An empirical note on tonic neck reflexes: control of the upper limb's proprioceptive sensation.

The effect of asymmetrical tonic reflexes on the upper limb in man was studied by analyzing errors in reproducing a targeted movement in right elbow extension following head rotation and vibration of the neck muscles. Overshoot of reproduction was observed only when the head was rotated to the left in contrast to no rotation or with rotation to the right. However, there was no influence on errors of reproduction after vibration of the neck muscles. These observations suggest that the proprioception in the rotated head controls the kinesthetic input by peripheral sensory receptors, namely, vestibular input plays a greater role in the accurate positioning of the upper limb, especially in inhibiting sensory input from the opposite side of the rotated head.