Brain Activity Study for Parkinson's Disease

Inclusion criteria (PD participants): 1. Age \>18 years 2. Clinically definite, advanced idiopathic PD based on consensus criteria. 3. Normal, or essentially normal, preoperative brain MRI. 4. Patient is available for follow-up visits over the length of the study 5. Patient has elected to undergo DBS surgery as part of routine care, and subthalamic nucleus (STN) is determined as the appropriate surgical target Inclusion criteria (control participants): 1. Age \>18 years. 2. No diagnosis of PD, other movement disorder, or other significant neurological disease. Exclusion criteria (PD participants): 1. Age \<18 years. 2. Medical contraindications such as current uncontrolled hypertension, heart disease, coagulopathy, or other conditions that might increase the risk of surgery 3. Diagnosis or suspicion of atypical Parkinsonism (PSP, MSA, CBD) or drug-induced Parkinsonism, or significant neurological disease other than PD. 4. Diagnosis of psychogenic movement disorder based on consensus criteria 5. Prior DBS surgery or ablation 6. Clinical dementia and/or Dementia Rating Scale (DRS) score of \<5th percentile adjusted for age and education level, based upon routine pre-op NP testing. 7. Unable to withhold dopaminergic medications for at least 12 hours prior to scheduled visit Exclusion criteria (control participants): 1. Age \<18 years. 2. Previous diagnosis of PD, other movement disorder, or other significant neurological disease.