Atypical Sound Perception in ASD Explained by Inter-Trial (In)consistency in EEG

Area of Science:

• Neuroscience
• Developmental Psychology
• Clinical Psychology

Background:

• Autism Spectrum Disorder (ASD) is characterized by indifference to human voices, but research on voice perception in ASD yields conflicting results.
• Previous studies show either an absence of preferential voice response or increased activation to vocal sounds in ASD compared to typically developing (TD) individuals.
• Contradictory findings in children with ASD have been linked to atypical responses to environmental sounds.

Purpose of the Study:

• To investigate inter- and intra-subject variability in auditory processing in children with ASD.
• To clarify discrepancies in previous research on voice perception in ASD by re-analyzing electroencephalographic (EEG) data.
• To explore the relationship between auditory processing, clinical parameters, and communication abilities in ASD.

Main Methods:

• Re-analysis of EEG data from 16 children with ASD and 16 age-matched TD children.
• Estimation of intra-subject variability using single-trial analysis and inter-trial consistency for vocal and non-vocal sounds.
• Application of logistic regression to assess the relationship between EEG measures, age, and clinical parameters.

Main Results:

• Significantly larger inter-subject variability in response to non-vocal sounds was observed in children with ASD.
• A subset of children with ASD (7/16) exhibited reduced inter-trial consistency for non-vocal sounds, lacking the typical negative Tb peak.
• Children with ASD and reduced inter-trial consistency were younger, had lower verbal developmental quotients, and showed fewer vocal communication attempts.

Conclusions:

• Atypical processing of environmental sounds, characterized by reduced inter-trial consistency, may underlie the lack of social signal specialization in ASD.
• Heterogeneity in auditory processing contributes to discrepancies in ASD research findings.
• Auditory processing variability, particularly for non-vocal sounds, offers valuable insights for functional diagnostics and evaluating communication impairments in ASD, suggesting limitations in using only IQ or language abilities for subgrouping.