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https://www.readbyqxmd.com/read/28495368/the-dynamic-programming-high-order-dynamic-bayesian-networks-learning-for-identifying-effective-connectivity-in-human-brain-from-fmri
#1
Shilpa Dang, Santanu Chaudhury, Brejesh Lall, Prasun Kumar Roy
BACKGROUND: Determination of effective connectivity (EC) among brain regions using fMRI is helpful in understanding the underlying neural mechanisms. Dynamic Bayesian Networks (DBNs) are an appropriate class of probabilistic graphical temporal-models that have been used in past to model EC from fMRI, specifically order-one. NEW-METHOD: High-order DBNs (HO-DBNs) have still not been explored for fMRI data. A fundamental problem faced in the structure-learning of HO-DBN is high computational-burden and low accuracy by the existing heuristic search techniques used for EC detection from fMRI...
May 8, 2017: Journal of Neuroscience Methods
https://www.readbyqxmd.com/read/28469529/protected-areas-in-the-world-s-ecoregions-how-well-connected-are-they
#2
Santiago Saura, Lucy Bastin, Luca Battistella, Andrea Mandrici, Grégoire Dubois
Protected areas (PAs) are the main instrument for biodiversity conservation, which has triggered the development of numerous indicators and assessments on their coverage, performance and efficiency. The connectivity of the PA networks at a global scale has however been much less explored; previous studies have either focused on particular regions of the world or have only considered some types of PAs. Here we present, and globally assess, ProtConn, an indicator of PA connectivity that (i) quantifies the percentage of a study region covered by protected connected lands, (ii) can be partitioned in several components depicting different categories of land (unprotected, protected or transboundary) through which movement between protected locations may occur, (iii) is easy to communicate, to compare with PA coverage and to use in the assessment of global targets for PA systems...
May 2017: Ecological Indicators
https://www.readbyqxmd.com/read/28469187/habitat-connectivity-and-in-stream-vegetation-control-temporal-variability-of-benthic-invertebrate-communities
#3
K-L Huttunen, H Mykrä, J Oksanen, A Astorga, R Paavola, T Muotka
One of the key challenges to understanding patterns of β diversity is to disentangle deterministic patterns from stochastic ones. Stochastic processes may mask the influence of deterministic factors on community dynamics, hindering identification of the mechanisms causing variation in community composition. We studied temporal β diversity (among-year dissimilarity) of macroinvertebrate communities in near-pristine boreal streams across 14 years. To assess whether the observed β diversity deviates from that expected by chance, and to identify processes (deterministic vs...
May 3, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28467487/is-functional-brain-connectivity-atypical-in-autism-a-systematic-review-of-eeg-and-meg-studies
#4
Christian O'Reilly, John D Lewis, Mayada Elsabbagh
BACKGROUND: Although it is well recognized that autism is associated with altered patterns of over- and under-connectivity, specifics are still a matter of debate. Little has been done so far to synthesize available literature using whole-brain electroencephalography (EEG) and magnetoencephalography (MEG) recordings. OBJECTIVES: 1) To systematically review the literature on EEG/MEG functional and effective connectivity in autism spectrum disorder (ASD), 2) to synthesize and critically appraise findings related with the hypothesis that ASD is characterized by long-range underconnectivity and local overconnectivity, and 3) to provide, based on the literature, an analysis of tentative factors that are likely to mediate association between ASD and atypical connectivity (e...
2017: PloS One
https://www.readbyqxmd.com/read/28456171/on-the-role-of-the-entorhinal-cortex-in-the-effective-connectivity-of-the-hippocampal-formation
#5
Víctor J López-Madrona, Fernanda S Matias, Ernesto Pereda, Santiago Canals, Claudio R Mirasso
Inferring effective connectivity from neurophysiological data is a challenging task. In particular, only a finite (and usually small) number of sites are simultaneously recorded, while the response of one of these sites can be influenced by other sites that are not being recorded. In the hippocampal formation, for instance, the connections between areas CA1-CA3, the dentate gyrus (DG), and the entorhinal cortex (EC) are well established. However, little is known about the relations within the EC layers, which might strongly affect the resulting effective connectivity estimations...
