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dynamic brain connectivity

P A Robinson
Brain connectivity and structure-function relationships are analyzed from a physical perspective in place of common graph-theoretic and statistical approaches that overwhelmingly ignore the brain's physical structure and geometry. Field theory is used to define connectivity tensors in terms of bare and dressed propagators, and discretized representations are implemented that respect the physical nature and dimensionality of the quantities involved, retain the correct continuum limit, and enable diagrammatic analysis...
January 2019: Physical Review. E
Géza Ódor
I provide numerical evidence for the robustness of the Griffiths phase (GP) reported previously in dynamical threshold model simulations on a large human brain network with N=836733 connected nodes. The model, with equalized network sensitivity, is extended in two ways: introduction of refractory states or by randomized time-dependent thresholds. The nonuniversal power-law dynamics in an extended control parameter region survives these modifications for a short refractory state and weak disorder. In case of temporal disorder the GP shrinks and for stronger heterogeneity disappears, leaving behind a mean-field type of critical transition...
January 2019: Physical Review. E
Anya Topiwala, Sana Suri, Charlotte Allan, Vyara Valkanova, Nicola Filippini, Claire E Sexton, Verena Heise, Enikő Zsoldos, Abda Mahmood, Archana Singh-Manoux, Clare E Mackay, Mika Kivimäki, Klaus P Ebmeier
BACKGROUND: There is significant heterogeneity in the clinical expression of structural brain abnormalities, including Alzheimer's disease biomarkers. Some individuals preserve their memory despite the presence of risk factors or pathological brain changes, indicating resilience. We aimed to test whether resilient individuals could be distinguished from those who develop cognitive impairment, using sociodemographic variables and neuroimaging. METHODS: We included 550 older adults participating in the Whitehall II study with longitudinal data, cognitive test results, and multi-modal MRI...
2019: PloS One
Guo-Chun Yang, Zheng-Han Li, Hai-Yan Wu, Xun Liu
As a high-level cognitive function of actively regulating human behaviors, cognitive control plays essential roles in conflict processing, working memory, decision making and so on. However, it is still under debate whether a universal cognitive control mechanism underlies the processing of various conflicts. Many existing theories tend to hold that cognitive control is domain-general; however, this view has been challenged by recent empirical studies. The logics of studying generality/specificity mainly include transferability, parallel comparison, correlation and resources competition, etc...
February 25, 2019: Sheng Li Xue Bao: [Acta Physiologica Sinica]
Patrícia Klobušiaková, Radek Mareček, Jan Fousek, Eva Výtvarová, Irena Rektorová
BACKGROUND: Cognitive impairment in Parkinson's disease (PD) is associated with altered connectivity of the resting state networks (RSNs). Longitudinal studies in well cognitively characterized PD subgroups are missing. OBJECTIVES: To assess changes of the whole-brain connectivity and between-network connectivity (BNC) of large-scale functional networks related to cognition in well characterized PD patients using a longitudinal study design and various analytical methods...
2019: Journal of Alzheimer's Disease: JAD
A Demertzi, E Tagliazucchi, S Dehaene, G Deco, P Barttfeld, F Raimondo, C Martial, D Fernández-Espejo, B Rohaut, H U Voss, N D Schiff, A M Owen, S Laureys, L Naccache, J D Sitt
Adopting the framework of brain dynamics as a cornerstone of human consciousness, we determined whether dynamic signal coordination provides specific and generalizable patterns pertaining to conscious and unconscious states after brain damage. A dynamic pattern of coordinated and anticoordinated functional magnetic resonance imaging signals characterized healthy individuals and minimally conscious patients. The brains of unresponsive patients showed primarily a pattern of low interareal phase coherence mainly mediated by structural connectivity, and had smaller chances to transition between patterns...
February 2019: Science Advances
Vatika Harlalka, Raju S Bapi, P K Vinod, Dipanjan Roy
Resting-state functional connectivity (FC) analyses have shown atypical connectivity in autism spectrum disorder (ASD) as compared to typically developing (TD). However, this view emerges from investigating static FC overlooking the whole brain transient connectivity patterns. In our study, we investigated how age and disease influence the dynamic changes in functional connectivity of TD and ASD. We used resting-state functional magnetic resonance imaging (rs-fMRI) data stratified into three cohorts: children (7-11 years), adolescents (12-17 years), and adults (18+ years) for the analysis...
