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graph theory connectivity

Lin Li, Mary Cazzell, Olajide Babawale, Hanli Liu
Atlas-guided diffuse optical tomography (atlas-DOT) is a computational means to image changes in cortical hemodynamic signals during human brain activities. Graph theory analysis (GTA) is a network analysis tool commonly used in functional neuroimaging to study brain networks. Atlas-DOT has not been analyzed with GTA to derive large-scale brain connectivity/networks based on near-infrared spectroscopy (NIRS) measurements. We introduced an automated voxel classification (AVC) method that facilitated the use of GTA with atlas-DOT images by grouping unequal-sized finite element voxels into anatomically meaningful regions of interest within the human brain...
October 2016: Neurophotonics
Michelle N Servaas, Linda Geerligs, Jojanneke A Bastiaansen, Remco J Renken, Jan-Bernard C Marsman, Ilja M Nolte, Johan Ormel, André Aleman, Harriëtte Riese
Neuroticism and genetic variation in the serotonin-transporter (SLC6A4) and catechol-O-methyltransferase (COMT) gene are risk factors for psychopathology. Alterations in the functional integration and segregation of neural circuits have recently been found in individuals scoring higher on neuroticism. The aim of the current study was to investigate how genetic risk factors impact functional network organization and whether genetic risk factors moderate the association between neuroticism and functional network organization...
October 14, 2016: Brain Imaging and Behavior
Bethany Lusch, Pedro D Maia, J Nathan Kutz
Determining the interactions and causal relationships between nodes in an unknown networked dynamical system from measurement data alone is a challenging, contemporary task across the physical, biological, and engineering sciences. Statistical methods, such as the increasingly popular Granger causality, are being broadly applied for data-driven discovery of connectivity in fields from economics to neuroscience. A common version of the algorithm is called pairwise-conditional Granger causality, which we systematically test on data generated from a nonlinear model with known causal network structure...
September 2016: Physical Review. E
Jeffrey R Wozniak, Bryon A Mueller, Sarah N Mattson, Claire D Coles, Julie A Kable, Kenneth L Jones, Christopher J Boys, Kelvin O Lim, Edward P Riley, Elizabeth R Sowell
: Consistent with well-documented structural and microstructural abnormalities in prenatal alcohol exposure (PAE), recent studies suggest that functional connectivity (FC) may also be disrupted. We evaluated whole-brain FC in a large multi-site sample, examined its cognitive correlates, and explored its potential to objectively identify neurodevelopmental abnormality in individuals without definitive dysmorphic features. Included were 75 children with PAE and 68 controls from four sites...
October 12, 2016: Brain Imaging and Behavior
Qingbao Yu, Lei Wu, David A Bridwell, Erik B Erhardt, Yuhui Du, Hao He, Jiayu Chen, Peng Liu, Jing Sui, Godfrey Pearlson, Vince D Calhoun
The topological architecture of brain connectivity has been well-characterized by graph theory based analysis. However, previous studies have primarily built brain graphs based on a single modality of brain imaging data. Here we develop a framework to construct multi-modal brain graphs using concurrent EEG-fMRI data which are simultaneously collected during eyes open (EO) and eyes closed (EC) resting states. FMRI data are decomposed into independent components with associated time courses by group independent component analysis (ICA)...
2016: Frontiers in Human Neuroscience
Johannes Textor, Judith N Mandl, Rob J de Boer
Lymph nodes are meeting points for circulating immune cells. A network of reticular cells that ensheathe a mesh of collagen fibers crisscrosses the tissue in each lymph node. This reticular cell network distributes key molecules and provides a structure for immune cells to move around on. During infections, the network can suffer damage. A new study has now investigated the network's structure in detail, using methods from graph theory. The study showed that the network is remarkably robust to damage: it can still support immune responses even when half of the reticular cells are destroyed...
October 2016: PLoS Biology
Octavian V Lie, Pieter van Mierlo
The visual interpretation of intracranial EEG (iEEG) is the standard method used in complex epilepsy surgery cases to map the regions of seizure onset targeted for resection. Still, visual iEEG analysis is labor-intensive and biased due to interpreter dependency. Multivariate parametric functional connectivity measures using adaptive autoregressive (AR) modeling of the iEEG signals based on the Kalman filter algorithm have been used successfully to localize the electrographic seizure onsets. Due to their high computational cost, these methods have been applied to a limited number of iEEG time-series (<60)...
