population of interstitial neurons in the white matter. Surviving subplate cells’ axons project throughout the overlying laminae, reaching layer 1 and issuing axon collaterals within white matter and in lower layer 6. This suggests that they participate in local synaptic networks, as well. Moreover, they receive excitatory and inhibitory synaptic inputs, potentially monitoring outputs from axon collaterals of cortical efferents, from cortical afferents and/or from each other. We explore our understanding of the functional connectivity of

  9. Opening up the solar box: Cultural resource management and actor network theory in solar energy projects in the Mojave Desert

    Science.gov (United States)

    Gorrie, Bryan F.

    This project considers the ways that Actor-Network Theory (ANT) can be brought to bear upon Cultural Resource Management (CRM) practices on renewable energy projects. ANT is a way of making inquiry into scientific knowledge practices and as CRM is intended to preserve environmental, historic, and prehistoric resources, it necessarily involves certain kinds of knowledge generation about regions in which projects are being developed. Because the practice of CRM is complex, involving a range of actors from developers to biologists, native peoples to academics, private landholders to environmental and cultural activists, it is imperative to account for the interests of all stakeholders and to resist devolving into the polemical relations of winners and losers, good and bad participants, or simple situations of right and wrong. This project intends to account for the "matters of concern" of various actors, both primary and secondary, by examining the case study of a single solar installation project in the Mojave Desert. A theoretical description of ANT is provided at the beginning and the concerns of this theory are brought to bear upon the case study project through describing the project, discussing the laws governing CRM on federal lands and in the state of California, and providing the points of view of various interviewees who worked directly or indirectly on various aspects of CRM for the solar project. The creators of ANT claim that it is not a methodology but it does speak to ethnomethodologies in that it insists that there is always something more to learn from inquiring into and describing any given situation. These descriptions avoid generalizations, providing instead various points of entry, from diverse perspectives to the project. There is an invitation to avoid assuming that one knows all there is to know about a given situation and to choose instead to continue investigating and thus give voice to the more obscure, often marginalized, voices in the

  10. Culture, Role and Group Work: A Social Network Analysis Perspective on an Online Collaborative Course

    Science.gov (United States)

    Stepanyan, Karen; Mather, Richard; Dalrymple, Roger

    2014-01-01

    This paper discusses the patterns of network dynamics within a multicultural online collaborative learning environment. It analyses the interaction of participants (both students and facilitators) within a discussion board that was established as part of a 3-month online collaborative course. The study employs longitudinal probabilistic social…

  11. A Cross-cultural Qualitative Examination of Social-networking Sites and Academic Performance

    NARCIS (Netherlands)

    Ozer, Ipek; Karpinski, Aryn; Kirschner, Paul A.

    2018-01-01

    Social-networking site (SNS) use, specifically Facebook®, has remained a controversial subject for many educators and media. Recent studies discuss the negative and positive impacts of SNSs on students’ academic performance. This qualitative study examines the impact of SNSs on students’ academic

  12. Synaptic potentiation facilitates memory-like attractor dynamics in cultured in vitro hippocampal networks.

    Directory of Open Access Journals (Sweden)

    Mark Niedringhaus

    Full Text Available Collective rhythmic dynamics from neurons is vital for cognitive functions such as memory formation but how neurons self-organize to produce such activity is not well understood. Attractor-based computational models have been successfully implemented as a theoretical framework for memory storage in networks of neurons. Additionally, activity-dependent modification of synaptic transmission is thought to be the physiological basis of learning and memory. The goal of this study is to demonstrate that using a pharmacological treatment that has been shown to increase synaptic strength within in vitro networks of hippocampal neurons follows the dynamical postulates theorized by attractor models. We use a grid of extracellular electrodes to study changes in network activity after this perturbation and show that there is a persistent increase in overall spiking and bursting activity after treatment. This increase in activity appears to recruit more "errant" spikes into bursts. Phase plots indicate a conserved activity pattern suggesting that a synaptic potentiation perturbation to the attractor leaves it unchanged. Lastly, we construct a computational model to demonstrate that these synaptic perturbations can account for the dynamical changes seen within the network.

  13. Conserving agrobiodiversity amid global change, migration, and nontraditional livelihood networks: the dynamic uses of cultural landscape knowledge

    Directory of Open Access Journals (Sweden)

    Karl S. Zimmerer

    2014-06-01

    agrobiodiversity between 2006 and 2012 is shown to have occurred amid a transition toward the integral roles of multiple migration-related groups, namely women farmers, consumers, and local business owners; migrants; field caretakers; and local in-migrant laborers. The nontraditional social networks among these livelihood groups must be incorporated into analysis and planning of the design, participation, and monitoring of management and policy options for cultural landscapes ensuring the use, in situ conservation, and sustainability, including ecosystem services, of food plant landraces in global agrobiodiversity hot spots.

  14. Socio-cultural valuation of ecosystem services in a transhumance social-ecological network

    DEFF Research Database (Denmark)

    Oteros-Rozas, E.; Martín-López, B.; González, J.A.

    2014-01-01

    the importance of 34 ecosystem services (10 provisioning, 12 regulating, and 12 cultural) for both social and personal well-being. Overall, the ecosystem services considered to be the most important for social well-being were fire prevention, air purification and livestock. Most of the ecosystem services...

  15. Traditional music and the anatomy of the festival network between Yugoslavian cultural politics and vernacular values

    Directory of Open Access Journals (Sweden)

    Jakovljević Rastko

    2012-01-01

    Full Text Available As official policies in the post-war Yugoslavia were oriented towards economy, mainly tied to towns, rural areas were focused on agriculture to a large extent, as it had been before. However, the Party was determined to revive villages, being of the opinion that life in those areas should be purified from “primitivism” so that it could be set to a higher level concerning issues of education, political structure, local organization and cultural life. Since people in villages felt determined to maintain their local culture, customs and music, the State officials had to find ways to articulate uncanny social behaviors. At the time, folklore and vernacular creative impulse in Serbia was sustained as a “hard cultural form” that by accident or on purpose converted into “soft cultural form” through a wide range of festival activities in Yugoslavia. This significant turn permitted “relatively easy separation of embodied performance from meaning and value, and relatively successful transformation at each level” (Appadurai 1996: 90. The discussion of this paper intends to form a dialogue on the transformation of social structure and politics, which gradually led to severe changes in the areas of traditional musical practice.

