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Changes in vestibulo-ocular reflex (VOR) anticipate changes in vergence angle in monkey.
L H Snyder1, D M Lawrence, W M King
1Department of Physiology, University of Rochester Medical Center, NY 14642.
Vision Research
|March 1, 1992
Summary
The vestibulo-ocular reflex (VOR) stabilizes vision during head movements. This study found that the VOR adjusts based on a central command signal, not eye position feedback, anticipating visual target changes.
Area of Science:
- Neuroscience
- Ophthalmology
- Vestibular System
Background:
- The vestibulo-ocular reflex (VOR) stabilizes gaze during head movements by compensating for head motion.
- Accurate VOR requires modulation based on viewing distance to stabilize retinal images.
- The neural basis for modulating VOR with viewing distance is unknown.
Purpose of the Study:
- To investigate the neural mechanisms underlying VOR modulation based on viewing distance.
- To determine if VOR adjustments rely on efference copy or afferent feedback of vergence eye position.
Main Methods:
- Monkeys performed vergence eye movements while undergoing brief rotational stimuli.
- The amplitude of the VOR was measured during these vergence movements.
- The time-course of VOR changes was compared with the time-course of vergence angle changes.
Main Results:
- The amplitude of the VOR systematically varied with the vergence eye movement.
- Changes in VOR amplitude anticipated vergence angle changes by approximately 50 ms.
- Anticipation of vergence changes by the VOR reached up to 200 ms in some cases.
Conclusions:
- The findings suggest that a central neural command signal, not efference copy or proprioceptive feedback, modulates the VOR.
- This central signal likely encodes viewing distance to ensure accurate visual stabilization.