RecruitingEarly Phase 1Drug trialEffect of Neural Constraints on Movement in StrokeThis study investigates the effects of Tizanidine on the voluntary movement controls of the arms of participants who have had a stroke and have not had a stroke by measuring medication-induced changes in upper extremity kinematics, pupillometry, and brain activity. Tizanidine is approved by the U.S. Food and Drug Administration. Understanding how different areas of the brain are involved in movement impairments may help rehabilitation efforts and assist in restoring healthy movement in individuals who have had a stroke.