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Topic: Trichromacy

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	How do people inherit colorblindness? How often?
		Anomalous trichromacy is characterized by a shift in the sensitivity of one or more cone types.
		Anomalous trichromacy is by far the most common form of colorblindness, and in many senses it is the least severe.
		Dichromacy is much less common than anomalous trichromacy, but for protanopia and deutanopia at least, the effect is similar.
	webexhibits.org /causesofcolor/2C.html (1140 words)

	Colorblindness - Preliminary Draft (Site not responding. Last check: 2007-11-04)
		In red-green color blindness only one of the two pigments is expressed; whereas, in anomalous trichromacy two pigments are expressed, but the anomalous pigment is displaced to a spectral location closer to that of it’s normal partners.
		Trichromacy is still achieved, but the ability to distinguish colors is slightly abnormal (Lancet).
		Anomalous trichromacy uses a three-variable color vision system like the normal trichromat but they differ from the norm in the relative proportions of the three mixture components they use to match the appearance of various monochromatic lights.
	srv2.lycoming.edu /~newman/courses/bio22298/disorderpapers/Colorblindness/preliminary.htm (1290 words)

	Trichromacy (Site not responding. Last check: 2007-11-04)
		The Young-Helmholtz theory of colour vision was built around the assumption of there being three classes of receptors although direct proof for this was not obtained until 1964 when microspectrophotopic recordings of single cone cells were obtained.
		The roots of trichromacy are firmly understood to be in the receptoral stage of colour vision.
		It is important to realize that a yellow stimulus produced by the additive mixture of appropriate red and green lights does not simply match monochromatic yellow light but is indistinguishable from it.
	www.radioqualia.net /illata/bibliotheca/cscience/s5.html (387 words)

	Oligocone trichromacy: a rare and unusual cone dysfunction syndrome -- Michaelides et al. 88 (4): 497 -- British ...
		Oligocone trichromacy is perceived of as a rare disorder, and
		Analysis of a progressive foveal dystrophy and a nonprogressive oligo-cone trichromacy (general cone dysfunction without achromatopsia), both of which at first had been diagnosed as achromatopsia.
		Mutations in the cone photoreceptor G-protein alpha-subunit gene GNAT2 in patients with achromatopsia.
	bjo.bmjjournals.com /cgi/content/full/88/4/497 (1897 words)

	Trichromacy Definition / Trichromacy Research (Site not responding. Last check: 2007-11-04)
		A trichromat is an organism for which the perceptual effect of any arbitrarily chosen light from its visible spectrum can be matched by a mixture of no further than three different pure spectral lights.
		The normal explanation of trichromacy is that the organism's retinaThe retina is a thin layer of cells at the back of the eyeball of vertebrates and some cephalopods; it is the part of the eye which transduces light into neural signals.
		The retina contains photoreceptor cells (mainly rods and cones, but additionally some retinal ganglion cells) which receive the light; the resulting neural signals then undergo complex processing by other neurons of the retina, and are transformed into action potentials in retinal ganglion cells whose axons form the optic nerve.
	www.elresearch.com /Trichromacy (323 words)

	Phylogeny (Site not responding. Last check: 2007-11-04)
		Trichromacy exists only among humans, apes, Old World monkeys, and the howler monkey.
		Both sexes are trichromatic, which is known as routine trichromacy (no sexual dimorphism as in most other species).
		Trichromacy is believed to have evolved relatively recently in primates, the L and M cones responsible for red-green (RG) systems.
	instruct1.cit.cornell.edu /courses/bionb424/students2004/lmd39/phylogeny.htm (107 words)

	Sensory Ecology: Primate Trichromacy as a Model of Optimal Visual Processing (Site not responding. Last check: 2007-11-04)
		This argument that the visual system is optimized for the processing of visual information has been applied to the foraging behavior of primates.
		Primate trichromacy has historically been interpreted as an adaptation to detect foods against a foliage background.
		Trichromacy, as opposed to dichromacy, is the ability to see a wider spectrum of colors due to the interaction of three cone receptors.
	instruct1.cit.cornell.edu /courses/bionb424/students2004/lmd39/intro.htm (411 words)

