Download or read book Spatiotemporal Dynamics of Functional Brain Networks in Autism Spectrum Disorder written by Lisa Elena Mash and published by . This book was released on 2021 with total page 143 pages. Available in PDF, EPUB and Kindle. Book excerpt: Autism spectrum disorder (ASD) is a behaviorally diagnosed neurodevelopmental condition that is associated with atypical functional connectivity (FC). However, no consistent biomarkers have been identified. Most studies to date have focused on static FC, and relatively little is known about time-varying properties of FC. This three-paper dissertation aimed to better characterize brain networks in ASD by evaluating: 1) transient connectivity states, 2) BOLD lag structure, and 3) associations between hemodynamic and electrophysiological measures of brain function. Study 1 (Mash et al., 2019) used sliding window analysis to examine FC variability and describe transient connectivity in children and adolescents (ages 6-18) with ASD (n=62) and their typically developing (TD) peers (n=57). Across all regions, the ASD group showed FC overconnectivity and hypervariability, on average. Distinct patterns of FC group differences were found in two transient states, but not in static FC analyses. Study 2 (Mash, et al., under review) explored resting-state and task-related BOLD lag structure in adolescents and young adults (ages 12-21) with ASD (n=28) and typical development (n=22). Lag patterns did not significantly differ between groups, with common 'early' and 'late' regions emerging in both groups. However, lag structure was associated with both task condition and vascular supply, suggesting a combination of neural and vascular contributions to BOLD latency. Study 3 (Mash et al., 2020) characterized relationships between separately acquired resting-state fMRI and EEG activity in a sample of children and adolescents (ages 6-18) with ASD and typical development (EEG-only: n=36 per group; fMRI-only: n=66 ASD, 57 TD; EEG-fMRI: n=17 per group). Reduced EEG alpha power, increased BOLD activity in right temporal regions, and widespread thalamocortical BOLD overconnectivity were observed in the ASD group. Multilevel modeling (with brain regions nested within individuals) revealed mostly positive relationships between EEG alpha power and regional BOLD activity in typical development, which were not observed in ASD. Overall, findings suggest that in comparison to conventional static FC studies, dynamic and multimodal analyses reveal more complex FC and activity patterns that may distinguish ASD from typical development.

Download or read book Brain Connectivity in Autism written by Rajesh K. Kana and published by Frontiers E-books. This book was released on 2014-09-23 with total page 265 pages. Available in PDF, EPUB and Kindle. Book excerpt: The brain's ability to process information crucially relies on connectivity. Understanding how the brain processes complex information and how such abilities are disrupted in individuals with neuropsychological disorders will require an improved understanding of brain connectivity. Autism is an intriguingly complex neurodevelopmental disorder with multidimensional symptoms and cognitive characteristics. A biological origin for autism spectrum disorders (ASD) had been proposed even in the earliest published accounts (Kanner, 1943; Asperger, 1944). Despite decades of research, a focal neurobiological marker for autism has been elusive. Nevertheless, disruptions in interregional and functional and anatomical connectivity have been a hallmark of neural functioning in ASD. Theoretical accounts of connectivity perceive ASD as a cognitive and neurobiological disorder associated with altered functioning of integrative circuitry. Neuroimaging studies have reported disruptions in functional connectivity (synchronization of activated brain areas) during cognitive tasks and during task-free resting states. While these insights are valuable, they do not address the time-lagged causality and directionality of such correlations. Despite the general promise of the connectivity account of ASD, inconsistencies and methodological differences among studies call for more thorough investigations. A comprehensive neurological account of ASD should incorporate functional, effective, and anatomical connectivity measures and test the diagnostic utility of such measures. In addition, questions pertaining to how cognitive and behavioral intervention can target connection abnormalities in ASD should be addressed. This research topic of the Frontiers in Human Neuroscience addresses “Brain Connectivity in Autism” primarily from cognitive neuroscience and neuroimaging perspectives.

