title: Receptive field properties of bipolar cell axon terminals in direction-selective sublaminas of the mouse retina.
abstract: Retinal bipolar cells (BCs) transmit visual signals in parallel channels from the outer to the inner retina, where they provide glutamatergic inputs to specific networks of amacrine and ganglion cells. Intricate network computation at BC axon terminals has been proposed as a mechanism for complex network computation, such as direction selectivity, but direct knowledge of the receptive field property and the synaptic connectivity of the axon terminals of various BC types is required in order to understand the role of axonal computation by BCs. The present study tested the essential assumptions of the presynaptic model of direction selectivity at axon terminals of three functionally distinct BC types that ramify in the direction-selective strata of the mouse retina. Results from two-photon Ca(2+) imaging, optogenetic stimulation, and dual patch-clamp recording demonstrated that 1) CB5 cells do not receive fast GABAergic synaptic feedback from starburst amacrine cells (SACs); 2) light-evoked and spontaneous Ca(2+) responses are well coordinated among various local regions of CB5 axon terminals; 3) CB5 axon terminals are not directionally selective; 4) CB5 cells consist of two novel functional subtypes with distinct receptive field structures; 5) CB7 cells provide direct excitatory synaptic inputs to, but receive no direct GABAergic synaptic feedback from, SACs; and 6) CB7 axon terminals are not directionally selective, either. These findings help to simplify models of direction selectivity by ruling out complex computation at BC terminals. They also show that CB5 comprises two functional subclasses of BCs.
authors.affiliation: Department of Ophthalmology and Visual Science, Yale University School of Medicine, New Haven, Connecticut;
authors.forename: Minggang
authors.initials: M
authors.lastname: Chen
authors.affiliation: Department of Ophthalmology and Visual Science, Yale University School of Medicine, New Haven, Connecticut;
authors.forename: Seunghoon
authors.initials: S
authors.lastname: Lee
authors.affiliation: Department of Ophthalmology and Visual Science, Yale University School of Medicine, New Haven, Connecticut;
authors.forename: Silvia J H
authors.initials: SJ
authors.lastname: Park
authors.affiliation: Howard Hughes Medical Institute, Janelia Farm Research Campus, Ashburn, Virginia.
authors.forename: Loren L
authors.initials: LL
authors.lastname: Looger
authors.affiliation: Department of Ophthalmology and Visual Science, Yale University School of Medicine, New Haven, Connecticut; Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut; Department of Neurobiology, Yale University School of Medicine, New Haven, Connecticut; and jimmy.zhou@yale.edu.
authors.forename: Z Jimmy
authors.initials: ZJ
authors.lastname: Zhou
mesh_terms: D025042:Amacrine Cells / Q000502:physiology; D000818:Animals; D001369:Axons / Q000502:physiology*; D020013:Calcium Signaling; D005260:Female; D059330:GABAergic Neurons / Q000502:physiology; D008297:Male; D051379:Mice; D008959:Models, Neurological; D009415:Nerve Net / Q000502:physiology; D062308:Optogenetics; D010775:Photic Stimulation; D051245:Retinal Bipolar Cells / Q000166:cytology / Q000502:physiology*; D013569:Synapses / Q000502:physiology; D014794:Visual Fields / Q000502:physiology*
keywords: GCaMP3; bipolar cell; channelrhodopsin-2; direction selectivity; mouse retina; receptive field; starburst amacrine cell; two-photon imaging