Modulation of Vestibulo-Ocular Reflex (VOR) by Active Stabilization of Head to Trunk

Abstract

Horizontal vestibulo-ocular reflex (VOR) with covered eyes was tested in 15 healthy subjects sitting on a rotation chair (40°, 0.05, 0.1, 0.2, 0.33 Hz) under two conditions: (a) head fixed to chair by a neck support; (b) with instruction to turn the head together with the passively moved trunk. In situation (b), saccadic amplitudes/sec, nystagmus frequency, gain of nystagmus slow phase velocity and amplitudes of maximum eye shift were enhanced significantly. The phase of maximum eye shift changed from 180° up to 270° with respect to stimulus position. The distribution of nystagmus saccades over the stimulus period showed enhanced peak values and a slight phase shift.

Key Words:

• Vestibulo-ocular reflex (VOR)
• eye-head coordination
• cervico-ocular reflex (COR)