The UCSF Movement Disorder and Neuromodulation Center is the largest center for the surgical treatment of Parkinson's disease and other movement disorders in Northern California. Dr. Phillip Starr and Dr. Jill Ostrem, the center's co-directors, are pioneers in the use of deep brain stimulation (DBS) therapy to treat conditions such as Parkinson's disease, dystonia, essential tremor, spasticity and chorea. The center is also leading several clinical trials (studies with human volunteers) to improve the understanding and treatment of these and other movement disorders.