The vestibulo-ocular reflex (VOR) is driven by head movement and moves the eyes in the direction opposite to the head movement, automatically stabilizing vision relative to space. The VOR is mediated by a trineuronal arc composed of the primary vestibular neurons, relay neurons in vestibular nuclei, and motoneurons for the extraocular muscles. The optokinetic eye-movement response (OKR) is another ocular reflex induced by optokinetic stimuli generated by movements of the visual field relative to the head. VOR and OKR share the same vestibular nuclear neurons and oculomotor neurons, and synergistically stabilize vision. The VOR/OKR pathways are attached with commissural connections between the bilateral vestibular nuclei, internuclear connections between motor nuclei, and other connections with the tegmentum and the cerebellum.

Two types of plasticity have been recognized in the VOR/OKR. The first is gradual recovery of the heavy nystagmus induced by...