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https://www.readbyqxmd.com/read/28208475/exotic-phase-transitions-of-k-cores-in-clustered-networks
#1
Uttam Bhat, Munik Shrestha, Laurent Hébert-Dufresne
The giant k-core-maximal connected subgraph of a network where each node has at least k neighbors-is important in the study of phase transitions and in applications of network theory. Unlike Erdős-Rényi graphs and other random networks where k-cores emerge discontinuously for k≥3, we show that transitive linking (or triadic closure) leads to 3-cores emerging through single or double phase transitions of both discontinuous and continuous nature. We also develop a k-core calculation that includes clustering and provides insights into how high-level connectivity emerges...
January 2017: Physical Review. E
https://www.readbyqxmd.com/read/28197801/team-sports-performance-analysed-through-the-lens-of-social-network-theory-implications-for-research-and-practice
#2
João Ribeiro, Pedro Silva, Ricardo Duarte, Keith Davids, Júlio Garganta
This paper discusses how social network analyses and graph theory can be implemented in team sports performance analyses to evaluate individual (micro) and collective (macro) performance data, and how to use this information for designing practice tasks. Moreover, we briefly outline possible limitations of social network studies and provide suggestions for future research. Instead of cataloguing discrete events or player actions, it has been argued that researchers need to consider the synergistic interpersonal processes emerging between teammates in competitive performance environments...
February 15, 2017: Sports Medicine
https://www.readbyqxmd.com/read/28177260/graph-theory-at-the-service-of-electroencephalograms
#3
Nantia D Iakovidou
The brain is one of the largest and most complex organs in the human body and electroencephalography (EEG) is a non-invasive electrophysiological monitoring method that is used to record the electrical activity of the brain. Lately, the functional connectivity in human brain has been regarded and studied as a complex network using electroencephalographic (EEG) signals. This means that the brain is studied as a connected system where nodes, or units, represent different specialized brain regions and links, or connections, represent communication pathways between the nodes...
February 8, 2017: Brain Connectivity
https://www.readbyqxmd.com/read/28176413/anomalous-single-subject-based-morphological-cortical-networks-in-drug-naive-first-episode-major-depressive-disorder
#4
Taolin Chen, Keith M Kendrick, Jinhui Wang, Min Wu, Kaiming Li, Xiaoqi Huang, Yuejia Luo, Su Lui, John A Sweeney, Qiyong Gong
Major depressive disorder (MDD) has been associated with disruptions in the topological organization of brain morphological networks in group-level data. Such disruptions have not yet been identified in single-patients, which is needed to show relations with symptom severity and to evaluate their potential as biomarkers for illness. To address this issue, we conducted a cross-sectional structural brain network study of 33 treatment-naive, first-episode MDD patients and 33 age-, gender-, and education-matched healthy controls (HCs)...
February 8, 2017: Human Brain Mapping
https://www.readbyqxmd.com/read/28154557/robust-inference-of-genetic-exchange-communities-from-microbial-genomes-using-tf-idf
#5
Yingnan Cong, Yao-Ban Chan, Charles A Phillips, Michael A Langston, Mark A Ragan
Bacteria and archaea can exchange genetic material across lineages through processes of lateral genetic transfer (LGT). Collectively, these exchange relationships can be modeled as a network and analyzed using concepts from graph theory. In particular, densely connected regions within an LGT network have been defined as genetic exchange communities (GECs). However, it has been problematic to construct networks in which edges solely represent LGT. Here we apply term frequency-inverse document frequency (TF-IDF), an alignment-free method originating from document analysis, to infer regions of lateral origin in bacterial genomes...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28127519/increased-thalamic-centrality-and-putamen-thalamic-connectivity-in-patients-with-parkinsonian-resting-tremor
#6
Quanquan Gu, Hengyi Cao, Min Xuan, Wei Luo, Xiaojun Guan, Jingjing Xu, Peiyu Huang, Minming Zhang, Xiaojun Xu
INTRODUCTION: Evidence has indicated a strong association between hyperactivity in the cerebello-thalamo-motor cortical loop and resting tremor in Parkinson's disease (PD). Within this loop, the thalamus serves as a central hub based on its structural centrality in the generation of resting tremor. To study whether this thalamic abnormality leads to an alteration at the whole-brain level, our study investigated the role of the thalamus in patients with parkinsonian resting tremor in a large-scale brain network context...
