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Brain Connectivity

Enrico Amico, Olivier Bodart, Mario Rosanova, Olivia Gosseries, Lizette Heine, Pieter Van Mierlo, Charlotte Martial, Marcello Massimini, Daniele Marinazzo, Steven Laureys
Transcranial magnetic stimulation (TMS) in combination with neuroimaging techniques allows to measure the effects of a direct perturbation of the brain. When coupled to high density electroencephalography (TMS/hd-EEG), TMS pulses revealed electrophysiological signatures of different cortical modules in health and disease. However, the neural underpinnings of these signatures remain unclear. Here, by applying multimodal analyses of cortical response to TMS recordings and diffusion magnetic resonance imaging (dMRI) tractography, we investigated the relationship between functional and structural features of different cortical modules in a cohort of awake healthy volunteers...
January 16, 2017: Brain Connectivity
Rocco Marchitelli, Olivier Collignon, Jorge Jovicich
Head-motion is a known challenge in resting-state fMRI studies for biasing functional connectivity among distinct anatomical regions. These persist even with small motion, limiting comparisons of groups with different head-motion characteristics. This motivates an interest in the optimization of acquisition and correction strategies to minimize motion sensitivity. In this test-retest study of healthy young volunteers (N=24), we investigate the effects of slice-order acquisitions (sequential or interleaved) and head-motion correction methods (volume- or slice-based) on the test-retest reproducibility of intrinsic connectivity of the default mode network (DMN)...
January 13, 2017: Brain Connectivity
Laurie M Baker, Sarah Cooley, Ryan P Cabeen, David H Laidlaw, John A Joska, Jacqueline Hoare, Dan J Stein, Jodi Heaps-Woodruff, Lauren E Salminen, Robert H Paul
Infection with human immunodeficiency virus (HIV) is associated with neuroimaging alterations. However, little is known about the topological organization of whole-brain networks and the corresponding association with cognition. As such, we examined structural whole-brain white matter connectivity patterns and cognitive performance in 29 HIV+ young adults (mean age = 25.9) with limited or no HIV treatment history. HIV+ participants and demographically similar HIV- controls (n = 16) residing in South Africa underwent magnetic resonance imaging (MRI) and neuropsychological testing...
January 11, 2017: Brain Connectivity
Lauren E Mak, Luciano Minuzzi, Glenda MacQueen, Geoffrey Hall, Sidney H Kennedy, Roumen Milev
When the brain is not engaged in goal-directed activities and at rest, there are still measureable patterns of activity. One resting-state network, the default mode network (DMN) is responsible for a self-referential introspective state. There are many factors that influence normal changes in brain activity. The purpose of this review is to summarize differences in DMN functional connectivity in healthy individuals by age, sex, cognitive function, and analysis type to characterize what is "normal." Studies were systematically selected up to August 2016...
January 9, 2017: Brain Connectivity
Jingyuan E Chen, Hesamoddin Jahanian, Gary H Glover
Recently, emerging studies have demonstrated the existence of brain resting-state spontaneous activity at frequencies higher than the conventional 0.1 Hz. A few groups utilizing accelerated acquisitions have reported persisting signals beyond 1 Hz, which seems too high to be accommodated by the sluggish hemodynamic process underpinning blood oxygen level-dependent contrasts (the upper limit of the canonical model is ∼0.3 Hz). It is thus questionable whether the observed high-frequency (HF) functional connectivity originates from alternative mechanisms (e...
January 5, 2017: Brain Connectivity
Chunxia Li, Xiaodong Zhang
Isoflurane is an inhalational anesthetic widely used in medical procedures or biomedical researches. The duration of anesthesia administration varies from minutes to hours. It is known isoflurane has dose-dependent effects on brain functionality and physiology and long-duration anesthesia administration could cause neurocognitive decline in animals and humans. However, the duration effect of isoflurane on the brain physiology and functionality still remains poorly understood. In the present study, cerebral blood flow (CBF) and functional connectivity of adult rhesus monkeys (maintained with 1% isoflurane for four hours) was examined using MRI...
