Vestibulo-ocular reflex suppression during head-fixed saccades reveals gaze feedback control

Area of Science:

• Neuroscience
• Ophthalmology
• Vestibular System

Background:

• The vestibulo-ocular reflex (VOR) stabilizes gaze during head movements.
• Previous studies show VOR suppression during active eye-head or passive head movements with active eye movements.

Purpose of the Study:

• To investigate VOR suppression during combined head and body rotations (en bloc gaze saccades).
• To determine if VOR modulation differs when gaze shifts involve the head and body together versus eye-only movements.

Main Methods:

• Human subjects performed saccades to track a target light.
• Passive body rotation (via chair) was applied before, during, or after saccades.
• VOR modulation was analyzed based on saccade amplitude and timing of body perturbation.

Main Results:

• VOR modulation during en bloc gaze saccades was dependent on saccade amplitude and perturbation timing.
• Despite passive body motion, gaze accuracy was maintained.
• VOR modulation patterns were similar to those observed in eye-only gaze shifts.

Conclusions:

• The brain exhibits similar VOR modulation whether gaze shifts are programmed for eyes alone or for combined head and body movements.
• This implies the brain utilizes feedback from integrated gaze and head signals for programming gaze changes, not separate eye and head trajectories.