Download or read book Quantifying Brain Network Abnormalities in Children with Autism Spectrum Disorders written by and published by . This book was released on 2018 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: There is evidence of abnormal organization of functional brain networks in Autism spectrum disorders (ASDs); however, findings have been mixed, with reports of both increased and decreased functional connectivity (FC) between and within networks. The present study sought to investigate if children and adolescents with ASDs have increased network FC variability and atypical network segregation and integration, compared to TD peers. Archival functional and anatomical magnetic resonance imaging data was utilized from 91 children and adolescents with ASDs and 71 age-matched TD controls. To capture a broad range of functional domains, six neurotypical networks were selected: default mode network (DMN), central executive network (CEN), salience network (SN), motor network (MOT), visual network (VIN), and mirror neuron system (MNS). Within-network (WN) and outside-network (ON) masks were then created. Seed-based whole-brain functional connectivity analyses were conducted for each network node; the resulting correlations were Fisher r-to-z transformed. An index of network segregation and integration (NSI) was calculated for each participant and WN, ON, and NSI were compared between groups. Additionally, inter-subject spatial similarity correlations were performed both within and between groups, to assess network spatial variability. Group comparisons of WN, ON, and NSI yielded one significant difference: CEN WN connectivity was significantly greater in the ASD group. Step one of the spatial similarity analyses revealed that within group similarity was comparable between the ASD and TD groups for all comparisons except DMN ON, which was significantly decreased in the ASD group. Step two demonstrated that participants in the ASD group were significantly less similar to TD participants for DMN ON, SN ON, MOT ON, and MNS ON connectivity. The final step of the analysis demonstrated that ASD participants were, on average, more spatially similar to other ASD participants than to TD participants. The results indicated that the pattern of spatial connectivity observed within the ASD group was distinct but comparable to the pattern of spatial connectivity observed in the TD group and it was not influenced by differences in strength of network connectivity, suggesting that spatial similarity in the ASD group can be attributed to abnormal network integration and segregation.

Download or read book Altered Structure function Relationships in Children Born Preterm and in Autism Spectrum Disorder written by Adonay Nunes Sastre and published by . This book was released on 2020 with total page 175 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sensation, perception, cognition and behavior depend on complex neural processes carried by the coordinated function of brain structures. This coordination is achieved through oscillatory activity and synchronization, and the main pathways can be captured with resting-state activity. Structural alterations might affect the functional coordination with other brain structures, and a structure-function approach can provide a better understanding of the underlying neural mechanism that characterizes human populations. This thesis will study altered structure-function relationships in Autism Spectrum Disorder and in children born preterm at school age. Functional activity is assessed with MEG or fMRI resting-state data and structural characteristics with MRI. Both populations present brain oscillatory and structural alterations related to the thalamic-cortical system. Recent evidence indicates that the development of brain networks connectivity is altered in ASD and in very preterm born children. Evidence remains scant, however, regarding the relationship between atypical brain network connectivity and altered structure-function relationships in these groups. In ASD, there is contradictory evidence on the nature of such alterations with some studies suggesting increased or decreased functional connectivity involving particular structural areas. In very preterm children, evidence regarding the overall nature of structure-function network alterations remains scarce. Both populations present structural alterations and atypical oscillatory activity, and this research will investigate how structure-function relationships in brain networks are altered in ASD and in very preterm children and their association with developmental difficulties. Specifically, in ASD it will be assessed the functional brain networks spatial maps variability and atypical structural developmental trajectories of cortical thickness, and in preterm, atypical oscillatory activity and synchrony, and altered thalamic structural measures.