  16. Lifespan anxiety is reflected in human amygdala cortical connectivity

    Science.gov (United States)

    He, Ye; Xu, Ting; Zhang, Wei

    2016-01-01

    Abstract The amygdala plays a pivotal role in processing anxiety and connects to large‐scale brain networks. However, intrinsic functional connectivity (iFC) between amygdala and these networks has rarely been examined in relation to anxiety, especially across the lifespan. We employed resting‐state functional MRI data from 280 healthy adults (18–83.5 yrs) to elucidate the relationship between anxiety and amygdala iFC with common cortical networks including the visual network, somatomotor network, dorsal attention network, ventral attention network, limbic network, frontoparietal network, and default network. Global and network‐specific iFC were separately computed as mean iFC of amygdala with the entire cerebral cortex and each cortical network. We detected negative correlation between global positive amygdala iFC and trait anxiety. Network‐specific associations between amygdala iFC and anxiety were also detectable. Specifically, the higher iFC strength between the left amygdala and the limbic network predicted lower state anxiety. For the trait anxiety, left amygdala anxiety–connectivity correlation was observed in both somatomotor and dorsal attention networks, whereas the right amygdala anxiety–connectivity correlation was primarily distributed in the frontoparietal and ventral attention networks. Ventral attention network exhibited significant anxiety–gender interactions on its iFC with amygdala. Together with findings from additional vertex‐wise analysis, these data clearly indicated that both low‐level sensory networks and high‐level associative networks could contribute to detectable predictions of anxiety behaviors by their iFC profiles with the amygdala. This set of systems neuroscience findings could lead to novel functional network models on neural correlates of human anxiety and provide targets for novel treatment strategies on anxiety disorders. Hum Brain Mapp 37:1178–1193, 2016. © 2015 The Authors Human Brain Mapping

  17. Basic visual function and cortical thickness patterns in posterior cortical atrophy.

    Science.gov (United States)

    Lehmann, Manja; Barnes, Josephine; Ridgway, Gerard R; Wattam-Bell, John; Warrington, Elizabeth K; Fox, Nick C; Crutch, Sebastian J

    2011-09-01

    Posterior cortical atrophy (PCA) is characterized by a progressive decline in higher-visual object and space processing, but the extent to which these deficits are underpinned by basic visual impairments is unknown. This study aimed to assess basic and higher-order visual deficits in 21 PCA patients. Basic visual skills including form detection and discrimination, color discrimination, motion coherence, and point localization were measured, and associations and dissociations between specific basic visual functions and measures of higher-order object and space perception were identified. All participants showed impairment in at least one aspect of basic visual processing. However, a number of dissociations between basic visual skills indicated a heterogeneous pattern of visual impairment among the PCA patients. Furthermore, basic visual impairments were associated with particular higher-order object and space perception deficits, but not with nonvisual parietal tasks, suggesting the specific involvement of visual networks in PCA. Cortical thickness analysis revealed trends toward lower cortical thickness in occipitotemporal (ventral) and occipitoparietal (dorsal) regions in patients with visuoperceptual and visuospatial deficits, respectively. However, there was also a lot of overlap in their patterns of cortical thinning. These findings suggest that different presentations of PCA represent points in a continuum of phenotypical variation.

  18. Cortico-cortical communication dynamics

    Directory of Open Access Journals (Sweden)

    Per E Roland

    2014-05-01

    Full Text Available IIn principle, cortico-cortical communication dynamics is simple: neurons in one cortical area communicate by sending action potentials that release glutamate and excite their target neurons in other cortical areas. In practice, knowledge about cortico-cortical communication dynamics is minute. One reason is that no current technique can capture the fast spatio-temporal cortico-cortical evolution of action potential transmission and membrane conductances with sufficient spatial resolution. A combination of optogenetics and monosynaptic tracing with virus can reveal the spatio-temporal cortico-cortical dynamics of specific neurons and their targets, but does not reveal how the dynamics evolves under natural conditions. Spontaneous ongoing action potentials also spread across cortical areas and are difficult to separate from structured evoked and intrinsic brain activity such as thinking. At a certain state of evolution, the dynamics may engage larger populations of neurons to drive the brain to decisions, percepts and behaviors. For example, successfully evolving dynamics to sensory transients can appear at the mesoscopic scale revealing how the transient is perceived. As a consequence of these methodological and conceptual difficulties, studies in this field comprise a wide range of computational models, large-scale measurements (e.g., by MEG, EEG, and a combination of invasive measurements in animal experiments. Further obstacles and challenges of studying cortico-cortical communication dynamics are outlined in this critical review.

  19. Progressive posterior cortical dysfunction

    Directory of Open Access Journals (Sweden)

    Fábio Henrique de Gobbi Porto

    Full Text Available Abstract Progressive posterior cortical dysfunction (PPCD is an insidious syndrome characterized by prominent disorders of higher visual processing. It affects both dorsal (occipito-parietal and ventral (occipito-temporal pathways, disturbing visuospatial processing and visual recognition, respectively. We report a case of a 67-year-old woman presenting with progressive impairment of visual functions. Neurologic examination showed agraphia, alexia, hemispatial neglect (left side visual extinction, complete Balint's syndrome and visual agnosia. Magnetic resonance imaging showed circumscribed atrophy involving the bilateral parieto-occipital regions, slightly more predominant to the right . Our aim was to describe a case of this syndrome, to present a video showing the main abnormalities, and to discuss this unusual presentation of dementia. We believe this article can contribute by improving the recognition of PPCD.

  20. Progressive posterior cortical dysfunction

    Science.gov (United States)

    Porto, Fábio Henrique de Gobbi; Machado, Gislaine Cristina Lopes; Morillo, Lilian Schafirovits; Brucki, Sonia Maria Dozzi

    2010-01-01

    Progressive posterior cortical dysfunction (PPCD) is an insidious syndrome characterized by prominent disorders of higher visual processing. It affects both dorsal (occipito-parietal) and ventral (occipito-temporal) pathways, disturbing visuospatial processing and visual recognition, respectively. We report a case of a 67-year-old woman presenting with progressive impairment of visual functions. Neurologic examination showed agraphia, alexia, hemispatial neglect (left side visual extinction), complete Balint’s syndrome and visual agnosia. Magnetic resonance imaging showed circumscribed atrophy involving the bilateral parieto-occipital regions, slightly more predominant to the right. Our aim was to describe a case of this syndrome, to present a video showing the main abnormalities, and to discuss this unusual presentation of dementia. We believe this article can contribute by improving the recognition of PPCD. PMID:29213665

  1. Modeling cortical circuits.

    Energy Technology Data Exchange (ETDEWEB)

    Rohrer, Brandon Robinson; Rothganger, Fredrick H.; Verzi, Stephen J.; Xavier, Patrick Gordon

    2010-09-01

    The neocortex is perhaps the highest region of the human brain, where audio and visual perception takes place along with many important cognitive functions. An important research goal is to describe the mechanisms implemented by the neocortex. There is an apparent regularity in the structure of the neocortex [Brodmann 1909, Mountcastle 1957] which may help simplify this task. The work reported here addresses the problem of how to describe the putative repeated units ('cortical circuits') in a manner that is easily understood and manipulated, with the long-term goal of developing a mathematical and algorithmic description of their function. The approach is to reduce each algorithm to an enhanced perceptron-like structure and describe its computation using difference equations. We organize this algorithmic processing into larger structures based on physiological observations, and implement key modeling concepts in software which runs on parallel computing hardware.

