Department of Neurobiology, Pharmacology, and Physiology, University of Chicago, 5807 South Ellis Avenue, Chicago, Illinois 60637, USA
The contributions of vestibular nerve afferents and central
vestibular pathways to the angular (AVOR) and linear (LVOR)
vestibulo-ocular reflex were studied in squirrel monkeys during
fixation of near and far targets. Irregular vestibular afferents
did not appear to be necessary for the LVOR, since when they
were selectively silenced with galvanic currents the LVOR was
essentially unaffected during both far- and near-target viewing.
The linear translation signals generated by secondary AVOR neurons
in the vestibular nuclei were, on average, in phase with head
velocity, inversely related to viewing distance, and were nearly
as strong as AVOR-related signals. We suggest that spatial-temporal
transformation of linear head translation signals to angular
eye velocity commands is accomplished primarily by the addition
of viewing distance multiplied, centrally integrated, otolith
regular afferent signals to angular VOR pathways.
