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Dynamic properties of the human vestibulo-ocular reflex during head rotations in rollWe investigated the dynamic properties of the human vestibulo-ocular reflex (VOR) during roll head rotations in three human subjects using the magnetic search coil technique. In the first of two experiments, we quantify the behavior of the ocular motor plant in the torsional plane. The subject's eye was mechanically displaced into intorsion, extorsion or abduction, and the dynamic course of return of the eye to its resting position was measured. The mean predominant time constants of return were 210 msec from intorsion, 83 msec from extorsion, and 217 msec from abduction, although there was considerable variability of results from different trials and subjects. In the second experiment, we quantify the efficacy of velocity-to-position integration of the vestibular signal. Position-step stimuli were used to test the torsional or horizontal VOR, being applied with subjects heads erect or supine. After a torsional position-step, the eye drifted back to its resting position, but after a horizontal position-step the eye held its new horizontal position. To interpret these responses we used a simple model of the VOR with parameters of the ocular motor plant set to values determined during Exp 1. The time constant of the velocity-to-position neural integrator was smaller (typically 2 sec) in the torsional plane than in the horizontal plane (> 20 sec). No disconjugacy of torsional eye movements was observed. Thus, the dynamic properties of the VOR in roll differ significantly from those of the VOR in yaw, reflecting different visual demands placed on this reflex in these two planes.
Document ID
20050000222
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Seidman, S. H.
(Department of Veterans Affairs Medical Center Cleveland, Ohio)
Leigh, R. J.
Tomsak, R. L.
Grant, M. P.
Dell'Osso, L. F.
Date Acquired
August 22, 2013
Publication Date
March 1, 1995
Publication Information
Publication: Vision research
Volume: 35
Issue: 5
ISSN: 0042-6989
Subject Category
Aerospace Medicine
Funding Number(s)
CONTRACT_GRANT: EY06717
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Neuroscience
Non-NASA Center
NASA Program Space Physiology and Countermeasures
NASA Discipline Number 16-10

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