  2. Neuroanatomical phenotypes in mental illness: identifying convergent and divergent cortical phenotypes across autism, ADHD and schizophrenia.

    Science.gov (United States)

    Park, Min Tae M; Raznahan, Armin; Shaw, Philip; Gogtay, Nitin; Lerch, Jason P; Chakravarty, M Mallar

    2018-05-01

    There is evidence suggesting neuropsychiatric disorders share genomic, cognitive and clinical features. Here, we ask if autism-spectrum disorders (ASD), attention-deficit/hyperactivity disorder (ADHD) and schizophrenia share neuroanatomical variations. First, we used measures of cortical anatomy to estimate spatial overlap of neuroanatomical variation using univariate methods. Next, we developed a novel methodology to determine whether cortical deficits specifically target or are "enriched" within functional resting-state networks. We found cortical anomalies were preferentially enriched across functional networks rather than clustering spatially. Specifically, cortical thickness showed significant enrichment between patients with ASD and those with ADHD in the default mode network, between patients with ASD and those with schizophrenia in the frontoparietal and limbic networks, and between patients with ADHD and those with schizophrenia in the ventral attention network. Networks enriched in cortical thickness anomalies were also strongly represented in functional MRI results (Neurosynth; r = 0.64, p = 0.032). We did not account for variable symptom dimensions and severity in patient populations, and our cross-sectional design prevented longitudinal analyses of developmental trajectories. These findings suggest that common deficits across neuropsychiatric disorders cannot simply be characterized as arising out of local changes in cortical grey matter, but rather as entities of both local and systemic alterations targeting brain networks.

  3. Estimation of network structure for signal propagations by the analysis of multichannel action potentials in cultured neural networks; Ta channel katsudo den`i kaiseki ni yoru baiyo shinkei kairomonai kofun denpa keiro no suitei

    Energy Technology Data Exchange (ETDEWEB)

    Konno, N.; Fukami, T.; Shiina, T. [University of Tsukuba, Tsukuba (Japan); Jinbo, Y. [Nippon Telegraph and Telephone Corp., Tokyo (Japan)

    1998-07-01

    We have fabricated a 64 embedded microelectrode-array substrate using semiconductor technology to investigate the biological signal processing in brain by using cultured neural networks of fetal rat neocortex in vitro. We analyzed temporal and spatial neural networks patterns cultured on electrode-array substrate and attempted to examine the network structure constituted by neurons and the propagating patterns of electrical activity induced by the electric stimulus. In the experiments, each microelectrode size was 30 {mu}m squared and 150{mu} m spaced. For stimulation, one of the electrodes was selected and current pulses were applied through an isolated circuit. After the network was cultured in about 50 days, responses of neurons to electric stimulus were monitored extracellularly through 64-channel electrode array. Data recorded at each electrode consist of several spike trains generated by different cells. Therefore, these trains were separated by using wavelet transform and template matching for each electrode. We referred the temporal patterns of generated spikes for each electrode to as `spike sequences`. Next, we compared With the spike sequences among multichannel data and visualized the Cultured neural networks structure by identifying the directions of propagations and cell connections. 15 refs., 9 figs.

  4. Knowledge-Sharing Networks in Hunter-Gatherers and the Evolution of Cumulative Culture.

    Science.gov (United States)

    Salali, Gul Deniz; Chaudhary, Nikhil; Thompson, James; Grace, Olwen Megan; van der Burgt, Xander M; Dyble, Mark; Page, Abigail E; Smith, Daniel; Lewis, Jerome; Mace, Ruth; Vinicius, Lucio; Migliano, Andrea Bamberg

    2016-09-26

    Humans possess the unique ability for cumulative culture [1, 2]. It has been argued that hunter-gatherer's complex social structure [3-9] has facilitated the evolution of cumulative culture by allowing information exchange among large pools of individuals [10-13]. However, empirical evidence for the interaction between social structure and cultural transmission is scant [14]. Here we examine the reported co-occurrence of plant uses between individuals in dyads (which we define as their "shared knowledge" of plant uses) in BaYaka Pygmies from Congo. We studied reported uses of 33 plants of 219 individuals from four camps. We show that (1) plant uses by BaYaka fall into three main domains: medicinal, foraging, and social norms/beliefs; (2) most medicinal plants have known bioactive properties, and some are positively associated with children's BMI, suggesting that their use is adaptive; (3) knowledge of medicinal plants is mainly shared between spouses and biological and affinal kin; and (4) knowledge of plant uses associated with foraging and social norms is shared more widely among campmates, regardless of relatedness, and is important for camp-wide activities that require cooperation. Our results show the interdependence between social structure and knowledge sharing. We propose that long-term pair bonds, affinal kin recognition, exogamy, and multi-locality create ties between unrelated families, facilitating the transmission of medicinal knowledge and its fitness implications. Additionally, multi-family camps with low inter-relatedness between camp members provide a framework for the exchange of functional information related to cooperative activities beyond the family unit, such as foraging and regulation of social life. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Social Networking Sites and Self-Promotional Culture. Notes for a Theory of the Mosaic Identity

    Directory of Open Access Journals (Sweden)

    Lucía Caro Castaño

    2017-05-01

    Full Text Available This exploratory work theorizes about how social networking sites favor, as identity technologies, a way of conceiving and presenting individual identity in self-promotional terms. As a result of the normalization of this logic –which is coherent with the late capitalism’ promotional culture–, it is growing the incorporation of self-branding practices in the users's daily communication. Besides, it is increasing the perception of the social profiles as micro-media and the interpretation of the own network as a personal audience. In brief, four main trends in the presentation of identity which are promoted by these web services are identified: a distributed and fragmented conception of the self, where the tiles from mass media become key content to express subjectivity; a tendency to quantify relationships and affections; the perception of being in an unavoidable competition with others; and standardization of the audiovisual presentation of self as a communicative material capable of attracting attention and communicate authenticity.

