Characterizing the Pathophysiological Role of the Pallido-thalamocortical Motor Pathway in Parkinson's Disease.

The goal of this study is to understand the relationship between network brain activity and motor signs of Parkinson's disease, and to determine if brain activity can predict optimal locations or network pathways for stimulation. During deep brain stimulation lead placement surgery, research participants will have an FDA approved ECoG strip placed through the DBS lead burr hole over the primary motor cortex. The study team will record brain activity from the DBS lead and the ECoG strip simultaneously while the participant performs a reach-to-target motor task, to understand how different brain regions communicate and are associated with motor signs of Parkinson's disease. The study team will look for specific brain activity biomarkers hypothesized to be associated with Parkinson's disease and will then direct stimulation through the DBS lead toward regions showing those biomarkers and compare to stimulation directed to areas not showing the specified biomarkers. Neural pathways being activated by stimulation and behavioral measures of the reach task will be compared between the two stimulation conditions. Intervention: 1. Stimulation through the DBS lead contact showing the most coherence with brain activity in the motor cortex 2. Stimulation through the DBS lead contact showing the least coherence with brain activity in the motor cortex During the mapping session patients will either be asked to perform motor tasks such as finger-tapping, pronating/supinating the wrist, manipulating a joystick, or pointing to targets on a touch-sensitive, LCD positioned in front of them. Patients may also be asked to perform cognitive tasks such as maintaining items in working memory or deciding between potentially rewarding stimuli with either a joystick or a finger response pad.