Date of Award

Spring 2020

Project Type

Thesis

Program or Major

Communication Sciences and Disorders

Degree Name

Master of Science

First Advisor

Amy E Ramage

Second Advisor

Kathryn J Greenslade

Abstract

Autism Spectrum Disorder (ASD) and Traumatic Brain Injury (TBI) are clinical populations with social cognition difficulties, exhibited by deficits in controlling impulsive or perseverative behaviors. These difficulties have been attributed to executive functioning (EF) impairments, particularly for inhibition. Thus, understanding the neural bases of inhibition is preliminary to understanding EF impairments in populations like ASD and TBI. A coordinate-based meta-analysis of functional magnetic resonance imaging (fMRI) studies was used to identify the neural basis of response inhibition in neurotypical adults to compare with TBI and ASD. Inclusion criteria for studies required reported foci for adults (17+ years of age), reported on normal mapping, and used inhibition experiential tasks that revealed activations results. Five ASD and seven TBI studies met inclusion criteria, pooling fMRI data from 1431 neurotypical subjects, 145 TBI and 71 ASD subjects engaged in inhibition tasks, yielding 98 experiments in controls and 15 experiments (9 TBI) for contrast analyses. Brain regions found to be uniquely active in the ASD or TBI and in the Control groups were further analyzed using meta-analytic connectivity modeling (MACM) to determine whether differences in these regions were functionally relevant and associated with differing behavioral patterns. The MACM analyses included 480 neurotypical experiments (6820 subjects, 7008 foci) reporting activity in the left medial frontal gyrus region of interest and 809 experiments (11568 subjects, 11855 foci) reporting activity in the right medial frontal gyrus region of interest. Results provide evidence that the brain region involved to the greatest extent for response inhibition, the medial frontal cortex, is active in individuals with TBI, with ASD and Controls. However, the groups had differences in the peaks of activity in this region. Though subtle, these differences may indicate these clinical populations are relying more on top-down, higher-level cognitive processing to accomplish response inhibition than do neurotypical controls. Results support a hypothesis that those with ASD or TBI are engaging a smaller network of brain regions, with a higher proportion of activity in the frontal lobes, and therefore less efficient than that seen in the Controls. Given the heterogeneity of TBI and ASD demographics and the variability of inhibition tasks used, these findings are speculative and require further study. This study provides support of concept for further research on functional imaging, attention, and inhibition.

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