Abstract
We examined to investigate the sensory conflict theory hypothesizing for the space motion sickness. In the last meeting, we reported results of equilibrium tests while subjects were exposed to simulating condition using reversing prisms; shift of deviation angle in vertical writing test, elongation of total length and start-end distance in square drawing test. Under the reversing visual conditions, moreover, transitional positions of stepping test were localized similarly to those under blindfolded condition. Statokinesigram detected slight increases in trajectory length and enveloped area, decrease in Romberg ratio, and an increase in power spectrum ratio. These modifications were more significant in right-left reversing prisms than in up-down inversing ones. Therefore the reversing prisms were more suitable for simulating experiment in the space motion sickness than inversing prisms. In the present study, we investigated cardiac responses and electrogastrography (EGG) during simulating condition caused by reversing prisms. Experimental protocol was quite same as the previous reports. Only 7 of all 21 subjects completely tolerated for 6 hours. Their chief complaints were nausea, vertigo and a headache. Intolerable subjects revealed an increase of low frequency (LF) of R-R interval, a decrease in high frequency (HF), and an increase of LF/HF. We discuss effects of reversing prisms upon the cardiac responses as well as EGG, and also partly refer to mechanisms of space motion sickness. [Jpn J Physiol 54 Suppl:S245 (2004)]
