NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Parabolic flight reveals independent binocular control of otolith-induced eye torsionTo examine otolith-governed ocular torsion in hyper- and hypogravity, eight subjects, including two astronauts, underwent parabolic flight while seated upright with head fixed. A mask fitted with two video cameras provided synchronized images of both eyes at a rate of 25/sec during 15 parabolas, the individual parabolas separated by a few minutes of level 1 G flight. Three main findings emerged: 1) After the first parabola, most subjects showed differential torsional offset of the two eyes in the 1 G portions between parabolas, compared to the conjugate baseline position of the eyes prior to the first parabola. 2) Changes in binocular torsion in the 0 G and 1.8 G portions of parabolic flight revealed in most subjects systematic reversal of direction. The reversal was consistent within, but not across subjects. 3) Disconjugacy defined as the moment-to-moment difference in the movements of the two eyes, and evaluated without the contribution of the differential offset, found two subjects with relatively high disconjugacy scores, and the remaining six with low scores. On the basis of prior studies (9, 20), we would predict the first two would be subject to SMS, the remainder not. The two astronauts, who did not have SMS on their space missions, fell into the low scoring group. We propose that the disconjugacies may be due to intrinsic asymmetries in the otolith receptors on the two sides of the head, which appear to be independently linked to the extraocular muscles of the two eyes, a phenomenon masked in normal 1 G states by adaptation. The apparently independent control of the two sides cannot be detected by the simpler and more common monocular studies.
Document ID
20040141735
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Markham, C. H.
(University of California Santa Barbara, 93106, United States)
Diamond, S. G.
Stoller, D. F.
Date Acquired
August 22, 2013
Publication Date
January 1, 2000
Publication Information
Publication: Archives italiennes de biologie
Volume: 138
Issue: 1
ISSN: 0003-9829
Subject Category
Aerospace Medicine
Distribution Limits
Public
Copyright
Other
Keywords
Non-NASA Center
Flight Experiment
NASA Discipline Neuroscience
short duration
Parabolic Flight
manned

Available Downloads

There are no available downloads for this record.
No Preview Available