Talk:Visual cortex

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Redundancy in V2 section[edit]

Please note the redundancies in the V2 section and remove them. — Preceding unsigned comment added by 131.215.9.89 (talk) 21:53, 3 February 2015 (UTC)

Question[edit]

What's the "input" of the Visual Cortex? It gets signals from the eyes, are those signals pure "pixel information", are are the pixels detected by the rods and cones already processed into something else by the retina?

Before the "signal" reaches the visual cortex, it gets processed by the retina, which transforms images in several ways - first of all along specific color axes, and also a general "edge-detection" sort of transformation. Then it runs through the optic chiasm, which repartitions the information from both eyes into right and left hemispheres. THEN it goes to the LGN (which may or may not be considered part of the visual cortex), before going to the VC proper. So, in brief, yes, they are already heavily processed. Graft 04:05, 19 May 2005 (UTC)

Merge[edit]

  • I merged the info in primary visual cortex to this page and set a redirect on that page to here. Let me know if you have any questions. Semiconscious (talk · home) 09:19, 17 August 2005 (UTC)
  • I've also merged all the info from the individual visual areas (V1-V5) to this page as well. I've set redirects from those pages to point here. 20:54, 17 August 2005 (UTC)
Maybe there's not much in the separate V sections right now, but it seems to me that there's plenty to be written about each, and thus that they'll deserve their own articles eventually. I'll start expanding MT and see whether people think it needs it's own page. Epugachev 03:36, 3 December 2006 (UTC)

Weasel?[edit]

Anybody care to explain what the section V2 warning

refers to?

Uncertain[edit]

I encountered this problem in the LGN page and fixed it. It didn't explicitly state there exists a right and a left hemisphere for the LGN, but then made references to ipsilateral vs. contralateral eye. I researched it a bit and as it turned out there were two sides tot eh LGN. is it the same case with the visual cortex? because on page 412 of "from neuron to brain", figure 20.5 makes reference to the "Right primary visual cortex" Paskari 18:15, 18 February 2007 (UTC) Yes that's correct. Jjhunt 11:47, 17 July 2007 (UTC)

Made some changes about this. Myrvin (talk) 14:34, 23 January 2010 (UTC)

V1: Function[edit]

The use of 'time' in para 2 is obscure. The first sentence reads as if things change with the age of the brain. Later, it is not clear when the 'time' starts. Does it start when the photon hits the retina, or maybe when the signal reaches the V1? Myrvin (talk) 14:37, 23 January 2010 (UTC)

The reference I want to add about connections (direct and via pulvinar) from V1 to V2 is : Sincich L.C. & Horton J.C. The circuitry of V1 and V2:Integration of Color, Form and Motion Ann. Revs Neurosci. 28 303 (2005) —Preceding unsigned comment added by 204.236.73.246 (talk) 22:00, 18 April 2010 (UTC)

V1: references[edit]

The actual articles of the references are missing eg (Angelucci et al., 2003; Hupe et al., 2001) is it possible to add them to the reference list so readers can follow the papers? I figured out a few but I could not find the common named ones.

Angelucci, A., & Bullier, J. (2003). Reaching beyond the classical receptive field of V1 neurons: Horizontal or feedback axons? Journal of Physiology, Paris, 97(2/3), 141-154.

Hupe JM, James AC, Payne BR, Lomber SG, Girard P, Bullier J (1998) Cortical feedback improves discrimination between figure and background by V1, V2 and V3 neurons. Nature 394: 784-787

Hupé J-M, James AC, Girard P, Lomber SG, Payne BR, Bullier J (2001) Feedback connections act on the early part of the responses in monkey visual cortex. J Neurophysiol

Sillito, A. M., Cudeiro, J. & Jones, H. E. Always returning: feedback and sensory processing in visual cortex and thalamus. Trends Neurosci. 29, 307–316 (2006) --Achler (talk) 19:16, 30 April 2010 (UTC)

Mathematical model of V1[edit]

There's a very interesting model of V1 using sub-Riemannian geometry, with applications to image disocclusion and inpainting. For example, see articles by Citti-Sarti or Hladky-Pauls. I can write a paragraph if there's interest. Issildur (talk) 22:53, 28 November 2011 (UTC)

Error?[edit]

To whom it may concern,(and for the record, I am totally a novice when it comes to editing things on wikipedia, as well as just some random nobody), but it seems that there is a typo in the article in regards to the primary visual cortex, specifically that it is mentioned that V1 has six layers for processing information received from the LGN. I think that this might be a typo in that (assuming I am understanding the material correctly) the LGN has six layers for processing visual information which is then sent to V1. Perhaps someone can confirm this? And feel free to disregard and delete if I am incorrect. Apologies for not following procedure and all that- first time doing this. — Preceding unsigned comment added by 74.90.17.220 (talk) 02:35, 10 January 2013 (UTC)

Hi 74.90.17.220, and welcome to Wikipedia! Once you start editing you'll be a Wikipedia editor and no longer a random nobody. SFriendly.gif I'm not that knowledgeable either about the visual system, however, V1 does have six layers. For instance here you can see the six layers (scroll down for a picture). With friendly regards! Lova Falk talk 09:56, 12 January 2013 (UTC)

