Prestimulus top-down reflection of obsessive-compulsive disorder in EEG frontal theta and occipital alpha oscillations

► OCD patients showed lower prestimulus frontal EEG theta power than normal controls. ► OCD patients showed task-related prestimulus modulation of EEG alpha/theta power. ► Prestimulus EEG dynamics of OCD is consistent with the default mode network model. ► Our findings can be applied to objective diagnosis of the degree of OCD symptoms.