Prior research has suggested that any cortical volume (CV) abnormalities in Autism Spectrum Disorder (ASD) need to be further explored by examination of the two determinants of CV, that being cortical thickness (CT) and pial surface area (PSA; Murphy, Beecham, Craig, & Ecker, 2011). The current study suggests that the two determinants of CV should be explored even in the presence of null CV findings, if structure-function analyses are significant (i.e., bi-lateral precentral gyrus and neuropsychological motor test) as demonstrated in the current sample (see Duffield et al., 2013). The only significant anatomic finding was reduced CT in the left frontal motor regions (primarily left precentral gyrus), which also corresponded to the only significant relationship between a motor variable (i.e., grooved pegboard test) and motor region-of-interest (ROI) where ASD had a stronger relationship than typically developing controls (TDC; ASD > TDC). Left hemisphere biased CT group differences has been shown to have the highest classification accuracy (i.e., designation of ASD versus TDC) of morphological parameters (Ecker et al., 2010), yet PSA has been shown to have far greater modulation of CV abnormalities. This is particularly true for subthreshold PSA (Ecker et al., 2013). These prior findings are not only consistent with the current motor ROI findings, but also provide an explanatory framework for the functional neuroanatomy of a generally worse left handed performance (i.e., non-dominant hand) for ASD compared to controls in a generally right handed dominant sample (no significant group differences on handedness). The only significant motor ROI finding was in the left hemisphere (i.e., ipsilateral to worse left handed performance), but subthreshold PSA findings in the right precentral were found and likely provide explanatory power of motor performances in the aggregate, despite a lack of significant statistical differences in a specific motor ROI individually.



College and Department

Family, Home, and Social Sciences; Psychology



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cortical thickness, voxel-based morphometry, motor, autism spectrum disorder

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Psychology Commons