Motor control of wrist and elbow unidirectional extension movement during muscle vibration and skin cold stimulation

Abstract

  We aimed to confirm kinesthetic illusion occurs in the spinal cord by using a skin cold stimulation. The main new findings of the present study are as follows: First, vibratory stimulation was applied to the antagonist muscle (FCU or BB) responsible for the simultaneous extension movements of the wrist and elbow. Movement of the agonist muscle undershot the target position of the wrist and elbow with FCU vibration, respectively. Similarly, elbow movement undershot the target position during BB vibration. Second, the movement errors consisted of significant overshoots during FCU vibration plus skin cold stimulation and correct attainment of the target during the simultaneous extension movements of the wrist and elbow. With skin cold stimulation of antagonist muscle (FCU), the rms-EMG of the agonist (ECR) significantly increased during the simultaneous extension movements of the wrist. In addition, correlation between rms-EMG of the ECR and TB was significant in FCU with vibration plus skin cold stimulation. We found that the illusory movement disappeared upon application of the skin cold stimulation, indicating the kinesthetic illusion in the spinal cord.