Part damaged

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Biolink
Biolink's picture
Part damaged

Where would damage most likely be found in a patient who has difficulty in distinquishing between red and green?
magnocellular LGN
parital cortex
retina
superior colliculi
Im not getting information in the net to get the correct option, kindly someone help with reference to find out the options
 

Jason King
Jason King's picture
Most "patients" who have

Most "patients" who have difficulty in distinguishing between red and green do not have any organic damage at all.
The most common are red-green hereditary (genetic) photoreceptor disorders, but it is also possible to acquire color blindness through damage to the retina, optic nerve, or higher brain areas. Higher brain areas implicated in color processing include the parvocellular pathway of the lateral geniculate nucleus of the thalamus, and visual area V4 of the visual cortex.
 
From:
http://en.wikipedia.org/wiki/Colorblindness#Red-green_color_blindness

Guy Sovak
Guy Sovak's picture
Are you speaking about

Are you speaking about Daltonism?
If so,
Majoority of the cases is due to genetic mutation that would affect the rods.
Two types: Dichromacy (protanopia and deuteranopia),  Anomalous trichromacy (protanomaly and deuteranomaly)
But some studies also found that it could as a result from problem in area IV in the cortex:

Vis Neurosci. 2001 Jul-Aug;18(4):527-40.
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Links
Cortical mapping of gamma oscillations in areas V1 and V4 of the macaque monkey.
Rols G, Tallon-Baudry C, Girard P, Bertrand O, Bullier J.
 
 

 
 

Arvind Singh Pundir
Arvind Singh Pundir's picture
colour blindness results from

colour blindness results from deficiency of one type of cone cells in retina, as the retina is largely composed of two types of cells; rods and cones. Only the cones are responsible for colour perception
here are certain causes

  • Cones (color sensitive receptors) containing single visual pigments selective for red, green, and blue light, are present in the normal human eye. Disturbances of color vision will occur if the amount of pigment per cone is reduced or if one or more of the three cone systems are absent.
  • Although defective color vision may be acquired as a result of another eye disorder, the vast majority of color blind cases are hereditary - present at birth. The gene for this is carried in the X chromosome. Since males have an X-Y pairing and females have X-X, color blindness can occur much more easily in males and is typically passed to them by their mothers.
  • Color blindness is rooted in the chromosomal differences between males and females. Females may be carriers of color blindness, but males are more commonly affected.
  • Color blindness is a malfunction of the retina, which converts light energy into electircal energy that is then transmitted to the brain. This conversion is accomplished by two types of photoreceptor cells in the retina: rods and cones.
  • The cones are responsible for encoding color. Each cone contains structures or visual pigments sensitive to one of three wavelengths of light: red, green, and blue. Normal persons are able to match all colors of the spectrum by mixtures of only three fundamental color sensitivities. Hence, the huge variety of colors we perceive stems from the cone cells' response to different compositions of wavelengths of light.
  • Defects in color vision occur when one of the three cone cell color coding structures fails to function properly. One of the visual pigments may be present and functioning abnormally, or it may be absent altogether.(www.toledo-bend.com/colorblind/aboutcb.asp)

for more information refer  : www.webexhibits.org/causesofcolor/2A.html