  6. Dependence of synchronized bursting activity on medium stirring and the perfusion rate in a cultured network of neurons

    Science.gov (United States)

    Heo, Ryoun; Kim, Hyun; Lee, Kyoung J.

    2016-05-01

    A cultured network of neurons coupled with a multi-electrode-array (MEA) recording system has been a useful platform for investigating various issues in neuroscience and engineering. The neural activity supported by the system can be sensitive to environmental fluctuations, for example, in the medium's nutrient composition, ph, and temperature, and to mechanical disturbances, yet this issue has not been the subject. Especially, a normal practice in maintaining neuronal cell cultures involves an intermittent sequence of medium exchanges, typically at a time interval of a few days, and one such sudden medium exchange is unavoidably accompanied by many unintended disturbances. Here, based on a quantitative time-series analysis of synchronized bursting events, we explicitly demonstrate that such a medium exchange can, indeed, bring a huge change in the existing neural activity. Subsequently, we develop a medium perfusion-stirring system and an ideal protocol that can be used in conjunction with a MEA recording system, providing long-term stability. Specifically, we systematically evaluate the effects of medium stirring and perfusion rates. Unexpectedly, even some vigorous mechanical agitations do not have any impacts on neural activity. On the other hand, too much replenishment ( e.g., 1.8 ml/day for a 1.8-ml dish) of neurobasal medium results in an excitotoxicity.

  7. Osteocyte lacunar properties in rat cortical bone

    DEFF Research Database (Denmark)

    Bach-Gansmo, Fiona Linnea; Weaver, James C.; Jensen, Mads Hartmann

    2015-01-01

    Recently, the roles of osteocytes in bone maintenance have gained increasing attention. Osteocytes reside in lacunae that are interconnected by canaliculi resulting in a vast cellular network within the mineralized bone matrix. As the structure of the lacuno-canalicular network is highly connected......-species but also inter-site variation in lacunar properties. Here, osteocyte lacunae in rat cortical bone have been studied using synchrotron radiation micro computed tomography (SR μCT) and backscattered electron (BE) microscopy. Quantitative lacunar geometric characteristics are reported based on the synchrotron...... radiation data, differentiating between circumferential lamellar bone and a central, more disordered bone type. From these studies, no significant differences were found in lacunar volumes between lamellar and central bone, whereas significant differences in lacunar orientation, shape and density values...

  8. HEPES activates a MiT/TFE-dependent lysosomal-autophagic gene network in cultured cells: A call for caution.

    Science.gov (United States)

    Tol, Marc J; van der Lienden, Martijn J C; Gabriel, Tanit L; Hagen, Jacob J; Scheij, Saskia; Veenendaal, Tineke; Klumperman, Judith; Donker-Koopman, Wilma E; Verhoeven, Arthur J; Overkleeft, Hermen; Aerts, Johannes M; Argmann, Carmen A; van Eijk, Marco

    2018-01-01

    In recent years, the lysosome has emerged as a highly dynamic, transcriptionally regulated organelle that is integral to nutrient-sensing and metabolic rewiring. This is coordinated by a lysosome-to-nucleus signaling nexus in which MTORC1 controls the subcellular distribution of the microphthalmia-transcription factor E (MiT/TFE) family of "master lysosomal regulators". Yet, despite the importance of the lysosome in cellular metabolism, the impact of traditional in vitro culture media on lysosomal dynamics and/or MiT/TFE localization has not been fully appreciated. Here, we identify HEPES, a chemical buffering agent that is broadly applied in cell culture, as a potent inducer of lysosome biogenesis. Supplementation of HEPES to cell growth media is sufficient to decouple the MiT/TFE family members-TFEB, TFE3 and MITF-from regulatory mechanisms that control their cytosolic retention. Increased MiT/TFE nuclear import in turn drives the expression of a global network of lysosomal-autophagic and innate host-immune response genes, altering lysosomal dynamics, proteolytic capacity, autophagic flux, and inflammatory signaling. In addition, siRNA-mediated MiT/TFE knockdown effectively blunted HEPES-induced lysosome biogenesis and gene expression profiles. Mechanistically, we show that MiT/TFE activation in response to HEPES requires its macropinocytic ingestion and aberrant lysosomal storage/pH, but is independent of MTORC1 signaling. Altogether, our data underscore the cautionary use of chemical buffering agents in cell culture media due to their potentially confounding effects on experimental results.

  9. Altering the trajectory of early postnatal cortical development can lead to structural and behavioural features of autism

    Directory of Open Access Journals (Sweden)

    Chomiak Taylor

    2010-08-01

    Full Text Available Abstract Background Autism is a behaviourally defined neurodevelopmental disorder with unknown etiology. Recent studies in autistic children consistently point to neuropathological and functional abnormalities in the temporal association cortex (TeA and its associated structures. It has been proposed that the trajectory of postnatal development in these regions may undergo accelerated maturational alterations that predominantly affect sensory recognition and social interaction. Indeed, the temporal association regions that are important for sensory recognition and social interaction are one of the last regions to mature suggesting a potential vulnerability to early maturation. However, direct evaluation of the emerging hypothesis that an altered time course of early postnatal development can lead to an ASD phenotype remains lacking. Results We used electrophysiological, histological, and behavioural techniques to investigate if the known neuronal maturational promoter valproate, similar to that in culture systems, can influence the normal developmental trajectory of TeA in vivo. Brain sections obtained from postnatal rat pups treated with VPA in vivo revealed that almost 40% of cortical cells in TeA prematurely exhibited adult-like intrinsic electrophysiological properties and that this was often associated with gross cortical hypertrophy and a reduced predisposition for social play behaviour. Conclusions The co-manifestation of these functional, structural and behavioural features suggests that alteration of the developmental time course in certain high-order cortical networks may play an important role in the neurophysiological basis of autism.

