Error-related brain activity in patients with obsessive compulsive disorder and in healthy controls

Obsessive-compulsive disorder (OCD) has been related to a hyperactive frontal-striatal-thalamic circuit and associated with altered mechanisms of action and error monitoring. In the present study, we examined whether these results only hold for errors in choice reaction time experiments and Stroop tasks or extend to errors of commission in a Go/NoGo task, as well. We investigated the electrophysiological correlates of error monitoring in 11 patients with OCD and 11 age-, sex-, and education-matched healthy controls using event-related potentials (ERPs). Participants performed a Go/NoGo task while a 64-channel EEG was recorded. Our study focused on three ERP components: the error-related negativity (ERN)/error negativity (Ne), the "early" error positivity ("early" Pe) reflecting automatic error processing, and the "late" error positivity ("late" Pe), which is thought to mirror the awareness of erroneous responses. Artifact-free EEG-segments were used to compute ERPs on correct Go trials and incorrect NoGo trials (i.e., errors of commission), separately. Patients with OCD showed enhanced (more negative) ERN/Ne amplitudes compared to control subjects. Groups did not differ with regard to the early Pe component and the late Pe component. Our results support the view that compulsivity in OCD patients is related to hyper-functioning error monitoring processes.