Human Vestibulo-Ocular Response During 3-Gz Centrifuge Stimulation

摘要

The vestibulo-ocular reflex (VOR) and spatial orientation perceptions wererecorded in 15 subjects during a 3-Gz centrifuge run. These data were obtained to study two issues; first, to gain insight into reports of asymmetrical disorientation and disturbance during acceleration and deceleration of G-induced loss of consciousness (G-LOC) training centrifuges. Secondly, to study the effects of sustained vertical linear acceleration on the vestibular system. The centrifuge run consisted of an acceleration to 3-Gz in 19 s, sustained 3-Gz for 5 min, and a deceleration to 1 Gz in 19 s. The runs were repeated three times with the subject facing the motion, and three times with the subject's back to the motion. The VOR and spatial orientation perceptions from the eight subjects who completed all six runs were analyzed. The total VOR response during acceleration and deceleration of a centrifuge run is composed of interacting angular and linear VOR components. However, the VOR response did not correspond to reported asymmetries in pitch orientation perception between centrifuge acceleration and deceleration. During the constant velocity high G phase of a centrifuge run, a sustained up-beating (Lz) nystagmus was observed in 14 of the 15 subjects. For the eight subjects analyzed, Lz nystagmus was shown to be an individual subject characteristic, and displayed a range of mean magnitudes from 0 to 10 deg/s at 90 s. Assuming a normal visual suppression ratio of the VOR, the magnitudes of the Lz nystagmus in our subject sample did not appear sufficient to degrade visual acuity.