Identification of lateralized compensatory neural activities within the social brain due to autism spectrum disorder in adolescent males

: Socio-behavioral impairments are important characteristics of autism spectrum disorders (ASD) and MRI-based studies are pursued to identify a neurobiological basis behind these conditions. This paper presents an MRI-based study undertaken to (i) identify the differences in brain activities due to ASD, (ii) verify whether such differences exist within the 'social brain' circuit which is hypothesized to be responsible for social functions, and (iii) uncover potential compensatory mechanisms within the identified differences in brain activities. In this study, a whole-brain voxel-wise analysis is performed using resting-state fMRI data from 598 adolescent males, that is openly available from the ABIDE consortium. A new method is developed, which can (i) extract the discriminative brain activities, that provide high separability between the blood oxygenation time-series signals from ASD and neurotypical populations, (ii) select the activities that are relevant to ASD by evaluating the correlation between the separability and traditional severity scores, and (iii) map the spatial pattern of regions responsible for generating the discriminative activities. The results show that the most discriminative brain activities occur within a subset of the social brain that is involved with affective aspects of social processing, thereby supporting the idea of the social brain and also its fractionalization in ASD. Further, it has also been found that the diminished activities in the posterior cingulate area are potentially compensated by enhanced activities in the ventromedial prefrontal and anterior temporal areas within the social brain. Hemispherical lateralization is also observed on such compensatory activities.