This group will use the AVK system in combination with targeted FES to provide training of independent movement of each digit of the paretic hand. This training has two modes: Key Combination and Song. In the Key Combination mode, the subject will attempt to play the discrete key or key combinations specified on the computer screen to practice difficult movements and combinations. In the Song mode, sequential, rhythmic movements will be practiced as the participant is guided to play a series of keys, specified as falling keys, constituting five-note songs. Key Combination will be employed at the beginning and end of each training session to practice discrete movements that proved troubling during the current or previous session. Most of the session will be spent in the Song mode to emphasize the transitions from one movement to the next. In both modes the AVK system will trigger FES for the finger matching the desired key and signal the PneuGlove to resist movement of other digits.

An occupational therapist will provide therapy of matching duration to the OT subject group. This will consist of 10 minutes of stretching of the finger muscles, particularly of the extrinsic finger flexors. This stretching will be followed by two 20-minute sessions of therapy focused on active task practice, object manipulation, and individuated movement of the digits. The Canadian Occupational Performance Measure (COPM) will be administered to identify goals that incorporate dexterous use of the paretic hand. Part of each training session will be used to practice these tasks, while the remainder will be used to practice component skills. Active practice will be followed by a final 10 minutes of stretching of muscles of the digits.

The participant controls an avatar hand by the movement of their own digits. Each avatar digit corresponds to a given virtual key. "Sufficient" digit flexion results in "playing" of that key, with visual and auditory feedback of key strike. Participants will wear a soft exoskeleton, the PneuGlove, with embedded bend sensors to provide real-time measurement of digit flexion. Pneumatic resistance to flexion can be applied to each digit independently, along with extension assistance, through air chambers running through the glove. The FES is intended to assist finger flexion by activating extrinsic finger flexor muscles. A high-density 2×8 stimulation electrode grid will be placed over the median and ulnar nerves at the medial side of the upper arm. The stimulator can deliver electrical stimulation to any pair of electrodes. At the beginning of each session, the investigators will identify the electrode pairs which best produce flexion of each digit with minimal discomfort.

A standardized and objective measure of fine and gross motor hand function using simulated activities of daily living.

Force produced when the thumb pinches against the radial side of the index finger as if holding a key.