title: OFF ganglion cells cannot drive the optokinetic reflex in zebrafish.
abstract: Whereas the zebrafish retina has long been an important model system for developmental and genetic studies, little is known about the responses of the inner retinal neurons. Here we report single-unit ganglion cell recordings from 5- to 6-day-old zebrafish larvae. In wild-type larvae we identify at least five subtypes of ganglion cell responses to full-field illumination, with ON-OFF and ON-type cells predominating. In the nrc mutant retina, in which the photoreceptor terminals develop abnormally, we observe normal OFF responses but abnormal ON-OFF responses and no ON responses. Previously characterized as blind, these mutants lack an optokinetic reflex (OKR), but in another behavioral assay nrc mutant fish have near-normal responses to the offset of light and slow and sluggish responses to the onset of light. Pharmacological block of the ON pathway mimics most of the nrc visual defects. We conclude that the abnormal photoreceptor terminals in nrc mutants predominantly perturb the ON pathway and that the ON pathway is necessary to drive the OKR in larval zebrafish.
authors.affiliation: Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138-2020, USA.
authors.forename: Farida
authors.initials: F
authors.lastname: Emran
authors.forename: Jason
authors.initials: J
authors.lastname: Rihel
authors.forename: Alan R
authors.initials: AR
authors.lastname: Adolph
authors.forename: Kwoon Y
authors.initials: KY
authors.lastname: Wong
authors.forename: Sebastian
authors.initials: S
authors.lastname: Kraves
authors.forename: John E
authors.initials: JE
authors.lastname: Dowling
mesh_terms: D000200:Action Potentials / Q000528:radiation effects; D000613:Aminobutyrates / Q000494:pharmacology; D000818:Animals; D001224:Aspartic Acid / Q000494:pharmacology; D004596:Electroretinography; D009039:Motion Perception / Q000502:physiology; D017120:Nystagmus, Optokinetic / Q000502:physiology*; D010744:Phosphoric Monoester Hydrolases / Q000172:deficiency / Q000235:genetics; D010775:Photic Stimulation; D010786:Photoreceptor Cells / Q000002:abnormalities; D051245:Retinal Bipolar Cells / Q000502:physiology; D012165:Retinal Ganglion Cells / Q000187:drug effects / Q000502:physiology*; D014786:Vision Disorders / Q000235:genetics; D014795:Visual Pathways / Q000187:drug effects; D015027:Zebrafish / Q000235:genetics / Q000502:physiology*; D029961:Zebrafish Proteins / Q000172:deficiency / Q000235:genetics
chemical_list: D000613:Aminobutyrates; D029961:Zebrafish Proteins; C120673:benzyloxyaspartate; D001224:Aspartic Acid; C498882:synj1 protein, zebrafish; D010744:Phosphoric Monoester Hydrolases; C012729:2-amino-4-phosphonobutyric acid