Atypical Age-Related Patterns of Neural Signal Complexity in Autism Spectrum Disorder

Autism spectrum disorder (ASD) is increasingly conceptualized as a neurodevelopmental condition involving atypical organization of large-scale neural dynamics. While EEG studies have largely focused on spectral power and connectivity, how neural signal complexity is organized across development in ASD remains poorly understood.

Resting-state EEG was recorded from 186 children aged 3-11 years, including children with ASD and typically developing (TD) peers. Participants were further categorized into preschool-aged and school-aged groups to examine developmental differences. Multiscale entropy (MSE) was computed across 20 temporal scales to characterize neural signal complexity, and group differences, age-related patterns, and associations with autism symptom severity were examined.

Across the full sample, children with ASD exhibited significantly higher MSE than TD children across brain regions and temporal scales. Group differences were most pronounced in preschool-aged children, whereas in school-aged children they were more restricted to lower temporal scales and frontoparietal regions. In TD children, MSE increased robustly with age across scales, while age-related associations in ASD were more variable and region-specific. Additionally, individual differences in MSE were associated with autism symptom severity, particularly in frontal and parietal regions.

These findings indicate that ASD is characterized by atypical developmental organization of neural signal complexity across temporal scales, underscoring the importance of a multiscale developmental perspective for understanding neural dynamics in autism.