Propensity to Develop Plasticity in the Parieto-Motor Networks in Dystonia From the Perspective of Abnormal High-Order Motor Processing

Background: \- People with dystonia have muscle contractions they can t control. These cause slow, repeated motions or abnormal postures. People with dystonia have abnormalities in certain parts of the brain. Researchers want to study the activity of two different brain areas in people with writer s cramp and cervical dystonia. Objective: \- To compare brain activity in people with dystonia to that in healthy people. Eligibility: * Right-handed people ages of 18-65 with cervical dystonia or writer s cramp. * Healthy volunteers the same ages. Design: * Participants will be screened with a physical exam. They will answer questions about being right- or left-handed. * At study visit 1, participants will:\ * Have a neurological exam. * Answer questions about how their disease impacts their daily activities. * Have a structural magnetic resonance imaging (MRI) scan. Participants will lie on a table that can slide \in and out of a metal cylinder. This is surrounded by a strong magnetic field. * Do 2 simple computer tasks. * At study visit 2: * Participants will have transcranial magnetic stimulations (TMS) at 2 places on the head. Two wire coils will be held on the scalp. A brief electrical current creates a magnetic pulse that affects brain activity. Muscles of the face, arm, or leg might twitch. Participants may have to tense certain muscles or do simple tasks during TMS. They may be asked to rate any discomfort caused by TMS. * Muscle activity in the right hand will be recorded by electrodes stuck to the skin of that hand.