Eye movements in normal subjects induced by vibratory activation of neck muscle proprioceptors

Versional eye movements, induced by neck muscle vibration at 70 Hz in 8 normal subjects, were recorded with infrared reflection technique in each eye separately with one eye fixating a target and the other covered. The direction of eye movements was horizontal when the sternocleidomastoid muscle on one side of the neck and the splenius on the other side were activated, and downward when both splenii muscles were vibrated. The direction was the same as that of the illusory movements of the target also induced by the vibration. These findings would imply that the proprioceptive messages originating in the neck muscles are processed together with visual information of eye position in determining gaze direction.