title: Ephrin-As are required for the topographic mapping but not laminar choice of physiologically distinct RGC types.
abstract: In the retinocollicular projection, the axons from functionally distinct retinal ganglion cell (RGC) types form synapses in a stereotypical manner along the superficial to deep axis of the superior colliculus (SC). Each lamina contains an orderly topographic map of the visual scene but different laminae receive inputs from distinct sets of RGCs, and inputs to each lamina are aligned with the others to integrate parallel streams of visual information. To determine the relationship between laminar organization and topography of physiologically defined RGC types, we used genetic and anatomical axon tracing techniques in wild type and ephrin-A mutant mice. We find that adjacent RGCs of the same physiological type can send axons to both ectopic and normal topographic locations, supporting a penetrance model for ephrin-A independent mapping cues. While the overall laminar organization in the SC is unaffected in ephrin-A2/A5 double mutant mice, analysis of the laminar locations of ectopic terminations shows that the topographic maps of different RGC types are misaligned. These data lend support to the hypothesis that the retinocollicular projection is a superimposition of a number of individual two-dimensional topographic maps that originate from specific types of RGCs, require ephrin-A signaling, and form independently of the other maps.
authors: Molecular, Cell & Developmental Biology, University of California, Santa Cruz, Santa Cruz, California, 95064.
authors: Neal T
authors: NT
authors: Sweeney
authors: Molecular, Cell & Developmental Biology, University of California, Santa Cruz, Santa Cruz, California, 95064.
authors: Kiely N
authors: KN
authors: James
authors: Molecular, Cell & Developmental Biology, University of California, Santa Cruz, Santa Cruz, California, 95064.
authors: Emily C
authors: EC
authors: Sales
authors: Molecular, Cell & Developmental Biology, University of California, Santa Cruz, Santa Cruz, California, 95064.
authors: David A
authors: DA
authors: Feldheim
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000033:anatomy & histology / Q000378:metabolism; D001931:Brain Mapping; D036342:Ephrins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D009154:Mutation / Q000235:genetics; D012165:Retinal Ganglion Cells / Q000145:classification / Q000502:physiology*; D013477:Superior Colliculi / Q000378:metabolism; D014795:Visual Pathways / Q000166:cytology / Q000502:physiology
chemical_list: D000596:Amino Acids; D036342:Ephrins; C098463:dolaisoleucine
keywords: ephrin-A; topographic mapping; visual system development
references: Front Neural Circuits. 2014;8:23
references: 24723853
references: Neuron. 2008 Jun 26;58(6):851-8
references: 18579076
references: Cell Rep. 2014 Aug 21;8(4):1006-17
references: 25088424
references: Neuron. 2008 Aug 14;59(3):425-38
references: 18701068
references: J Neurosci. 2008 Oct 22;28(43):11015-23
references: 18945909
references: Neuron. 2009 May 14;62(3):327-34
references: 19447089
references: Cell. 2009 Oct 2;139(1):175-85
references: 19804762
references: J Neurosci. 2010 Jan 27;30(4):1452-62
references: 20107072
references: Cold Spring Harb Perspect Biol. 2010 Mar;2(3):a001743
references: 20300211
references: Cold Spring Harb Perspect Biol. 2010 Nov;2(11):a001768
references: 20880989
references: J Neurosci. 2011 May 25;31(21):7753-62
references: 21613488
references: J Neurosci. 2011 Jun 15;31(24):8760-9
references: 21677160
references: Cell. 2011 Jul 8;146(1):164-76
references: 21729787
references: Proc Natl Acad Sci U S A. 2011 Nov 22;108(47):19060-5
references: 22065784
references: Annu Rev Neurosci. 2013 Jul 8;36:51-77
references: 23642132
references: Curr Opin Neurobiol. 2014 Feb;24(1):133-42
references: 24492089
references: Neuron. 2000 Mar;25(3):563-74
references: 10774725
references: J Neurosci. 2004 Mar 10;24(10):2542-50
references: 15014130
references: Neuron. 2004 Aug 19;43(4):475-85
references: 15312647
references: J Neurosci. 1992 Apr;12(4):1212-32
references: 1313491
references: Neuron. 1998 Feb;20(2):235-43
references: 9491985
references: Neuron. 2005 Jul 7;47(1):57-69
references: 15996548
references: J Neurosci. 2006 Dec 13;26(50):12873-84
references: 17167078
references: Neuron. 2014 May 21;82(4):781-8
references: 24853938