Fronto-temporal connectivity is preserved during sung but not spoken word listening, across the autism spectrum.

Abstract

Co-occurrence of preserved musical function with language and socio-communicative impairments is a common but understudied feature of Autism Spectrum Disorders (ASD). Given the significant overlap in neural organization of these processes, investigating brain mechanisms underlying speech and music may not only help dissociate the nature of these auditory processes in ASD but also provide a neurobiological basis for development of interventions. Using a passive-listening functional magnetic resonance imaging paradigm with spoken words, sung words and piano tones, we found that 22 children with ASD, with varying levels of functioning, activated bilateral temporal brain networks during sung-word perception, similarly to an age and gender-matched control group. In contrast, spoken-word perception was right-lateralized in ASD and elicited reduced inferior frontal gyrus (IFG) activity which varied as a function of language ability. Diffusion tensor imaging analysis reflected reduced integrity of the left hemisphere fronto-temporal tract in the ASD group and further showed that the hypoactivation in IFG was predicted by integrity of this tract. Subsequent psychophysiological interactions revealed that functional fronto-temporal connectivity, disrupted during spoken-word perception, was preserved during sung-word listening in ASD, suggesting alternate mechanisms of speech and music processing in ASD. Our results thus demonstrate the ability of song to overcome the structural deficit for speech across the autism spectrum and provide a mechanistic basis for efficacy of song-based interventions in ASD.