Optokinetic nystagmus and after-nystagmus during a 6 hour bedrest study.

Conclusions: A lengthy alteration of gravity direction produced different effects on the intrinsic horizontal and vertical optokinetic oculomotor systems.

Objective: To examine both optokinetic nystagmus (OKN) and optokinetic after-nystagmus (OKAN) in a 6 h 6 degrees head-down bedrest study, in which the subjects were kept lying under simulated micro-gravity conditions.

Subjects And Methods: In six normal healthy adults, we repeatedly (five times) and comparatively studied OKN and OKAN evoked by horizontal and vertical stimuli.

[Changes in postural control mechanism after a long-time tilt].

In order to investigate the time-dependent dynamics of otolith organ-spinomotor function, we analyzed postural control biomechanically, in eight healthy adult volunteers, using a dynamic posturography (EquiTest System), before and after a four-hours lateral head and body tilt (90 degrees). After the tilt, a half of the subjects exhibited some changes. Their equilibrium scores decreased; i.