Study of the Recovery of Muscle Function in the Arm/Hand After a Stroke

Stroke is a leading cause of long-term adult disability in the United States, and hemiparesis is the most common motor impairment that frequently leads to persistent deficits in hand function. The mechanisms of recovery of hand motor function after stroke are poorly understood, and the protocols used in clinical practice lack a solid scientific rationale. The long-term objective of this research is to understand the neural mechanisms underlying the recovery of voluntary motor functions in brain-injured patients in order to provide a more objective and scientific basis to rehabilitation protocols used in clinical practice. These devices will be used to facilitate the training of either unimanual or bimanual movements that can be used both in the acute and chronic post-stroke period, even when there is little active movement in the affected upper extremity. The specially designed mechanical devices (BAT, PST and WIFIT), Psychophysical methods using an instrumented glove, and electromyographic recordings from upper extremity muscles to investigate the following specific aims in patients with post-stroke hemiparesis will lead to: * greater extensor muscle activation and out of synergy movement compared with unimanual training facilitated by an external agent (e.g. another person). * Bimanual training with the specially designed mechanical devices (BAT, PST and WIFIT) over 6 weeks will produce greater functional recovery in the affected upper extremity in patients with post-stroke hemiparesis, compared with conventional therapy. * The gains in motor control and function will be greater in patients who begin bimanual training in the acute post-stroke phase (0-6) months, compared with those that begin in the chronic post-stroke phase (\> 6 months).