title: Binocular eye movement control and motion perception: what is being tracked?
abstract: OBJECTIVE
  We investigated under what conditions humans can make independent slow phase eye movements. The ability to make independent movements of the two eyes generally is attributed to few specialized lateral eyed animal species, for example chameleons. In our study, we showed that humans also can move the eyes in different directions. To maintain binocular retinal correspondence independent slow phase movements of each eye are produced.
  
  
  METHODS
  We used the scleral search coil method to measure binocular eye movements in response to dichoptically viewed visual stimuli oscillating in orthogonal direction.
  
  
  RESULTS
  Correlated stimuli led to orthogonal slow eye movements, while the binocularly perceived motion was the vector sum of the motion presented to each eye. The importance of binocular fusion on independency of the movements of the two eyes was investigated with anti-correlated stimuli. The perceived global motion pattern of anti-correlated dichoptic stimuli was perceived as an oblique oscillatory motion, as well as resulted in a conjugate oblique motion of the eyes.
  
  
  CONCLUSIONS
  We propose that the ability to make independent slow phase eye movements in humans is used to maintain binocular retinal correspondence. Eye-of-origin and binocular information are used during the processing of binocular visual information, and it is decided at an early stage whether binocular or monocular motion information and independent slow phase eye movements of each eye are produced during binocular tracking.
authors.affiliation: Department of Neuroscience, Erasmus MC, Rotterdam, The Netherlands. j.vandersteen@erasmusmc.nl
authors.forename: Johannes
authors.initials: J
authors.lastname: van der Steen
authors.forename: Joyce
authors.initials: J
authors.lastname: Dits
mesh_terms: D000328:Adult; D003867:Depth Perception / Q000502:physiology*; D005133:Eye Movements / Q000502:physiology*; D006801:Humans; D008875:Middle Aged; D009039:Motion Perception / Q000502:physiology*; D010775:Photic Stimulation; D015357:Vision Disparity; D015348:Vision, Binocular / Q000502:physiology*; D055815:Young Adult