  10. RELIGIOUS NETWORKS IN MADURA Pesantren, Nahdlatul Ulama and Kiai as the Core of Santri Culture

    Directory of Open Access Journals (Sweden)

    Yanwar Pribadi

    2013-07-01

    Full Text Available This paper addresses three institutions in Madurese santri culture: the pesantren (Islamic traditional education system, the Nahdlatul Ulama, and the kiai (tradisional Islamic authority. These three elements have characterised and become central part of both Islam and politics in Madura. The issues are raised in this paper: the nature of pesantren, the role of Nahdlatul Ulama, and kiais within the whole tradition of santri Islam in Madura. How does each of these elements form relationships with the others? These questions lead to answer the main question: Is Islam in Madura different from Islam in other places in Indonesia? Today, it seems clear that despite their rather changed perceptions of modern education, Islamic associations, and men of religion, Madurese people continue to preserve their sacred values, as the main three elements of the santri culture in Madura which have had a great influence on society, in both religious and worldly domains. The people share the view that Islamic law (shari’a is fundamental to daily life and thus must be integrated in all aspects of life. However, like Islam in other places in Indonesia, the characteristic of Islam in Madura emphasises primarily, but not exclusively, on aspects such as mysticism and local cultures. [Artikel ini menjelaskan tiga elemen penting budaya santri yang melekat pada masyarakat Madura, yaitu pesantren, mewakili elemen pendidikan Islam tradisional, Nahdlatul Ulama, mewakili organisasi Islam, dan kiai, merepresentasikan tokoh Islam. Ketiga elemen tersebut berjalin-kelindan dan membentuk relasi yang kompleks antara Islam dan politik sebagaimana dipraktikkan dalam masyarakat Madura. Dua persoalan penting yang hendak dijawab melalui artikel ini yaitu bagaimana karakter pesantren, Nahdlatul Ulama, dan kiai yang menjadi dasar Islam-santri di Madura dan bagaimana ketiga elemen tersebut saling terkait satu sama lain. Persoalan ini kemudian mengantarkan pada pertanyaan penting lainnya

  11. The public space of social media connected cultures of the network society

    CERN Document Server

    Tierney, Therese

    2013-01-01

    Social media is restructuring urban practices-through ad-hoc experimentation, commercial software development, and communities of participation. This book is the first to consider how practices contained within social media are situated within a larger genealogy of public space, including theories of communal identity, civitas and democracy, the fete, and self-expression. Through empirical research, the actual social practices of participants of networked publics are described and analyzed. Documenting how online counterpublics use the Internet to transmit classified photos, mobilize activists, and challenge the status quo, Tierney argues that online activities do not stop in online conversations; they are physically grounded through mobile GPS coordinates which are then transformed into activities in physical space-the street, the plaza, the places where people have traditionally gathered to demonstrate and express their opinions publicly.

  12. Electrical responses and spontaneous activity of human iPS-derived neuronal networks characterized for three-month culture with 4096-electrode arrays

    Directory of Open Access Journals (Sweden)

    Hayder eAmin

    2016-03-01

    Full Text Available The recent availability of human induced pluripotent stem cells (hiPSCs holds great promise as a novel source of human-derived neurons for cell and tissue therapies as well as for in vitro drug screenings that might replace the use of animal models. However, there is still a considerable lack of knowledge on the functional properties of hiPSC-derived neuronal networks, thus limiting their application. Here, upon optimization of cell culture protocols, we demonstrate that both spontaneous and evoked electrical spiking activities of these networks can be characterized on-chip by taking advantage of the resolution provided by CMOS multielectrode arrays (CMOS-MEAs. These devices feature a large and closely-spaced array of 4096 simultaneously recording electrodes and multi-site on-chip electrical stimulation. Our results show that networks of human-derived neurons can respond to electrical stimulation with a physiological repertoire of spike waveforms after three months of cell culture, a period of time during which the network undergoes the expression of developing patterns of spontaneous spiking activity. To achieve this, we have investigated the impact on the network formation and on the emerging network-wide functional properties induced by different biochemical substrates, i.e. poly-dl-ornithine (PDLO, poly-l-ornithine (PLO, and polyethylenimine (PEI, that were used as adhesion promoters for the cell culture. Interestingly, we found that neuronal networks grown on PDLO coated substrates show significantly higher spontaneous firing activity, reliable responses to low-frequency electrical stimuli, and an appropriate level of PSD-95 that may denote a physiological neuronal maturation profile and synapse stabilization. However, our results also suggest that even three-month culture might not be sufficient for human-derived neuronal network maturation. Taken together, our results highlight the tight relationship existing between substrate coatings

  13. Classification of Cortical Brain Malformations

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2008-03-01

    Full Text Available Clinical, radiological, and genetic classifications of 113 cases of malformations of cortical development (MCD were evaluated at the Erasmus Medical Center-Sophia Children's Hospital, Rotterdam, the Netherlands.

  14. Focal cortical dysplasia – review

    International Nuclear Information System (INIS)

    Kabat, Joanna; Król, Przemysław

    2012-01-01

    Focal cortical dysplasia is a malformation of cortical development, which is the most common cause of medically refractory epilepsy in the pediatric population and the second/third most common etiology of medically intractable seizures in adults. Both genetic and acquired factors are involved in the pathogenesis of cortical dysplasia. Numerous classifications of the complex structural abnormalities of focal cortical dysplasia have been proposed – from Taylor et al. in 1971 to the last modification of Palmini classification made by Blumcke in 2011. In general, three types of cortical dysplasia are recognized. Type I focal cortical dysplasia with mild symptomatic expression and late onset, is more often seen in adults, with changes present in the temporal lobe. Clinical symptoms are more severe in type II of cortical dysplasia usually seen in children. In this type, more extensive changes occur outside the temporal lobe with predilection for the frontal lobes. New type III is one of the above dysplasias with associated another principal lesion as hippocampal sclerosis, tumor, vascular malformation or acquired pathology during early life. Brain MRI imaging shows abnormalities in the majority of type II dysplasias and in only some of type I cortical dysplasias. The most common findings on MRI imaging include: focal cortical thickening or thinning, areas of focal brain atrophy, blurring of the gray-white junction, increased signal on T2- and FLAIR-weighted images in the gray and subcortical white matter often tapering toward the ventricle. On the basis of the MRI findings, it is possible to differentiate between type I and type II cortical dysplasia. A complete resection of the epileptogenic zone is required for seizure-free life. MRI imaging is very helpful to identify those patients who are likely to benefit from surgical treatment in a group of patients with drug-resistant epilepsy. However, in type I cortical dysplasia, MR imaging is often normal, and also in both

  15. Networking

    OpenAIRE

    Rauno Lindholm, Daniel; Boisen Devantier, Lykke; Nyborg, Karoline Lykke; Høgsbro, Andreas; Fries, de; Skovlund, Louise

    2016-01-01

    The purpose of this project was to examine what influencing factor that has had an impact on the presumed increasement of the use of networking among academics on the labour market and how it is expressed. On the basis of the influence from globalization on the labour market it can be concluded that the globalization has transformed the labour market into a market based on the organization of networks. In this new organization there is a greater emphasis on employees having social qualificati...

