Inclusion Criteria:  Men and women between 50 and 90 years of age, without a diagnosis of severe dementia Carry a diagnosis of idiopathic Parkinson's disease based on the United Kingdom Parkinson's Disease Society Brain Bank clinical diagnostic criteria Have had symptoms of Parkinson's disease for at least 3 years Hospital's study-specific informed consent must be obtained Must have capacity to provide informed consent in English For female participants, confirmation that a menstrual period has not occurred in over 12 months, or that an effective form of contraception will be used during the study  Exclusion Criteria:  Inability to provide informed consent. Severe dementia History of epilepsy or brain surgery Severe tremor or dyskinesia that would interfere with EEG as determined by the PI Parkinson's patients with clinically significant medical or neurological conditions which may be an alternative cause of orthostatic hypotension, such as neuropathy, renal failure, heart failure, cardiac arrhythmias, severe diabetes, or spinal cord injuries The investigators will exclude patients who are treated with medications which can significantly lower blood pressure or heart rate, such as antihypertensive medications, diuretics, and alpha-blocking medications Presence of other known central nervous system disease that may interfere with performance or interpretation of EEG or TMS Presence of any implanted metal devices including, but not limited to, pacemakers, deep brain stimulators, vagal nerve stimulators, bladder stimulators, or cochlear implants.