Beyond the Vestibulo-Ocular Reflex: Vestibular Input is Processed Centrally to Achieve Visual Stability

Edwin Dalmaijer

doi:10.3390/vision2020016

Edwin Dalmaijer

Open Access

https://doi.org/10.3390/vision2020016

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Abstract

The current study presents a re-analysis of data from Zink et al. (1998, Electroencephalography and Clinical Neurophysiology, 107), who administered galvanic vestibular stimulation through unipolar direct current. They placed electrodes on each mastoid and applied either right or left anodal stimulation. Ocular torsion and visual tilt were measured under different stimulation intensities. New modelling introduced here demonstrates that directly proportional linear models fit reasonably well with the relationship between vestibular input and visual tilt, but not to that between vestibular input and ocular torsion. Instead, an exponential model characterised by a decreasing slope and an asymptote fitted best. These results demonstrate that in the results presented by Zink et al. (1998), ocular torsion could not completely account for visual tilt. This suggests that vestibular input is processed centrally to stabilise vision when ocular torsion is insufficient. Potential mechanisms and seemingly conflicting literature are discussed.

Highlights

During everyday movements like walking, the human head and eyes continuously move, yet humans have a relatively stable visual perception of the world
The best fits for ocular torsion were ao = 0.483 and bo = 0.913 for the linear model (Equation (1)), ao = 0.672 for the directly proportional linear model (Equation (3)), and ao = 3.722 and bo = 4.714 for the exponential model (Equation (5))
The best fits for visual tilt were av = 1.421 and bv = 0.000 for the linear model (Equation (2)), av = 1.421 in the directly proportional linear model (Equation (4)), and av = 3.649 and bv = 7.00 for the exponential model (Equation (6))

Summary

Introduction

During everyday movements like walking, the human head and eyes continuously move, yet humans have a relatively stable visual perception of the world. Torsional eye movements induced by the vestibulo-ocular reflex can be prevented by fixating the eyeballs of anaesthetised cats to a metal ring In these cats, the receptive fields of a proportion of neurons in the visual cortex tilted when the cat’s head was tilted (roll motion), compared to when it was in an upright position [1,2,3]. The receptive fields of a proportion of neurons in the visual cortex tilted when the cat’s head was tilted (roll motion), compared to when it was in an upright position [1,2,3] These results suggest that another mechanism might exist to centrally process vestibular information when the vestibulo-ocular reflex is disrupted (Figure 1D)

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Discussion

Conclusion