Adaptation of the vestibulo-ocular reflex in albino rabbits by selective exposure of the anterior sector of the visual field.

Horizontal optokinetic reflexes (OKN) are inverted in an anterior (90-180 degrees) sector of the visual field in albino rabbits. We investigated whether the inverted processing of direction-selective information would affect long-term adaptation of the vestibulo-ocular reflex (VOR). Normal posterior parts of the visual fields were masked for periods up to 80 days. The inversion of OKN, with instability of the eyes and head in the light, was not corrected in this period. The amplitude of the VOR was progressively reduced, but a true inversion was not achieved. Recovery was seen after removal of the masks. These changes were larger and more consistent in Himalayan than in Polish rabbits. Normal, Dutch pigmented rabbits which served as controls showed no significant reduction of VOR gain. Phase lead of the VOR for low stimulus frequencies increased in both pigmented and albino rabbits. In short-term experiments with forced oscillation, similar but smaller changes were observed.