It is proposed to study the neurocircuitry of the outer and inner plexiform layers of the retina of the turtle by various light and electron microscope techniques. We wish to understand the morphological basis for functional pathways being described from intracellular physiological experiments. The turtle retina has advantages over other vertebrate retinas in that the spectral types of photoreceptors are morphologically identifiable and these and second order neurons have yielded nice intracellular recordings. Thus it is more feasible to unravel color coded pathways, ON and OFF center pathways, orientation and directionally selective pathways in the turtle retina than in any other vertebrate retina at present. Specifically we plan to a) characterize the cone photoreceptor type with the large clear, fluorescent oil droplet and determine its connections with other spectral types of cone in the OPL, b) determine which cone or rod photoreceptors are involved in the large gap junctions seen between telodendria in the neuropil of the OPL, c) determine the connectivity of H2, H3 and H4 horizontal cells with specific cone types, d) determine the spectral connections and exact morphology of the synapses of bipolars B1, B2 and B9 (the latter may be serotonergic and is of particular interest), e) begin a serial section EM study of the neuropil of the IPL in the visual streak with particular concentration on bipolar cell connectivity and f) study the type and distribution of synaptic inputs upon directionally selective and orientation selective ganglion cells.

National Institute of Health (NIH)
National Eye Institute (NEI)
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Visual Sciences A Study Section (VISA)
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University of Utah
Schools of Medicine
Salt Lake City
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Deng, P; Cuenca, N; Doerr, T et al. (2001) Localization of neurotransmitters and calcium binding proteins to neurons of salamander and mudpuppy retinas. Vision Res 41:1771-83
Cuenca, N; Haverkamp, S; Kolb, H (2000) Choline acetyltransferase is found in terminals of horizontal cells that label with GABA, nitric oxide synthase and calcium binding proteins in the turtle retina. Brain Res 878:228-39
Haverkamp, S; Kolb, H; Blute, T A et al. (1999) Gamma-atrial natriuretic peptide 1-25 is found in bipolar cells in turtle and rat retinas. Vis Neurosci 16:771-9
Haverkamp, S; Kolb, H; Cuenca, N (1999) Endothelial nitric oxide synthase (eNOS) is localized to Muller cells in all vertebrate retinas. Vision Res 39:2299-303
Kolb, H; Netzer, E; Ammermuller, J (1997) Neural circuitry and light responses of the dopamine amacrine cell of the turtle retina. Mol Vis 3:6
Kolb, H (1997) Amacrine cells of the mammalian retina: neurocircuitry and functional roles. Eye (Lond) 11 ( Pt 6):904-23
Ammermuller, J; Kolb, H (1995) The organization of the turtle inner retina. I. ON- and OFF-center pathways. J Comp Neurol 358:1-34
Ammermuller, J; Muller, J F; Kolb, H (1995) The organization of the turtle inner retina. II. Analysis of color-coded and directionally selective cells. J Comp Neurol 358:35-62
Kolb, H; Fernandez, E; Ammermuller, J et al. (1995) Substance P: a neurotransmitter of amacrine and ganglion cells in the vertebrate retina. Histol Histopathol 10:947-68
Guiloff, G D; Kolb, H (1994) Ultrastructural and immunocytochemical analysis of the circuitry of two putative directionally selective ganglion cells in turtle retina. J Comp Neurol 347:321-39

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