ABSTRACT
The vestibular and optokinetic systems are intrinsicly three-dimensional (3D) trying to stabilize the retinal image in all three rotational degrees of freedom. Only 3D eye movement recording techniques will suffice to describe the complex dependence of the elicited eye movements on the stimulation condition. The lateral canal plane vectors (CPV) response corresponds to horizontal nystagmus, the posterior and anterior CPV responses are eye movements with various combinations of vertical and torsional components. The search coil signals were sampled with 100 Hz, and 3D eye angular position and velocity were computed off-line using the algorithms described by D. Tweed and coworkers. In standard caloric position the eye velocity vectors clustered in all subjects closely along the direction expected from an excitation of the right horizontal semicircular canals. The eye velocities during maximal BPPN were closely aligned with the axes of the involved canal.
