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Essay / or is a characteristic that very few mammals possess. K. Tansely, in one of his books on the vertebrate visual system, commented that "on the whole, mammals do not seem to have color vision, with the exception of primates where it is well developed and almost certainly trichomatic.” The word trichomatic is derived from a theory given by the French physiologist Palmer in 1777, which claimed the presence of three different types of an infinite number of molecules present in the human retina. These types are intended for detecting colors like red, blue and yellow. A few years later, Thomas Young postulated the presence of three types of cones responsible for the detection of these primary colors or metamers and their concept was empirically proven by Maxwell in 1860. This trichomatic character of the perception of the human retina seemed a limitation in the extent to which the human eye can perceive millions of colors. These millions of colors are limited to Grassman's laws explaining the additive, scalar and associative properties of metamers to prove the different color combinations perceived by the visual system. The human range of light perception is 380 nm to 760 nm. Color perception depends on the ability of photoreceptors to separate different wavelengths. Bowmaker et al in 1979 were able to identify the cone using microspectrometry by seeing the absorption spectrum of the cone. The cones were in a blue, green and red spectrum with a wavelength of 420 nm, 534 nm and 564 nm. The identified rod absorbed the spectrum at 498 nm. The results on the absorption spectrum were quite similar to the results found on the rhesus monkey by the same author.*Bowmaker et al. The names given to the cones on the absorption spectrum are S(Short), L(Long) and (M) moderate. . T...... middle of paper ...... cells in the gnocellular pathway are represented by gray cells. (Martin 2004) The third and smallest layer is Koniocellular, present between the parvocellular and the magnocellular, consisting mainly of interneurons. Blue-ON cells form a connection with small bistratified ganglion cells and end in Koniocellular cells. These small neurons project into supragranular layers 2, 3 and upper 4, including the cytochrome oxidase-rich “blob” region of the visual cortex.*The sampling density of blue-ON cells relative to the network of S cones is indicated by white circles. *Martin 2004) There is an unknown pathway that begins from yellow-ON ganglion cells with a wide receptive field and ends at an unknown destination in the lateral geniculate nucleus. *The small white circle at the S cone position represents the postulated blue dwarf-OFF ganglion cells. . (Martin 2004)
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