December 28, 2016: Brain Connectivity
Jared Rowland, Jennifer Stapleton-Kotloski, Greg Alberto, Justin Rawley, Robert Kotloski, Katherine Taber, Dwayne Godwin
The aim of the current study was to evaluate alterations in whole-brain resting-state networks associated with posttraumatic stress disorder (PTSD) and mild traumatic brain injury (mTBI). Networks were constructed from locations of peak statistical power on an individual basis from magnetoencephalography (MEG) source series data by applying the weighted phase lag index and surrogate data thresholding procedures. Networks representing activity in the alpha bandwidth as well as wide band activity (DC-80 Hz) were created...
December 23, 2016: Brain Connectivity
Yuncong Ma, Christina Hamilton, Nanyin Zhang
Brain functional connectivity undergoes dynamic changes from the awake to unconscious states. However, how the dynamics of functional connectivity patterns are linked to consciousness at the behavioral level remains elusive. In this study, we acquired resting-state functional magnetic resonance imaging data during wakefulness and graded levels of consciousness in rats. Data were analyzed using a dynamic approach combining the sliding window method and k-means clustering. Our results demonstrate that whole-brain networks contained several quasi-stable patterns that dynamically recurred from the awake state into anesthetized states...
December 15, 2016: Brain Connectivity
Anja Baenninger, Vanessa A Palzes, Brian J Roach, Daniel H Mathalon, Judith Ford, Thomas Koenig
Common-phase synchronization of neuronal oscillations is a mechanism by which distributed brain regions can be integrated into transiently stable networks. Based on the hypothesis that schizophrenia is characterized by deficits in functional integration within neuronal networks, this study aimed to explore whether psychotic patients exhibit differences in brain regions involved in integrative mechanisms. We report an EEG-informed fMRI analysis of eyes-open resting state data collected from patients and healthy controls at two study sites...
November 29, 2016: Brain Connectivity
William Hedley Thompson, Peter Fransson
Assessment of dynamic functional brain connectivity based on functional magnetic resonance imaging (fMRI) data is an increasingly popular strategy to investigate temporal dynamics of the brain's large-scale network architecture. Current practice when deriving connectivity estimates over time is to use the Fisher transformation, which aims to stabilize the variance of correlation values that fluctuate around varying true correlation values. It is, however, unclear how well the stabilization of signal variance performed by the Fisher transformation works for each connectivity time series, when the true correlation is assumed to be fluctuating...
December 2016: Brain Connectivity
Sean R McWhinney, Antoine Tremblay, Thérèse M Chevalier, Vanessa K Lim, Aaron J Newman
Healthy aging has been associated with a global reduction in white matter integrity, which is thought to reflect cognitive decline. The present study aimed to investigate this reduction over a broad range of the life span, using diffusion tensor imaging analyzed with conditional inference random forest modeling (CForest). This approach is sensitive to subtle and potentially nonlinear effects over the age continuum and was used to characterize the progression of decline in greater detail than has been possible in the past...
December 2016: Brain Connectivity
Ariel Haimovici, Pablo Balenzuela, Enzo Tagliazucchi
Synchronization of brain activity fluctuations is believed to represent communication between spatially distant neural processes. These interareal functional interactions develop in the background of a complex network of axonal connections linking cortical and subcortical neurons, termed the human "structural connectome." Theoretical considerations and experimental evidence support the view that the human brain can be modeled as a system operating at a critical point between ordered (subcritical) and disordered (supercritical) phases...
December 2016: Brain Connectivity
Bhim M Adhikari, Martin Norgaard, Kristen M Quinn, Jenine Ampudia, Justin Squirek, Mukesh Dhamala
Musical improvisation offers an excellent experimental paradigm for the study of real-time human creativity. It involves moment-to-moment decision-making, monitoring of one's performance, and utilizing external feedback to spontaneously create new melodies or variations on a melody. Recent neuroimaging studies have begun to study the brain activity during musical improvisation, aiming to unlock the mystery of human creativity. What brain resources come together and how these are utilized during musical improvisation are not well understood...
December 2016: Brain Connectivity
Keith M Vogt, Christopher J Becker, Ajay D Wasan, James W Ibinson
The objective in this study was to directly compare MRI-based functional connectivity between conditions of rest and painful electrical nerve stimulation for key regions involved in pain processing: the anterior and posterior insula and the anterior cingulate cortex. Electric nerve stimulation, rated 7/10 for pain, was delivered to the right index finger of 14 healthy pain-free adult volunteers in four 30-sec blocks and continuously for 2 min. Functional connectivity maps obtained at rest and during both pain tasks were compared using seed time courses from the left anterior and posterior insula and anterior cingulate...
