Resting State Functional Connectivity of Social Brain Regions in Autism Spectrum Disorder: Correlate with Social Symptom Severity in ASD

Background:  Autism spectrum disorder (ASD) is neurodevelopmental disorder characterized by　qualitative deficits in social and emotional cognition (Baron-Cohen et al., 2005).　Recent functional neuroimaging studies of ASD in ‘social brain’ predict that deficits　of function in social brain regions impede social and emotional cognition in ASD. However, much work needs to be done in order to advance evidence for the social brain network in ASD because social brain is defined as the complex network of areas. 

Objectives:  The aims of the present research are (1) to test the hypothesis that lower intrinsic functional connectivity of social brain in ASD relative to individual with typical development (TD), using resting state functional MRI (rs-fMRI) and (2) to evaluate degree of lower intrinsic functional connectivity between social brain regions predicted symptom severity for social skill in individual with ASD.

Methods:  Using the seed-based approach and functional amplitude of low frequency fluctuation (fALFF) approach (Zou et al., 2008) based on rs-fMRI, we investigated intrinsic functional connectivity of social brain in 18 young male adults with high-functioning ASD (25.6 ± 7.2 years; full scale IQ [F-IQ] = 106.8 ± 13.9) compared to 26 age-matched young male adults from the TD group (23.9 ± 3.8 years; F-IQ = 113.3 ± 9.8). We also performed logistic regression analysis between functional connectivities and social skill symptom severity using AQ score.

Results:  ASD showed over 10 difference significantly lower strength of rs-FCs in the social brain seeds with right inferior frontal gyrus (IFG), left dorsal medial prefrontal cortex (dMPFC) and right amygdala (figure A). Moreover, the ASD group showed significantly lower strength of resting state functional connectivities from bilateral IFG, bilateral dMPFC, bilateral ventral medial prefrontal cortex (vMPFC), bilateral insula, bilateral middle cingulate cortex (MCC), right posterior cingulate cortex (PCC), bilateral amygdala, right fusiform gyrus (FFG), and bilateral temporal pole (figure B). In the logistic regression analysis, the strength of rs-FC among left IFG (R² = 0.380; p < 0.05), left dMPFC (R² = 0.415; p < 0.05), left insula (R² = 0.345; p < 0.05), right IFG (R² = 0.472; p < 0.05), and right amygdala (R² = 0.518; p < 0.05) were predictive of social skill symptom severity on ASD group.

Conclusions:  We found that not only are the lower intrinsic functional connectivity of social brain regions in ASD compared to TD, but also there are difference range of function connectivities in social brain regions in dMPFC, IFG, and amygdala. In particular, our findings suggest that lower functional connectivity of IFG, dMPFC, amygdala, and insula compared to other social brain regions involved in social and emotional cognition may impair the individual with ASD to experience social interaction which needed social and emotional cognition.