Ocular stability in the horizontal, frontal and sagittal planes in the rabbit

Eye and head movements in the horizontal, frontal and sagittal planes were recorded in the rabbit with a newly developed technique using dual scleral search coils in a rotating magnetic field. The compensatory eye movements elicited by passive sinusoidal oscillation deteriorated for frequencies below 0.1 Hz in the horizontal, but not in the frontal and sagittal planes. In the light gain was relatively independent of frequency in all planes and amounted to 0.82-0.69, 0.92-0.83 and 0.65-0.59 in the horizontal, frontal and sagittal plane, respectively. In freely moving animals, similar input-output relations were found. The stability of the retinal image thus proved to be inversely proportional to the amount of head movements associated with behavioural activity. Maximal retinal image velocities varied between 2-4 degree/s for a rabbit sitting quietly and 30-40 degrees/s during locomotor activity. Gaze displacements showed different characteristics in the various planes, possibly in relation with the structure of the retinal visual streak. Horizontal gaze changes were mainly effected by saccades. Gaze changes in the frontal plane were relatively rare and effected by non-saccadic, combined head and eye movements with temporary suppression of compensatory eye movements. Eye rotations in the sagittal plane, possibly functioning to adjust the direction of binocular vision vertically, were abundant and effected by large head movements in combination with a low gain of compensatory eye movements in this plane.