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Adaptation of Orientation of Central Otolith‐only Neurons
Author(s) -
Eron Julia N.,
Cohen Bernard,
Raphan Theodore,
Yakushin Sergei B.
Publication year - 2009
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1111/j.1749-6632.2009.03848.x
Subject(s) - otolith , vestibular system , orientation (vector space) , vestibular nuclei , anatomy , saccade , horizontal plane , geodesy , biology , neuroscience , geology , geometry , mathematics , eye movement , fish <actinopterygii> , fishery
Otolith‐only neurons were recorded extracellularly in the vestibular nuclei before and after cynomolgus monkeys were held on‐side for up to 3 hr. The aim was to determine whether the polarization vectors of these neurons reorient toward the spatial vertical as do canal‐otolith convergent neurons. Otolith input was characterized by tilting the animal 30° from the upright position while positioning the head in different directions in yaw. This determined the response vector orientation (RVO), that is, the projection of the otolith polarization vector onto the head horizontal plane. Changes in the RVO of otolith‐only neurons ranged from 2°–16°, which was on average considerably less than the changes previously noted in canal‐otolith convergent vestibulo‐only (VO) and vestibular plus saccade (VPS) neurons, which ranged up to 109°. Some of the otolith‐only neurons had marked sensitivity changes. These findings suggest that otolith‐only neurons tend to maintain a head‐fixed orientation during prolonged head tilts relative to gravity. In contrast, canal‐convergent VO and VPS neurons optimize their response vector orientation to gravity when the head is oriented for prolonged periods.