The purpose of this clinical trial is to evaluate the safety and effectiveness of ONO-2808 in patients with Multiple System Atrophy with cerebellar variant (MSA-C)and Multiple System Atrophy with parkinsonian variant (MSA-P).MSA is a rare, rapidly progressing, fatal, adult-onset neurodegenerative disorder of the central and autonomic nervous systems that is characterized clinically by a variable combination of parkinsonism, cerebellar impairment, and autonomic and motor dysfunctions ONO-2808 is an investigational drug meaning that its safety, effects, and how it works are still being studied. This is a randomized (assigned by chance), placebo-controlled study, which means that some participants will receive a fake treatment (placebo) while others get the real treatment. The placebo treatment looks like the ONO-2808 medications but doesn't contain any active ingredient. The medication is in pill form and will be administered orally. This research is also double-blind, meaning that neither the participants nor the researcher will know which treatment they will be receiving. If participants choose to take part in the study they will be asked to attend up to 16 visits and the study will take up to 34 weeks. During the study, participants will be asked to go through a screening period (up to 6 weeks). The purpose of this screening period is to make sure study participants meet all the study criteria. If participants meet all study criteria, they may be asked to volunteer for the double-blind treatments. The duration of the double-blind treatment is 24 weeks which consists of 14 visits, some visits will be done at the study center/ hospital and the remaining visits will be done by a nurse from IQVIA's Research Nurse and Phlebotomy Solutions (RNPS) at participants' home. During visits, participants should anticipate tests including electrocardiograms (ECGs), vitals measurements (including temperature, blood pressure, and heart rate), and a physical/neurological examination. Some of the risks include nausea, vomiting, abdominal pain, loss of appetite, dark urine, yellow eyes, and persistent fatigue.

For this study, we are recruiting 54 individuals with Parkinson's Disease and Freezing of Gait (FOG) who are planning to undergo Deep Brain Stimulation (DBS). The objective of this study is to better understand the FOG response to DBS. Prior to DBS study participants will undergo a MRI scan, behavioral assessment related to walking, a cognitive evaluation, and assessment of other Parkinson's disease symptoms. Following DBS participants will repeat these assessments at multiple timepoints over the period of one year. Overall, participants will complete a total of 7 visits over a period of approximately 1 year.

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.