What is the role of the cerebellum in vestibular function and compensation after unilateral loss?

• A. The cerebellum directly drives VOR without adaptation
• B. The cerebellum inhibits vestibular inputs during movement
• C. The cerebellum has no role in vestibular compensation
• D. The cerebellum modulates VOR gain and assists adaptation by recalibrating internal models

Answer: (D)

The cerebellum acts as the adaptive controller of the vestibulo-ocular reflex, not as the direct motor driver. It doesn’t push the eyes to move by itself; instead it tunes the reflex by adjusting its gain and updating the brain’s internal model of how head movements produce eye movements. When one labyrinth is lost, the input becomes asymmetric and retinal slip occurs, so the cerebellum uses error signals to recalibrate how strong the eye movement should be for a given head move. This recalibration helps restore stable gaze and enables compensation, with specific cerebellar regions (like the flocculus/paraflocculus and related circuits) guiding changes in the VOR through plasticity at Purkinje cell synapses that adjust the output to the vestibular nuclei. In short, the cerebellum modulates VOR gain and assists adaptation by recalibrating internal models, which is exactly what supports vestibular compensation after unilateral loss.