Effect of motor imagery coupled with voluntary movement on excitability of spinal excitability and its impact on accuracy in movement

Abstract

This study aimed to examine the effect of motor imagery (MI) coupled with voluntary movement on the excitability of spinal motor neurons and its impact on accuracy in movement. The study participants were eight healthy individuals (mean age: 20.1 years) with a Kinesthetic and Visual Imagery Questionnaire score of ≥3. First, the participants rested (rest). Second, the participants practiced adjusting finger-pinch forces at 20% of maximal voluntary contraction (MVC) using visual feedback (motor practice [MP]). Third, the participants adjusted the finger-pinch forces at 20% MVC without visual feedback (pinch task 1). Fourth, the participants performed MI. Fifth, the participants repeated pinch task 1 (pinch task 2). Sixth, the participants performed MI with actual motion using visual feedback (MP+MI). Seventh, the participants repeated pinch task 1 again (pinch task 3). Eighth, the participants rested again (rest 2). The F-waves were recorded in the rest, MP, MI, MP+MI, and rest 2 conditions. The indices of accuracy were measured for pinch tasks 1, 2, and 3. The accuracy in movement showed no significant differences among the tasks. The increase in the F-wave/M-wave amplitude ratio was determined by subtracting the value in the rest condition for each trial. Participants with improved accuracy showed moderately increased excitability of the spinal neurons.