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Description
There is evidence of abnormal organization of functional brain networks in Autism spectrum disorders (ASDs); however, findings have been mixed, with reports of both increased and decreased functional connectivity (FC) between and within networks. The present study sought to investigate if children and adolescents with ASDs have increased network FC variability and atypical network segregation and integration, compared to TD peers. Archival functional and anatomical magnetic resonance imaging data was utilized from 91 children and adolescents with ASDs and 71 age-matched TD controls. To capture a broad range of functional domains, six neurotypical networks were selected: default mode network (DMN), central executive network (CEN), salience network (SN), motor network (MOT), visual network (VIN), and mirror neuron system (MNS). Within-network (WN) and outside-network (ON) masks were then created. Seed-based whole-brain functional connectivity analyses were conducted for each network node; the resulting correlations were Fisher r-to-z transformed. An index of network segregation and integration (NSI) was calculated for each participant and WN, ON, and NSI were compared between groups. Additionally, inter-subject spatial similarity correlations were performed both within and between groups, to assess network spatial variability. Group comparisons of WN, ON, and NSI yielded one significant difference: CEN WN connectivity was significantly greater in the ASD group. Step one of the spatial similarity analyses revealed that within group similarity was comparable between the ASD and TD groups for all comparisons except DMN ON, which was significantly decreased in the ASD group. Step two demonstrated that participants in the ASD group were significantly less similar to TD participants for DMN ON, SN ON, MOT ON, and MNS ON connectivity. The final step of the analysis demonstrated that ASD participants were, on average, more spatially similar to other ASD participants than to TD participants. The results indicated that the pattern of spatial connectivity observed within the ASD group was distinct but comparable to the pattern of spatial connectivity observed in the TD group and it was not influenced by differences in strength of network connectivity, suggesting that spatial similarity in the ASD group can be attributed to abnormal network integration and segregation.
