421 Coherence Between the Subthalamic Nucleus and the Primary Motor Cortex in Patients With Parkinson's Disease

Abstract

INTRODUCTION: DBS is established as a safe and effective treatment for Parkinson’s Disease (PD). The development of second generation stimulators based on closed loop systems is dependent upon deeper understanding of the cortical control of motricity and its coupling with STN oscillations. METHODS: Experimental study on human subjects involving 10 patients with idiopathic PD with indication for deep brain stimulation implants into the STN. Primary motor area of the hands were identified preoperatively with fMRI. Corkscrew electrodes were implanted in the scalp to obtain C3-Cz and C4-Cz derivations of the EEG. Needle electrodes were implanted into the thenar and hypothenar muscles of both hands to record motor evoked potentials and voluntary myoelectric activity. At the time of implantation of the definitive macro-electrodes, the best contacts were connected to the electrophysiological monitoring device to record STN local field potentials (LFP) from 1 side at a time. During the next 3 minutes, the patient was asked to perform closing and opening movements of the hand contralateral to the implant. Simultaneously recordings of hand-EMG, EEG signals from M1, and STN field potentials were acquired for off line analysis. RESULTS: Our data indicate that during epochs of hand movements, theta and beta range components of the EEG related to M1 were significantly increased as compared with rest epochs. Additionally, we demonstrated that, during movement, the cross correlation between STN-LFP and M1 significantly increased (p < 0.001). CONCLUSION: Movement control is highly dependent upon theta and beta EEG components and upon a high coherence between STN and M1 specifically occurring during movement. The development of closed-loop stimulation devices should consider this physiology to reach better results.