Influence of gravitoinertial force on vestibular nystagmus in man observed in a centrifuge.

The influence of gravity load on the vestibular system in man was investigated in a centrifuge operating on the free swing principle. The vertical vestibular nystagmus induced by acceleration to 3G was analyzed and compared with reference measurements during 1G. Our data indicate that the effects of increased gravity load include a prolonged decay time constant of upbeat nystagmus and a subject-dependent persisting upbeat nystagmus. In an attempt to explain these findings, an extension of the velocity storage model is proposed, with gravity as a second stimulus function in addition to angular acceleration.