Emotions modulate subthalamic nucleus activity: new evidence in obsessive-compulsive disorder and Parkinson disease patients

Abstract Background Subthalamic nucleus (STN) deep brain stimulation (DBS) alleviates obsessive-compulsive disorder (OCD) symptoms, suggesting that this basal ganglia structure may play a key role in integrating limbic and motor information. We explored the modulation of STN neural activity by visual emotional information under different motor demands. Methods We compared STN local field potentials acquired in 7 obsessive-compulsive disorder (OCD) and 15 Parkinson’s disease (PD) patients Off and On-levodopa while patients categorized pictures as unpleasant, pleasant or neutral, and pressed a button for one of these 3 categories depending on the instruction. Results During image presentation, theta power increased for unpleasant compared to neutral images in both OCD and PD patients. Only in OCD patients was theta power also increased in pleasant compared to neutral trials. During the button-press in OCD patients, no modification of STN activity was seen on average but theta power increased when the image triggering the motor response was unpleasant. Conversely in PD patients, a beta decrease was observed during the button press unrelated to the valence of the stimulus. Finally, in OCD patients, a significant positive relationship was observed between the amplitude of the emotionally-related theta response and symptom severity (measured using Yale Brown OCD scale [YBOCS]). Conclusion We highlighted modulations of STN theta band activity related to emotions that were specific to OCD and correlated with OCD symptoms severity. STN theta induced activity might therefore underlie dysfunction of the limbic STN and its related network leading to OCD pathophysiology.