Abnormally Enhanced Midfrontal Theta-Band Activity During Response Monitoring in Youth with Obsessive-Compulsive Disorder

Background: Response monitoring, as reflected in the electroencephalogram (EEG) recording after commission of errors, has been consistently shown to be abnormally enhanced in individuals with obsessive-compulsive disorder (OCD). This has been traditionally quantified as error-related negativity (ERN) and may reflect abnormal neurophysiological mechanisms underlying OCD. However, the ERN reflects the increase in phase-locked activities, particularly in the theta-band (4-8 Hz), and does not reflect non-phase-locked activities. To more broadly interrogate midfrontal theta-band activity in a brain region essential for complex cognition, this study investigated theta-band abnormalities during response monitoring in OCD participants for a better understanding of the mechanism underlying the ERN. Methods: EEG data were recorded from 99 participants with pediatric OCD and 99 sex- and age-matched healthy control (HC) participants while they completed the arrow flanker task. Effects of Group (OCD, HC) and Response type (Error, Correct) on post-response theta-band total power and inter-trial phase coherence (ITPC) were examined using mixed analysis of covariance and Bayesian analyses controlling for sex and accuracy. Results: Theta-band total power was larger on Error than Correct trials and larger in OCD than HC participants, but there was no effect of response type between groups. Theta-band ITPC was larger on Error than Correct trials, but there were no group difference nor response type difference between groups. Correlations of theta-band total power and ITPC with clinical measures were overall small. Conclusions: Abnormally enhanced midfrontal theta-band total power, but not ITPC, may reflect ineffective heightened response monitoring or compensatory activity in pediatric OCD.