Maladaptive laterality in cortical networks related to social communication in autism spectrum disorder

Neuroimaging studies of individuals with autism spectrum disorders (ASD) consistently find an aberrant pattern of “reduced” laterality in brain networks that support functions related to social communication and language. However, it is unclear how the underlying functional organization of these brain networks is altered in ASD individuals. We tested four models of “reduced” laterality in a social-communication network in seventy ASD individuals (14 females) and a control group of the same number of tightly matched typically developing (TD) individuals (19 females) using high quality resting-state fMRI data and a method of measuring patterns of functional laterality across the brain. We found that a functionally defined social-communication network exhibited the typical pattern of left laterality in both groups, while there was a significant increase in laterality of homotopic regions in the right hemisphere in ASD individuals. Furthermore, left laterality was positively correlated with a measure of verbal ability in both groups, while right laterality in ASD, but not TD, individuals was negatively correlated with the same verbal measure. Crucially, these differences in patterns of laterality were not found in two other functional networks and were specifically correlated to a measure of verbal, but not visuospatial, ability. These results suggest that previous reports of “reduced” laterality in social-communication regions in ASD is due to a shift towards functional decoupling of the two hemispheres, which may cause them to act as independent systems with the atypical right-lateralized network being maladaptive.