Cone cell

Cone cells, or cones, are photoreceptor cells in the retinas of vertebrate eyes including the human eye. They respond differently to light of different wavelengths, and are thus responsible for color vision, and function best in relatively bright light, as opposed to rod cells, which work better in dim light. Cone cells are densely packed in the fovea centralis, a 0.3 mm diameter rod-free area with very thin, densely packed cones which quickly reduce in number towards the periphery of the retina. Conversely, they are absent from the optic disc, contributing to the blind spot. There are about six to seven million cones in a human eye and are most concentrated towards the macula.[1]

Cone cells
Normalized responsivity spectra of human cone cells, S, M, and L types
Details
LocationRetina of mammals
FunctionColor vision
Identifiers
MeSHD017949
NeuroLex IDsao1103104164
THH3.11.08.3.01046
FMA67748
Anatomical terms of neuroanatomy

Cones are less sensitive to light than the rod cells in the retina (which support vision at low light levels), but allow the perception of color. They are also able to perceive finer detail and more rapid changes in images because their response times to stimuli are faster than those of rods.[2] Cones are normally one of the three types, each with different pigment, namely: S-cones, M-cones and L-cones. Each cone is therefore sensitive to visible wavelengths of light that correspond to short-wavelength, medium-wavelength and longer-wavelength light.[3] Because humans usually have three kinds of cones with different photopsins, which have different response curves and thus respond to variation in color in different ways, humans have trichromatic vision. Being color blind can change this, and there have been some verified reports of people with four or more types of cones, giving them tetrachromatic vision.[4][5][6] The three pigments responsible for detecting light have been shown to vary in their exact chemical composition due to genetic mutation; different individuals will have cones with different color sensitivity.


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