1. Human Motor Control Section National Institute of Neurological Disorders and Stroke, National Institutes of Health Bethesda Maryland USA
2. Facultad de Medicina Clínica Alemana Universidad del Desarrollo Santiago Chile
3. Office of the Clinical Director National Institute of Neurological Disorders and Stroke, National Institutes of Health Bethesda Maryland USA
4. Wilmington Veterans Administration Medical Center Wilmington Delaware USA
5. Parkinson's Disease Clinic, Office of the Clinical Director National Institute of Neurological Disorders and Stroke, National Institutes of Health Bethesda Maryland USA