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.