Date of Award

Summer 2013

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Clinical Psychology

First Advisor

Van Hecke, Amy Vaughan

Second Advisor

Grych, John H.

Third Advisor

Gordon, Nakia S.

Abstract

The Extreme Male Brain (EMB) theory (Baron-Cohen, 2003) is a behavioral theory of autism spectrum disorders (ASD), suggesting that the triad of behavioral impairments in ASD can be conceptualized psychologically as impairment in empathizing, coupled with a superior capacity for systemizing. Despite studies of the behavioral manifestations of this theory, it lacks neurological findings, specifically evidence of less coordinated activity between the left and right hemisphere in ASD (i.e. more lateralized activity). This study attempted to investigate neural correlates of the EMB theory utilizing EEG coherence, an index of neural connectivity, to determine if a more lateralized profile exists in the brain of adolescents with ASD compared to typically developing teens. In addition, relationships among coherence values and behavioral data were explored, and group membership was predicted using a "traditional model" of ASD characteristics (social skills and ratings of autism symptomatology) and an "EMB theory model" (EEG coherence and behavioral ratings of empathizing and sympathizing). Results revealed that teenagers with ASD displayed decreased coherence between the left and right frontal lobes in the alpha and theta frequency bands, while coherence between the frontal and temporal-parietal lobes within each hemisphere did not differ from typically developing teens at any frequency band. This pattern of results suggests that teens with ASD displayed a more lateralized profile, consistent with the EMB theory. Also, increased frontal-frontal coherence at the alpha and theta frequencies was associated with increased social skills in the total sample. In addition, the EMB model and the traditional characteristics model did not differ in their ability to correctly classify the groups, as a significant difference between the percent classified by each group did not emerge. Taken together, it seems that male adolescents with ASD display a more lateralized neural profile with less connectivity between the hemispheres than their typically developing peers. This pattern provides neural support for the EMB theory of autism, while also highlighting a potentially important neural marker for ASD.

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