Download or read book Pediatric Brain Stimulation written by Adam Kirton and published by Academic Press. This book was released on 2016-05-04 with total page 504 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pediatric Brain Stimulation: Mapping and Modulating the Developing Brain presents the latest on this rapidly expanding field that has seen an exponential growth in publications over the past 10 years. Non-invasive modalities like TMS can painlessly map and measure complex neurophysiology in real patients. Neuromodulatory applications like rTMS and tDCS carry increasingly proven therapeutic applications. Rapidly advancing technological methodologies are increasing opportunities and indications. Despite all these benefits, applications in the more plastic developing brains of children are only just emerging. This book provides a comprehensive overview of brain stimulation in children. Chapters include Transcranial Magnetic Stimulation (TMS) fundamentals, brain stimulation in pediatric neurological conditions, and invasive brain stimulation. The main audience for this research will be those interested in applying brain stimulation technologies to advance clinical research and patient care, although a wide variety of clinicians and scientist will find this to be a valuable reference on brain stimulation with specific chapters on a variety of conditions. - Provides an overview of recent findings and knowledge of pediatric brain stimulation and the developing brain - Edited by renowned leaders in the field of pediatric brain stimulation - Presents a great resource for basic and clinical scientists and practitioners in neuroscience, neurology, neurosurgery, and psychiatry

Download or read book Patterns of Brain Functional Connectivity Within Neurocognitive Subtypes of Autism Spectrum Disorder written by Amanda E. Wagner and published by . This book was released on 2017 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt: Autism spectrum disorder (ASD) is a heterogeneous neurodevelopmental disorder. There have been increased efforts to identify meaningful subtypes of ASD based on a variety of measures (e.g., behavioral symptoms, genetic information, etc.). Elucidation of homogenous subtypes may lead to clearer understanding of underlying brain functioning and etiology of ASD. A recent exploratory study aimed to determine whether neuropsychological test data could be used to parse a group of individuals with high-functioning ASD into homogenous "subtypes" based on unique neurocognitive profiles (Wagner, 2014). Results of that study were promising and suggested the emergence of 3 clusters. This subset of individuals with ASD was successfully parsed into smaller more homogenous subgroups based on unique neurocognitive profiles driven by performance on measures of reasoning, receptive language, and learning/memory. Thus, corresponding brain regions were selected for further study in order to explore potential underlying differences in brain functioning across identified clusters. Resting state functional connectivity magnetic resonance imaging (rs-fcMRI) is an emerging neuroimaging tool used to examine functional correlations among spatially distinct brain regions. Previous rs-fcMRI studies examining individuals with ASD have found evidence for altered connectivity; however, results have been inconsistent. Inconsistencies may be related to the heterogeneous nature of ASD and underlying differences in potential neurocognitive subtypes within ASD samples. The current study aimed to extend preliminary research by comparing patterns of functional connectivity of frontal brain regions, Wernicke's area, and hippocampal regions across previously identified clusters to examine potential differences in underlying brain function. Results indicated The ASD subgroup with above average reasoning and language skills had increased frontal functional connectivity in comparison to other ASD subjects and controls, as well as increased posterior superior temporal gyrus connectivity in comparison to other ASD subjects. The ASD subgroup with below average learning and memory had decreased hippocampal functional connectivity in comparison to controls. However, when ASD subgroups were combined, there were no differences in functional connectivity between ASD and controls. Thus, ASD may be related to unique alterations in functional connectivity networks, however meaningful subgroup differences are easily masked by sample heterogeneity. Identification of neurocognitive profiles may provide diagnostic utility both within the spectrum and between ASD and other disorders. Diagnostic clarification in the form of a "neurocognitive subtype" could provide useful information about cognitive strengths and weaknesses and directions for treatment and intervention planning. Further delineation of the ASD spectrum, including variations in cognitive profiles and related underlying brain networks, may reveal important differences in underlying etiology and response to treatment.

Download or read book Pattern Analysis of the Human Connectome written by Dewen Hu and published by Springer. This book was released on 2020-11-20 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents recent advances in pattern analysis of the human connectome. The human connectome, measured by magnetic resonance imaging at the macroscale, provides a comprehensive description of how brain regions are connected. Based on machine learning methods, multiviarate pattern analysis can directly decode psychological or cognitive states from brain connectivity patterns. Although there are a number of works with chapters on conventional human connectome encoding (brain-mapping), there are few resources on human connectome decoding (brain-reading). Focusing mainly on advances made over the past decade in the field of manifold learning, sparse coding, multi-task learning, and deep learning of the human connectome and applications, this book helps students and researchers gain an overall picture of pattern analysis of the human connectome. It also offers valuable insights for clinicians involved in the clinical diagnosis and treatment evaluation of neuropsychiatric disorders.

