Cortical Folding Abnormalities in Autism Revealed by Surface-Based Morphometry

Abstract

We tested for cortical shape abnormalities using surface-based morphometry across a range of autism spectrum disorders (7.5-18 years of age). We generated sulcal depth maps from structural magnetic resonance imaging data and compared typically developing controls to three autism spectrum disorder subgroups: low-functioning autism, high-functioning autism, and Asperger's syndrome. The lowfunctioning autism group had a prominent shape abnormality centered on the pars opercularis of the inferior frontal gyrus that was associated with a sulcal depth difference in the anterior insula and frontal operculum. The high-functioning autism group had bilateral shape abnormalities similar to the low-functioning group, but smaller in size and centered more posteriorly, in and near the parietal operculum and ventral postcentral gyrus. Individuals with Asperger's syndrome had bilateral abnormalities in the intraparietal sulcus that correlated with age, intelligence quotient, and Autism Diagnostic Interview-Revised social and repetitive behavior scores. Because of evidence suggesting age-related differences in the developmental time course of neural alterations in autism, separate analyses on children (7.5-12.5 years of age) and adolescents (12.75-18 years of age) were also carried out. All of the cortical shape abnormalities identified across all ages were more pronounced in the children. These findings are consistent with evidence of an altered trajectory of early brain development in autism, and they identify several regions that may have abnormal patterns of connectivity in individuals with autism.

Right Temporoparietal Gray Matter Predicts Accuracy of Social Perception in the Autism Spectrum

“…Moreover, our data provide the first anatomical evidence of a compromised structure of the temporoparietal cortex predicting social dysfunctions in ASD, highlighting the behavioral significance of ASD-related structural changes. Regional gray matter changes in ASD, however, might vary, for example as a function of age or diagnostic subgroup (Brambilla et al 2003;Nordahl et al 2007;Amaral et al 2008). Here we only investigated adult highfunctioning individuals with ASD, and our conclusions are limited by a rather small sample size.…”

“…However, other studies have found gray matter increases in some of these and other regions in ASD, making the current picture on structural brain differences in ASD somewhat inconsistent (Amaral et al 2008). These inconsistencies may be related to the recently often discussed heterogeneity in the spectrum, as well as between-study differences with respect to functionality and age of the ASD group (Brambilla et al 2003;Nordahl et al 2007;Amaral et al 2008;Nickl-Jockschat et al 2011). …”

3D Cerebral Cortical Morphometry in Autism: Increased Folding in Children and Adolescents in Frontal, Parietal, and Temporal Lobes

“…Some SBM approaches estimate the outer cortical surface relying on the accuracy of the inner cortical surface and assuming that the outer cortical surface has a similar shape as the inner one. Subsequently, they select the mid-cortical surface [8] which is even more similar to the inner cortical surface than the outer surface.…”

“…Levitt et al [7] create maps of 22 major sulci and report anatomical shifts for some sulci in frontal and temporal lobes. Nordahl et al [8] report increased sulcal depths for autistic subjects in the operculum and the intraparietal sulcus using surface-based morphometry (SBM). They found all abnormalities to be more pronounced in children than adolescents.…”

Gender Differences in Cerebral Cortical Folding: Multivariate Complexity-Shape Analysis with Insights into Handling Brain-Volume Differences

“…For the last few decades, magnetic resonance (MR) imaging has enabled in vivo studies of human cortical folding patterns. One class of approaches to folding analysis rely on spatial normalization [1,2] and subsequently perform statistical hypothesis testing at every voxel or surface element in the normalized space. However, the difficulty in finding sufficiently-many homologous features [3,4] may directly affect the normalization and, thereby, the reliability of findings in the clinical study.…”