Vestibulo-Ocular Refelex Gain as a Measure of Vestibular Function in Guinea PigsWhile in a Recompression Chamber: Apparatus Design and Effects of Nitrogen Narcosis

摘要

There are several mechanisms whereby alteration of barometric pressure canproduce vertigo in divers or aviators. Development of a reliable measure of vestibular function in an animal model is the first requirement for fiber study of these mechanisms. This report presents the development of a rotatory table device capable of evoking the vestibulo-ocular reflex (VOR) of a guinea pig while in a hyperbaric chamber. To assess the reproducibility of this response, eight animals were monitored by electronystagniography during rotations at three table velocities (62.4,% 83.3, and 100 degrees/s). Two test sessions were performed on each animal with a 6-hour interval between sessions. The VOR gain was calculated by dividing the average peak velocity of the slow phase component of the nystagmus by the peak stimulus velocity. At least eight observations per test speed were averaged; calibration of eye movement was performed prior to each session by forced ocular abduction. Multifactorial analysis of variance revealed no significant differences (p> .05) between the differing rotation speeds nor between test sessions for individual animals. However, there was a significant difference in VOR gain between animals (p <.002). The VOR gain was then measured, using the same techniques, in another group.