December 2016: Brain Connectivity
Madelon Pijnenburg, S M Hadi Hosseini, Simon Brumagne, Lotte Janssens, Nina Goossens, Karen Caeyenberghs
Individuals with nonspecific low back pain (NSLBP) show an impaired sensorimotor control. They need significantly more time to perform five consecutive sit-to-stand-to-sit (STSTS) movements compared with healthy controls. Optimal sensorimotor control depends on the coactivation of many brain regions, which have to operate as a coordinated network to achieve correct motor output. Therefore, the examination of brain connectivity from a network perspective is crucial for understanding the factors that drive sensorimotor control...
December 2016: Brain Connectivity
Sarah Kann, Sheng Zhang, Peter Manza, Hoi-Chung Leung, Chiang-Shan R Li
Resting-state functional connectivity (rsFC) is widely used to examine cerebral functional organization. The imaging literature has described lateralization of insula activations during cognitive and affective processing. Evidence appears to support a role of the right-hemispheric insula in attentional orientation to salient stimulus, interoception, and physiological arousal, and a role of the left-hemispheric insula in cognitive and affective control, as well as perspective taking. In this study, in a large data set of healthy adults, we examined lateralization of the rsFC of the anterior insula (AI) by computing a laterality index (LI) of connectivity with 54 regions from the Automated Anatomic Labeling atlas...
November 2016: Brain Connectivity
Gregory C Burgess, Sridhar Kandala, Dan Nolan, Timothy O Laumann, Jonathan D Power, Babatunde Adeyemo, Michael P Harms, Steven E Petersen, Deanna M Barch
Like all resting-state functional connectivity data, the data from the Human Connectome Project (HCP) are adversely affected by structured noise artifacts arising from head motion and physiological processes. Functional connectivity estimates (Pearson's correlation coefficients) were inflated for high-motion time points and for high-motion participants. This inflation occurred across the brain, suggesting the presence of globally distributed artifacts. The degree of inflation was further increased for connections between nearby regions compared with distant regions, suggesting the presence of distance-dependent spatially specific artifacts...
November 2016: Brain Connectivity
Lauren E Libero, Wesley K Burge, Hrishikesh D Deshpande, Franco Pestilli, Rajesh K Kana
Autism spectrum disorder (ASD) is a neurodevelopmental disorder found to have widespread alterations in the function and synchrony of brain regions. These differences may underlie alterations in microstructural organization, such as in white matter pathways. To investigate the diffusion of major white matter tracts, the current study examined multiple indices of white matter diffusion in 42 children and adults with ASD and 44 typically developing (TD) age- and IQ-matched peers using diffusion tensor imaging...
November 2016: Brain Connectivity
Chao Zhang, Nathan D Cahill, Mohammad R Arbabshirani, Tonya White, Stefi A Baum, Andrew M Michael
Functional connectivity (FC) in resting-state functional magnetic resonance imaging (rs-fMRI) is widely used to find coactivating regions in the human brain. Despite its widespread use, the effects of sex and age on resting FC are not well characterized, especially during early adulthood. Here we apply regression and graph theoretical analyses to explore the effects of sex and age on FC between the 116 AAL atlas parcellations (a total of 6670 FC measures). rs-fMRI data of 494 healthy subjects (203 males and 291 females; age range: 22-36 years) from the Human Connectome Project were analyzed...
November 2016: Brain Connectivity
Syed Hamza Waheed, Saeedeh Mirbagheri, Shruti Agarwal, Arash Kamali, Noushin Yahyavi-Firouz-Abadi, Ammar Chaudhry, Michael DiGianvittorio, Sachin K Gujar, Jay J Pillai, Haris I Sair
There has been a rapid increase in resting-state functional magnetic resonance imaging (rs-fMRI) literature in the past few years. We aim to highlight the variability in the current reporting practices of rs-fMRI acquisition and preprocessing parameters. The PubMed database was searched for the selection of appropriate articles in the rs-fMRI literature and the most recent 100 articles were selected based on our criteria. These articles were evaluated based on a checklist for reporting of certain preprocessing steps...
November 2016: Brain Connectivity
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