Is central optokinetic nystagmus gravity-dependent?
Grigorova, V.; Kornilova, L.; Stambolieva, K.
Journal of Gravitational Physiology a Journal of the International Society for Gravitational Physiology 4(2): P107-P108
1997
ISSN/ISBN: 1077-9248 PMID: 11540664 Document Number: 480205
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?