color vision
DESCRIPTION
Color vision. Outlines. What is color Retinal circuitry for color vision Several ways to label retinal cells. Color history: discovery of color. Isaac Newton. Color history: discovery of color. Reflection makes colors. Retina anatomy of human being. Outer nuclear layer. - PowerPoint PPT PresentationTRANSCRIPT
Color vision
Outlines
• What is color
• Retinal circuitry for color vision
• Several ways to label retinal cells
Color history: discovery of color
Isaac Newton
Color history: discovery of color
Reflection makes colors
Retina anatomy of human being
Outer nuclear layer
Inner nuclear layer
Ganglion cell layer
Outer plexiform layer
Inner plexiform layer
Cone mosaic in human retina
L-cone M-coneS-cone
L-cone or M-cone
Immunohist-ochemistry
(IHC)S-cone
Immunohist-ochemistry
(IHC)
Trichromats vs Dichromats
Strategy to see color• Principle of Univariance: any single photopigment is “colour blind”. Given proper combination of wavelength and intensity, and can trigger same response in M-cone.
• Color-coding ganglion cells receive antagonistic input from cones: red-green; yellow-blue
Color opponency mechanism
Red-green opponent cells: midget ganglion cells
Blue-yellow opponent cells: small bistratified ganglion cells
Review by Dacey, 20001111
Dichromats
Review of Masland, 2012
S/M opponent ganglion cells in retina of guinea piga dichromatic mammal
Dye iontophoresis
To dye fill a cell: A. visualize the cell via quick and rough nucleus stainingB. A microelectrode filled with fluorescent dye is placed
carefully in contact with the somaC. Break into the cell and apply current. “injecting fluorescent
dye into the cell electronically”.D. How big is 10μm? The width (diameter) of a human hair
ranges from 0.017 to 0.181 mm.
Dye iontophoresisWhat is ?
Movie showing iontophoresis of dye into retinal ganglion cell
Summary of cell labeling techniques
1. Immunocytochemistry
2. Dye-filling
3. Genetic tags: GFP, YFP…
History of genetic tag: GFP
2008 Nobel prize winners Osamu Shimomura, Martin Chalfie, and Roger Tsien,
Genetic tags: YFP
Transgenic lines that mark RGC subtypes
“Most of my knowledge came from self-study,” says Dr. Shimomura. “If you find an interesting subject, study it through to the finish. If you confront difficulties, overcome them. Don’t be discouraged. There are always difficulties in research.”
The End