Impaired midfrontal‑motor theta phase synchronization characterizes maladaptive motivational behavior in people with obsessive‑compulsive disorder.

Obsessive‑compulsive disorder (OCD) is characterized by an insight‑action dissociation, in which people with OCD recognize that their behavior is irrational but still struggle to inhibit habitual responses. This dissociation may be related to abnormally strong motivational biases, reflected in excessive tendencies to approach reward and avoid punishment. We employed a motivational Go/NoGo learning task, combined with computational modeling and electroencephalography (EEG), to investigate how 36 people with OCD and 37 healthy controls (HC) regulate maladaptive biases during motivated action. People with OCD showed stronger Pavlovian bias and lower learning rates. Similar to HC, people with OCD also showed increased midfrontal theta power related to conflict detection and to the generation of a control demand to increase the weighting of instrumental action values during choice, suggesting that they were able to detect the mismatch between their behavior and task goals. However, in OCD, conflict‑related theta enhancement overlapped with the response window, indicating that control signals emerged or arrived too late to effectively influence choice. Midfrontal‑motor theta phase synchrony provided the strongest model evidence for the modulation of maladaptive biases in OCD, yet this pathway showed no significant conflict‑related enhancement and failed to effectively modulate motivational biases under conflict. Taken together, these findings suggest a neural mechanism underlying the insight‑action dissociation in OCD and identify midfrontal‑motor theta phase synchrony as a potential treatment target.