April 2017: Chaos
https://www.readbyqxmd.com/read/28454106/different-patterns-of-age-related-central-olfactory-decline-in-men-and-women-as-quantified-by-olfactory-fmri
#6
Brittany Martinez, Prasanna Karunanayaka, Jianli Wang, Michael J Tobia, Megha Vasavada, Paul J Eslinger, Qing X Yang
Age-related olfactory decline, or presbyosmia, is a prevalent condition with potentially devastating consequences on both quality of life and safety. Despite clear evidence for this decline, it is unknown whether presbyosmia is sex-dependent and also whether it is due to central or peripheral olfactory system deterioration. Therefore, the goals of this study were to investigate the neurofunctional substrate of olfactory decline and examine its relationship to age and sex in thirty-seven (18 women, 19 men) healthy older participants using olfactory functional MRI (fMRI)...
April 8, 2017: Oncotarget
https://www.readbyqxmd.com/read/28448272/automated-network-analysis-to-measure-brain-effective-connectivity-estimated-from-eeg-data-of-patients-with-alcoholism
#7
Youngoh Bae, Byeong Wook Yoo, Jung Chan Lee, Hee Chan Kim
OBJECTIVE: Detection and diagnosis based on extracting features and classification using electroencephalography (EEG) signals are being studied vigorously. A network analysis of time series EEG signal data is one of many techniques that could help study brain functions. In this study, we analyze EEG to diagnose alcoholism. APPROACH: We propose a novel methodology to estimate the differences in the status of the brain based on EEG data of normal subjects and data from alcoholics by computing many parameters stemming from effective network using Granger causality...
May 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28438665/effective-connectivity-gateways-to-the-theory-of-mind-network-in-processing-communicative-intention
#8
Marco Tettamanti, Matilde M Vaghi, Bruno G Bara, Stefano F Cappa, Ivan Enrici, Mauro Adenzato
An Intention Processing Network (IPN), involving the medial prefrontal cortex, precuneus, bilateral posterior superior temporal sulcus, and temporoparietal junctions, plays a fundamental role in comprehending intentions underlying action goals. In a previous fMRI study, we showed that, depending on the linguistic or extralinguistic (gestural) modality used to convey the intention, the IPN is complemented by activation of additional brain areas, reflecting distinct modality-specific input gateways to the IPN...
April 22, 2017: NeuroImage
https://www.readbyqxmd.com/read/28416773/changes-in-t-cell-subpopulations-and-cytokine-network-during-early-period-of-ibrutinib-therapy-in-chronic-lymphocytic-leukemia-patients-the-significant-decrease-in-t-regulatory-cells-number
#9
Monika Podhorecka, Aneta Goracy, Agnieszka Szymczyk, Malgorzata Kowal, Blanca Ibanez, Olga Jankowska-Lecka, Arkadiusz Macheta, Aleksandra Nowaczynska, Elzbieta Drab-Urbanek, Sylwia Chocholska, Dariusz Jawniak, Marek Hus
B cell receptor (BCR) stimulation signal plays an important role in the pathogenesis of chronic lymphocytic leukemia (CLL), and kinase inhibitors directed toward the BCR pathway are now the promising anti-leukemic drugs. Ibrutinib, a Bruton tyrosine kinase inhibitor, demonstrates promising clinical activity in CLL. It is reported that ibrutinib, additionally to directly targeting leukemic cells, also inhibits the interactions of these cells with T cells, macrophages and accessory cells. Assessment of these mechanisms is important because of their non -direct anti-leukemic effects and to identify possible side effects connected with long-term drug administration...
May 23, 2017: Oncotarget
https://www.readbyqxmd.com/read/28408874/editorial-mapping-psychopathology-with-fmri-and-effective-connectivity-analysis
#10
EDITORIAL
Baojuan Li, Adeel Razi, Karl J Friston
No abstract text is available yet for this article.
