title: Responses of cells in the midbrain near-response area in monkeys with strabismus.
abstract: OBJECTIVE
  To investigate whether neuronal activity within the supraoculomotor area (SOA-monosynaptically connected to medial rectus motoneurons and encode vergence angle) of strabismic monkeys was correlated with the angle of horizontal misalignment and therefore helps to define the state of strabismus.
  
  
  METHODS
  Single-cell neural activity was recorded from SOA neurons in two monkeys with exotropia as they performed eye movement tasks during monocular viewing.
  
  
  RESULTS
  Horizontal strabismus angle varied depending on eye of fixation (dissociated horizontal deviation) and the activity of SOA cells (n = 35) varied in correlation with the angle of strabismus. Both near-response (cells that showed larger firing rates for smaller angles of exotropia) and far-response (cells that showed lower firing rates for smaller angles of exotropia) cells were identified. SOA cells showed no modulation of activity with changes in conjugate eye position as tested during smooth-pursuit, thereby verifying that the responses were related to binocular misalignment. SOA cell activity was also not correlated with change in horizontal misalignment due to A-patterns of strabismus. Comparison of SOA population activity in strabismic animals and normal monkeys (described in the literature) show that both neural thresholds and neural sensitivities are altered in the strabismic animals compared with the normal animals.
  
  
  CONCLUSIONS
  SOA cell activity is important in determining the state of horizontal strabismus, possibly by altering vergence tone in extraocular muscle. The lack of correlated SOA activity with changes in misalignment due to A/V patterns suggest that circuits mediating horizontal strabismus angle and those that mediate A/V patterns are different.
authors.affiliation: College of Optometry, University of Houston, TX 77204, USA. vdas@optometry.uh.edu
authors.forename: Vallabh E
authors.initials: VE
authors.lastname: Das
mesh_terms: D000065:Accommodation, Ocular / Q000502:physiology; D000818:Animals; D004195:Disease Models, Animal; D004594:Electrophysiology; D005099:Exotropia / Q000503:physiopathology*; D005133:Eye Movements / Q000502:physiology; D008253:Macaca mulatta; D008636:Mesencephalon / Q000503:physiopathology*; D009046:Motor Neurons / Q000502:physiology*; D009801:Oculomotor Muscles / Q000294:innervation*; D011698:Pursuit, Smooth / Q000502:physiology; D015348:Vision, Binocular / Q000502:physiology