Comparison of vestibulo-ocular reflex (VOR) modification methods in cats.

The vestibulo-ocular reflex (VOR) has been measured and optically modified in several animal species. The VOR gain can be increased optokinetically by rotating the animal's visual surround opposite to the animal's direction of rotation or a VOR increase can result from the use of magnifying lenses. We describe here a comparison of three methods for producing VOR increases in cats: (i) optokinetic drum; (ii) a pair of 2.2 x telescopic lenses; (iii) Fresnel lens goggles. The animals were put through several preliminary calibrations followed by a sequence of VOR modification periods alternating with 10 testing periods. The results of the comparison in 4 cats show that the Fresnel lens system produces a greater and more stable VOR gain increase than the other two methods.