Plasticity in the Spinal Cord to Enhance Motor Retraining After Stroke
Phase: NA
Conditions: Stroke, Cerebrovascular Accident, Hemiparesis
Sponsor: VA Office of Research and Development

Plasticity in the Spinal Cord to Enhance 
Motor Retraining after Stroke
NCT03645122
July 25, 2024

OBJECTIVE: Noninvasive neuromodulation targeting synapses that link corticospinal neurons 
onto the final common pathway via spike-timing-dependent mechanisms can alter distal limb 
motor output on a transient basis, yet these effects appear subject to individual differences. The 
objective of this study was to investigate how this form of noninvasive neuromodulation interacts 
with task repetition to influence early learning of force control during hand movements 
foundational to everyday tasks and susceptible impairment after neurological injury. 
 
DESIGN: Experiments were conducted using a within-subject, repeated-measures design 
involving separate testing sessions under three counterbalanced conditions that were 
randomized within a subject and pseudorandomized across subjects: Rest, Sham, and Active. 
During conditioning stimulation, single-pulse TMS was used to depolarize corticospinal 
terminals and electrical current as applied to the ulnar nerve to depolarize spinal motor neurons 
antidromically. Depolarization of corticospinal terminals and spinal motor neurons occurred with 
hand muscles at rest in the Rest condition. Depolarization of only spinal motor neurons occurred 
immediately after precision grip force was stabilized in the Sham condition. Depolarization of 
corticospinal terminals and spinal motor neurons occurred immediately after precision grip force 
was stabilized in the Active condition. In this way, comparisons of PCMS alone, task repetition 
alone, and PCMS during task repetition was possible. RMSE was measured at baseline and 
following conditioning stimulation at three separate time points under each condition to quantify 
force stability. 
 
STATISTICAL ANALYSIS PLAN: A 4 (time point) × 3 (condition) repeated-measures ANOVA 
was used to test for differences in RMSE. The Bonferroni test was used to correct for multiple 
comparisons.