	Science News: Visionary research: scientists delve into the evolution of color vision in primates (Site not responding. Last check: 2007-11-04)
		Since females have two X chromosomes, they sometimes inherit two forms of the opsin gene that are different enough to give these females trichromacy.
		Compared with their dichromatic relatives, trichromatic tamarins were both faster at finding the boxes among the artificial leaves and more efficient at picking the "ripe" ones, Smith, Mundy, and their colleagues report in Sept. 15 Journal of Experimental Biology.
		The major challenge to the hypothesis that trichromacy evolved for finding fruit emerged in 1996, when Gerald H. Jacobs of the University of California, Santa Barbara and his colleagues reported that both male and female howler monkeys--New World primates that eat primarily leaves--have fully trichromatic vision.
	www.findarticles.com /p/articles/mi_m1200/is_15_164/ai_110266608 (1459 words)

	Andrew Smith, Psychology, Stirling University (Site not responding. Last check: 2007-11-04)
		I have recently completed a BBSRC funded postdoc with Hannah Buchanan-Smith, Nick Mundy and Alison Surridge on the functional utility of colour vision.
		This allows the relative benefits of di- and trichromacy to be tested without the confounds of species or other ecological variables.
		Trichromacy may be advantageous in the detection of ripe fruits against a leaf background, and in the selection of ripe from unripe fruits.
	www.stir.ac.uk /staff/psychology/acs2 (603 words)

	[No title] (Site not responding. Last check: 2007-11-04)
		Perhaps the most striking demonstration of this theory is to stare at one color of an opponent pair for a period time, then shift focus to a white space.
		The opponent color will appear as an “afterimage.” The goal of the present paper is to provide an easy, inexpensive method to demonstrate and integrate trichromacy and opponent-process theories using common software and a color printer.
		When used as part of a full lecture on the sensation and perception of color vision, this demonstration is effective in providing insight into the color vision process.
	trc.csusb.edu /symposium2003/abstracts/drescher.html (356 words)

	RedNova News - Science - Visionary research (Site not responding. Last check: 2007-11-04)
		The major challenge to the hypothesis that trichromacy evolved for finding fruit emerged in 1996, when Gerald H. Jacobs of the University of California, Santa Barbara and his colleagues reported that both male and female howler monkeys-New World primates that eat primarily leaves-have fully trichromatic vision.
		He and Lucas reported the data in 2001, claiming confirmation that trichromacy originally evolved for picking out the most nutritious leaves and not for finding ripe fruit.
		Given that the former all have full-fledged trichromacy, Gilad argued that olfactory-receptor genes, like the genes used to sense pheromones, deteriorated once the primates began to grow more dependent on visual information than on smells.
	www.rednova.com /news/stories/2/2003/10/19/story103.html (2481 words)

	The Evolution of Trichromatic Color Vision by Opsin Gene Duplication in New World and Old World Primates -- Dulai et ...
		Trichromacy in all Old World primates is dependent on separate X-linked MW and LW opsin genes that are organized into a head-to-tail
		An exception to this polymorphism-based trichromacy of New World primates has been identified by Jacobs et al.
		Trichromacy in all Old World primates depends on the presence of two separate X-linked opsin genes that encode a MW and LW opsin, with
	www.genome.org /cgi/content/full/9/7/629 (5208 words)

	[Simegen-L] Re: Dysgraphia (Site not responding. Last check: 2007-11-04)
		It turns out, BTW, that deuteranomalous trichromacy is the single most common color vision defect.
		It's just that protanopia and deuteranopia usually lead to much the same end results; it takes a full Ishihara test to reliably discriminate, so they get lumped as "red/green color blindness".
		Chemically, the red- and green-detecting pigments in the cones of the eye are almost identical: clearly trichromacy in humans and other animals who have it is a mutation that has now become "normal".
	www.simegen.com /pipermail/simegen-l/Week-of-Mon-20040802/014395.html (286 words)

