Funding discontinued.

Deep brain stimulation (DBS) has become the primary surgical therapy for the treatment of motor symptoms associated with Parkinson's disease (PD), and for essential tremor (ET). Although an effective and relatively safe procedure with expanding indications, opportunities exist for the optimization of the current procedure.

The investigators therefore propose, in a group of patients undergoing DBS surgery for the treatment of PD or ET, to use a combination of high-field imaging modalities, intraoperative electrophysiology, external sensor interfaces, and computational modeling, to gather information on the utility of using these techniques to optimize DBS electrode placement and programming.

Inclusion Criteria:

• A diagnosis of idiopathic Parkinson's disease or essential tremor
• Ability to provide informed consent

Exclusion Criteria:

• Claustrophobia or other conditions that prevent undergoing MR imaging
• MMSE score < 23
• Significant neurological diagnosis other than PD or ET.
• Idiopathic dystonia

Subjects will be recruited from the population of patients undergoing DBS surgery at the University of Minnesota Medical Center, for the treatment of (1) Parkinson's disease, or (2) essential tremor.