  16. Spatial integration and cortical dynamics.

    Science.gov (United States)

    Gilbert, C D; Das, A; Ito, M; Kapadia, M; Westheimer, G

    1996-01-23

    Cells in adult primary visual cortex are capable of integrating information over much larger portions of the visual field than was originally thought. Moreover, their receptive field properties can be altered by the context within which local features are presented and by changes in visual experience. The substrate for both spatial integration and cortical plasticity is likely to be found in a plexus of long-range horizontal connections, formed by cortical pyramidal cells, which link cells within each cortical area over distances of 6-8 mm. The relationship between horizontal connections and cortical functional architecture suggests a role in visual segmentation and spatial integration. The distribution of lateral interactions within striate cortex was visualized with optical recording, and their functional consequences were explored by using comparable stimuli in human psychophysical experiments and in recordings from alert monkeys. They may represent the substrate for perceptual phenomena such as illusory contours, surface fill-in, and contour saliency. The dynamic nature of receptive field properties and cortical architecture has been seen over time scales ranging from seconds to months. One can induce a remapping of the topography of visual cortex by making focal binocular retinal lesions. Shorter-term plasticity of cortical receptive fields was observed following brief periods of visual stimulation. The mechanisms involved entailed, for the short-term changes, altering the effectiveness of existing cortical connections, and for the long-term changes, sprouting of axon collaterals and synaptogenesis. The mutability of cortical function implies a continual process of calibration and normalization of the perception of visual attributes that is dependent on sensory experience throughout adulthood and might further represent the mechanism of perceptual learning.

  17. Spatial integration and cortical dynamics.

    OpenAIRE

    Gilbert, C D; Das, A; Ito, M; Kapadia, M; Westheimer, G

    1996-01-01

    Cells in adult primary visual cortex are capable of integrating information over much larger portions of the visual field than was originally thought. Moreover, their receptive field properties can be altered by the context within which local features are presented and by changes in visual experience. The substrate for both spatial integration and cortical plasticity is likely to be found in a plexus of long-range horizontal connections, formed by cortical pyramidal cells, which link cells wi...

  18. Remote assessment of cultural heritage environments with wireless sensor array networks.

    Science.gov (United States)

    Agbota, Henoc; Mitchell, John E; Odlyha, Marianne; Strlič, Matija

    2014-05-19

    The logistics and cost of environmental monitoring can represent challenges for heritage managers, partly because of the sheer number of environmental parameters to consider. There is a need for a system, capable of monitoring the holistic impact of the environment on cultural materials while remaining relatively easy to use and providing remote access. This paper describes a dosimetric system based on piezoelectric quartz crystal technology. The prototype sensing module consists of an array of piezoelectric quartz crystals (PQC) coated with different metals (Fe, Cu, Ni and Sn) and includes a temperature and relative humidity sensor. The communication module involves an 802.15.4 low-power radio and a GPRS gateway which allows real time visualisation of the measurements online. An energy management protocol ensures that the system consumes very low power between measurements. The paper also describes the results and experiences from two heritage field deployments, at Apsley House in London, UK, and at the Royal Palaces of Abomey in Benin. Evaluation of PQC measurements, temperature, relative humidity and the rate of successful transmission over the communication systems are also reported.

  19. Hiperostosis cortical infantil

    Directory of Open Access Journals (Sweden)

    Salvador Javier Santos Medina

    2015-04-01

    Full Text Available La enfermedad de Caffey, o hiperostosis cortical infantil, es una rara enfermedad ósea autolimitada, que aparece de preferencia en lactantes con signos inespecíficos sistémicos; el más relevante es la reacción subperióstica e hiperostosis en varios huesos del cuerpo, con predilección en el 75-80 % de los casos por la mandíbula. Su pronóstico es bueno, la mayoría no deja secuelas. El propósito del presente trabajo es describir las características clínicas, presentes en un lactante de cinco meses de edad, atendido en el Hospital Pediátrico Provincial “Mártires de Las Tunas” con este diagnóstico, quien ingresó en el servicio de miscelánea B por una celulitis facial. Presentaba aumento de volumen en la región geniana izquierda, febrícola e inapetencia. Se impuso tratamiento con cefazolina y se egresó a los siete días. Acudió nuevamente con tumefacción blanda y difusa de ambas hemicaras, irritabilidad y fiebre. Se interconsultó con cirugía maxilofacial, se indicaron estudios sanguíneos y radiológicos. Se diagnosticó como enfermedad de Caffey, basado en la edad del niño, tumefacción facial sin signos inflamatorios agudos e hiperostosis en ambas corticales mandibulares a la radiografía AP mandíbula; unido a anemia ligera, leucocitosis y eritrosedimentación acelerada. El paciente se trató sintomáticamente y con antinflamatorios no esteroideos. Esta rara entidad se debe tener presente en casos de niños y lactantes con irritabilidad y fiebre inespecífica

  20. Canonical cortical circuits: current evidence and theoretical implications

    Directory of Open Access Journals (Sweden)

    Capone F

    2016-04-01

    Full Text Available Fioravante Capone,1,2 Matteo Paolucci,1,2 Federica Assenza,1,2 Nicoletta Brunelli,1,2 Lorenzo Ricci,1,2 Lucia Florio,1,2 Vincenzo Di Lazzaro1,2 1Unit of Neurology, Neurophysiology, Neurobiology, Department of Medicine, Università Campus Bio-Medico di Roma, Rome, Italy; 2Fondazione Alberto Sordi – Research Institute for Aging, Rome, ItalyAbstract: Neurophysiological and neuroanatomical studies have found that the same basic structural and functional organization of neuronal circuits exists throughout the cortex. This kind of cortical organization, termed canonical circuit, has been functionally demonstrated primarily by studies involving visual striate cortex, and then, the concept has been extended to different cortical areas. In brief, the canonical circuit is composed of superficial pyramidal neurons of layers II/III receiving different inputs and deep pyramidal neurons of layer V that are responsible for cortex output. Superficial and deep pyramidal neurons are reciprocally connected, and inhibitory interneurons participate in modulating the activity of the circuit. The main intuition of this model is that the entire cortical network could be modeled as the repetition of relatively simple modules composed of relatively few types of excitatory and inhibitory, highly interconnected neurons. We will review the origin and the application of the canonical cortical circuit model in the six sections of this paper. The first section (The origins of the concept of canonical circuit: the cat visual cortex reviews the experiments performed in the cat visual cortex, from the origin of the concept of canonical circuit to the most recent developments in the modelization of cortex. The second (The canonical circuit in neocortex and third (Toward a canonical circuit in agranular cortex sections try to extend the concept of canonical circuit to other cortical areas, providing some significant examples of circuit functioning in different cytoarchitectonic

  1. Legal Analysis of Constructing Network Security System --View of Network Security Culture%建立网络安全保障体系的法律思考——以网络安全文化为视角

    Institute of Scientific and Technical Information of China (English)

