[Abstract Title]. - Society for Neuroscience

Support: NIH Grant R01-NS052509
Title: Effects of sensory manipulations on targeted arm movements after stroke
Authors: *M. O. CONRAD, R. A. SCHEIDT, B. D. SCHMIT;
Marquette Univ., Milwaukee, WI
Abstract: Stroke survivors commonly experience hemiparesis of the arm, resulting in decreased
strength and sensation in the limb as well as increased spasticity, discoordination, reduced range
of motion and instability of endpoint control. Because prior research suggests that sensory
information from hand and wrist musculature influences control of proximal joints, we
hypothesized that control of proximal musculature could be improved post-stroke by providing
augmented feedback from distal sensory systems. Here we study the influence of enhanced Ia
afferent input from distal forearm muscles on the kinematics of point-to-point reaching
movements (eg. endpoint stability and range of motion at the shoulder and elbow). Ten
hemiparetic, chronic stroke survivors were seated comfortably as they grasped the handle of a
horizontal planar two joint robot with their impaired hand. Participants made center-out reaching
movements in 8 directions in the horizontal plane. Movements were cued by the appearance of
targets on a screen that obstructed the view of the participant‟s arm. Visual feedback of hand
position was also projected as a cursor on the screen. After 80 baseline trials, custom designed
tendon vibrators (Faulhaber Group, Clearwater, FL) applied 70Hz vibration to the forearm flexor
tendons for 40 trials. Hand position, velocity and grip force data were compared prior to, during
and post tendon vibration. At baseline, stroke survivors generally experienced more success at
medial and lateral mobility than forward and backward movement, and often demonstrated
instability of the endpoint position about the target. Vibratory stimulation of the forearm altered
control of planar arm movements in stroke subjects. Endpoint stabilization was measured as the
variance in the tangential velocity after the primary reach towards a target was complete.
Vibratory stimulation enhanced stabilization in the upper arm as evidenced by a general decrease
in variance in tangential velocity at the end of the reaching movements. Removal of the stimulus
resulted in even greater increases in endpoint stabilization for those movements requiring
shoulder flexion and extension. Additionally, the presence of a vibratory stimulus tended to
decrease movement extent. Taken together, these results suggest that sensory stimulation of the
wrist and finger musculature alters motor control of the upper arm, particularly enhancing a
flexor response in the upper arm during planar reaches. After the removal of a vibratory
stimulus, additional improvements in endpoint stability suggest that neural plasticity may be
manipulated to promote improvements in movement kinematics post-stroke.
Disclosures: M.O. Conrad, None; R.A. Scheidt, None; B.D. Schmit, None.
Poster
276. Voluntary Movement: Stroke, Damage, or Disease