Neuroplasticity in Parkinson's Disease

Inclusion Criteria:

Participants with PD

* Diagnosis of idiopathic PD, as determined by a movement disorders neurologist in accordance with the PD Society Brain Bank diagnostic criteria
* Not receiving levodopa or dopamine agonist to treat PD (at baseline)
* Able to ambulate independently without the use of an assistive device (e.g. cane) for 50 meters Healthy Controls
* Age- (+/- 3 years) and sex-matched to participants with PD
* Able to ambulate independently without the use of an assistive device (e.g. cane) for 50 meters

Exclusion Criteria:

* Dementia diagnosis and/or a University of California Brief Assessment of Capacity to Consent (UBACC) score and MacCAT-CR score indicating impaired capacity to consent
* History of musculoskeletal disorders that significant affect movement of lower or upper limbs as determined at the time of enrollment
* History of bipolar disorder, post-traumatic stress disorder or major depressive disorder
* Other significant neurological disorders that may affect participation or performance in the study
* Implanted DBS or other neurosurgeries to treat PD
* Pregnancy

Additional exclusion criteria for TMS experiments (note that individuals who are excluded from the TMS experiment still have the opportunity to participate in the other data collection sessions):

* History of seizures, epilepsy, stroke, multiple sclerosis, or traumatic brain injury
* Recent history of frequent syncope (fainting) episodes in response to blood, emotional stress, or sensory triggers.
* Intracranial metallic or magnetic devices (e.g. cochlear implant, deep brain stimulator)
* Pacemaker or any implanted device
* History of surgery on blood vessels, brain, or heart
* Unexplained, recurring headaches or concussion within the last six months
* Severe hearing impairment