2019: Frontiers in Human Neuroscience
Xiao Wang, Wei Liao, Shaoqiang Han, Jiao Li, Yan Zhang, Jingping Zhao, Huafu Chen
Schizophrenia (SCZ) is a severe neuropsychiatric disease associated with dysfunction of brain regions and networks. Recent, functional magnetic resonance imaging (fMRI) studies have determined that the global signal (GS) is an important source of the local neuronal activity. However, the dynamics of this effect in SCZ remains unknown. To address this issue, 39 drug-naive patients with early-onset schizophrenia (EOS) and 31 age-, gender- and education-matched healthy controls underwent resting-state fMRI scans...
February 14, 2019: Schizophrenia Research
James C Sears, Woong Jae Choi, Kendal Broadie
Recent work shows Fragile X Mental Retardation Protein (FMRP) drives the translation of very large proteins (>2000 aa) mediating neurodevelopment. Loss of function results in Fragile X syndrome (FXS), the leading heritable cause of intellectual disability (ID) and autism spectrum disorder (ASD). Using the Drosophila FXS disease model, we discover FMRP positively regulates the translation of the very large A-Kinase Anchor Protein (AKAP) Rugose (>3000 aa), homolog of ASD-associated human Neurobeachin (NBEA)...
February 13, 2019: Neurobiology of Disease
Adela Desowska, Duncan L Turner
Recovery from a stroke is a dynamic time-dependent process, in which the central nervous system reorganises to accommodate for the impact of the injury. The purpose of this paper is to review recent longitudinal studies of changes in brain connectivity after stroke. A systematic review of research papers reporting functional or effective connectivity at two or more time points in stroke patients was conducted. Stroke leads to an early reduction of connectivity in the motor network. With recovery time, the connectivity increases and can reach the same levels as in healthy participants...
February 15, 2019: Reviews in the Neurosciences
Hsiang-Yuan Lin, Alistair Perry, Luca Cocchi, James A Roberts, Wen-Yih Isaac Tseng, Michael Breakspear, Susan Shur-Fen Gau
Structural neuroimaging studies suggest altered brain maturation in autism spectrum disorder (ASD) compared with typically developing controls (TDC). However, the prognostic value of whole-brain structural connectivity analysis in ASD has not been established. Diffusion magnetic imaging data were acquired in 27 high-functioning young ASD participants (2 females) and 29 age-matched TDC (12 females; age 8-18 years) at baseline and again following 3-7 years. Whole-brain structural connectomes were reconstructed from these data and analyzed using a longitudinal statistical model...
February 12, 2019: Translational Psychiatry
Kyle Joseph Edmunds, Hannes Petersen, Mahmoud Hassan, Sahar Yassine, Antonella Olivieri, Fabio Barollo, Rún Friðriksdóttir, Patricia Edmunds, Magnús Gíslason, Antonio Fratini, Paolo Gargiulo
Maintaining upright posture is a complex task governed by the integration of afferent sensorimotor and visual information with compensatory neuromuscular reactions. The objective of the present work was to characterize the visual dependency and functional dynamics of cortical activation during postural control. 
 Approach. Proprioceptic vibratory stimulation of calf muscles at 85 Hz was performed to evoke postural perturbation in open-eye (OE) and closed-eye (CE) experimental trials, with pseudorandom binary stimulation phases divided into four segments of 16 stimuli...
February 12, 2019: Journal of Neural Engineering
Anzar Abbas, Michaël Belloy, Amrit Kashyap, Jacob Billings, Maysam Nezafati, Eric Schumacher, Shella Keilholz
Functional connectivity is widely used to study the coordination of activity between brain regions over time. Functional connectivity in the default mode and task positive networks is particularly important for normal brain function. However, the processes that give rise to functional connectivity in the brain are not fully understood. It has been postulated that low-frequency neural activity plays a key role in establishing the functional architecture of the brain. Quasi-periodic patterns (QPPs) are a reliably observable form of low-frequency neural activity that involve the default mode and task positive networks...
