Is central optokinetic nystagmus gravity-dependent?
Up-down asymmetry of vertical optokinetic nystagmus (OKN) has been attributed to a potential effect of gravity. This suggestion has been supported by some investigations in microgravity where a reverse of up-down asymmetry (downward OKN greater than upward OKN) was found. In joint Bulgarian-Russian space experiment "Labyrinth", the part "Optokinez" was devoted to central OKN and its gravity dependence. We aimed at answering questions: 1) Was central optokinetic nystagmus gravity dependent, in particular vertical OKN? If it was: 2) What happened with up-down asymmetry in adaptation period to weightlessness and re-adaptation period to gravity. Furthermore, in our recent study (3) on upright standing humans we found a consistent downward prevalence in central vertical OKN. Thus, a new question arises: What determines the direction of up-down OKN asymmetry?
Grigorova
V
V
Institute of Physiology, Bulgarian Academy of Sciences, Sofia, Bulgaria.
Kornilova
L
L
Stambolieva
K
K
D005133:Eye Movements; D005260:Female; D006112:Gravitation; D006801:Humans; D008297:Male; D017120:Nystagmus, Optokinetic / Q000502:physiology*; D010037:Otolithic Membrane / Q000502:physiology*; D011187:Posture / Q000502:physiology; D013026:Space Flight; D014893:Weightlessness