2017: Frontiers in Human Neuroscience
https://www.readbyqxmd.com/read/28399440/altered-effective-brain-connectivity-at-early-response-of-antipsychotics-in-first-episode-schizophrenia-with-auditory-hallucinations
#11
Leilei Zheng, Weibo Liu, Wei He, Shaohua Yu, Guodong Zhong
OBJECTIVE: This study aimed to examine the alterations of cortical connectivity in first-episode schizophrenia (FES) with auditory hallucinations at early response of antipsychotics. METHODS: This was a nonexperimental control of medication study. We measured the cortical activity of 20 medicated patients with FES (medicated group), 19 nonmedicated patients with FES (nonmedicated group), and 22 healthy controls using electroencephalogram during eye-open resting state...
June 2017: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
https://www.readbyqxmd.com/read/28397708/effective-brain-network-analysis-with-resting-state-eeg-data-a-comparison-between-heroin-abstinent-and-non-addicted-subjects
#12
Bin Hu, Qunxi Dong, Yanrong Hao, Qinglin Zhao, Jian Shen, Fang Zheng
Abstract-Objective. Neuro-electrophysiological tools have been widely used in heroin addiction studies. Previous studies indicated that chronic heroin abuse would result in abnormal functional organization of the brain. While few heroin addiction studies apply the effective connectivity tool to analyze the brain functional system (BFS) alterations induced by heroin abuse. The present study aims to identify the abnormality of resting-state heroin abstinent BFS using source decomposition and effective connectivity tools...
April 11, 2017: Journal of Neural Engineering
https://www.readbyqxmd.com/read/28386778/gaba-content-within-medial-prefrontal-cortex-predicts-the-variability-of-fronto-limbic-effective-connectivity
#13
Stefano Delli Pizzi, Piero Chiacchieretta, Dante Mantini, Giovanna Bubbico, Richard A Edden, Marco Onofrj, Antonio Ferretti, Laura Bonanni
The amygdala-medial prefrontal cortex (mPFC) circuit plays a key role in social behavior. The amygdala and mPFC are bidirectionally connected, functionally and anatomically, via the uncinate fasciculus. Recent evidence suggests that GABA-ergic neurotransmission within the mPFC could be central to the regulation of amygdala activity related to emotions and anxiety processing. However, the functional and neurochemical interactions within amygdala-mPFC circuits are unclear. In the current study, multimodal magnetic resonance imaging techniques were combined to investigate effective connectivity within the amygdala-mPFC network and its relationship with mPFC neurotransmission in 22 healthy subjects aged between 41 and 88 years...
April 6, 2017: Brain Structure & Function
https://www.readbyqxmd.com/read/28378705/comparison-of-connectivity-analyses-for-resting-state-eeg-data
#14
Elzbieta Olejarczyk, Laura Marzetti, Vittorio Pizzella, Filippo Zappasodi
OBJECTIVE: In the present work, a nonlinear measure (transfer entropy, TE) was used in a multivariate approach for the analysis of effective connectivity in high density resting state EEG data in eyes open and eyes closed. Advantages of the multivariate approach in comparison to the bivariate one were tested. Moreover, the multivariate TE was compared to an effective linear measure, i.e. directed transfer function (DTF). Finally, the existence of a relationship between the information transfer and the level of brain synchronization as measured by phase synchronization value (PLV) was investigated...
June 2017: Journal of Neural Engineering
https://www.readbyqxmd.com/read/28364641/tracking-reorganization-of-large-scale-effective-connectivity-in-aphasia-following-right-hemisphere-stroke
#15
David W Gow, Seppo P Ahlfors
In this paper we demonstrate the application of new effective connectivity analyses to characterize changing patterns of task-related directed interaction in large (25-55 node) cortical networks following the onset of aphasia. The subject was a left-handed woman who became aphasic following a right-hemisphere stroke. She was tested on an auditory word-picture verification task administered one and seven months after the onset of aphasia. MEG/EEG and anatomical MRI data were used to create high spatiotemporal resolution estimates of task-related cortical activity...