Download or read book Imaging the Brain in Autism written by Manuel F. Casanova and published by Springer Science & Business Media. This book was released on 2013-05-24 with total page 399 pages. Available in PDF, EPUB and Kindle. Book excerpt: Data compiled by the Center for Disease Control and Prevention indicates an alarming and continuing increase in the prevalence of autism. Despite intensive research during the last few decades, autism remains a behavioral defined syndrome wherein diagnostic criteria lack in construct validity. And, contrary to other conditions like diabetes and hypertension, there are no biomarkers for autism. However, new imaging methods are changing the way we think about autism, bringing us closer to a falsifiable definition for the condition, identifying affected individuals earlier in life, and recognizing different subtypes of autism. The imaging modalities discussed in this book emphasize the power of new technology to uncover important clues about the condition with the hope of developing effective interventions. Imaging the Brain in Autism was created to examine autism from a unique perspective that would emphasize results from different imaging technologies. These techniques show brain abnormalities in a significant percentage of patients, abnormalities that translate into aberrant functioning and significant clinical symptomatology. It is our hope that this newfound understanding will make the field work collaborative and provide a path that minimizes technical impediments.

Download or read book Understanding the Role of Dynamics in Brain Networks written by MohammadMehdi Kafashan and published by . This book was released on 2016 with total page 215 pages. Available in PDF, EPUB and Kindle. Book excerpt: The brain is inherently a dynamical system whose networks interact at multiple spatial and temporal scales. Understanding the functional role of these dynamic interactions is a fundamental question in neuroscience. In this research, we approach this question through the development of new methods for characterizing brain dynamics from real data and new theories for linking dynamics to function. We perform our study at two scales: macro (at the level of brain regions) and micro (at the level of individual neurons). In the first part of this dissertation, we develop methods to identify the underlying dynamics at macro-scale that govern brain networks during states of health and disease in humans. First, we establish an optimization framework to actively probe connections in brain networks when the underlying network dynamics are changing over time. Then, we extend this framework to develop a data-driven approach for analyzing neurophysiological recordings without active stimulation, to describe the spatiotemporal structure of neural activity at different timescales. The overall goal is to detect how the dynamics of brain networks may change within and between particular cognitive states. We present the efficacy of this approach in characterizing spatiotemporal motifs of correlated neural activity during the transition from wakefulness to general anesthesia in functional magnetic resonance imaging (fMRI) data. Moreover, we demonstrate how such an approach can be utilized to construct an automatic classifier for detecting different levels of coma in electroencephalogram (EEG) data. In the second part, we study how ongoing function can constraint dynamics at micro-scale in recurrent neural networks, with particular application to sensory systems. Specifically, we develop theoretical conditions in a linear recurrent network in the presence of both disturbance and noise for exact and stable recovery of dynamic sparse stimuli applied to the network. We show how network dynamics can affect the decoding performance in such systems. Moreover, we formulate the problem of efficient encoding of an afferent input and its history in a nonlinear recurrent network. We show that a linear neural network architecture with a thresholding activation function is emergent if we assume that neurons optimize their activity based on a particular cost function. Such an architecture can enable the production of lightweight, history-sensitive encoding schemes.

