Objectives: Here, we used resting-state EEG to examine high-frequency oscillatory activity in preschool-aged children with ASD and TD, age-matched controls. Children with ASD were enrolled in a 3-month intensive day treatment program, and EEG data was gathered prior to and at the end of treatment. Our objectives were to (a) compare gamma activity in ASD and TD children, (b) investigate change in gamma activity after a treatment program, and (c) examine region differences between the groups of children.
Methods: Resting-state EEG was obtained for 2 minutes while the children were sitting quietly in a dark room, watching a video of bubbles. EEG data were bandpass filtered from 1 to 50 Hz. Segments containing artifacts arising from eye or muscle movements were removed from subsequent analysis. Only subjects with a minimum of 30 seconds of artifact-free data were analyzed. Data was then transformed into the frequency domain using a Fast Fourier Transform. Frontal gamma power was compared between ASD and TD children without. In addition, EEG data prior to treatment was compared to EEG data after treatment among the children with ASD. Lastly, we examined regional differences in the TD, the pre-treatment ASD children, and the post-treatment ASD children.
Results: We collected adequate data from 11 typically developing children, 17 children with ASD pre-treatment, and 6 children with ASD post-treatment. The data show that pre-treatment ASD children have increased gamma power when compared to TD children, most significantly in the left frontal region (p=.018). Additionally, there was a trend showing a decrease in frontal gamma power from pre-treatment to post-treatment (p=.095).
Conclusions: Our very novel data show that frontal gamma power differentiates children with ASD from TD controls. Furthermore, it appears that frontal gamma activity decreases over the course of the treatment program. These data support the use of resting EEG as a biomarker of diagnosis and treatment outcome. As our sample size increases we will be able to further investigate these preliminary trends and their potential implications for ASD treatment programs.