title: Optokinetic stimulation can break Listing's law without induction of eye movement.
abstract: OBJECTIVE
  Pseudo-images of three-dimensional eye movements captured on an infrared video oculogram can be translated onto a rotational expression around axial vector. This provides a subject's Listing's plane, which moves according to the head's orientation relative to gravity. Optokinetically induced changes in the cognitive gravitational reference frame will affect the context of Listing's plane. The purpose of this study was to estimate the effect of OKS on Listing's plane.
  
  
  METHODS
  In this study, we presented vertical optokinetic visual stimulation with fixation targets, which are thought to induce pseudo-inclination of the head, and evaluated changes in the subjects' Listing's plane.
  
  
  RESULTS
  We observed no stimulus-induced movement of Listing's plane that corresponded to the assumed pseudo-recognition of a change in verticality. On the other hand, we did observe vergence movement of Listing's plane (in the yaw plane), which corresponded to exposure to diminished and increased gravitational circumstance. In addition, the thickness of Listing's plane significantly increased with the load of each stimulation.
  
  
  CONCLUSIONS
  Vertical OKS leads to a rotation of Listing's plane mainly around a vertical axis. This may represent false exhibition of central compensatory re-weighting with respect to inherent otoconial mass asymmetry resulting from the OKS-mediated loss of the gravity reference. In addition, a OKS-mediated thickening of Listing's plane suggests to us that confusing visual input can reduce the stability of the internal model, which would likely manifest itself as a thickening of Listing's plane. In other words, fluctuation between the build-up and drop-out of vection induced by optokinetic stimulation will cause a thickening of Listing's plane. The thickness of Listing's plane could be a novel clinical parameter for quantitatively evaluating static vestibular function and accuracy of the internal model.
authors.affiliation: Department of Oto-Rhino-Laryngology, Saitama Medical University, Saitama Medical Center, Kamoda 1981, Kawagoe-shi, Saitama 350-8550, Japan. takeoto@saitama-med.ac.jp
authors.forename: Takeshi
authors.initials: T
authors.lastname: Tsutsumi
authors.forename: Takuo
authors.initials: T
authors.lastname: Ikeda
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Fukuoka
authors.forename: Kensuke
authors.initials: K
authors.lastname: Watanabe
authors.forename: Shigeru
authors.initials: S
authors.lastname: Kikuchi
mesh_terms: D000328:Adult; D053483:Eye Movement Measurements; D005133:Eye Movements / Q000502:physiology*; D005260:Female; D006112:Gravitation; D006801:Humans; D007259:Infrared Rays; D008297:Male; D010775:Photic Stimulation / Q000379:methods; D012027:Reflex, Vestibulo-Ocular / Q000502:physiology*; D012399:Rotation; D014722:Vestibule, Labyrinth / Q000502:physiology*; D014741:Video Recording