Patient description: The patient is a 55-year-old man who was recently diagnosed with Parkinson's disease. He is complaining of slowness of movement and tremors. His disease is ranked as mild, Hoehn-Yahr Stage I. His past medical history is significant for hypertension and hypercholesterolemia. He lives with his wife. They have three children. He used to be active with gardening before his diagnosis. He complains of shaking and slow movement. He had difficulty entering through a door, as he was frozen and needed guidance to step in. His handwriting is getting smaller. He is offered Levodopa and Trihexyphenidyl. He is an alert and cooperative man who does not have any signs of dementia. He does not smoke or use any illicit drugs.

Clinical trial eligibility criteria: eligible ages (years): 21.0-75.0,  Parkinson's Disease Potential participants must be undergoing DBS lead placement for Parkinson's Disease that requires them to be awake during microelectrode recording Potential participants have been treated with levodopa/carbidopa, and with a dopamine agonist, at the maximal tolerated doses as determined by a movement disorders neurologist Potential participants must have a Hoehn and Yahr stage >= 2 in the medications OFF state Potential participants must have documented improvement in motor signs on versus off dopaminergic medication, with a change in the Unified Parkinson's Disease Rating Scale motor (UPDRS III) score of >= 30% off to on medication. Patients with tremor predominant form of PD, quantified as a UPDRS tremor score in any one limb greater than or equal to 3 and UPDRS sum of axial score (speech, posture, gait, balance) less than or equal to 5, who do not reach the 30% threshold, may be included Potential participants must have evidence of complications of medication, e.g., wearing off signs, fluctuating responses and/or dyskinesias, and/or medication refractory tremor, and/or impairment in the quality of life on or off medication Potential participants must have the ability to understand instructions in English Potential participants are males or females between the ages of 21 and 75  Individuals who are pregnant, breastfeeding, or are capable of becoming pregnant and not using an acceptable method of birth control. Acceptable methods of birth control hormonal contraceptives, intrauterine device, abstinence or spermicide and barrier Individuals who have magnetic resonance imaging (MRI) scans demonstrating cortical atrophy out of proportion to age Individuals who have MRI scans showing focal brain lesions that could indicate a nonidiopathic movement disorder Individuals who have major comorbidity increasing the risk of surgery such as prior stroke, severe hypertension, severe diabetes, or need for chronic anticoagulation other than aspirin Individuals who have had any prior intracranial surgery Individuals who have clinically active depression defined according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) and scored on a validated depression assessment scale Individuals who have significant cognitive impairment and/or dementia as determined by a standardized neuropsychological battery Individuals who have a history of seizures Individuals who are immunocompromised Individuals who have an active infection