January 2017: Brain and Behavior
https://www.readbyqxmd.com/read/28123951/large-scale-cortico-subcortical-functional-networks-in-focal-epilepsies-the-role-of-the-basal-ganglia
#7
Eva Výtvarová, Radek Mareček, Jan Fousek, Ondřej Strýček, Ivan Rektor
OBJECTIVES: The aim was to describe the contribution of basal ganglia (BG) thalamo-cortical circuitry to the whole-brain functional connectivity in focal epilepsies. METHODS: Interictal resting-state fMRI recordings were acquired in 46 persons with focal epilepsies. Of these 46, 22 had temporal lobe epilepsy: 9 left temporal (LTLE), 13 right temporal (RTLE); 15 had frontal lobe epilepsy (FLE); and 9 had parietal/occipital lobe epilepsy (POLE). There were 20 healthy controls...
2017: NeuroImage: Clinical
https://www.readbyqxmd.com/read/28116232/changes-in-functional-organization-and-white-matter-integrity-in-the-connectome-in-parkinson-s-disease
#8
Sule Tinaz, Peter M Lauro, Pritha Ghosh, Codrin Lungu, Silvina G Horovitz
Parkinson's disease (PD) leads to dysfunction in multiple cortico-striatal circuits. The neurodegeneration has also been associated with impaired white matter integrity. This structural and functional "disconnection" in PD needs further characterization. We investigated the structural and functional organization of the PD whole brain connectome consisting of 200 nodes using diffusion tensor imaging and resting-state functional MRI, respectively. Data from 20 non-demented PD patients on dopaminergic medication and 20 matched controls were analyzed using graph theory-based methods...
2017: NeuroImage: Clinical
https://www.readbyqxmd.com/read/28113724/brain-modulyzer-interactive-visual-analysis-of-functional-brain-connectivity
#9
Sugeerth Murugesan, Kristofer Bouchard, Jesse A Brown, Bernd Hamann, William W Seeley, Andrew Trujillo, Gunther H Weber
We present Brain Modulyzer, an interactive visual exploration tool for functional magnetic resonance imaging (fMRI) brain scans, aimed at analyzing the correlation between different brain regions when resting or when performing mental tasks. Brain Modulyzer combines multiple coordinated views-such as heat maps, node link diagrams and anatomical views-using brushing and linking to provide an anatomical context for brain connectivity data. Integrating methods from graph theory and analysis, e.g., community detection and derived graph measures, makes it possible to explore the modular and hierarchical organization of functional brain networks...
May 9, 2016: IEEE/ACM Transactions on Computational Biology and Bioinformatics
https://www.readbyqxmd.com/read/28113682/exploring-the-epileptic-brain-network-using-time-variant-effective-connectivity-and-graph-theory
#10
Silvia Storti, Ilaria Boscolo Galazzo, Sehresh Khan, Paolo Manganotti, Gloria Menegaz
The application of time-varying measures of causality between source time series can be very informative to elucidate the direction of communication among the regions of an epileptic brain. The aim of the study was to identify the dynamic patterns of epileptic networks in focal epilepsy by applying multivariate adaptive directed transfer function (ADTF) analysis and graph-theory to high-density electroencephalographic (hdEEG) recordings. The cortical network was modeled after source reconstruction and topology modulations were detected during interictal spikes...
September 9, 2016: IEEE Journal of Biomedical and Health Informatics
https://www.readbyqxmd.com/read/28113670/dynamic-functional-segregation-and-integration-in-human-brain-network-during-complex-tasks
#11
Shen Ren, Junhua Li, Fumihiko Taya, Joshua deSouza, Nitish Thakor, Anastasios Bezerianos
The analysis of the topology and organisation of brain networks is known to greatly benefit from network measures in graph theory. However, to evaluate dynamic changes of brain functional connectivity, more sophisticated quantitative metrics characterising temporal evolution of brain topological features are required. To simplify conversion of time-varying brain connectivity to a static graph representation is straightforward but the procedure loses temporal information that could be critical in understanding the brain functions...
