Multisensory processing in children with autism: High-density electrical mapping of auditory-somatosensory integration

Successful integration of signals from the various sensory systems is crucial for normal sensory-perceptual functioning, allowing for the perception of coherent objects rather than a disconnected cluster of fragmented features. Several prominent theories of autism suggest that automatic integration is impaired in this population, but there have been few empirical tests of this thesis. A standard electrophysiological metric of multisensory integration (MSI) was used to test the integrity of auditory-somatosensory integration in children with autism (N=17, aged 6-16 years), compared to age- and IQ-matched typically developing (TD) children. High-density electrophysiology was recorded while participants were presented with either auditory or somatosensory stimuli alone (unisensory conditions), or as a combined auditory-somatosensory stimulus (multisensory condition), in randomized order. Participants watched a silent movie during testing, ignoring concurrent stimulation. Significant differences between neural responses to the multisensory auditory-somatosensory stimulus and the unisensory stimuli (the sum of the responses to the auditory and somatosensory stimuli when presented alone) served as the dependent measure. The data revealed group differences in the integration of auditory and somatosensory information that appeared at around 175ms, and were characterized by the presence of MSI for the TD but not the autism spectrum disorder (ASD) children. Overall, MSI was less extensive in the ASD group. These findings are discussed within the framework of current knowledge of MSI in typical development as well as in relation to theories of ASD.