Download or read book Fundamentals of Brain Network Analysis written by Alex Fornito and published by Academic Press. This book was released on 2016-03-04 with total page 496 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fundamentals of Brain Network Analysis is a comprehensive and accessible introduction to methods for unraveling the extraordinary complexity of neuronal connectivity. From the perspective of graph theory and network science, this book introduces, motivates and explains techniques for modeling brain networks as graphs of nodes connected by edges, and covers a diverse array of measures for quantifying their topological and spatial organization. It builds intuition for key concepts and methods by illustrating how they can be practically applied in diverse areas of neuroscience, ranging from the analysis of synaptic networks in the nematode worm to the characterization of large-scale human brain networks constructed with magnetic resonance imaging. This text is ideally suited to neuroscientists wanting to develop expertise in the rapidly developing field of neural connectomics, and to physical and computational scientists wanting to understand how these quantitative methods can be used to understand brain organization. - Winner of the 2017 PROSE Award in Biomedicine & Neuroscience and the 2017 British Medical Association (BMA) Award in Neurology - Extensively illustrated throughout by graphical representations of key mathematical concepts and their practical applications to analyses of nervous systems - Comprehensively covers graph theoretical analyses of structural and functional brain networks, from microscopic to macroscopic scales, using examples based on a wide variety of experimental methods in neuroscience - Designed to inform and empower scientists at all levels of experience, and from any specialist background, wanting to use modern methods of network science to understand the organization of the brain

Download or read book Infant EEG and Event Related Potentials written by Michelle de Haan and published by Psychology Press. This book was released on 2013-04-15 with total page 345 pages. Available in PDF, EPUB and Kindle. Book excerpt: Infancy is a time of rapid growth, when brain plasticity is at a maximum. Event-related potentials (ERPs) are one of the few methods that can easily and safely be used to study this process, and have led to exciting discoveries about human brain functioning and the neural basis of cognition. Over recent years, there has been a massive rise in the level of interest in ERPs and this book considers the advantages which they offer to researchers and clinicians. In particular, it looks at the benefits of this form of neuroimaging as a non-invasive tool for detecting impairments in brain and cognitive development very early in life. The potential use of ERPs for clinical settings is also explored in detail. The contributions are all from eminent researchers in the field and represent the latest thought on the topic. Infant EEG and Event-Related Potentials explains the basics of event-related potentials for those less familiar with the procedures and terminology, as well as offering a valuable handbook of the latest theories and empirical findings for those working in the field. This will be a valuable source for those interested in developmental psychology and neuropsychology, and for clinicians interested in application of ERPs.

Download or read book Brain Networks Involved in Higher Cognitive Functions in Adults with Autism Spectrum Disorder written by Veronica Wai-Jong Yuk and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: People with autism spectrum disorder (ASD) experience difficulties with higher cognitive functions, including executive functions and theory of mind (ToM). They show atypical recruitment of brain regions involved in these functions, but functional connectivity among these areas within particular frequency bands has been less well characterized in ASD. Examining these factors is crucial to elucidating the neural mechanisms by which long-range underconnectivity and short-range overconnectivity reported in ASD influences their cognitive abilities. Therefore, this thesis used magnetoencephalography to explore the frequency-specific functional networks subserving executive functions and ToM in three studies of overlapping groups of 39 control adults and 40 adults with ASD aged 18-40 years old. Study 1 demonstrated that during inhibitory control, lower alpha-band synchrony between the right inferior frontal gyrus (IFG) and areas not typically linked to inhibition was found in adults with ASD compared to controls and was associated with everyday inhibition, suggesting weaker suppression by the right IFG of extraneous brain activity. Study 2 revealed that while connectivity did not differ between groups when maintaining stimuli in working memory, adults with ASD showed reduced theta-band network synchrony involving the right IFG and left inferior parietal lobule when recognizing previously presented stimuli. Therefore, despite intact maintenance, recognition in adults with ASD may be affected by diminished inhibition of irrelevant stimulus representations. Study 3 determined that during a ToM false-belief task, adults with ASD had lower theta-band synchrony among brain regions implicated in ToM and the right IFG, suggesting reduced inhibition of their own belief when inferring another's false belief. Adults with ASD reported difficulties in all three functions assessed by these three studies. Together, this work suggests that reduced connectivity impacts higher cognitive functions in ASD, and that atypical inhibitory control may be a common, key contributor to cognitive difficulties in adults with ASD.