    王铁占; 安海兴

    2011-01-01

    The information network movement system frequency suffers the destruction, has the value information to steal repeatedly, is main threat which the current network security faces. Under the network security culture frame, through legislation, establishes the stan perfect network security legal li government by law function and be an urgent matter. the enhancement networking legislation and the safety control administration dard network security service industry development the legal framework, the ability system, raises the network user safety idea, the display morals in the so on, the establishment should to the threat network security safeguard system%信息网络运行系统频遭破坏导致有价值信息屡被窃取,是当前网络安全面临的主要威胁。在网络安全文化框架下,通过加强网络技术立法与安全管理行政立法,建立规范网络安全服务业发展的法律体系,完善网络安全法律责任制度,培养网络用户安全理念,发挥道德在法治中的作用,建立应对威胁的网络安全保障体系是当务之急。

  2. The cortical signature of amyotrophic lateral sclerosis.

    Directory of Open Access Journals (Sweden)

    Federica Agosta

    Full Text Available The aim of this study was to explore the pattern of regional cortical thickness in patients with non-familial amyotrophic lateral sclerosis (ALS and to investigate whether cortical thinning is associated with disease progression rate. Cortical thickness analysis was performed in 44 ALS patients and 26 healthy controls. Group differences in cortical thickness and the age-by-group effects were assessed using vertex-by-vertex and multivariate linear models. The discriminatory ability of MRI variables in distinguishing patients from controls was estimated using the Concordance Statistics (C-statistic within logistic regression analyses. Correlations between cortical thickness measures and disease progression rate were tested using the Pearson coefficient. Relative to controls, ALS patients showed a bilateral cortical thinning of the primary motor, prefrontal and ventral frontal cortices, cingulate gyrus, insula, superior and inferior temporal and parietal regions, and medial and lateral occipital areas. There was a significant age-by-group effect in the sensorimotor cortices bilaterally, suggesting a stronger association between age and cortical thinning in ALS patients compared to controls. The mean cortical thickness of the sensorimotor cortices distinguished patients with ALS from controls (C-statistic ≥ 0.74. Cortical thinning of the left sensorimotor cortices was related to a faster clinical progression (r = -0.33, p = 0.03. Cortical thickness measurements allowed the detection and quantification of motor and extramotor involvement in patients with ALS. Cortical thinning of the precentral gyrus might offer a marker of upper motor neuron involvement and disease progression.

  3. The cortical signature of amyotrophic lateral sclerosis.

    Science.gov (United States)

    Agosta, Federica; Valsasina, Paola; Riva, Nilo; Copetti, Massimiliano; Messina, Maria Josè; Prelle, Alessandro; Comi, Giancarlo; Filippi, Massimo

    2012-01-01

    The aim of this study was to explore the pattern of regional cortical thickness in patients with non-familial amyotrophic lateral sclerosis (ALS) and to investigate whether cortical thinning is associated with disease progression rate. Cortical thickness analysis was performed in 44 ALS patients and 26 healthy controls. Group differences in cortical thickness and the age-by-group effects were assessed using vertex-by-vertex and multivariate linear models. The discriminatory ability of MRI variables in distinguishing patients from controls was estimated using the Concordance Statistics (C-statistic) within logistic regression analyses. Correlations between cortical thickness measures and disease progression rate were tested using the Pearson coefficient. Relative to controls, ALS patients showed a bilateral cortical thinning of the primary motor, prefrontal and ventral frontal cortices, cingulate gyrus, insula, superior and inferior temporal and parietal regions, and medial and lateral occipital areas. There was a significant age-by-group effect in the sensorimotor cortices bilaterally, suggesting a stronger association between age and cortical thinning in ALS patients compared to controls. The mean cortical thickness of the sensorimotor cortices distinguished patients with ALS from controls (C-statistic ≥ 0.74). Cortical thinning of the left sensorimotor cortices was related to a faster clinical progression (r = -0.33, p = 0.03). Cortical thickness measurements allowed the detection and quantification of motor and extramotor involvement in patients with ALS. Cortical thinning of the precentral gyrus might offer a marker of upper motor neuron involvement and disease progression.

  4. Spectrotemporal dynamics of auditory cortical synaptic receptive field plasticity.

    Science.gov (United States)

    Froemke, Robert C; Martins, Ana Raquel O

    2011-09-01

    The nervous system must dynamically represent sensory information in order for animals to perceive and operate within a complex, changing environment. Receptive field plasticity in the auditory cortex allows cortical networks to organize around salient features of the sensory environment during postnatal development, and then subsequently refine these representations depending on behavioral context later in life. Here we review the major features of auditory cortical receptive field plasticity in young and adult animals, focusing on modifications to frequency tuning of synaptic inputs. Alteration in the patterns of acoustic input, including sensory deprivation and tonal exposure, leads to rapid adjustments of excitatory and inhibitory strengths that collectively determine the suprathreshold tuning curves of cortical neurons. Long-term cortical plasticity also requires co-activation of subcortical neuromodulatory control nuclei such as the cholinergic nucleus basalis, particularly in adults. Regardless of developmental stage, regulation of inhibition seems to be a general mechanism by which changes in sensory experience and neuromodulatory state can remodel cortical receptive fields. We discuss recent findings suggesting that the microdynamics of synaptic receptive field plasticity unfold as a multi-phase set of distinct phenomena, initiated by disrupting the balance between excitation and inhibition, and eventually leading to wide-scale changes to many synapses throughout the cortex. These changes are coordinated to enhance the representations of newly-significant stimuli, possibly for improved signal processing and language learning in humans. Copyright © 2011 Elsevier B.V. All rights reserved.

  5. Comparison of practice based research network based quality improvement technical assistance and evaluation to other ongoing quality improvement efforts for changes in agency culture.