	Trichromatic Color Vision in Primates -- Rowe 17 (3): 93 -- Physiology
		significance of trichromacy, 2) evolution and genetics of photopigments,
		fruit consumption is the principal factor in maintaining trichromacy,
		potential for uniform trichromacy in both males and females.
	physiologyonline.physiology.org /cgi/content/full/17/3/93 (3970 words)

	Visual Displays Overview
		Anomalous Trichromacy - Anomalous trichromacy covers a wide range of color vision deficiencies.
		With total non-function, anomalous trichromacy becomes dichromacy in which only two cone types are functioning.
		Protanomaly - Spectral sensitivities of L cones are shifted toward green.
	www.hf.faa.gov /Webtraining/VisualDisplays/HumanVisSys7.htm (221 words)

	ADVANCE for Occupational Therapy Practitioners \| Editorial
		Although people with reduced color vision may see colors differently from each other, CVD can be classified into two main groups: anomalous trichromacy and dichromacy.
		Those with anomalous trichromacy also use three colors of light to match all colors but in different proportions.
		People mildly affected with anomalous trichromacy may have no difficulty with a saturated color but may confuse pale shades even in excellent light.
	occupational-therapy.advanceweb.com /common/editorial/editorial.aspx?CC=54152 (1255 words)

	The effect of colour vision status on the detection and selection of fruits by tamarins (Saguinus spp.) -- Smith et al. ...
		Despite its theoretical advantages, trichromacy is not uniform
		The relative efficiency of di- and trichromacy for tamarins
		Although we have found that trichromacy is advantageous for
	jeb.biologists.org /cgi/content/full/206/18/3159 (3439 words)

	Citations: opponent colours coding and optimum colour information transmission in the retina - Buchsbaum, Gottschalk ... (Site not responding. Last check: 2007-11-04)
		Buchsbaum, G.; Gottschalk, A.: Trichromacy, opponent colours coding and optimum colour information transmission in the retina.
		Trichromacy, opponent colours coding and optimum colour information transmission in the retina.
		Sensory and Cognitive Contributions of Color to the..
	sherry.ifi.unizh.ch /context/1152549/0 (929 words)

	Color -- Comm326 (Site not responding. Last check: 2007-11-04)
		"Anomalous" trichromacy: About 6% of modern-day males are color-blind, that is two of their pigments peak very nearly at the same position, and they have very limited color discrimination in the red-green range.
		Normal trichromacy: Most humans have three types of cone pigments.
		The one that peaks in the violet is found in only about 3% of cones.
	www.goshen.edu /communication/comm326/color/color.shtml (590 words)

	Scientific Program (Site not responding. Last check: 2007-11-04)
		The past decade has seen considerable progress toward understanding the roots of primate trichromacy.
		An element recently added to this picture is that some prosimians have opsin gene/photopigment polymorphisms reminiscent of those seen in New World monkeys.
		This suggests that primate trichromacy may have appeared prior to the emergence of the anthropoids.
	www.physiol.usyd.edu.au /research/labs/vision/VISIUPS/Int_Abstracts/Jacobs.html (193 words)

	Journal of Vision - Trichromat-like representation of colors in dichromats: A hypothesis on the evolution of ... (Site not responding. Last check: 2007-11-04)
		Journal of Vision - Trichromat-like representation of colors in dichromats: A hypothesis on the evolution of trichromacy, by Wachtler, Rotter, and Hertel
		Color vision in trichromats is based on three types of photoreceptors with different spectral sensitivities.
		Wachtler, T., Rotter, S., and Hertel, R. Trichromat-like representation of colors in dichromats: A hypothesis on the evolution of trichromacy [Abstract].
	www.journalofvision.org /2/7/545 (266 words)

