Use of Sensory Substitution to Improve Arm Control After Stroke

This study has two distinct aims. In aim 1, data will be collected across four days:

Day 1: Participants complete baseline screening including a test of cognition (Montreal
Cognitive Assessment), clinical tests of sensory and motor function (Fugl-Meyer Assessment,
two-point discrimination, vibration sensation) and a robotic test of proprioception (Arm
Movement Detection Test).

Day 2: Participants will have their more affected hand wrapped around a robot handle. They
will either perform reaching-type movements or hold the handle still if it attempts to make
small movements. During these tasks, participants will receive vibrotactile feedback on the
other arm which will provide information about hand position and/or hand speed to guide the
movements.

Day 3: Participants will perform the holding-still task from the previous day while also
performing a grip task. They will be cued to lightly squeeze and then relax their grip in the
more affected hand while they are holding the handle as still as possible. During this time,
they will be provided vibrotactile feedback to help them maintain hand position.

Day 4: Participants will perform the same task as the previous day. In this experiment, the
vibrotactile feedback will be provided to the opposite arm, opposite thigh or on the same
(grasping) arm.

In aim 2, data will be collected across ten days:

Day 1: Participants complete baseline screening including a test of cognition (Montreal
Cognitive Assessment), clinical tests of sensory and motor function (Fugl-Meyer, two-point
discrimination, vibration sensation) and a robotic test of proprioception (Arm Movement
Detection Test).

Days 2-10: Participants will use the more affected arm to reach to specific 'unseen' targets
in three-dimensional space, using vibrotactile feedback to guide the movement of the arm.
Once participants reach the location, they will be asked to squeeze and release the fingers.
View of a computer monitor will also be used during part of the experiment to help the
participants guide the hand. Participants will also be asked to perform a simulated feeding
task at the beginning or end of practice on each day.

Inclusion Criteria:

- stroke survivors who can perform our stabilization and grip modulation tasks and who

- had a single ischemic or hemorrhagic stroke of the middle cerebral artery (MCA) in the
chronic state of recovery (> 6 months post-stroke).

- ability to give informed consent and be able to follow two-stage instructions.

- mild-to-moderate motor impairment as assessed using the upper extremity (UE) portion
of the Fugl-Meyer Motor Assessment (FM); i.e., UE-FM score between 28 and 50
(inclusive) out of a possible 66.

- proprioceptive deficit at the elbow in the more involved (contralesional) arm.

- preserved tactile sensation in either the ipsilesional arm and/or thigh.

- a minimal active wrist extension of 5°.

Exclusion Criteria:

- Inability of subjects to give informed consent or follow two-stage instructions.

- subjects with a bleeding disorder.

- subjects with fixed contractures or a history of tendon transfer in the involved limb.

- subjects with a diagnosis of myasthenia gravis, amyotrophic lateral sclerosis or any
disease that might interfere with neuromuscular function.

- subjects who are currently using or under the influence of aminoglycoside antibiotics,
curare-like agents, or other agents that may interfere with neuromuscular function.

- subjects with a history of epilepsy.

- history of other psychiatric co-morbidities (e.g. schizophrenia).

- malignant or benign intra-axial neoplasms.

- concurrent illness limiting the capacity to conform to study requirements.

- Cardiac pacemaker, cardiac arrhythmia or history of significant cardiovascular or
respiratory compromise.

- subjects with profound atrophy or excessive weakness of muscles in the target area(s)
of testing.

- subjects with a systemic infection.