Recovery from weakness due to stroke relies upon changes in the undamaged parts of the brain to compensate for the functions lost after stroke. Changes in brain function can be induced by stimulating two hand muscles simultaneously, but this technique currently has limited application because we do not fully understand how it works or how best to apply it. The proposed project will determine the optimal timing of paired muscle stimulation required to improve function in upper limb muscles important for arm function following stroke. The effects of paired muscle stimulation on hand function will be evaluated in a group of stroke survivors and age matched adults without neurological injury. The results of the project will help to improve existing treatments used in stroke rehabilitation.