    Science.gov (United States)

    Livingood, William C; Peden, Angela H; Shah, Gulzar H; Marshall, Nandi A; Gonzalez, Ketty M; Toal, Russell B; Alexander, Dayna S; Wright, Alesha R; Woodhouse, Lynn D

    2015-07-31

    Public health agencies in the USA are increasingly challenged to adopt Quality Improvement (QI) strategies to enhance performance. Many of the functional and structural barriers to effective use of QI can be found in the organizational culture of public health agencies. The purpose of this study was to assess the impact of public health practice based research network (PBRN) evaluation and technical assistance for QI interventions on the organizational culture of public health agencies in Georgia, USA. An online survey of key informants in Georgia's districts and county health departments was used to compare perceptions of characteristics of organizational QI culture between PBRN supported QI districts and non-PBRN supported districts before and after the QI interventions. The primary outcomes of concern were number and percentage of reported increases in characteristics of QI culture as measured by key informant responses to items assessing organizational QI practices from a validated instrument on QI Collaboratives. Survey results were analyzed using Multi-level Mixed Effects Logistic Model, which accounts for clustering/nesting. Increases in QI organizational culture were consistent for all 10- items on a QI organizational culture survey related to: leadership support, use of data, on-going QI, and team collaboration. Statistically significant odds ratios were calculated for differences in increased QI organizational culture between PBRN-QI supported districts compared to Non-PBRN supported districts for 5 of the 10 items, after adjusting for District clustering of county health departments. Agency culture, considered by many QI experts as the main goal of QI, is different than use of specific QI methods, such as Plan-Do-Study-Act (PDSA) cycles or root-cause analyses. The specific use of a QI method does not necessarily reflect culture change. Attempts to measure QI culture are newly emerging. This study documented significant improvements in characteristics of

  6. Cortical tremor: a variant of cortical reflex myoclonus.

    Science.gov (United States)

    Ikeda, A; Kakigi, R; Funai, N; Neshige, R; Kuroda, Y; Shibasaki, H

    1990-10-01

    Two patients with action tremor that was thought to originate in the cerebral cortex showed fine shivering-like finger twitching provoked mainly by action and posture. Surface EMG showed relatively rhythmic discharge at a rate of about 9 Hz, which resembled essential tremor. However, electrophysiologic studies revealed giant somatosensory evoked potentials (SEPs) with enhanced long-loop reflex and premovement cortical spike by the jerk-locked averaging method. Treatment with beta-blocker showed no effect, but anticonvulsants such as clonazepam, valproate, and primidone were effective to suppress the tremor and the amplitude of SEPs. We call this involuntary movement "cortical tremor," which is in fact a variant of cortical reflex myoclonus.

  7. Cortical activation in patients with functional hemispherectomy.

    Science.gov (United States)

    Leonhardt, G; Bingel, U; Spiekermann, G; Kurthen, M; Müller, S; Hufnagel, A

    2001-10-01

    Functional hemispherectomy, a safe and effective therapeutical procedure in medically intractable epilepsy, offers the chance to investigate a strictly unilateral cortical activation in ipsilateral limb movement. We assessed the pattern of cortical activation in a group of patients following functional hemispherectomy. We measured regional cerebral blood flow (rCBF) in 6 patients postoperatively and 6 normal subjects with positron emission tomography using 15[O]H2O as a tracer. Brain activation was achieved by passive elbow movements of the affected arm. Analysis of group results and between-group comparisons were performed with statistical parametric mapping, (SPM96). In normal subjects brain activation was found contralaterally in the cranial sensorimotor cortex and the supplementary motor area and ipsilaterally in the inferior parietal cortex. In patients significant rCBF increases were found in the inferior parietal cortex, caudal sensorimotor cortex and the supplementary motor area ipsilaterally. The activation was weaker than in normal subjects. Compared with normal subjects patients showed additional activation in the premotor cortex, caudal sensorimotor cortex and the inferior parietal cortex of the remaining hemisphere. Less activation compared with normal subjects was found in the cranial sensorimotor cortex and the supplementary motor area. A functional network connecting the inferior parietal cortex, premotor cortex and the supplementary motor area as well as the existence of ipsilateral projections originating from these regions may explain why these areas are predominantly involved in reorganization confined to a single hemisphere.

  8. Visualization of migration of human cortical neurons generated from induced pluripotent stem cells.

    Science.gov (United States)

    Bamba, Yohei; Kanemura, Yonehiro; Okano, Hideyuki; Yamasaki, Mami

    2017-09-01

    Neuronal migration is considered a key process in human brain development. However, direct observation of migrating human cortical neurons in the fetal brain is accompanied by ethical concerns and is a major obstacle in investigating human cortical neuronal migration. We established a novel system that enables direct visualization of migrating cortical neurons generated from human induced pluripotent stem cells (hiPSCs). We observed the migration of cortical neurons generated from hiPSCs derived from a control and from a patient with lissencephaly. Our system needs no viable brain tissue, which is usually used in slice culture. Migratory behavior of human cortical neuron can be observed more easily and more vividly by its fluorescence and glial scaffold than that by earlier methods. Our in vitro experimental system provides a new platform for investigating development of the human central nervous system and brain malformation. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Cortical oscillatory activity during spatial echoic memory.

    Science.gov (United States)

    Kaiser, Jochen; Walker, Florian; Leiberg, Susanne; Lutzenberger, Werner

    2005-01-01

    In human magnetoencephalogram, we have found gamma-band activity (GBA), a putative measure of cortical network synchronization, during both bottom-up and top-down auditory processing. When sound positions had to be retained in short-term memory for 800 ms, enhanced GBA was detected over posterior parietal cortex, possibly reflecting the activation of higher sensory storage systems along the hypothesized auditory dorsal space processing stream. Additional prefrontal GBA increases suggested an involvement of central executive networks in stimulus maintenance. The present study assessed spatial echoic memory with the same stimuli but a shorter memorization interval of 200 ms. Statistical probability mapping revealed posterior parietal GBA increases at 80 Hz near the end of the memory phase and both gamma and theta enhancements in response to the test stimulus. In contrast to the previous short-term memory study, no prefrontal gamma or theta enhancements were detected. This suggests that spatial echoic memory is performed by networks along the putative auditory dorsal stream, without requiring an involvement of prefrontal executive regions.

  10. Is cortical bone hip? What determines cortical bone properties?

    Science.gov (United States)

    Epstein, Sol

    2007-07-01

    Increased bone turnover may produce a disturbance in bone structure which may result in fracture. In cortical bone, both reduction in turnover and increase in hip bone mineral density (BMD) may be necessary to decrease hip fracture risk and may require relatively greater proportionate changes than for trabecular bone. It should also be noted that increased porosity produces disproportionate reduction in bone strength, and studies have shown that increased cortical porosity and decreased cortical thickness are associated with hip fracture. Continued studies for determining the causes of bone strength and deterioration show distinct promise. Osteocyte viability has been observed to be an indicator of bone strength, with viability as the result of maintaining physiological levels of loading and osteocyte apoptosis as the result of a decrease in loading. Osteocyte apoptosis and decrease are major factors in the bone loss and fracture associated with aging. Both the osteocyte and periosteal cell layer are assuming greater importance in the process of maintaining skeletal integrity as our knowledge of these cells expand, as well being a target for pharmacological agents to reduce fracture especially in cortical bone. The bisphosphonate alendronate has been seen to have a positive effect on co