Author: Amanda E. Wagner
Publisher:
ISBN:
Category :
Languages : en
Pages : 122
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Book Description
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.
Author: Sebastian Urchs
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
"Autism spectrum disorder (ASD) is a prevalent neurodevelopmental disorder of impaired social interaction and restrictive behaviours for which, with rare exceptions, theunderlying disease mechanisms and origin are unknown. My goal in this thesis has beento discover and differentiate robust neurobiological endophenotypes that are stronglyassociated with ASD symptoms and can inform us about these underlying mechanisms.This is challenging because of the extensive heterogeneity among individuals with ASDthat limits the usefulness of group averages. Decomposing and describing this heterogeneity is therefore an important prerequisite for a better understanding of ASD. Thisthesis uses resting state functional connectivity (FC) imaging data to characterize homogeneous subtypes of functional brain organization that are strongly associated with ASD.First, I show that an unsupervised clustering approach can identify robust subtypesof FC in a heterogeneous ASD dataset (Manuscript 2). These FC subtypes associatereproducibly but only moderately with ASD diagnosis and capture non-overlappingsignatures of ASD-related FC alterations. Based on these findings I show that highly targeted supervised machine learning is capable of identifying a generalizable FC signaturewith very strong association with a subset of ASD individuals (Manuscript 3). This FCsignature is characterized by underconnectivity in transmodal brain networks and confers a 7-fold increase in risk of ASD in the general population. These findings build upona third, methodological contribution of a fully annotated multi-resolution parcellationof functional brain networks (Manuscript 1) that helped guide the interpretation of myempirical findings. I show that this parcellation captures the hierarchical decompositionof large scale brain networks, is highly reproducible, and matches existing functionalbrain parcellations in internal homogeneity. This thesis contributes novel insight intothe limitations and potential of neuroimaging based decomposition of heterogeneityin ASD and establishes an independently validated FC endophenotype that is stronglyassociated with risk of ASD in the general population"--
Author: Dorothy V.M Bishop
Publisher: Psychology Press
ISBN: 1317715829
Category : Psychology
Languages : en
Pages : 320
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Book Description
Delayed development of speech and/or language is one of the commonest reasons for parents of preschool children to seek the advice of a paediatrician. Accessible to non-academic Speech and Language Impairments provides an overview of recent research developments in specific speech and language impairments, written by experts in the field. Topics include normal and disordered development of problems , crosslinguistic studies, pragmatic language impairments, early identification, educational and psychiatric outcomes, acquired epileptic aphasia and experimental studies of remediation. The book concludes with a chapter by Michael Rutter that gives guidelines for conducting and evaluating research in this field.
Author: Lisa Elena Mash
Publisher:
ISBN:
Category :
Languages : en
Pages : 143
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Book Description
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.
Author: Helen Tager-Flusberg
Publisher: Psychology Press
ISBN: 9781841690087
Category : Psychology
Languages : en
Pages : 275
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Book Description
This book presents a new perspective on the development of theory of mind based on an integration of empirical research that has been conducted on autism and William's syndrome.
Author: C. Gillberg
Publisher:
ISBN: 9781489908834
Category :
Languages : en
Pages : 464
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Book Description
Author: Isabelle Rapin
Publisher: Cambridge University Press
ISBN: 9781898683070
Category : Medical
Languages : en
Pages : 320
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Book Description
Multidisciplinary volume addressing the practicalities of assessment of ineffective communication in the preschool child.
Author: Andreas M. Grabrucker
Publisher:
ISBN:
Category :
Languages : en
Pages : 117
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Book Description
Autism spectrum disorders are developmental disorders. Individuals with autism spectrum disorders develop differently. These differences are usually present in social interaction, communication, and sensory processing, and become visible through a wide variety of behavioral responses that differ from individuals without autism spectrum disorders. Despite significant research efforts, the exact causes of autism spectrum disorders remain poorly understood; however, researchers have gained extensive insights into possible pathomechanisms, even at the molecular level of cells. Many diagnostic criteria have been developed, adapted, and improved. The eight chapters in this book highlight the current state-of-the-art in many areas of autism spectrum disorders. Chapter 1 provides an overview of the epidemiology of autism spectrum disorders and the current knowledge of the underlying pathogenic mechanisms. Chapter 2 summarizes the diagnostic criteria and procedures and highlights present and upcoming therapeutic strategies. Chapter 3 reviews the adverse events and trauma in people with autism spectrum disorders. Chapters 4 and 5 focus on atypical sensory processing, and Chapter 6 discusses the genetic overlap of autism spectrum disorders with other neuropsychiatric disorders such as attention deficit hyperactivity disorder (ADHD), depression, and schizophrenia. Chapter 7 focuses on the contribution of abnormalities in mitochondria, and chapter 8 discusses gut-brain interactions and a potential role for microbiota in autism spectrum disorders. This book is aimed primarily at clinicians and scientists, but many areas will also be of interest to the layperson.
Author:
Publisher:
ISBN:
Category : Electronic books
Languages : en
Pages : 52
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Book Description
Autism spectrum disorder (ASD) is a set of developmental disorders characterized by impacted social and communicative abilities, restricted interests, and repetitive behaviors. Recent ASD research has shown that network-level communication within the brain may play a large role in the manifestation of these symptoms. Specifically, recent studies have suggested domain-specific patterns of increased connectivity for sensorimotor connections and decreased connectivity for supramodal or associative connections for both thalamocortical and cerebrocerebellar circuits in ASD. The current study aimed to test whether functional connectivity between cerebellar lobules and the neocortex was related to functional connectivity between thalamic nuclei and the neocortex. We further sought to determine how these deep brain functional connectivity patterns correlated with ASD symptom severity as measured by clinical assessments. Archival resting state fMRI data from 49 ASD and 49 typically developing (TD) participants (aged 7 to 17 years) were used for this study. ASD and TD participants were matched at the group level on age, nonverbal IQ, and in-scanner head motion. A standard fMRI preprocessing pipeline was utilized, including motion, slice-time, and field map correction, spatial smoothing and bandpass filtering, and removal of nuisance regressors (i.e., 6 rigid-body motion parameters, and signal from white matter and ventricles). Regions of interest (ROIs) for cerebral cortex, thalamic regions, and cerebellar lobules were obtained from the Jülich histological and Harvard-Oxford atlases. Total correlation analyses between the mean time series of each cortical ROI and deep brain parcel showed widespread overconnectivity in the ASD group compared to the TD group. This was the case for both thalamocortical and cerebrocerebellar iFC circuits, stemming from both sensorimotor and supramodal cortical seeds. These circuits also showed far less specificity in ASD, with generally higher correlations between the iFC pairings themselves. Finally, it was shown that for participants with ASD, as iFC patterns deviated from those of the TD group, symptom severity based on clinical assessments also worsened across several domains. These findings suggest that thalamocortical and cerebrocerebellar iFC may be guided by similar neural dynamics, which may have many implications for developmental hypotheses of ASD that focus on network formation.
Author: Gareth W. Roberts
Publisher: Cambridge University Press
ISBN: 9780521425582
Category : Medical
Languages : en
Pages : 204
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Book Description
This volume provides an introduction to the essential techniques required for studying the molecular biology of brain disease. The approaches and strategies for investigations of gene structure and regulation are described with reference to the molecular genetics of prion and Alzheimer's disease. The effects of aberrant gene regulation can also be examined at the protein level by immunocytochemistry and autoradiography. Improved understanding of basic biology has resulted in new approaches to animal models using transgenic techniques and new therapeutic approaches. The volume is structured to illustrate all these approaches and demonstrate the practice and promise of molecular neuropathology.
