Use of Sensory Substitution to Improve Arm Control After Stroke

Inclusion Criteria: * stroke survivors who can perform our stabilization and grip modulation tasks and who * had a single ischemic or hemorrhagic stroke of the middle cerebral artery (MCA) in the chronic state of recovery (\> 6 months post-stroke). * ability to give informed consent and be able to follow two-stage instructions. * mild-to-moderate motor impairment as assessed using the upper extremity (UE) portion of the Fugl-Meyer Motor Assessment (FM); i.e., UE-FM score between 28 and 50 (inclusive) out of a possible 66. * proprioceptive deficit at the elbow in the more involved (contralesional) arm. * preserved tactile sensation in either the ipsilesional arm and/or thigh. * a minimal active wrist extension of 5°. Exclusion Criteria: * Inability of subjects to give informed consent or follow two-stage instructions. * subjects with a bleeding disorder. * subjects with fixed contractures or a history of tendon transfer in the involved limb. * subjects with a diagnosis of myasthenia gravis, amyotrophic lateral sclerosis or any disease that might interfere with neuromuscular function. * subjects who are currently using or under the influence of aminoglycoside antibiotics, curare-like agents, or other agents that may interfere with neuromuscular function. * subjects with a history of epilepsy. * history of other psychiatric co-morbidities (e.g. schizophrenia). * malignant or benign intra-axial neoplasms. * concurrent illness limiting the capacity to conform to study requirements. * Cardiac pacemaker, cardiac arrhythmia or history of significant cardiovascular or respiratory compromise. * subjects with profound atrophy or excessive weakness of muscles in the target area(s) of testing. * subjects with a systemic infection.