October 8, 2016: Brain Topography
Weihong Yuan, Artur Meller, Joshua S Shimony, Tiffany Nash, Blaise V Jones, Scott K Holland, Mekibib Altaye, Holly Barnard, Jannel Phillips, Stephanie Powell, Robert C McKinstry, David D Limbrick, Akila Rajagopal, Francesco T Mangano
Neuroimaging research in surgically treated pediatric hydrocephalus patients remains challenging due to the artifact caused by programmable shunt. Our previous study has demonstrated significant alterations in the whole brain white matter structural connectivity based on diffusion tensor imaging (DTI) and graph theoretical analysis in children with hydrocephalus prior to surgery or in surgically treated children without programmable shunts. This study seeks to investigate the impact of brain injury on the topological features in the left hemisphere, contratelateral to the shunt placement, which will avoid the influence of shunt artifacts and makes further group comparisons feasible for children with programmable shunt valves...
2016: NeuroImage: Clinical
John P Hegarty, Bradley J Ferguson, Rachel M Zamzow, Landon J Rohowetz, Jeffrey D Johnson, Shawn E Christ, David Q Beversdorf
The beta-adrenergic antagonist propranolol benefits some social and communication domains affected in autism spectrum disorder (ASD), and these benefits appear to be associated with increased functional connectivity (FC) in the brain during task performance. FC is implicated in ASD, with the majority of studies suggesting long distance hypo-connectivity combined with regionally specific local hyper-connectivity. The objective in the current investigation was to examine the effect of propranolol on FC at rest and determine whether ASD-specific effects exist...
October 6, 2016: Brain Imaging and Behavior
Chien-Hung Huang, Jin-Shuei Ciou, Shun-Tsung Chen, Victor C Kok, Yi Chung, Jeffrey J P Tsai, Nilubon Kurubanjerdjit, Chi-Ying F Huang, Ka-Lok Ng
BACKGROUND: Abnormal proliferation of vascular smooth muscle cells (VSMC) is a major cause of cardiovascular diseases (CVDs). Many studies suggest that vascular injury triggers VSMC dedifferentiation, which results in VSMC changes from a contractile to a synthetic phenotype; however, the underlying molecular mechanisms are still unclear. METHODS: In this study, we examined how VSMC responds under mechanical stress by using time-course microarray data. A three-phase study was proposed to investigate the stress-induced differentially expressed genes (DEGs) in VSMC...
2016: PeerJ
JeYoung Jung, Lauren L Cloutman, Richard J Binney, Matthew A Lambon Ralph
Human higher cognition arises from the main tertiary association cortices including the frontal, temporal and parietal lobes. Many studies have suggested that cortical functions must be shaped or emerge from the pattern of underlying physical (white matter) connectivity. Despite the importance of this hypothesis, there has not been a large-scale analysis of the white-matter connectivity within and between these associative cortices. Thus, we explored the pattern of intra- and inter-lobe white matter connectivity between multiple areas defined in each lobe...
September 2, 2016: Cortex; a Journal Devoted to the Study of the Nervous System and Behavior
Anna E Mechling, Tanzil Arefin, Hsu-Lei Lee, Thomas Bienert, Marco Reisert, Sami Ben Hamida, Emmanuel Darcq, Aliza Ehrlich, Claire Gaveriaux-Ruff, Maxime J Parent, Pedro Rosa-Neto, Jürgen Hennig, Dominik von Elverfeldt, Brigitte Lina Kieffer, Laura-Adela Harsan
Connectome genetics seeks to uncover how genetic factors shape brain functional connectivity; however, the causal impact of a single gene's activity on whole-brain networks remains unknown. We tested whether the sole targeted deletion of the mu opioid receptor gene (Oprm1) alters the brain connectome in living mice. Hypothesis-free analysis of combined resting-state fMRI diffusion tractography showed pronounced modifications of functional connectivity with only minor changes in structural pathways. Fine-grained resting-state fMRI mapping, graph theory, and intergroup comparison revealed Oprm1-specific hubs and captured a unique Oprm1 gene-to-network signature...
