STUDIES INTERINDIVIDUAL SUSCEPTIBILITY TO MOTION SICKNESS

Several different theories exist about the orign of kinetosis and the space adaption syndrome, with individual sensitivities differing signi ficantly. One explanation involves the hypothesis of a different otoli th mass between the right and left statolith organ and especially a di fference in the utricles. A difference in mass results in a different sensitivity to acceleration. For this reason we measured interindividu al variances in saccular and utricular otolith mass. Since the anatomy of the vestibular organ in vertebrates is based as similar principles , we selected fish (salmon and trout) as our study model to facilitati on preparations. The maximum difference in mass in the saccule was 17% and was generally smaller in the utricle, although in individual case s was much higher. We assume that a misbalanced sensitivity of the sta tolith organs occurs but is totally compensated for by the vestibular system as long as physiological motion patterns take place. Decompensa tion leads to kinetosis under non-physiological motion patterns. When the vestibular system is better balanced and has an equally distribute d otolith ii mass to both sides, the possibility for developing kineto sis or space adaption syndrome is much less likely.