Enlarged right superior temporal gyrus in children and adolescents with autism

Abstract

The superior temporal gyrus has been implicated in language processing and social perception. Therefore, anatomical abnormalities of this structure may underlie some of the deficits observed in autism, a severe neurodevelopmental disorder characterized by impairments in social interaction and communication. In this study, volumes of the left and right superior temporal gyri were measured using magnetic resonance imaging obtained from 18 boys with high-functioning autism (mean age=13.5±3.4years; full-scale IQ=103.6±13.4) and 19 healthy controls (mean age=13.7±3.0years; full-scale IQ=103.9±10.5), group-matched on age, gender, and handedness. When compared to the control group, right superior temporal gyral volumes was significantly increased in the autism group after controlling for age and total brain volume. There was no significant difference in the volume of the left superior temporal gyrus. Post-hoc analysis revealed a significant increase of the right posterior superior temporal gyral volume in the autism group, before and after controlling for age and total brain volume. Examination of the symmetry index for the superior temporal gyral volumes did not yield statistically significant between-group differences. Findings from this preliminary investigation suggest the existence of volumetric alterations in the right superior temporal gyrus in children and adolescents with autism, providing support for a neuroanatomical basis of the social perceptual deficits characterizing this severe neurodevelopmental disorder.

Figure 1

Scatter plots depicting superior temporal gyral volumes (y-axis) for individual participants separated by study group membership (x-axis). The asterisk indentifies the outlier excluded from the final analysis. HFA = high-functioning autism, TDC = typically developing controls, STG = superior temporal gyrus, cc = cubic centimeters

Figure 1

Scatter plots depicting superior temporal gyral volumes (y-axis) for individual participants separated by study group membership (x-axis). The asterisk indentifies the outlier excluded from the final analysis. HFA = high-functioning autism, TDC = typically developing controls, STG = superior temporal gyrus, cc = cubic centimeters

Figure 2

Box plots representing superior temporal gyral volumes (y-axis) separated by study group membership (x-axis). The outlier excluded from the final analysis is clearly identified by the solid dot. HFA = high-functioning autism, TDC = typically developing controls, STG = superior temporal gyrus, cc = cubic centimeters

Figure 2

Box plots representing superior temporal gyral volumes (y-axis) separated by study group membership (x-axis). The outlier excluded from the final analysis is clearly identified by the solid dot. HFA = high-functioning autism, TDC = typically developing controls, STG = superior temporal gyrus, cc = cubic centimeters

Figure 3

Manually tracing the outer boundaries of the superior temporal gyrus. The superior temporal gyrus was identified bilaterally in reference to standard brain atlases. Each coronal slice containing the STG was manually traced along the gyral boundaries. An automated algorithm was used to multiply cross sectional area by slice thickness to obtain volumetric measurements.