September 9, 2016: IEEE Transactions on Neural Systems and Rehabilitation Engineering
https://www.readbyqxmd.com/read/28112460/from-hippocampus-to-whole-brain-the-role-of-integrative-processing-in-episodic-memory-retrieval
#12
Benjamin R Geib, Matthew L Stanley, Nancy A Dennis, Marty G Woldorff, Roberto Cabeza
Multivariate functional connectivity analyses of neuroimaging data have revealed the importance of complex, distributed interactions between disparate yet interdependent brain regions. Recent work has shown that topological properties of functional brain networks are associated with individual and group differences in cognitive performance, including in episodic memory. After constructing functional whole-brain networks derived from an event-related fMRI study of memory retrieval, we examined differences in functional brain network architecture between forgotten and remembered words...
January 23, 2017: Human Brain Mapping
https://www.readbyqxmd.com/read/28092321/dexmedetomidine-disrupts-the-local-and-global-efficiencies-of-large-scale-brain-networks
#13
Javeria A Hashmi, Marco L Loggia, Sheraz Khan, Lei Gao, Jieun Kim, Vitaly Napadow, Emery N Brown, Oluwaseun Akeju
BACKGROUND: A clear understanding of the neural basis of consciousness is fundamental to research in clinical and basic neuroscience disciplines and anesthesia. Recently, decreased efficiency of information integration was suggested as a core network feature of propofol-induced unconsciousness. However, it is unclear whether this finding can be generalized to dexmedetomidine, which has a different molecular target. METHODS: Dexmedetomidine was administered as a 1-μg/kg bolus over 10 min, followed by a 0...
March 2017: Anesthesiology
https://www.readbyqxmd.com/read/28072380/network-functional-connectivity-and-whole-brain-functional-connectomics-to-investigate-cognitive-decline-in-neurodegenerative-conditions
#14
REVIEW
O Dipasquale, Mara Cercignani
Non-invasive mapping of brain functional connectivity (FC) has played a fundamental role in neuroscience, and numerous scientists have been fascinated by its ability to reveal the brain's intricate morphology and functional properties. In recent years, two different techniques have been developed that are able to explore FC in pathophysiological conditions and to provide simple and non-invasive biomarkers for the detection of disease onset, severity and progression. These techniques are independent component analysis, which allows a network-based functional exploration of the brain, and graph theory, which provides a quantitative characterization of the whole-brain FC...
October 2016: Functional Neurology
https://www.readbyqxmd.com/read/28070001/neuroimaging-biomarkers-predict-brain-structural-connectivity-change-in-a-mouse-model-of-vascular-cognitive-impairment
#15
Philipp Boehm-Sturm, Martina Füchtemeier, Marco Foddis, Susanne Mueller, Rebecca C Trueman, Marietta Zille, Jan Leo Rinnenthal, Theodore Kypraios, Laurence Shaw, Ulrich Dirnagl, Tracy D Farr
BACKGROUND AND PURPOSE: Chronic hypoperfusion in the mouse brain has been suggested to mimic aspects of vascular cognitive impairment, such as white matter damage. Although this model has attracted attention, our group has struggled to generate a reliable cognitive and pathological phenotype. This study aimed to identify neuroimaging biomarkers of brain pathology in aged, more severely hypoperfused mice. METHODS: We used magnetic resonance imaging to characterize brain degeneration in mice hypoperfused by refining the surgical procedure to use the smallest reported diameter microcoils (160 μm)...
February 2017: Stroke; a Journal of Cerebral Circulation
https://www.readbyqxmd.com/read/28066709/alterations-of-white-matter-structural-networks-in-patients-with-non-neuropsychiatric-systemic-lupus-erythematosus-identified-by-probabilistic-tractography-and-connectivity-based-analyses
#16
Man Xu, Xiangliang Tan, Xinyuan Zhang, Yihao Guo, Yingjie Mei, Qianjin Feng, Yikai Xu, Yanqiu Feng
PURPOSE: Systemic lupus erythematosus (SLE) is a chronic inflammatory female-predominant autoimmune disease that can affect the central nervous system and exhibit neuropsychiatric symptoms. In SLE patients without neuropsychiatric symptoms (non-NPSLE), recent diffusion tensor imaging studies showed white matter abnormalities in their brains. The present study investigated the entire brain white matter structural connectivity in non-NPSLE patients by using probabilistic tractography and connectivity-based analyses...
