Abnormal Structural and Functional Connectivity of the Corpus Callosum in Autism Spectrum Disorders: A Review

Autism spectrum disorder (ASD) is characterised by difficulties with social communication, interaction, and repetitive and stereotypical patterns of behaviour. Recent studies suggest that abnormalities in the corpus callosum (CC) can produce autistic symptoms, so this cerebral structure is a target for autism research. It is the largest area of white matter fibre that connects the cerebral hemispheres and has been considered an index of interhemispheric connectivity. The poor connectivity that is a characteristic of autism could be due to CC abnormalities. In this review, we describe empirical studies that have used functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) to investigate the role of the CC in functional and structural brain connectivity in individuals with ASD. Establishing the anatomical correlates of abnormal connectivity in ASD is a major objective of structural and functional connectivity studies. Reduced CC volume is one of the most consistent findings in studies of autistic brains. Structural connectivity studies have shown that the CC is generally altered in ASD. In addition, functional connectivity studies show atypical activity in individuals with ASD during social cognition tasks, working memory tasks, and tests of executive function. Research on functional and structural connectivity has contributed to understanding the role of the CC in the clinical symptoms and social and cognitive deficits associated with ASD.