We will test on persons with chronic impairment due to stroke:

1. whether the order in which robot therapy is delivered influences outcomes (shoulder-and-elbow before wrist vs. wrist before shoulder-and-elbow).
2. whether we should train the shoulder, elbow, and wrist at the same time or on different days.

The Effect of Proximal and Distal Training on Stroke Recovery:

Specific Aim 1. Test whether task specific wrist robotic training improves motor performance among persons with chronic impairment after stroke.

Specific Aim 2. Test whether the order in which robot therapy is delivered influences outcomes (shoulder-and-elbow before wrist vs. wrist before shoulder-and-elbow).

Specific Aim 3. Test whether there is generalization across different joints (shoulder & elbow vs wrist).

Specific Aim 4: Test whether there is any interference between training across different joints among persons with chronic impairment after stroke.

Briefly we will invite persons with chronic impairment due to stroke to participate in a study that will train them first on wrist for 6 weeks and then on the shoulder-and-elbow for an additional 6 weeks or vice-versa. A third group will train in alternate days for 12 weeks on the shoulder-and-elbow or the wrist, while a fourth group will be trained on the shoulder, elbow, and wrist on the same day. Outcomes will be measured using standard instruments as well as robot-based measures. We expect that results from this study will provide an objective basis for maximizing this kind of therapy.

Inclusion Criteria:

Patients will be included in the study if they meet the following criteria:

1. naïve subjects who have never experienced robot-assisted therapy as inpatients or outpatients;
2. first single focal unilateral lesion with diagnosis verified by brain imaging (MRI or CT scans) that has occurred at least 6 months prior;
3. cognitive function sufficient to understand the experiments and follow instructions (Mini-Mental Status Score of 22 and higher or interview for aphasic subjects);
4. average Motor Power score >= 1/5 or <= 3/5 (neither hemiplegic nor fully recovered motor function in 6 muscles of the shoulder, elbow, and wrist);
5. informed written consent to participate in the study.

Exclusion Criteria:

Patients will be excluded from the study if they have a fixed contraction deformity in the affected limb.