Talk:Visual system/Archive 1

Archive 1

The task of the visual system...

The article currently states: The task of the visual system is to interpret what would otherwise be a two-dimensional image of the world as a moving, colored three-dimensional world. There also would not be a two-dimensional world without the visual system. Isn't the task of the visual system to interpret what would otherwise be sensed only by touch, smell, taste, and hearing? AED 03:43, 7 October 2005 (UTC)

I agree that this definition is imprecise. I just changed it. Fell free to change further, obviously, and be bold! :) Gaelle 06:12, 24 October 2005 (UTC)

From the new york times - what you see depends on what you expect to see

"Photons bouncing off a flower first reach the eye, where they are turned into a pattern that is sent to the primary visual cortex. There, the rough shape of the flower is recognized. The pattern is next sent to a higher - in terms of function - region, where color is recognized, and then to a higher region, where the flower's identity is encoded along with other knowledge about the particular bloom. The same processing stream, from lower to higher regions, exists for sounds, touch and other sensory information. Researchers call this direction of flow feedforward. As raw sensory data is carried to a part of the brain that creates a comprehensible, conscious impression, the data is moving from bottom to top. Bundles of nerve cells dedicated to each sense carry sensory information. The surprise is the amount of traffic the other way, from top to bottom, called feedback. There are 10 times as many nerve fibers carrying information down as there are carrying it up. These extensive feedback circuits mean that consciousness, what people see, hear, feel and believe, is based on what neuroscientists call "top down processing." What you see is not always what you get, because what you see depends on a framework built by experience that stands ready to interpret the raw information" [1] 4.250.168.126 16:02, 22 November 2005 (UTC)

139.xxx

I reverted the changes by 139.xxx on the strength of the related changes to the Eye article which was detected by others and partially reverted; I completely backed out 139's changes on this article and on Eye. --Ancheta Wis 02:52, 29 November 2005 (UTC)

Links to the Somatosensory system components

I can't find Edinger-Westphal nucleus in the index of Martin Tovée's book; perhaps this link should be part of a section which links to Somatosensory system, as part of the proprioception chain. But proprioception is not in Tovée's book either. Would it be acceptable for us to work out a way to include discusssion of the Edinger-Westphal nucleus in the proprioception article? We could craft the text here, if you like. --Ancheta Wis 01:47, 7 December 2005 (UTC)

The subsection regarding the eye mentions the lens which the EWN affects during accommodation. I guess it is only indirectly related to the processing of light, so I'm OK if you prefer to remove it. AED 05:40, 7 December 2005 (UTC)

While trying to link to somatosensory material, I was struck by a possible parasympathetic connection of the Postcentral gyrus and Edinger-Westphal nucleus. Is there anything about this? --Ancheta Wis 09:14, 7 December 2005 (UTC)

I'm afraid I can't help you. Cheers! AED 21:53, 7 December 2005 (UTC)

Strange sentence

From the article: In humans, the optic nerve is connected directly to the brain rather than through exclusive connection through the medulla

This doesn't really make sense to me. The medulla is part of the brain, so how can the optic nerve connect "directly to the brain rather than through ... the medulla"? Also, the olfactory nerve connects directly to cortex without going through the thalamus, and the optic nerve projects to they hypothalamus (for circadian and pupilary light response regulation) and the tectum. This seems misleading to me.

--Selket ^Talk 00:02, 16 March 2007 (UTC)

Clarified that the optical pathway described in the article bypasses the brain stem -- Ancheta Wis (talk

No offense meant, but that really doesn't fix the problem I was trying to raise. I may not have articulated my concern as well as I would have liked. Adding that the medulla is in the brain stem is helpful but doesn't address my concern. The brain stem is part of the brain. Therefore anything that does go through the medulla is still connected directly to the brain. --Selket ^Talk 00:49, 16 March 2007 (UTC)

Base of the brain. Brain stem is the part chopped off, next to the cerebellum

That is the point of the article. The neocortex is closer to the visual system than the brain stem. It is not stated anywhere that I can cite, but there appears to be a closer connection between the somatosensory system and the brain stem, not visual system. Have you looked at some of the other articles about the brain? Our brains are not unitary, but are composed of many other subsystems. I suppose that is the reason that we can live without significant amounts of cortex, but without the brain stem, we die. That's why neurosurgeons took out parts of Bob Woodruff's skull, to keep the swelling of the cortex (brain) from squashing the brain stem, which saved his life. The picture has been known for 400 years. The brain stem is what you see below the optic chiasm which is different from the cortex. But our eyes follow the red pathway to V1, the last part of the cortex which we can follow directly from our eyes. This is in the article. I agree that we should not discount other pathways, but this article has only items which I could cite from the references listed. If you have other information which you can cite, let's have it. Some of the very interesting information about mirror neurons etc appear to rely on these other nerve pathways which need citations for the encyclopedia. --Ancheta Wis 03:03, 16 March 2007 (UTC)