March 29, 2017: Brain and Language
https://www.readbyqxmd.com/read/28364547/stable-functional-networks-exhibit-consistent-timing-in-the-human-brain
#16
Julio I Chapeton, Sara K Inati, Kareem A Zaghloul
Despite many advances in the study of large-scale human functional networks, the question of timing, stability, and direction of communication between cortical regions has not been fully addressed. At the cellular level, neuronal communication occurs through axons and dendrites, and the time required for such communication is well defined and preserved. At larger spatial scales, however, the relationship between timing, direction, and communication between brain regions is less clear. Here, we use a measure of effective connectivity to identify connections between brain regions that exhibit communication with consistent timing...
March 1, 2017: Brain: a Journal of Neurology
https://www.readbyqxmd.com/read/28342831/inference-of-direct-and-multistep-effective-connectivities-from-functional-connectivity-of-the-brain-and-of-relationships-to-cortical-geometry
#17
Grishma Mehta-Pandejee, P A Robinson, James A Henderson, K M Aquino, Somwrita Sarkar
BACKGROUND: The problem of inferring effective brain connectivity from functional connectivity is under active investigation, and connectivity via multistep paths is poorly understood. NEW METHOD: A method is presented to calculate the direct effective connection matrix (deCM), which embodies direct connection strengths between brain regions, from functional CMs (fCMs) by minimizing the difference between an experimental fCM and one calculated via neural field theory from an ansatz deCM based on an experimental anatomical CM...
March 22, 2017: Journal of Neuroscience Methods
https://www.readbyqxmd.com/read/28341164/expectation-violation-and-attention-to-pain-jointly-modulate-neural-gain-in-somatosensory-cortex
#18
Francesca Fardo, Ryszard Auksztulewicz, Micah Allen, Martin J Dietz, Andreas Roepstorff, Karl J Friston
The neural processing and experience of pain are influenced by both expectations and attention. For example, the amplitude of event-related pain responses is enhanced by both novel and unexpected pain, and by moving the focus of attention towards a painful stimulus. Under predictive coding, this congruence can be explained by appeal to a precision-weighting mechanism, which mediates bottom-up and top-down attentional processes by modulating the influence of feedforward and feedback signals throughout the cortical hierarchy...
March 21, 2017: NeuroImage
https://www.readbyqxmd.com/read/28340406/a-local-adjustment-strategy-for-the-initialization-of-dynamic-causal-modelling-to-infer-effective-connectivity-in-brain-epileptic-structures
#19
Wentao Xiang, Ahmad Karfoul, Huazhong Shu, Régine Le Bouquin Jeannès
This paper addresses the question of effective connectivity in the human cerebral cortex in the context of epilepsy. Among model based approaches to infer brain connectivity, spectral Dynamic Causal Modelling is a conventional technique for which we propose an alternative to estimate cross spectral density. The proposed strategy we investigated tackles the sub-estimation of the free energy using the well-known variational Expectation-Maximization algorithm highly sensitive to the initialization of the parameters vector by a permanent local adjustment of the initialization process...
March 7, 2017: Computers in Biology and Medicine
https://www.readbyqxmd.com/read/28334882/decreased-integration-and-information-capacity-in-stroke-measured-by-whole-brain-models-of-resting-state-activity
#20
Mohit H Adhikari, Carl D Hacker, Josh S Siegel, Alessandra Griffa, Patric Hagmann, Gustavo Deco, Maurizio Corbetta
While several studies have shown that focal lesions affect the communication between structurally normal regions of the brain, and that these changes may correlate with behavioural deficits, their impact on brain's information processing capacity is currently unknown. Here we test the hypothesis that focal lesions decrease the brain's information processing capacity, of which changes in functional connectivity may be a measurable correlate. To measure processing capacity, we turned to whole brain computational modelling to estimate the integration and segregation of information in brain networks...
April 1, 2017: Brain: a Journal of Neurology
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