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Brief Communication Foveal Versus Full-Field Visual Stabilization Strategies for
 

Summary: 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
Becauseweviewtheworldfromaconstantlyshiftingplatformwhenourheadandbodymoveinspace,vestibularandvisuomotorreflexes
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 im-
portantforfovealvisionandstereopsis.ToinvestigatethehypothesisthatthefunctionoftheTVORisindeedrelatedtofoveal(asopposed
to full-field) image stabilization, we compared the three-dimensional ocular kinematics during lateral translation and rotational move-
ments 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,singletarget,orcompletedarkness).Theslopesforthiseye-positiondependenceaveraged0.7 0.07fortheTVOR,
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 trans-
lation 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
thetwovestibular-drivenmechanismsforvisualstabilityduringrotationsandtranslationsandestablishclearlythefunctionalgoalofthe
TVOR as that for foveal visual acuity.

  

Source: Angelaki, Dora - Department of Anatomy and Neurobiology, Washington University in St. Louis

 

Collections: Biology and Medicine