Abstract
Abstract: The present study investigated the tonic vibration reflex (TVR) in humans elicited by vibratory stimulation applied to the muscle of the triceps brachii and examined the effects of rotation of the neck on misperception of movement of the elbow. Fifteen healthy subjects actively flexed their elbows from 0° to 90° for 3 s with their eyes closed. During the time that the elbow was flexed, vibratory stimulation (100 Hz) was applied to the tendon of the right triceps brachii. In the first experiment, only the right elbow was flexed (one-arm experiment), whereas in the second experiment both elbows were flexed simultaneously (two-arm experiment). In the two-arm experiment with vibratory stimulation, the mean ( ± SD) angle of the elbow was 63.2 ± 11.2° with neck rotation at 0°, which decreased significantly to 53.0 ± 15.5° (P < 0.05) when the neck was rotated back to 0° from the position of maximal right rotation. This suggests that there is an asymmetric tonic neck reflex as a result of neck movement, with the pathways involved in the crossed extension reflex enhanced by the simultaneous movement of both elbows. The TVR is an effective tool with which the convergence of various reflexes on α-motor neurons innervating the muscles of the extremity can be examined.
