Associations between symptom severity in autism and functional neuroimaging measures of audiovisual speech perception

Individuals on the Autism Spectrum do not benefit as much from visual articulatory cues when compared to neurotypicals, especially under noisy environmental conditions. We hypothesized that this deficit would vary with the severity of Autism related symptoms and assessed this relationship in a behavioral speech-in-noise task (n = 32) and a functional neuroimaging study (n = 37). We found that Calibrated Symptom Severity Scores (CSS) were associated with poorer audiovisual performance but not performance in the auditory-alone condition indicating that impairments are limited to multisensory (MS) information processing. These findings underscore the validity of MS deficits and their potential relevance to the broader symptomatology in Autism. We also found that CSS significantly correlated with hemodynamic responses to audiovisual stimulation. Here, higher symptom severity was associated with lower multisensory gain in dorsal speech and language regions. Subsequent exploratory analysis suggested that individuals with Autism may not engage speech motor regions in similar ways to typically developing (TD) individuals.