Influence of vestibulo-ocular reflex gain on human optokinetic responses

Abstract
In 15 patients with severe bilateral vestibular impairment (mean vestibulo-ocular reflex (VOR) gain < 0.05), constant velocity optokinetic nystagmus (OKN) gain, optokinetic after nystagmus (OKAN) initial velocity, and OKAN duration were siginificantly (p < 0.0025) lower than in 20 normal subjects of similar age. In the normal subjects VOR gain was significantly correlated (p < 0.05) with OKAN initial velocity but not with OKAN duration or OKN gain. The results of this study provide additional evidence for the existence in human subjects of an optokinetic pathway whose function, like that of the subcortical optokinetic pathway in animals, varies with VOR gain.