Several strategies or contexts help patients with Parkinson's disease to move more quickly or normally, however the brain mechanisms underlying these phenomena are poorly understood. The proposed studies use intraoperative recordings during DBS surgery for Parkinson's disease to understand the brain mechanisms supporting improved movements elicited by external cues. The central hypothesis is that distinct networks are involved in movement improvement depending on characteristics of the facilitating stimulus. Participants will perform movement tasks during awake surgery performed exclusively for clinical indications. The identified biomarkers may provide targets for future neuromodulation therapies to improve symptoms that are refractory to current treatments, such as freezing of gait.

Patients with Parkinson's disease (PD) will perform computer tasks involving reaching and tapping movements during video recording of movements and electrophysiological recording of brain signals during deep brain stimulation surgery. Experimental manipulations involve different computer stimuli that manipulate the presence or absence of sensory and motivational movement cues. The same experimental manipulations are delivered to all individual subjects. 40 PD patients who are undergoing deep brain stimulation (DBS) surgery for treatment of Parkinson's disease, will perform the tasks during awake surgery and recordings will be obtained from 2 implanted DBS electrodes as well as 2 temporary electrode strips placed on the surface of the brain for research purposes. Study procedures are limited to the intraoperative environment with no additional study visits. All patients will also be asked to perform clinical rating scales and questionnaires and undergo a movement disorders neurological exam.

Inclusion Criteria:

• Diagnosis of idiopathic Parkinson's disease based on presence of at least 2 cardinal PD features (tremor, rigidity, or bradykinesia)
• Undergoing deep brain stimulation surgery for treatment of advanced Parkinson's disease, according to clinical evaluation, including the following criteria:
• advanced idiopathic PD as determined by OFF unified Parkinson's Disease Rating Scale (UPDRS) part III motor subscale > 25
• L-dopa responsive symptoms with at least 30% improvement in UPDRS III scores on vs. off medication OR medication refractory disabling tremor
• Persistent disabling motor symptoms or drug side effects (dyskinesias, motor fluctuations, disabling "off" periods) despite optimal medical therapy
• preoperative MRI without evidence of cortical or subdural adhesions or vascular abnormalities
• Willingness and ability to cooperate during conscious operative procedure for up to 40 minutes

Exclusion Criteria:

• medical contraindication to surgery, including use of anticoagulant or antiplatelet therapy within 1 week
• significant cognitive or psychiatric disease based on clinical neuropsychological testing

Electrophysiological and behavioral data obtained during task performance will be made available upon request to Dr. Cross (PI) via secured server access. Data sharing agreement will be required for all requests.