The purpose of this research study is to identify brain activation patterns in response to deep brain stimulation (DBS). To participate in this study, participants are required to have had a DBS implant or to be healthy controls without a history of a neurological disorder. Participants will undergo screening, a motor assessment session and a 30-minute Magnetic Resonance Imaging (MRI) session where their DBS device will be turned on and off in a cycled pattern. This study will be separated over 3 visits (Visit 1 for screening, Visit 2 for motor assessments and Visit 3 for the MRI scans). The total study duration will be approximately 5 hours.

Parkinson's disease and stroke can cause lasting changes in walking and mobility. Non-invasive brain imaging methods including Magnetic Resonance Imaging (MRI) have been useful tools to understand the brains contribution to disrupted gait. In this study we are evaluating how activity in the brain in stroke and Parkinson participants changes when they are engaged in a gait-like behavior in the MRI scanner. We are seeking to recruit 10 participants with a diagnosis of PD, 10 participants with a history of stroke, and 10 age matched healthy control participants without a diagnosis of PD to undergo an hour of MRI scanning and an hour of gait assessments.