All ETDs from UAB

Advisory Committee Chair

Rajesh K Kana

Advisory Committee Members

Sarah O'Kelley

Kristina M Visscher

Jane B Allendorfer

Farah Lubin

Document Type

Dissertation

Date of Award

2018

Degree Name by School

Doctor of Philosophy (PhD) College of Arts and Sciences

Abstract

Autism Spectrum Disorder (ASD) is characterized by impairments in social communication and the presence of repetitive behaviors and restricted interests. Studies examining functional brain networks have risen exponentially over the last decade and have characterized ASD as a disorder of altered brain network connectivity and organization. These studies typically rely on blood oxygen level-dependent (BOLD) signal correlations between two or more regions in the cerebral cortex and make inferences about brain connectivity. However, brain connectivity differences might span subcortical regions such as the thalamus and basal ganglia as well; and only a few studies have examined cortico-subcortical connectivity in ASD. This project examined cortico-subcortical functional connectivity in ASD using the Autism Brain Imaging Data Exchange (ABIDE-II) repository. The goal of this study was to characterize the functional connectivity between cortex and subcortical regions in ASD compared to typically developing (TD) individuals, and how ASD phenotype was related to cortico-subcortical connectivity. Resting-state functional MRI (rs-fMRI) data were used from 168 TD and 138 ASD participants across different sites. The results are as follows: 1) group differences emerged in terms of overconnectivity in ASD between unimodal and subcortical regions, and underconnectivity in ASD between supramodal and subcortical regions; and 2) positive correlations between ASD phenotype with unimodal-subcortical connectivity were found, and negative ones with supramodal-subcortical connectivity. Brain networks heavily involved in sensory processing showed increased functional connectivity with subcortical regions while those involved in higher-order thinking showed decreased connectivity in ASD. In addition, significant brain-behavior correlations indicated a relationship between ASD symptoms and brain connectivity. Thus, differences between basic and high-order cognitive processes seem to influence cortico-subcortical connectivity profiles in ASD, which can further enhance our understanding of in the neurobiology of ASD.

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