Abstract
The mammalian retina is fundamentally dichromatic, with trichromacy only recently emerging in some primates. In dichromats, an array of short wavelength-sensitive (S, blue) and middle wavelength-sensitive (M, green) cones is sampled by approximately ten bipolar cell types, and the sampling pattern determines how retinal ganglion cells and ultimately higher visual centers encode color and luminance. By recording from cone-bipolar cell pairs in the retina of the ground squirrel, we show that the bipolar cell types sample cone signals in three ways: one type receives input exclusively from S-cones, two types receive mixed S/M-cone input and the remaining types receive an almost pure M-cone signal. Bipolar cells that carry S- or M-cone signals can have a role in color discrimination and may contact color-opponent ganglion cells. Bipolar cells that sum signals from S- and M-cones may signal to ganglion cells that encode luminance.
Publication types
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Comparative Study
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Biotin / analogs & derivatives
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Biotin / pharmacokinetics
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Calcium / metabolism
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Color
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Color Perception / physiology*
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Contrast Sensitivity / physiology*
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Imaging, Three-Dimensional / methods
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Immunohistochemistry / methods
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In Vitro Techniques
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Light
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Membrane Potentials / drug effects
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Membrane Potentials / physiology
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Membrane Potentials / radiation effects
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Models, Neurological
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Patch-Clamp Techniques / methods
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Photic Stimulation / methods
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Receptors, Metabotropic Glutamate / metabolism
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Retina* / anatomy & histology
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Retina* / physiology
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Retinal Bipolar Cells / drug effects
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Retinal Bipolar Cells / physiology*
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Retinal Cone Photoreceptor Cells / physiology
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Rod Opsins / metabolism
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Sciuridae
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Visual Pathways / anatomy & histology
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Visual Pathways / drug effects
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Visual Pathways / physiology*
Substances
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Receptors, Metabotropic Glutamate
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Rod Opsins
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neurobiotin
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Biotin
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Calcium