Auditory-Visual Multisensory Integration in Autism: an ERP study

Background:   It is widely believed that individuals with autism spectrum disorders (ASD) experience severe difficulties integrating inputs from the various sensory systems (sight, touch, hearing) – the so-called sensory integration theory of autism. While most typically developing individuals appear to integrate multisensory information effortlessly, many individuals with ASD reportedly find the sensory environment overwhelming. It has been hypothesized that a failure to integrate the sensory inputs into meaningful and manageable units is a major component of autism and related neurodevelopmental disorders. However, this has not been rigorously tested and is lacking direct neurophysiological evidence.

Objectives: Our overarching goal is to establish whether multisensory deficits are present in children with ASD and to characterize the neurophysiological basis of these deficits. Here we use high-density electrical mapping to investigate basic auditory-visual integration in children with ASD and children with typical development (TD).

Methods: Children with ASD and TD were matched for age, sex, and intellectual functioning. All participants were presented with auditory (simple tones) and visual (red circles) stimuli together or alone. The children performed a simple reaction-time task while recordings of electrical brain activity were made. Average ERP waveforms elicited from the auditory-alone condition and the visual-alone condition were summed for each participant. Comparisons were made between the ‘sum’ ERPs and the ‘simultaneous’ ERPs in both groups.

Results: Our preliminary findings suggest that the time course and scalp topography of multisensory integration processes are different in the children with ASD compared to the children with TD. In general the children with TD exhibited multisensory interactions that are more similar to those typically seen in adults while the multisensory interactions observed in children with ASD had markedly different temporal and spatial properties.

Conclusions:  Our data suggests that different cortical processes and regions are involved in integrating basic auditory-visual information for ASD and TD children.