Repetitive Motor Practice Impacts Neuromuscular System Plasticity in Healthy and Stroke Populations

Neuroplasticity is an important factor for upper-extremity stroke rehabilitation, yet the amount of neuromodulation achieved with an acute session of motor practice is not fully characterized. The objective of this study was to determine how engaging in isometric motor practice acutely influences motor control, dexterity, and neuromodulation. Thirteen healthy controls and 5 stroke survivors participated in 2 separate experiments. Assessments [Box and Block Test (BBT), force steadiness, Transcranial Magnetic Stimulation (TMS)] were completed immediately before and following motor practice. Two force steadiness trials were completed at 10 and 20% of the maximum voluntary contraction (MVC). The TMS outcome included an average of 12 suprathreshold stimulations with motor evoked potentials (MEP) amplitudes recorded. Data were analyzed using paired t-tests for each experiment. Both participant groups were able to move significantly more blocks with the hand that practiced, but not with the non-practicing side. Force steadiness and muscle activity significantly improved for both groups, yet the MEP amplitudes did not. These results suggest that a short intervention of isometric wrist extension can influence motor control and dexterity, but may have a slight impact on neuromodulation. This demonstrates the importance of better understanding how possible rehabilitation interventions influence neuroplasticity through neuromodulation.