Gaze shift during optokinetic stimulation in head free cats.

During horizontal optokinetic stimulation (moving random dot pattern) in freely standing cats, gaze, head, and eye movements were measured with the search coil technique. The position values ('beating field') were evaluated. Gaze position depended on stimulus direction and stimulus velocity; it shifted to where the stimulus came from, the more the faster the stimulus velocity (mean values reached 15 degrees during high velocities). The head contributed about two-thirds of the gaze shift and eye-in-head about one-third, thus remaining near to the center of the orbit. During monocular optokinetic stimulation, the cats showed a directional asymmetry: a prominent position shift of gaze and head during temporal-to-nasal stimulation and almost no shift during nasal-to-temporal stimulation. It is discussed that the shift of gaze position represents an orienting movement towards a 'center of interest'.