Download or read book Networks of the Brain written by Olaf Sporns and published by MIT Press. This book was released on 2016-02-12 with total page 433 pages. Available in PDF, EPUB and Kindle. Book excerpt: An integrative overview of network approaches to neuroscience explores the origins of brain complexity and the link between brain structure and function. Over the last decade, the study of complex networks has expanded across diverse scientific fields. Increasingly, science is concerned with the structure, behavior, and evolution of complex systems ranging from cells to ecosystems. In Networks of the Brain, Olaf Sporns describes how the integrative nature of brain function can be illuminated from a complex network perspective. Highlighting the many emerging points of contact between neuroscience and network science, the book serves to introduce network theory to neuroscientists and neuroscience to those working on theoretical network models. Sporns emphasizes how networks connect levels of organization in the brain and how they link structure to function, offering an informal and nonmathematical treatment of the subject. Networks of the Brain provides a synthesis of the sciences of complex networks and the brain that will be an essential foundation for future research.

Download or read book Neuroscience in the 21st Century written by Donald W. Pfaff and published by Springer. This book was released on 2016-10-27 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Edited and authored by a wealth of international experts in neuroscience and related disciplines, this key new resource aims to offer medical students and graduate researchers around the world a comprehensive introduction and overview of modern neuroscience. Neuroscience research is certain to prove a vital element in combating mental illness in its various incarnations, a strategic battleground in the future of medicine, as the prevalence of mental disorders is becoming better understood each year. Hundreds of millions of people worldwide are affected by mental, behavioral, neurological and substance use disorders. The World Health Organization estimated in 2002 that 154 million people globally suffer from depression and 25 million people from schizophrenia; 91 million people are affected by alcohol use disorders and 15 million by drug use disorders. A more recent WHO report shows that 50 million people suffer from epilepsy and 24 million from Alzheimer’s and other dementias. Because neuroscience takes the etiology of disease—the complex interplay between biological, psychological, and sociocultural factors—as its object of inquiry, it is increasingly valuable in understanding an array of medical conditions. A recent report by the United States’ Surgeon General cites several such diseases: schizophrenia, bipolar disorder, early-onset depression, autism, attention deficit/ hyperactivity disorder, anorexia nervosa, and panic disorder, among many others. Not only is this volume a boon to those wishing to understand the future of neuroscience, it also aims to encourage the initiation of neuroscience programs in developing countries, featuring as it does an appendix full of advice on how to develop such programs. With broad coverage of both basic science and clinical issues, comprising around 150 chapters from a diversity of international authors and including complementary video components, Neuroscience in the 21st Century in its second edition serves as a comprehensive resource to students and researchers alike.

Download or read book Structural and Functional Network Organization of the Brain written by David Grayson and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Substantial research effort is currently being directed at establishing the system of pathways that connect the functional regions of the normal human brain. At the same time, the past decade has seen an explosion of network science as a new methodology to study human brain structure and function. Despite the impressive scale of these efforts, the relationship between brain structure and brain function is still murky. It remains a difficult and crucial challenge to relate functional aberrations (e.g. changes in brain activity and/or behavior) seen in neuropsychiatric disorders to underlying changes in neuroanatomy. This dissertation aims to contribute new knowledge in this area through controlled experimental manipulations in animal models and through investigation of brain structural connectivity in people with Autism Spectrum Disorder (ASD). Functional and structural connectivity data were obtained in these experiments via non-invasive magnetic resonance imaging (MRI). First, the effects of focal perturbation were examined via pharmacogenetic inactivation of the amygdala in rhesus monkeys. Positive and negative downstream changes in functional connectivity (i.e. correlated activity between other regions) were examined via resting-state fMRI. These changes were shown to be partly predictable using a network-based analysis of experimentally established structural connectivity to simulate disconnection of the amygdala. The results of this study validated the use of a particular network metric of mutual communication, termed communicability, for predicting baseline functional connectivity measurements from structural connectivity networks and for simulating the effects of focal perturbation. Next, the long-term structural consequences of early focal damage were examined in adult rhesus monkeys that received amygdala lesions as neonates. These monkeys demonstrated permanent atrophy of areas typically well-connected with the amygdala and impaired communicability of temporal and orbitofrontal cortex. On the other hand, these animals exhibited an abnormally large middle cingulate cortex. The spatial distribution of altered gray matter morphometry bore meaningful overlap with the pattern of altered functional connectivity due to transient inactivation. Finally, alterations in communicability were examined within a large dataset of young children with and without ASD. There were significant network-level alterations in children with ASD relative to their typically developing peers. Within the cohort of children with ASD, there were effects of different biological variables such as 1) sex, 2) age, 3) sex-by-age interactions, and 4) having a disproportionately large brain relative to body size. Together, these experiments demonstrate that focal perturbations in brain structure result in distributed impacts on brain structure and function that are at least partly predictable using network analysis. Network metrics that are useful for predicting function from structure (i.e. communicability) are shown here to be valuable for assessing the neurophenotype of ASD and exploring clinical heterogeneity.

