Altered functional connectivity of unimodal sensory and multisensory integration networks is related to symptom severity in autism spectrum disorders.

Background: Atypical sensory processing is a prevalent feature in autism spectrum disorders (ASD) and constitutes a core diagnostic criterion in the Diagnostic and Statistical Manual of Mental of Disorders, 5th edition (DSM-5). However, neurocognitive underpinnings of atypical unimodal and multimodal sensory processing and their relationships with autism symptoms remain unclear.

Methods: This study examined intrinsic functional connectivity (FC) patterns among five unimodal sensory and multisensory integration (MSI) networks in ASD with a large multi-site dataset (n = 646), and investigated the relationships among altered FC, atypical sensory processing, social communicative deficits, and overall autism symptoms with correlation and mediation analyses.

Results: Relative to typically developing (TD) controls, the ASD group demonstrated increased FC of the olfactory network, decreased FC within the MSI network, and decreased FC of the MSI-unimodal-sensory networks. Furthermore, altered FC was positively associated with autism symptom severity, and such associations were completely mediated by atypical sensory processing and social communicative deficits.

Conclusions: ASD-specific olfactory overconnectivity and MSI-unimodal-sensory underconnectivity lend support to the Intense World Theory and Weak Central Coherence Theory, suggesting olfactory hypersensitivity at the expense of multisensory integration as potential neural mechanisms underlying atypical sensory processing in ASD. These atypical FC patterns further suggest potential targets for psychological and neuromodulatory interventions.