title: Individual larvae of the zebrafish mutant belladonna display multiple infantile nystagmus-like waveforms that are influenced by viewing conditions.
abstract: OBJECTIVE
  Infantile nystagmus syndrome (INS) is characterized by involuntary eye oscillations that can assume different waveforms. Previous attempts to uncover reasons for the presence of several nystagmus waveforms have not led to a general consensus in the community. Recently, we characterized the belladonna (bel) zebrafish mutant strain, in which INS-like ocular motor abnormalities are caused by misprojection of a variable fraction of optic nerve fibers. Here we studied intrinsic and extrinsic factors influencing the occurrence of different waveforms in bel larvae.
  
  
  METHODS
  Eye movements of bel larvae were recorded in the presence of a stationary grating pattern. Waveforms of spontaneous oscillations were grouped in three categories: "pendular," "unidirectional jerk," and "bidirectional jerk," and the occurrences of each category were compared within and between individual larvae. Moreover, the effects of the characteristics of a preceding optokinetic response (OKR), of the field of view, and of the eye orbital position were analyzed.
  
  
  RESULTS
  The different waveform categories co-occurred in most individuals. We found waveforms being influenced by the preceding OKR and by the field of view. Moreover, we found different kinds of relationships between orbital position and initiation of a specific waveform, including pendular nystagmus in a more eccentric orbital position, and differences among jerk oscillations regarding the beating direction of the first saccade or waveform amplitude.
  
  
  CONCLUSIONS
  Our data suggest that waveform categories in bel larvae do not reflect the severity of the morphological phenotype but rather are influenced by viewing conditions.
authors.affiliation: Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland Life Science Graduate School, Zurich, Switzerland.
authors.forename: Sabina P
authors.initials: SP
authors.lastname: Huber-Reggi
authors.affiliation: Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland.
authors.forename: Kaspar P
authors.initials: KP
authors.lastname: Mueller
authors.affiliation: Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland Department of Neurology, University Hospital Zurich, Zurich, Switzerland.
authors.forename: Dominik
authors.initials: D
authors.lastname: Straumann
authors.affiliation: Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland Department of Neurology, University Hospital Zurich, Zurich, Switzerland.
authors.forename: Melody Ying-Yu
authors.initials: MY
authors.lastname: Huang
authors.affiliation: Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland.
authors.forename: Stephan C F
authors.initials: SC
authors.lastname: Neuhauss
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D060850:LIM-Homeodomain Proteins / Q000235:genetics*; D007814:Larva; D009154:Mutation; D009412:Nerve Fibers / Q000502:physiology; D009419:Nerve Tissue Proteins / Q000235:genetics*; D020417:Nystagmus, Congenital / Q000235:genetics / Q000503:physiopathology*; D017120:Nystagmus, Optokinetic / Q000502:physiology*; D009900:Optic Nerve / Q000503:physiopathology; D014157:Transcription Factors / Q000235:genetics*; D015348:Vision, Binocular / Q000502:physiology; D014794:Visual Fields / Q000502:physiology; D015027:Zebrafish / Q000502:physiology*; D029961:Zebrafish Proteins / Q000235:genetics*
chemical_list: D060850:LIM-Homeodomain Proteins; D009419:Nerve Tissue Proteins; D014157:Transcription Factors; D029961:Zebrafish Proteins; C509734:lhx2b protein, zebrafish
keywords: infantile nystagmus; waveforms; zebrafish