2017: NeuroImage: Clinical
https://www.readbyqxmd.com/read/28065848/viewing-socio-affective-stimuli-increases-connectivity-within-an-extended-default-mode-network
#17
Martin Göttlich, Zheng Ye, Antoni Rodriguez-Fornells, Thomas F Münte, Ulrike M Krämer
Empathy is an essential ability for prosocial behavior. Previous imaging studies identified a number of brain regions implicated in affective and cognitive aspects of empathy. In this study, we investigated the neural correlates of empathy from a network perspective using graph theory and beta-series correlations. Two independent data sets were acquired using the same paradigm that elicited empathic responses to socio-affective stimuli. One data set was used to define the network nodes and modular structure, the other data set was used to investigate the effects of emotional versus neutral stimuli on network connectivity...
January 5, 2017: NeuroImage
https://www.readbyqxmd.com/read/28050344/structural-networks-involved-in-attention-and-executive-functions-in-multiple-sclerosis
#18
Sara Llufriu, Eloy Martinez-Heras, Elisabeth Solana, Nuria Sola-Valls, Maria Sepulveda, Yolanda Blanco, Elena H Martinez-Lapiscina, Magi Andorra, Pablo Villoslada, Alberto Prats-Galino, Albert Saiz
Attention and executive deficits are disabling symptoms in multiple sclerosis (MS) that have been related to disconnection mechanisms. We aimed to investigate changes in structural connectivity in MS and their association with attention and executive performance applying an improved framework that combines high order probabilistic tractography and anatomical exclusion criteria postprocessing. We compared graph theory metrics of structural networks and fractional anisotropy (FA) of white matter (WM) connections or edges between 72 MS subjects and 38 healthy volunteers (HV) and assessed their correlation with cognition...
2017: NeuroImage: Clinical
https://www.readbyqxmd.com/read/28031150/functional-dysconnection-of-the-inferior-frontal-gyrus-in-young-people-with-bipolar-disorder-or-at-genetic-high-risk
#19
Gloria Roberts, Anton Lord, Andrew Frankland, Adam Wright, Phoebe Lau, Florence Levy, Rhoshel K Lenroot, Philip B Mitchell, Michael Breakspear
BACKGROUND: Bipolar disorder (BD) is characterized by a dysregulation of affect and impaired integration of emotion with cognition. These traits are also expressed in probands at high genetic risk of BD. The inferior frontal gyrus (IFG) is a key cortical hub in the circuits of emotion and cognitive control, and it has been frequently associated with BD. Here, we studied resting-state functional connectivity of the left IFG in participants with BD and in those at increased genetic risk...
August 18, 2016: Biological Psychiatry
https://www.readbyqxmd.com/read/28029725/epicenters-of-dynamic-connectivity-in-the-adaptation-of-the-ventral-visual-system
#20
Vesna Prčkovska, Willem Huijbers, Aaron Schultz, Laura Ortiz-Teran, Cleofe Peña-Gomez, Pablo Villoslada, Keith Johnson, Reisa Sperling, Jorge Sepulcre
OBJECTIVES AND DESIGN: Neuronal responses adapt to familiar and repeated sensory stimuli. Enhanced synchrony across wide brain systems has been postulated as a potential mechanism for this adaptation phenomenon. Here, we used recently developed graph theory methods to investigate hidden connectivity features of dynamic synchrony changes during a visual repetition paradigm. Particularly, we focused on strength connectivity changes occurring at local and distant brain neighborhoods. PRINCIPAL OBSERVATIONS: We found that connectivity reorganization in visual modal cortex-such as local suppressed connectivity in primary visual areas and distant suppressed connectivity in fusiform areas-is accompanied by enhanced local and distant connectivity in higher cognitive processing areas in multimodal and association cortex...
December 28, 2016: Human Brain Mapping
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