Colourblind users[edit]

Apologise in advance for awkward grammar, English isn't my first language. Now that that's out of the way... Could you Wikipedians spare a thought for the colourblind Wikipedia users? For instance the picture at the top right of the page shows the different areas in red, orange and yellow which, especially since they appear to be so interwoven, doesn't give me much more information than if just one colour was used. Maybe someone could change it to blue, green and yellow? That triple has the advantage of being much more visible to me and presumably to other colourblind users as well and retains the characteristic of middle colour is a mix of the other two. It is admittedly a minor matter, it's not like I am going to perform brain surgery based on a Wikipedia pic, but if information is presented in graphical format, it would be nice if as large a part of users could access that information as is possible, especially since all it would take is a simple change of colours. Quite a few people suffer from a more or less severe form of colourblindness, males being overrepresented as the gene resides on the X chromosome. — Preceding unsigned comment added by 87.211.115.30 (talk) 16:43, 19 July 2015 (UTC)

The visual cortex of "the brain"[edit]

I think the lead section should be more specific about what kind of brain is discussed in the article. Now this article give the illusion that all brains are structured in the same way.

I can think of two things that can be done to solve this problem:

  • the article should put more emphasis on the differences in structure between species
  • narrow the topic of the article, for example to "visual cortex of the human brain" or "visual cortex of the primate brain" since much of the relevant research occurred on primates.

VeniVidiVicipedia (talk) 14:28, 7 October 2016 (UTC)

@VeniVidiVicipedia, I started to compile a list of the similarities in visual processing among all brains, but it may be worthwhile to include the dissimilarities also:
Input from the eye
  1. Octopus eyes and human eyes both have retinas, but humans have a blind spot
  2. Both octopus and human use long term potentiation
  3. Fly eyes are compound
  4. Both octopus and chameleon change their skin color; sensory neurons in octopus skin can synthesise an opsin protein (which is found in photoreceptors), along with G protein alpha and phospholipase C, two enzymes which start the skin cell's response to a background color to mimic for camouflage.
  5. Neither octopus nor human use ocelloids as eyes
  6. Octopus has peripheral processing in its arms, but only one? arm (the hectocotyl arm) for reproductive purposes
  7. Both octopus and human feel pain
  8. Both octopus and human distinguish and detect personhood in others
Ancheta Wis   (talk | contribs) 19:11, 8 October 2016 (UTC)
@Ancheta Wis
It's a nice list =] , however this article is about the visual cortex and not about the eyes. Octopuses don't have a cortex.
The article gives the idea that visual processing in the cortex is the same for everyone with a cortex (all mammals). However most of the references used in the article are about humans, macaques and owl monkeys.
Would it be an idea to change the subject of the article to "visual cortex of the human brain"? with a section called something like "Evidence from studies on other primates"?
This way evidence from different species (with different visual cortices) cannot be used throughout the article resulting in some imaginary "frankenstein" visual cortex.
VeniVidiVicipedia (talk) 19:11, 10 October 2016 (UTC)

columns in v1[edit]

orientation column and ocular dominance column are both articles about stuff in the primary visual cortices. Maybe someone is able to add this information in an understandable way. --VeniVidiVicipedia (talk) 20:42, 22 November 2016 (UTC)

Question[edit]

I'm experiencing something visually that I think is interesting, and I came to this page to see whether it's a well-known phenomenon. I quickly got lost in the weeds and gave up. So I'm just going to say what I'm seeing, and others can respond or not.

I have had cataract surgery in my left eye. The surgery in my right eye has been postponed for various reasons. So I have had several weeks to observe this. If I look out a window on an overcast day, the right side of my visual field (dominated by my left eye) registers as true color; the left side (dominated by the eye that still has a cataract) has a distinct yellow cast to it. This is to be expected.

Here's the thing I'm noticing, though. If the window has typical narrow muntins and I'm standing a distance from it, the color gradient spans the whole window. But if the window has wide mullions (as is the case with the lights at the top of my entry door, for example, where the mullions are a couple inches across) or if I'm close to the window, so the muntins subtend a relatively larger arc, the color gradient repeats in each pane. Reading left to right I see yellow, blue, yellow, blue, yellow blue, . . .

So some part of the processing in the visual cortex is recognizing the vertical edge defined by the mullion as the end of one visual subfield in some sense and then repeating the left-to-right dominance pattern in the next subfield.

I didn't come here for a medical consult. None of this bothers me as I navigate the world. I just thought it was interesting enough to report, on the off chance that it's something no one has investigated. Dmargulis (talk) 17:56, 28 March 2017 (UTC)

I'm not a doctor. With that said, the whole window vs the panes reminds me of local and global processing. See Global precedence for more info. I think the color "gradient" is "applied" on the object or objects, that is the whole window or a pane depending on the distance. Here are two more wiki pages with the direction in which you might want to look further. Principles of grouping Gestalt psychology
I couldn't find anything about local vs global in combination with color. --VENIVIDIVICIPEDIAtalk 18:34, 31 March 2017 (UTC)

V4 ref[edit]

- Jytdog (talk) 09:26, 3 April 2017 (UTC)