Studying the structure of the visual cortex, it seems there are many neural structures specifically dedicated to detecting and interpreting colour. For example, parvocellular cells are particularly sensitive to colour. Consequently, in a colour blind person, are parvocellular cells or other neural structures less prominent? What are the differences in brain structure between a colour blind person and a normal seeing person?
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$\begingroup$ One important note, which I believe is important here, is to consider that (a) true color-blindness is extremely rare - much more common is a deficiency, where the individual can perceive the colors but at a reduced intensity; also (b) there are several forms of color-deficiencies out there, as well as levels of severity. You would almost certainly need to conduct your own research into this question. $\endgroup$– theMayerCommented Dec 16, 2014 at 17:35
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2 Answers
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Interesting question! I performed a fairly extensive search in Google Scholar and Scopus using various keyword searches, including, but not limited to "color blindness and plasticity", "color blind and brain", "dichromates brain", and "monochromates brain". Strikingly, I found nothing. The reason is aptly explained by Solomon & Rosa, 2014 and I quote from their interesting review:
As yet no anatomical correlates of color blindness have been found in the retina (Chan and Grünert,1998; Chan et al.,2001; Jusuf et al.,2006a,b), thalamus, or primary visual cortex (Goodchild and Martin,1998; Solomon, 2002).
If desirable, you should be able to re-trace the relevant citations from the cited review, as it is open source.
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$\begingroup$ I am VERY curious to more answers! Nice question! $\endgroup$– AliceD ♦Commented Dec 15, 2014 at 3:02
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I can't speak to color blindness, but a little about the neural correlates of color processing in general. There has been some thought that macaque V4 (non-primary or extrastriate visual cortex) and the human V4 topologue may be responsible for color processing--some studies have found wavelength-specific cells in V4, but other studies have found no greater concentration of these in V4 than in V1. There has been significant disagreement about this depending on methodology and task details; it seems that overall, imaging studies tend to find selective activity for color in V4 but lesion studies with damage to V4 often do not find damaged color discrimination. It also seems that the macaque V4 has both a dorsal and a ventral component, where the human dorsal component does not seem to respond to color, complicating the topologue comparison.
Imaging studies
Brouwer and Heeger (2013). Clustering of the Neural Representation of Color. J. Neurosci., 33(39):15454 –15465. DOI:10.1523/JNEUROSCI.2472-13.2013
Brouwer and Heeger (2009). Decoding and Reconstructing Color. J. Neurosci., 29(44):13992–14003. DOI:10.1523/JNEUROSCI.3577-09.2009
Goddard et al. (2011). Color responsiveness argues against a dorsal
component of human V4. Journal of Vision, 11(4):3, 1–21. doi: 10.1167/11.4.3
Lesion studies
Schiller PH (1993) The effects of V4 and middle temporal (MT) area lesions on visual performance in the rhesus monkey. Vis Neurosci 10:717–746.
Walsh V, Carden D, Butler SR, Kulikowski JJ (1993) The effects of V4 lesions on the visual abilities of macaques: hue discrimination and colour constancy. Behav Brain Res 53:51–62.
Heywood CA, Gadotti A, Cowey A (1992) Cortical area V4 and its role in the perception of color. J Neurosci 12:4056–4065.
Heywood CA, Gaffan D, Cowey A (1995) Cerebral achromatopsia in monkeys. Eur J Neurosci 7:1064–1073.
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1$\begingroup$ Indeed V4 lesions have a more pronounced effect on object recognition than on color vision. Therefore, V4 is probably not of much interest in terms of structural differences in color blind people. $\endgroup$– AliceD ♦Commented Dec 16, 2014 at 12:09
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$\begingroup$ Any idea why imaging studies have found color responsiveness in V4 so often? $\endgroup$– KrystaCommented Dec 16, 2014 at 12:40
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$\begingroup$ Nope, sorry. V4 is definitely involved in color vision, don't get me wrong, but it also serves other, perhaps more prominent purposes as far as I know. $\endgroup$– AliceD ♦Commented Dec 16, 2014 at 12:41
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$\begingroup$ bevil conway has interesting theories on v4 function in color perception academics.wellesley.edu/Neuroscience/Faculty_page/Conway/…. In particular, he says that color perception is primarily for object recognition (stop signs are red, yield signs are yellow) and for emotional valence. $\endgroup$– honiCommented May 15, 2015 at 7:33