Separate control of arm position and velocity demonstrated by vibration of muscle tendon in man.

The effect of muscle tendon vibration on the performance of some simple motor tasks and on kinesthesia was studied in normal humans. Subjects performed non-visually-guided slow arm movements to match either the position or the velocity of a visual target. In the experiments designed to study kinesthesia subjects indicated the perceived position or velocity of their passively moved arm. Vibration was applied over either the biceps or the triceps tendon. Position and velocity matching were found to be disturbed by vibration in essentially different ways, as were the perception of imposed position and the perception of imposed velocity. However, the vibration induced disturbance of position matching was congruent with the distortion of position perception. The effect of vibration on velocity matching was in accordance with the effect of vibration on the perception of velocity. It is concluded that the afferent information pathways that give rise to the perception of position and velocity respectively can be used separately in the control of slow movements under different conditions.