The Journal of Neuroscience, February 15, 2003, 23(4):1104
BRIEF COMMUNICATION
Foveal Versus Full-Field Visual Stabilization Strategies
for Translational and Rotational Head Movements
Dora E.
Angelaki,
Hui-Hui
Zhou, and
Min
Wei
Department of Neurobiology, Washington University School of
Medicine, St. Louis, Missouri 63110
Because we view the world from a constantly shifting platform when
our head and body move in space, vestibular and visuomotor reflexes are
critical to maintain visual acuity. In contrast to the phylogenetically
old rotational vestibulo-ocular reflex (RVOR), it has been proposed
that the translational vestibulo-ocular reflex (TVOR) represents a
newly developed vestibular-driven mechanism that is important for
foveal vision and stereopsis. To investigate the hypothesis that the
function of the TVOR is indeed related to foveal (as opposed to
full-field) image stabilization, we compared the three-dimensional
ocular kinematics during lateral translation and rotational movements
with those during pursuit of a small moving target in four rhesus
monkeys. Specifically, we tested whether TVOR rotation axes tilt with
eye position as in visually driven systems such as pursuit, or whether
they stay relatively fixed in the head as in the RVOR. We found a
significant dependence of three-dimensional eye velocity on eye
position that was independent of viewing distance and viewing
conditions (full-field, single target, or complete darkness). The
slopes for this eye-position dependence averaged 0.7 ± 0.07 for
the TVOR, compared with 0.6 ± 0.07 for visually guided pursuit
eye movements and 0.18 ± 0.09 for the RVOR. Because the torsional
tilt versus vertical gaze slopes during translation were slightly
higher than those during pursuit, three-dimensional eye movements
during translation could partly reflect a compromise between the two
different solutions for foveal gaze control, that of Listing's law and
minimum velocity strategies. These results with respect to
three-dimensional kinematics provide additional support for a
functional difference in the two vestibular-driven mechanisms for
visual stability during rotations and translations and establish
clearly the functional goal of the TVOR as that for foveal visual acuity.
Key words:
eye movement; binocular; vestibular; vestibulo-ocular; vergence; kinematics; torsion; stereopsis
Copyright © 2003 Society for Neuroscience 0270-6474/03/2341104-05$05.00/0
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