Vestibulo-collic reflex (VCR) in mice.

The vestibulo-collic reflex (VCR) attempts to stabilize head position in space during motion of the body. Similar to the better-studied vestibulo-ocular reflex, the VCR is subserved by relatively direct, as well as indirect pathways linking vestibular nerve activity to cervical motor neurons. We measured the VCR using an electromagnetic technique often employed to measure eye movements; we attached a loop of wire (head coil) to an animal's head using an adhesive; then the animal was gently restrained with its head free to move within an electromagnetic field, and was subjected to sinusoidal (0.5-3 Hz) or abrupt angular acceleration (peak velocity approximately 200 degrees/s). Head rotation opposite in direction to body rotation was assumed to be driven by the VCR. To confirm that the compensatory head movements were in fact vestibular in origin, we plugged the horizontal canal unilaterally and then retested the animals 2, 8 and 15 days after the lesion. Two days after surgery, the putative VCR was almost absent in response to abrupt or sinusoidal rotations. Recovery commenced by day 8 and was nearly complete by day 15. We conclude that the compensatory head movements are vestibular in origin produced by the VCR. Similar to other species, there are robust compensatory mechanisms that restore the VCR following peripheral lesions.