Increased Resting State EEG Gamma Power in Children with HFA

Background: There is a growing body of evidence indicating that individuals with autism spectrum disorder (ASD) show abnormal patterns of gamma (> 30 Hz) oscillations in their EEG. These abnormalities have been observed during perceptual and cognitive processing but more recently also during resting state conditions. Excessive power in the gamma frequency band has been argued to reflect abnormally high excitability of cortical structures and/or a temporal binding deficit. Resting state EEG studies on gamma power in children with ASD are however still scarce.

Objectives: To investigate resting state EEG gamma power in children with high-functioning autism (HFA).

Methods: A group of children (9 to 13 years) with HFA were compared with a group of age-matched typically developing peers. Eyes-closed resting EEG was measured for three minutes, using a 128-channel EEG system. Power in the gamma frequency band was extracted from the EEG signal and compared between groups.

Results: As hypothesized, children with ASD showed higher power in the gamma band. Importantly, this increase of gamma activity was found at electrode positions that are distant from potential sources of myogenic artefacts.

Conclusions: Excessive resting state EEG gamma power in children with ASD seems to represent a robust phenomenon, which may have important implications for diagnostics and interventions. However future studies are needed to investigate the specificity of the findings by directly comparing clinical groups and to elucidate the functional meaning of enhanced gamma in ASD.