2000 Volume 103 Issue 8 Pages 916-921
To investigate the dynamics of otolith and oculomotor function, we subjected volunteers to a lateral body tilt for a period of two hours and analyzed ocular counter-rolling. Six healthy adult volunteers were roll-tilted along the naso-occipital axis at a speed of 0°/sec. from the 0° earth vertical position to the 90° lateral tilt position.
After two hours, the volunteers were returned to the 0° earth vertical position.
Ocular counter-rolling was recorded using an infrared CCD camera. The video recordings were made in the dark while the volunteers had their eyes open. Recordings were obtained (1) as the volunteers was moved from the 0° earth vertical position to the 90° lateral position, (2) 5 minutes after reaching the lateral position, (3) during the roll-back from the 90° lateral position to the 0° upright position, two hours after the lateral tilt loading, and (4) 5
momites after reaching the final upright position.
The occurrence of ocular counter-rolling between the 0° upright position and the 30° tilt position was confirmed during both roll mavements from 0° to 90° and from 90° to 0°. The counter-rolling was most noticeable between the 0° and the 30° positions. No differences in ocular cournter-rolling during the roll-tilt and the roll-back situations were observed, These results indicate that the two-hour lateral tilt position did not produce any functional changes in the hair cells and/or the otolith-oculomotor system.
All of the subjects exhibited ocular counter-counter-rolling during the initial stage of their roll-back to a normal upright position. This phenomenon might result from the additional bending of the hairs by inertia during the initiation of the backward roll motion.
