Objectives: The current study measured event-related potential (ERP) effects during an auditory oddball task in young children with autism, in order to examine the sensory, perceptual, and cognitive processing of auditory information in the disorder.
Methods: Participants include children with autism spectrum disorder (ASD), children with other developmental disabilities (DD), and neurotypically developing children (NT), between 4 and 12 years of age, with a mean age of 7. ERPs were collected during a passive listening task, during which participants watched a video of their choice, while ignoring sounds played over speakers. The stimuli consisted of 2200 standard tones, 100 duration deviant tones, 100 pitch deviant tones, and 100 novel sounds, randomly presented. Data was collected from 11 electrode sites and was analyzed using EEGLab and FieldTrip MATLAB functions. ERP components examined include (1) the P1, reflecting early sensory processes; (2) the N1 and mismatch negativity - MMN, reflecting pre-attentive perceptual processes; and (3) the P3a, reflecting post-sensory attentional processes.
Results: Preliminary results with 36 in the ASD group and 41 in the NT group suggest that children with ASD have an attenuated response to novel sounds. The P3a response for the comparison of novel sounds to standard sounds was significantly smaller in ASD. This component of the neural signal occurs relatively late (around 300 ms) and indicates post-sensory involuntary attention. Therefore, this finding suggests that the children with ASD show evidence of reduced attentional orienting to novel sounds in this passive listening paradigm. The children with ASD also had a smaller amplitude for the N1 for standard sounds, reflecting atypical pre-attentive perceptual processes even for standard, repeated tones.
Conclusions: These preliminary findings suggest atypical electrophysiology responses to sensory stimuli in children with ASD, particularly in the P3a. This may reflect abnormal attentional orienting to environmental novel stimuli, consistent with the prevalence of aberrant sensory sensitivities in many children with autism. Further analyses will include the developmental disabilities participant group to determine if these neural characteristics are specific to ASD. We will also examine relations between these ERP components and clinical sensory features in the participants with ASD.