October 11, 2016: Proceedings of the National Academy of Sciences of the United States of America
Laura Serra, Matteo Mancini, Mara Cercignani, Carlotta Di Domenico, Barbara Spanò, Giovanni Giulietti, Giacomo Koch, Camillo Marra, Marco Bozzali
Cognitive reserve (CR) is known to modulate the clinical features of Alzheimer's disease (AD). This concept may be critical for the development of non-pharmacological interventions able to slow down patients' cognitive decline in the absence of disease-modifying treatments. We aimed at identifying the neurobiological substrates of CR (i.e., neural reserve) over the transition between normal aging and AD, by assessing the underlying brain networks and their topological properties. A cohort of 154 participants (n = 68 with AD, n = 61 with amnestic mild cognitive impairment (aMCI), and 25 healthy subjects) underwent resting-state functional MRI and neuropsychological testing...
September 21, 2016: Journal of Alzheimer's Disease: JAD
Abdol Aziz O Ould Ismail, Ghoncheh Amouzandeh, Samuel C Grant
Diffusion tensor imaging (DTI) provides a unique contrast based on the restricted directionality of water movement in an anisotropic environment. As such, DTI-based tractography can be used to characterize and quantify the structural connectivity within neural tissue. Here, DTI-based connectivity within isolated abdominal ganglia of Aplysia californica (ABG) is analyzed using network theory. In addition to quantifying the regional physical proprieties of the fractional anisotropy and apparent diffusion coefficient, DTI tractography was used to probe inner-connections of local communities, yielding unweighted, undirected graphs that represent community structures...
September 19, 2016: Neuroscience
Peifen Chang, Xin Li, Chao Ma, Sisi Zhang, Zhen Liu, Kewei Chen, Lin Ai, Jingling Chang, Zhanjun Zhang
Polymorphisms of the apolipoprotein E (APOE) promoter rs405509 are related to Alzheimer's disease (AD). The T/T allele of rs405509 decreases the transcription of the APOE gene and leads to impairments in a specific brain structural network in aged individuals; thus, it is an important risk factor for AD. However, it remains unknown whether rs405509 affects white matter networks during aging. Here, we investigated the effect of the rs405509 genotype (T/T versus G-allele) on age-related brain white matter structural networks via construction of the graph theory-based structural connectome using diffusion MRI data in a large cohort...
September 13, 2016: Journal of Alzheimer's Disease: JAD
Harm Jan van der Horn, Jelmer G Kok, Myrthe Elisabeth de Koning, Myrthe Elisabeth Scheenen, Alexander Leemans, Jacoba M Spikman, Joukje van der Naalt
In this study, structural connectivity after mild traumatic brain injury (mTBI) was examined from a network perspective, with a particular focus on post-traumatic complaints. Fifty-three patients with and without self-reported complaints at two weeks after uncomplicated mTBI were included in addition to 20 matched healthy controls. Diffusion weighted imaging was performed at four weeks post-injury, and neuropsychological tests measuring processing speed and verbal memory were administered at three months post-injury to determine cognitive outcome...
September 15, 2016: Journal of Neurotrauma
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
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
Geon Ha Kim, Kiho Im, Hunki Kwon, Sang Won Seo, Byoung Seok Ye, Hanna Cho, Young Noh, Jong Min Lee, Sung Tae Kim, Sang Eon Park, Hojeong Kim, Jung Won Hwang, Sue J Kang, Jee Hyang Jeong, Duk L Na
The purpose of this study was to demonstrate the potential alterations in structural network properties related to physical activity (PA) in healthy elderly. We recruited 76 elderly individuals with normal cognition from Samsung Medical Center in Seoul, Korea. All participants underwent the Cambridge Neuropsychological Test Automated Battery and 3.0T brain magnetic resonance imaging (MRI). Participants were subdivided into quartiles according to the International Physical Activity Questionnaire scores, which represents the amount of PA...
2016: Frontiers in Aging Neuroscience
Zhe Charles Zhou, Andrew P Salzwedel, Susanne Radtke-Schuller, Yuhui Li, Kristin K Sellers, John H Gilmore, Yen-Yu Ian Shih, Flavio Fröhlich, Wei Gao
Resting state functional magnetic resonance imaging (rsfMRI) has emerged as a versatile tool for non-invasive measurement of functional connectivity patterns in the brain. RsfMRI brain dynamics in rodents, non-human primates, and humans share similar properties; however, little is known about the resting state functional connectivity patterns in the ferret, an animal model with high potential for developmental and cognitive translational study. To address this knowledge-gap, we performed rsfMRI on anesthetized ferrets using a 9...
September 2, 2016: NeuroImage
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