title: Behavior of the human translational vestibulo-ocular reflex during simultaneous head translation and rotation.
abstract: BACKGROUND
  During head translations, vestibular eye movements are ∼ 60% of those required to hold the line of sight on target but, during translation of the orbits due to head rotation about an eccentric axis, the eyes are held %eye on target.
  
  
  OBJECTIVE
  To resolve this paradoxical behavior of vestibulo-ocular reflexes.
  
  
  METHODS
  Subjects sat on a moving platform viewing a near target and were: (1) rotated en bloc in yaw about a vertical axis centered on the head at 1 Hz; (2) rotated with their head displaced ∼ 10 cm anterior (eccentric rotation) at 1 Hz; (3) translated along the inter-aural axis at 1.9 Hz; (4) rotated with the head centered at 1 Hz while they were translated along the inter-aural axis at 1.9 Hz. We calculated compensation ratio (CR): Eye velocity/eye velocity geometrically required to hold the eye on target.
  
  
  RESULTS
  During yaw, mean CR was 0.88 and during eccentric rotation CR was 0.93. During translation at 1.9 Hz, CR was 0.65. During combined rotation at 1.0 Hz and translation at 1.9 Hz, CR was 0.81 for head rotations and 0.74 for head translations.
  
  
  CONCLUSIONS
  Translations of the orbits due to head rotation are better compensated for than translations of the orbits due to head translation. These different behaviors may be determined by context, the important difference being whether the subject is moving through the environment.
authors.affiliation: Department of Veterans Affairs Medical Center, Case Western Reserve University, Cleveland, OH, USA.
authors.forename: Rosalyn
authors.initials: R
authors.lastname: Schneider
authors.affiliation: Department of Veterans Affairs Medical Center, Case Western Reserve University, Cleveland, OH, USA.
authors.forename: Ke
authors.initials: K
authors.lastname: Liao
authors.affiliation: Department of Veterans Affairs Medical Center, Case Western Reserve University, Cleveland, OH, USA.
authors.forename: Mark F
authors.initials: MF
authors.lastname: Walker
authors.affiliation: Neuro-Otology Unit, Division of Experimental Medicine, Imperial College London, Charing Cross Hospital, London, UK.
authors.forename: Adolfo
authors.initials: A
authors.lastname: Bronstein
authors.affiliation: Department of Veterans Affairs Medical Center, Case Western Reserve University, Cleveland, OH, USA.
authors.forename: R John
authors.initials: RJ
authors.lastname: Leigh
mesh_terms: D000328:Adult; D000368:Aged; D053483:Eye Movement Measurements; D005133:Eye Movements / Q000502:physiology*; D005260:Female; D019416:Head Movements / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012027:Reflex, Vestibulo-Ocular / Q000502:physiology*; D012399:Rotation
keywords: Vestibulo-ocular reflex; head rotation; head translation; motion parallax