title: Adaptation to background light enables contrast coding at rod bipolar cell synapses.
abstract: Rod photoreceptors contribute to vision over an ∼ 6-log-unit range of light intensities. The wide dynamic range of rod vision is thought to depend upon light intensity-dependent switching between two parallel pathways linking rods to ganglion cells: a rod → rod bipolar (RB) cell pathway that operates at dim backgrounds and a rod → cone → cone bipolar cell pathway that operates at brighter backgrounds. We evaluated this conventional model of rod vision by recording rod-mediated light responses from ganglion and AII amacrine cells and by recording RB-mediated synaptic currents from AII amacrine cells in mouse retina. Contrary to the conventional model, we found that the RB pathway functioned at backgrounds sufficient to activate the rod → cone pathway. As background light intensity increased, the RB's role changed from encoding the absorption of single photons to encoding contrast modulations around mean luminance. This transition is explained by the intrinsic dynamics of transmission from RB synapses.
authors.affiliation: Department of Biology, University of Maryland, College Park, MD 20742, USA.
authors.forename: Jiang-Bin
authors.initials: JB
authors.lastname: Ke
authors.affiliation: Department of Cellular and Molecular Physiology, Yale University, New Haven, CT 06511, USA; Department of Ophthalmology and Visual Science, Yale University, New Haven, CT 06511, USA.
authors.forename: Yanbin V
authors.initials: YV
authors.lastname: Wang
authors.affiliation: Department of Ophthalmology and Visual Science, Yale University, New Haven, CT 06511, USA.
authors.forename: Bart G
authors.initials: BG
authors.lastname: Borghuis
authors.affiliation: Howard Hughes Medical Institute, Janelia Farm Research Campus, Ashburn, VA 20147, USA.
authors.forename: Mark S
authors.initials: MS
authors.lastname: Cembrowski
authors.affiliation: Department of Engineering Sciences and Applied Mathematics, Northwestern University, Evanston, IL 60208, USA.
authors.forename: Hermann
authors.initials: H
authors.lastname: Riecke
authors.affiliation: Department of Engineering Sciences and Applied Mathematics, Northwestern University, Evanston, IL 60208, USA; Department of Neurobiology and Physiology, Northwestern University, Evanston, IL 60208, USA.
authors.forename: William L
authors.initials: WL
authors.lastname: Kath
authors.affiliation: Department of Cellular and Molecular Physiology, Yale University, New Haven, CT 06511, USA; Department of Ophthalmology and Visual Science, Yale University, New Haven, CT 06511, USA. Electronic address: jonathan.demb@yale.edu.
authors.forename: Jonathan B
authors.initials: JB
authors.lastname: Demb
authors.affiliation: Department of Biology, University of Maryland, College Park, MD 20742, USA. Electronic address: jhsinger@umd.edu.
authors.forename: Joshua H
authors.initials: JH
authors.lastname: Singer
mesh_terms: D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D000221:Adaptation, Ocular / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D001703:Biophysics; D003198:Computer Simulation; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D051081:Glucosamine 6-Phosphate N-Acetyltransferase / Q000172:deficiency / Q000235:genetics; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D066298:In Vitro Techniques; D008027:Light; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D008959:Models, Neurological; D018408:Patch-Clamp Techniques; D011810:Quinoxalines / Q000494:pharmacology; D051245:Retinal Bipolar Cells / Q000502:physiology*; D017948:Retinal Rod Photoreceptor Cells / Q000187:drug effects / Q000502:physiology*; D013569:Synapses / Q000187:drug effects / Q000502:physiology*; D014795:Visual Pathways / Q000502:physiology
chemical_list: D018691:Excitatory Amino Acid Antagonists; D011810:Quinoxalines; D049452:Green Fluorescent Proteins; C056723:FG 9041; D015763:2-Amino-5-phosphonovalerate; D051081:Glucosamine 6-Phosphate N-Acetyltransferase; C494972:Gnpnat1 protein, mouse