Role of Dopamine Receptors in Primary Focal Dystonias

Inclusion Criteria: * Age \>20 * Male or Female * Any race or ethnicity * Primary focal dystonia (arm or cranial) * Ability to give informed consent Exclusion criteria: * Family history of dystonia * Pregnancy (confirmed with negative urine pregnancy test in women of child bearing potential), breastfeeding * Exposure to radiation therapy * Any MRI contraindications such as foreign metallic implants, pacemaker, and aneurysm clip etc. * History of cardiac disease, uncontrolled hypertension, abnormal EKG during screening phase * History of exposure to any drugs affecting dopaminergic systems within the last 6 months (e.g. dopamine receptor blocking agents, cocaine, amphetamine, tetrabenazine, reserpine, L-dopa, dopamine agonists, as they might affect the dopamine receptor binding or endogenous dopamine). * Active depression (Beck Depression Inventory\_II \>14) * Cognitive impairment (Mini-Mental State Score \<27) * CNS active medications such as gabapentin or narcotics, muscle relaxants which might be given for pain in the 3 days prior to study * History of stroke, seizure, cerebral palsy, generalized dystonia, parkinsonism, inability to hold head still during the scanning time.