Previous functional neuroimaging studies have reported differential activation in the cingulate and insula in relation to social impairments in individuals with ASD. However, as of late more recent morphometric studies have indicated that structural atypicalities in these brain regions may also contribute to impaired social abilities in this sample.
To explore structural abnormalities in the cingulate and insula in children and adults with ASD and how they relate to social cognitive deficits.
First, a meta-analysis was performed on the data from 19 structural imaging studies examining grey matter density alterations in children and adults with ASD. Probabilistic maps of grey and white matter differences in the ASD populations relative to healthy controls were calculated using the Activation Likelihood Estimate (ALE) method.
Then, a total of 28 children and adults (age range: 7-39 years) who carried a clinical diagnosis of ASD underwent magnetic resonance imaging (MRI) at 3 Telsa. Cortical thickness and surface area were calculated using a standard protocol within the CIVET processing pipeline. Surface area values were calculated for the each cortical lobe, the parahippocampal gyrus, cingulate, insula and the isthmus of the cingulate gyrus.
Children were more likely than adults to have increased grey matter in the cingulate and insula. The results in our sample suggest that increased cortical thickness in the rostral portion of the anterior cingulate cortex is associated with greater social impairments. Greater surface area in the insula and the isthmus of the cingulate gyrus was also associated with more severe social cognition deficits.
Findings indicate that structural atypicalities in the cingulate and insula are associated with impaired social processing, with some evidence for developmental changes. Future work will focus on combined functional and structural studies to elucidate the neural mechanisms of social impairments in both children and adults with ASD.
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