On the first day of the study, after 4 weeks and after 8 weeks, all participants will have a gap detection test for sensory perception testing. The test uses eight plastic devices called JVP-Domes with ridges of different widths on the surface. The subject's arm and hand are held in palm-up position and the right index finger is tested for about 1 second 20 times with each dome. The subject is asked to report whether the direction of the dome is vertical or horizontal. The test takes about 30 minutes. Patients with dystonia will also have a their symptoms evaluated at these visits. The evaluation involves completing a written questionnaire and writing a paragraph.