Neurobiology of sensory deviance: Using EEG to measure visual and auditory mismatch negativity in children with autism

Sensory processing, in particular processing of sensory deviance in one's environment, is important for functioning in a fast-paced world. Deficits in sensory processing may underlie the deficits in social interaction, communication, and restricted or repetitive behaviors seen in autism. We can use Event Related Potential (ERP) research to investigate processing of sensory changes through the mismatch negativity (MMN), or a difference ERP waveform computed by subtracting a neural response to a frequently-occurring standard event from a rare deviant event. Until recently, most research has focused on mismatch negativity in the auditory modality, but there is evidence that visual mismatch negativity (vMMN) can provide important information about sensory processing in both typical development and autism. In addition, the ways in which auditory ERP components interact with behavioral responses to changing sensory stimuli measured through behavioral observations and parent reports are poorly understood. Preliminary results in the auditory modality showed that the amplitude of the P3a and N2 ERP components predicted high levels of sensory seeking behaviors, and further that this relationship was dependent on the amplitude of P1. This suggests that task orienting may be related to sensory seeking behaviors, given modulation by early mechanisms of stimulus detection. Preliminary data also indicate relationships between auditory ERP components and behaviorally measured sensory response patterns. The goal of this research was two-fold. The first aim was to characterize vMMN in typically developing 8-12-year-old children, and the second aim was to investigate differences in vMMN observed in children with autism. Results from this work showed that both typically developing children and children with autism display a vMMN with two negativities, while adults only display one negativity. Further, the first negativity observed in the children with autism occurred earlier than in the typically developing children, and amplitude of the second negativity correlated with age in the typically developing children only. These results suggest that children with autism may exhibit enhanced processing of basic stimulus features and attenuated processing of memory comparisons with standard events. Further research may result in improved intervention strategies customized to individual sensory processing deficit type and severity.