Journal of Neuroscience, Vol 1, 351-357, Copyright © 1981 by Society for Neuroscience
The effect of habituating vestibular and optokinetic nystagmus on each other
AA Skavenski, SM Blair and G Westheimer
Currently, the vestibulo-ocular and optokinetic reflexes are both thought
to require a velocity storage mechanism within their neural pathways. To
test whether these storage mechanisms are shared by both reflexes, animals
were given programs of stimulation known to change the status of the
storage mechanism of one of the type of nystagmus. The other type of
nystagmus was examined then to ascertain whether the characteristic of its
velocity storage system had remained invariant. Horizontal eye movements of
three macaque monkeys were recorded during post-rotatory nystagmus and
optokinetic afternystagmus (OKAN) before and after 20 habituating exposures
to either vestibular or optokinetic stimulation. Repetitive exposures to
vestibular stimulation alone markedly reduced the time constant of
post-rotatory nystagmus and this effect was accompanied only occasionally
by a reduction in the time constant of OKAN. Repetitive exposure to
optokinetic stimulation alone reliably reduced the time constant of OKAN
but produced no reliable change in the time constant of post-rotatory
nystagmus. These results suggest that the vestibulo-ocular and optokinetic
reflexes do not share a single common velocity storage mechanism.