	Find in a Library: Trichromacy and the ecology of food selection in four African primates
		Find in a Library: Trichromacy and the ecology of food selection in four African primates
		Trichromacy and the ecology of food selection in four African primates
		WorldCat is provided by OCLC Online Computer Library Center, Inc. on behalf of its member libraries.
	worldcatlibraries.org /wcpa/ow/bb3d67c8a0f299c9a19afeb4da09e526.html (71 words)

	Nat' Academies Press, (NAS Colloquium) Vision: From Photon to Perception (1999)
		Please use the page image as the authoritative form to ensure accuracy.
		The next set of papers dealt with the circuitry and development of the retina.
		This mixed-surround model provides a simple basis for the evolutionary transition from dichromacy to trichromacy.
	www.nap.edu /books/0309068347/html/2.html (1484 words)

	The Leakey Foundation - Funded Research Project
		Nathaniel Dominy of the University of Chicago demonstrates the use of the spectrometer to measure forest light under different canopy conditions.
		Most color vision hypotheses focus on diet and the advantages of detecting young foliage.
		We humans appear to be losing our trichromacy.
	www.leakeyfoundation.org /discoveries/d3_x_x.jsp?id=2917 (169 words)

	ICVS 2001 - Papers included in "Normal and Defective Colour Vision"
		Jacobs, G. and Degan, J. "Photopigment polymorphism in prosimians and the origins of primate trichromacy"
		Jagla, W., Breitsprecher, T., Kucsera, I., Kovacs, G., Wissinger, B., Deeb, S. and Sharpe, L. "Hybrid pigment genes, dichromacy and anomalous trichromacy"
		Sumner, P. and Mollon, J. "Did primate trichromacy evolve for frugivory or folivory?"
	vision.psychol.cam.ac.uk /icvs2001/papers.html (765 words)

	Studies in Visual Perception, IV.
		The corresponding demonstration in case of color, i.e.
		experimental verification of color trichromacy, is greatly simplified by the physical fact that every perceptible form of light must be a linear mixture of wavelengths drawn from the visible spectrum.
		As noted above, Julesz has posited such a full set of discriminators, at last for the restricted case of fl/white textures.
	www.settheory.com /Glass_paper/Texture_Paper.html (6255 words)

	Exploring Texture Ensembles by Efficient Markov Chain Monte Carlo - Towards a "Trichromacy" Theory of Texture - Zhu, ... (Site not responding. Last check: 2007-11-04)
		Exploring Texture Ensembles by Efficient Markov Chain Monte Carlo - Towards a "Trichromacy" Theory of Texture - Zhu, Liu, Wu (ResearchIndex)
		Exploring Texture Ensembles by Efficient Markov Chain Monte Carlo Towards a "Trichromacy" Theory of Texture (1999)
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	citeseer.ist.psu.edu /302456.html (755 words)

	The red and green cone visual pigments of deuternomalous trichromacy -- Alpern and Moeller 266 (3): 647 -- The Journal ...
		The red and green cone visual pigments of deuternomalous trichromacy -- Alpern and Moeller 266 (3): 647 -- The Journal of Physiology Online
		The red and green cone visual pigments of deuternomalous trichromacy
		Three "simple" deuteranomalous trichromats match with abnormally low
	jp.physoc.org /cgi/content/abstract/266/3/647 (456 words)

	Citations: The cost of trichromacy for spatial vision - Williams, Sekiguchi, Haake, Brainard, Packer (ResearchIndex) (Site not responding. Last check: 2007-11-04)
		Citations: The cost of trichromacy for spatial vision - Williams, Sekiguchi, Haake, Brainard, Packer (ResearchIndex)
		Williams, N. Sekiguchi, W. Haake, D. Brainard, and O. Packer, "The cost of trichromacy for spatial vision," in From Pigments to Perception, A. Valberg and B. Lee, eds., NATO ASI Series A, Life Sciences, Vol.
		Online articles have much greater impact More about CiteSeer Add search form to your site Submit documents Feedback
	sherry.ifi.unizh.ch /context/1332279/0 (169 words)

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