EVIDENCE FOR SEPARATE EYE AND HEAD POSITION COMMAND SIGNALS IN UNRESTRAINED RATS

Compensatory horizontal eye-head movements of unrestrained rats were r ecorded with search coils in a magnetic field in response to combined optokinetic plus vestibular sinusoidal oscillations (0.05-1 Hz). The v elocity contribution of compensatory slow head movements for image sta bilization was relatively small (about 30%). The beating field of ocul ar nystagmus shifted during each half cycle in quick phase direction. These changes in eye position were counterbalanced by concomitant chan ges in head position. As a result, the orientation of gaze position wa s kept straight ahead with respect to the body length axis. These resu lts imply independent and task-specific recruitment orders for the ocu lar and neck motor system.