Visual modularity: Difference between revisions

Revision as of 23:30, 14 May 2017

Revision as of 23:22, 17 June 2017

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== Color processing ==

Similar converging evidence suggests modularity for color. Beginning with Gowers’ finding<ref name=gowers>{{cite book|last=Gowers|first=W.|title=A manual of diseases of the brain|year=1888|publisher=J & A Churchill}}</ref> that damage to the fusiform/lingual [[gyri]] in [[occipitotemporal cortex]] correlates with a loss in color perception ([[achromatopsia]]), the notion of a "color centre" in the primate brain has had growing support.<ref name=meadows>{{cite journal|last=Meadows|first=JC|title=Disturbed perception of colours associated with localized cerebral lesions|journal=Brain : a journal of neurology|date=Dec 1974|volume=97|issue=4|pages=615–32|doi=10.1093/brain/97.1.615|pmid=4547992}}</ref><ref name=zeki2>{{cite journal|last=Zeki|first=S.|title=Parallelism and Functional Specialization in Human Visual Cortex|journal=Cold Spring Harbor Symposia on Quantitative Biology|date=1 January 1990|volume=55|issue=0|pages=651–661|doi=10.1101/SQB.1990.055.01.062}}</ref><ref name=grusser>{{cite book|last=Grüsser and Landis|title=Visual agnosias and other disturbances of visual perception and cognition|year=1991|publisher=MacMillan|pages=297–303}}</ref> Again, such clinical evidence only implies that this region is critical to color [[perception]], and nothing more. Other evidence, however, including [[neuroimaging]]<ref name="stiers"/><ref name=barzek2>{{Cite journal |author1=Bartels, A. |author2=Zeki, S. |lastauthoramp=yes |title=Brain dynamics during natural viewing conditions - a new guide for mapping connectivity ''in vivo'' |journal=[[NeuroImage]] |volume=24 |issue=2 |pages=339–349 |year=2005 |doi=10.1016/j.neuroimage.2004.08.044 |quote=no |pmid=15627577}}</ref><ref name=barzek1>{{Cite journal |author1=Bartels, A. |author2=Zeki, S. |lastauthoramp=yes |title=The architecture of the colour centre in the human visual brain: new results and a review |journal=[[European Journal of Neuroscience]] |volume=12 |issue=1 |pages=172–193 |year=2000 |doi=10.1046/j.1460-9568.2000.00905.x |quote=no |pmid=10651872}}</ref> and physiology<ref name=wachtler>{{cite journal|last=Wachtler|first=T|author2=Sejnowski, TJ |author3=Albright, TD |title=Representation of color stimuli in awake macaque primary visual cortex|journal=Neuron|date=Feb 20, 2003|volume=37|issue=4|pages=681–91|doi=10.1016/S0896-6273(03)00035-7|pmid=12597864|pmc=2948212}}</ref><ref name=kusunoki>{{cite journal|last=Kusunoki|first=M|author2=Moutoussis, K |author3=Zeki, S |title=Effect of background colors on the tuning of color-selective cells in monkey area V4|journal=Journal of Neurophysiology|date=May 2006|volume=95|issue=5|pages=3047–59|doi=10.1152/jn.00597.2005|pmid=16617176}}</ref> converges on V4 as necessary to color perception. A recent [[meta-analysis]] has also shown a specific [[lesion]] common to achromats corresponding to V4.<ref name=bouvier>{{cite journal|last=Bouvier|first=S. E.|author2=Engel, SA |title=Behavioral Deficits and Cortical Damage Loci in Cerebral Achromatopsia|journal=Cerebral Cortex|date=27 April 2005|volume=16|issue=2|pages=183–191|doi=10.1093/cercor/bhi096|pmid=15858161}}</ref> From another direction altogether it has been found that when [[synesthesia|synaesthetes]] experience color by a non-visual stimulus, V4 is active.<ref name=rich>{{cite journal|last=Rich|first=AN|author2=Williams, MA |author3=Puce, A |author4=Syngeniotis, A |author5=Howard, MA |author6=McGlone, F |author7= Mattingley, JB |title=Neural correlates of imagined and synaesthetic colours|journal=Neuropsychologia|year=2006|volume=44|issue=14|pages=2918–25|doi=10.1016/j.neuropsychologia.2006.06.024|pmid=16901521}}</ref><ref name=sperling>{{cite journal|last=Sperling|first=JM|author2=Prvulovic, D |author3=Linden, DE |author4=Singer, W |author5= Stirn, A |title=Neuronal correlates of colour-graphemic synaesthesia: a fMRI study|journal=Cortex; a journal devoted to the study of the nervous system and behavior|date=Feb 2006|volume=42|issue=2|pages=295–303|doi=10.1016/S0010-9452(08)70355-1|pmid=16683504}}</ref> On the basis of this evidence it would seem that color processing is modular. However, as with motion processing it is likely that this conclusion is inaccurate. Other evidence shown in Table 3 implies different areas’ involvement with color. It may thus be more instructive to consider a multistage color processing stream from the retina through to cortical areas including at least [[Visual cortex#Primary visual cortex .28V1.29|V1]], [[Visual cortex#V2|V2]], [[Visual cortex#V4|V4]], PITd and TEO. Consonant with motion perception, there appears to be a constellation of areas drawn upon for [[color perception]]. In addition, V4 may have a special, but not exclusive, role. For example, single cell recording has shown that only V4 cells respond to the color of a stimuli rather than its waveband, whereas other areas involved with color do not.<ref name=wachtler/><ref name=kusunoki/>

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