Download or read book Characterizing Resting State Brain Dynamics in Individuals with and Without Autism Spectrum Disorder written by Amanda Kathleen Easson and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Autism spectrum disorder (ASD) is a neurodevelopmental disorder that is characterized by impairments in social communication as well as restricted, repetitive and stereotyped behaviours. ASD is a highly heterogeneous disorder, with a broad range of the types and severities of symptoms that can be displayed. It has been proposed that ASD is characterized by abnormal functional connectivity (FC) between brain regions, which can be defined as the correlations of functional magnetic resonance imaging (fMRI) time series between pairs of regions of interest. However, studies of FC in ASD have presented mixed results. Further, it has been suggested that there is a complex developmental trajectory of FC in ASD. Inconsistent results across studies may, in part, be related to differences in fMRI data processing strategies, as well as heterogeneity of sample characteristics. Other aspects of brain dynamics, including variability and complexity of blood oxygen-level dependent (BOLD) time series, are not well characterized in ASD. The goal of this dissertation is to analyze resting-state brain dynamics in ASD, and to address the inconsistencies in previous studies of resting-state fMRI in ASD. Study 1 involves the characterization of FC-based subtypes of ASD and typically developing (TD) participants to elucidate unique relationships between FC and behaviour. In Study 2, different fMRI data processing strategies are examined to determine the effects of these processing choices on group differences in FC in children and adolescents with and without ASD. Study 3 involves examining BOLD signal variability and complexity, and relating these metrics to structural connectivity, age, and behavioural severity. Overall, these studies reveal the importance of considering subtypes of ASD and TD individuals, the effects of preprocessing strategies, and relationships between brain dynamics and brain structure, age, and behavioural severity when analyzing resting-state brain dynamics in those with and without ASD.

Download or read book Salience Network of the Human Brain written by Lucina Q. Uddin and published by Academic Press. This book was released on 2016-08-24 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: Salience Network of the Human Brain focuses on the multiple sources of stimuli that compete for our attention, providing interesting discussions on how the relative salience—importance or prominence—of each of these inputs determines which ones we choose to focus on for more in-depth processing. The salience network is a collection of regions of the brain that select which stimuli are deserving of our attention. The network has key nodes in the insular cortex and is critical for detecting behaviorally relevant stimuli and for coordinating the brain's neural resources in response to these stimuli. The insular cortex is a complex and multipurpose structure that plays a role in numerous cognitive functions related to perception, emotion, and interpersonal experience—and the failure of this network to function properly can lead to numerous neuropsychiatric disorders, including autism spectrum disorder, psychosis, and dementia. - Presents the only publication available that summarizes our understanding of the salience network in one resource - Authored by a leading research on this important aspect of attention - Focuses on the multiple sources of stimuli that compete for our attention, providing interesting discussions on how the relative salience—importance or prominence—of each of these inputs determines which ones we choose to focus on for more in-depth processing