Alternate Hand Training or Affected Hand Training:

40 patients with stroke and 40 control subjects will participate over 7 visits. After completion of informed consent, subjects will undergo clinical assessments (Visit 1) which will involve testing for kinesthetic, visual, tactile and motor impairments and upper limb function. Visit 2, subjects will undergo no contrast MRI to identify lesion location. Healthy controls will not be imaged.

Visits 3-7 will involve psychophysical experiments to test adaptation with short-term Alternate Hand Training and Affected Hand Training. During 5 visits the subjects will grasp and lift an instrumented grip device of different weights, textures and shapes while data is being collected via surface electrodes from, upper arm and back muscles.

Alternate Hand Training or Affected Hand Training:

Subjects will be randomized into two groups one receiving Alternate Hand Training and the other receiving Affected Hand Training. The groups will be matched by age, gender, handedness, side of lesion, extent of motor impairment and lesion location. They will complete 17 Study visits.

Visits 1 and 2 will involve clinical assessments and MRI. Visit 3. Pre-intervention assessments involving grasping and lifting objects of different weights, textures and shapes while fingertip forces, finger and arm movements. Muscle activity and performance is measured.

Visits 4-15. Subjects will participate in 12 training visits for 1 hour a day, twice a week for 6 weeks.

Visits 16-17. Recovery of hand function will be measured by repeating the pre-intervention clinical and grasping assessments (in 2 visits) immediately after 6-weeks of training, and another 6 weeks later.

Participants will receive a training intervention with either the Alternate Hand Training Strategy, or Affected Hand Training alone.

5 experiments will be performed over 7 visits to examine the best approach to retrain adaptation.

Subjects will be randomized to Alternate Hand Training or Affected Hand Training arms and receive training twice a week for 6 weeks.

Recovery of hand function will be measured by repeating the pre-intervention clinical and grasping assessments 6-weeks after the end of training.