February 9, 2019: NeuroImage
Heather Shappell, Brian S Caffo, James J Pekar, Martin A Lindquist
The study of functional brain networks has grown rapidly over the past decade. While most functional connectivity (FC) analyses estimate one static network structure for the entire length of the functional magnetic resonance imaging (fMRI) time series, recently there has been increased interest in studying time-varying changes in FC. Hidden Markov models (HMMs) have proven to be a useful modeling approach for discovering repeating graphs of interacting brain regions (brain states). However, a limitation lies in HMMs assuming that the sojourn time, the number of consecutive time points in a state, is geometrically distributed...
February 9, 2019: NeuroImage
Kelly Shen, Alexandros Goulas, David S Grayson, John Eusebio, Joseph S Gati, Ravi S Menon, Anthony R McIntosh, Stefan Everling
Reconstructing the anatomical pathways of the brain to study the human connectome has become an important endeavour for understanding brain function and dynamics. Reconstruction of the cortico-cortical connectivity matrix in vivo often relies on noninvasive diffusion-weighted imaging (DWI) techniques but the extent to which they can accurately represent the topological characteristics of structural connectomes remains unknown. We addressed this question by constructing connectomes using DWI data collected from macaque monkeys in vivo and with data from published invasive tracer studies...
February 7, 2019: NeuroImage
Yuji Kawai, Jihoon Park, Minoru Asada
Cortical neural connectivity has been shown to exhibit a small-world (SW) network topology. However, the role of the topology in neural information processing remains unclear. In this study, we investigated the learning performance of an echo state network (ESN) that includes the SW topology as a reservoir. To elucidate the potential of the SW topology, we limited the numbers of the input and output nodes in the ESN and spatially segregated the output nodes from the input nodes. We tested the ESNs in two benchmark tasks: memory capacity and nonlinear time-series prediction...
January 16, 2019: Neural Networks: the Official Journal of the International Neural Network Society
Luis R Peraza, Antonio Díaz-Parra, Oliver Kennion, David Moratal, John-Paul Taylor, Marcus Kaiser, Roman Bauer
Introduction: The pathophysiological process of Alzheimer's disease is thought to begin years before clinical decline, with evidence suggesting prion-like spreading processes of neurofibrillary tangles and amyloid plaques. Methods: Using diffusion magnetic resonance imaging data from the Alzheimer's Disease Neuroimaging Initiative database, we first identified relevant features for dementia diagnosis. We then created dynamic models with the Nathan Kline Institute-Rockland Sample database to estimate the earliest detectable stage associated with dementia in the simulated disease progression...
December 2019: Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring
Fatemeh Mokhtari, Milad I Akhlaghi, Sean L Simpson, Guorong Wu, Paul J Laurienti
The sliding window correlation (SWC) analysis is a straightforward and common approach for evaluating dynamic functional connectivity. Despite the fact that sliding window analyses have been long used, there are still considerable technical issues associated with the approach. A great effort has recently been dedicated to investigate the window setting effects on dynamic connectivity estimation. In this direction, tapered windows have been proposed to alleviate the effect of sudden changes associated with the edges of rectangular windows...
February 2, 2019: NeuroImage
Daniel Aguilar-Velázquez, Lev Guzmán-Vargas
In recent years, diverse studies have reported that different brain regions, which are internally densely connected, are also highly connected to each other. This configuration seems to play a key role in integrating and interchanging information between brain areas. Also, changes in the rich-club connectivity and the shift from inhibitory to excitatory behavior of hub neurons have been associated with several diseases. However, there is not a clear understanding about the role of the proportion of inhibitory/excitatory hub neurons, the dynamic consequences of rich-club disconnection, and hub inhibitory/excitatory shifts...
February 4, 2019: Scientific Reports
Evan L Nichols, Cody J Smith
Sensory axons must traverse a spinal cord glia limitans to connect the brain with the periphery. The fundamental mechanism of how these axons enter the spinal cord is still debatable; both Ramon y Cajal's battering ram hypothesis and a boundary cap model have been proposed. To distinguish between these hypotheses, we visualized the entry of pioneer axons into the dorsal root entry zone (DREZ) with time-lapse imaging in zebrafish. Here, we identify that DRG pioneer axons enter the DREZ before the arrival of neural crest cells at the DREZ...
February 4, 2019: Nature Communications
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