Editing Cone cell (section)

{{Short description|Photoreceptor cells responsible for color vision made to function in bright light}}
{{Use US English|date=January 2018}}

{{Infobox neuron
| name = Cone cells
| image= Cone-fundamentals-with-srgb-spectrum.svg
| caption = Normalized [[responsivity]] spectra of human cone cells, S, M, and L types
|location = [[Retina]] of vertebrates
|function = [[Color vision]]
|neurotransmitter =
|morphology =
|afferents =
|efferents =
}}

'''Cone cells''' or '''cones''' are [[photoreceptor cells]] in the [[retina]] of the vertebrate [[eye]]. Cones are active in daylight conditions and enable [[photopic vision]], as opposed to [[rod cell]]s, which are active in dim light and enable [[scotopic vision]]. Most vertebrates (including humans) have several classes of cones, each sensitive to a different part of the [[visible spectrum]] of [[light]]. The comparison of the responses of different cone cell classes enables [[color vision]]. There are about six to seven million cones in a human eye (vs ~92 million rods), with the highest concentration occurring towards the [[macula]] and most densely packed in the [[fovea centralis]], a {{val|0.3|u=mm}} diameter rod-free area with very thin, densely packed cones. Conversely, like rods, they are absent from the [[optic disc]], contributing to the [[Blind spot (vision)|blind spot]].<ref>{{cite web |title=The Rods and Cones of the Human Eye |url=http://hyperphysics.phy-astr.gsu.edu/hbase/vision/rodcone.html |website=HyperPhysics Concepts - Georgia State University}}</ref>

Cones are less sensitive to light than the [[Rod cell|rod cells]] in the retina (which support vision at low light levels), but allow the [[Visual perception|perception]] of color. They are also able to perceive finer detail and more rapid changes in images because their response times to [[Stimulus (physiology)#Vision|stimuli]] are faster than those of rods.<ref name="Kandel">{{cite book
| first = E.R.
| last = Kandel
|author2=Schwartz, J.H |author3=Jessell, T. M.
| year = 2000
| title = Principles of Neural Science
| url = https://archive.org/details/isbn_9780838577011
| url-access = registration
| edition = 4th
| pages = [https://archive.org/details/isbn_9780838577011/page/507 507–513]
| publisher = McGraw-Hill
| location = New York
| isbn = 9780838577011
}}</ref> In humans, cones are normally one of three types: S-cones, M-cones and L-cones, with each type bearing a different [[Opsin#Vertebrate_visual_opsins|opsin]]: [[OPN1SW]], [[OPN1MW]], and [[OPN1LW]] respectively. These cones are sensitive to visible wavelengths of light that correspond to short-wavelength, medium-wavelength and longer-wavelength light respectively.<ref>Schacter, Gilbert, Wegner, "Psychology", New York: Worth Publishers,2009.</ref> Because [[Human|humans]] usually have three kinds of cones with different [[photopsin]]s, which have different response curves and thus respond to variation in color in different ways, humans have [[trichromatic vision]]. Being [[color blindness|color blind]] can change this, and there have been some verified reports of people with four types of cones, giving them [[tetrachromat]]ic vision.<ref name="Jameson 2001" >
{{cite journal
|doi=10.3758/BF03196159
|author=Jameson, K. A.
|author2=Highnote, S. M.
|author3=Wasserman, L. M.
|name-list-style=amp
|year=2001
|title=Richer color experience in observers with multiple photopigment opsin genes
|journal=Psychonomic Bulletin and Review
|volume=8 |issue=2 |pages=244–261
|pmid=11495112
|s2cid=2389566
|url=https://link.springer.com/content/pdf/10.3758/BF03196159.pdf
|doi-access=free
}}<!---former link broken: http://www.klab.caltech.edu/cns186/papers/Jameson01.pdf---></ref><ref>{{cite news |date=7 March 2007 |title=You won't believe your eyes: The mysteries of sight revealed |newspaper=[[The Independent]] |url=http://news.independent.co.uk/world/science_technology/article2336163.ece |url-status=dead |access-date=22 August 2009 |archive-url=https://web.archive.org/web/20080706001354/http://news.independent.co.uk/world/science_technology/article2336163.ece |archive-date=6 July 2008 |quote=Equipped with four receptors instead of three, Mrs M - an English social worker, and the first known human "tetrachromat" - sees rare subtleties of colour.}}</ref><ref name="Roth 2006">{{cite news |author=Mark Roth |date=September 13, 2006 |title=Some women may see 100,000,000 colors, thanks to their genes |newspaper=Pittsburgh Post-Gazette |url=http://www.post-gazette.com/pg/06256/721190-114.stm |quote=A tetrachromat is a woman who can see four distinct ranges of color, instead of the three that most of us live with. |access-date=August 22, 2009 |archive-date=November 8, 2006 |archive-url=https://web.archive.org/web/20061108171635/http://www.post-gazette.com/pg/06256/721190-114.stm |url-status=dead }}</ref>
The three pigments responsible for detecting light have been shown to vary in their exact chemical composition due to [[Mutation|genetic mutation]]; different individuals will have cones with different color sensitivity.