(edit conflict) Again, I mean no offense, but Bob Woodruff aside, we can't live without our brainstem because it controls breathing. We can live without visual cortex, but we're blind; we can live without motor cortex, but we're paralyzed; we can live without a temporal lobes, but we are unable to form memories (see: HM (patient)). Function is distributed and specialized, that is why some regions are required to sustain life and others aren't. But, you make my point for me. The medulla is part of the brain, so it is impossible to go directly to the brain not bypassing the medulla, because as soon as you get to the medulla, you are in the brain. Some of the somatosensory system's inputs go through the medulla other's don't. Tactile input from the face, for example, goes through the trigeminal nerve (Nolte explains it better) enters at the pons and then projects caudally to the medulla before projecting anteriorly to VPL and VPO in the thalamus.

I've fixed up the section somewhat and added references. If you have a citation for "there appears to be a closer connection between the somatosensory system and the brain stem, not visual system," put it back. I think it is unlikely that you will find one though. --Selket ^Talk 03:43, 16 March 2007 (UTC)

I like your citations. They send the article in another direction, which is not part of vision, but which appears to be part of our subsystem for attention. This begs for another article. Is there an article for the reticular activating system, for example. --Ancheta Wis 03:45, 16 March 2007 (UTC)

reduce indent There are articles for visual perception and the visual system. There is considerable overlap. This article seems to focus more on anatomy, while the other emphasizes psychology. You are right that the projections to the SCN, the VLPO, and the Edinger-Westphal nucleus are not part of the visual system per se. They use the visual system to regulate other functions. However, I think the superior colliculus is part of the visual system in that to do basically any visual task require eye movements. It is part of the system the same way the muscles that control rat whiskers are part of the whisker system. --Selket ^Talk 03:54, 16 March 2007 (UTC)

I thought of an experiment which should disambiguate the visual pathway processing (eye to V1) of the article from the attention processing which you are bringing up.

1. Find trained people, such as airplane pilots, who can act in specified ways based on what is in their visual field. Verify that their reactions to some feature will consistently trigger that visual pathway.
2. Increase the rate of stimulus of the visual pathway so that they cannot react consciously, but only automatically.
3. Identify the specific areas of the brain which are reacting.
4. Now find trained pilots who have damage to those areas
5. If your hypothesis is true, then the visual part of the brains of the damaged pilots will still fire under the stimulus, which would indicate that the visual pathway does not only depend on the eye-to-V1 path, but also on the posited brain stem connections. --Ancheta Wis 04:07, 16 March 2007 (UTC)

It is an interesting experiment. I don't think it has been tried exactly, but similar things have - I'll try to find a reference for you. I do think there is a problem in that it seems to confuse necessity with sufficiency. I agree that without V1, you can't see, but without the superior colliculus, vision is severely impaired as well. (See: here) Just because V1 is necessary for vision doesn't mean the the optic tectum is not. --Selket ^Talk 04:28, 16 March 2007 (UTC)

Newborns seeing world upside down?

I've heard it several times. It seems like it takes time for the brain to process the picture and put it the way adults perceive the reality. Is that true?

I suspect that's a myth. It makes intuitive sense, since the retinal image is upside down, but it ignores the fact that there isn't a wee homunculus in our head looking at the upside down image. Different parts of the brain analyse different aspects of the visual scene. There is no image in our brain to be "upside down" or, for that matter "right way up". Famousdog (talk) 13:41, 30 September 2009 (UTC)

The LGN is not a relay nucleus

There is no such thing as a relay nucleus. Data transformations occur within the LGN so it is not strictly a dumb relay nucleus. —Preceding unsigned comment added by 99.255.163.210 (talk) 21:05, 12 December 2009 (UTC)

There is a post which raises more issues before it can be added to the article:

• even though there is corticothalamocortical action (from cortex to thalamus and back to cortex, apparently thru dedicated fibers and
• even though the visual system (and auditory system) seem to feed this action,
• we still need a reference to an article which demonstrates the entire pathway (thalamus, cortex, back to thalamus, then back to cortex) in the visual stream.

--Ancheta Wis (talk) 22:46, 12 December 2009 (UTC)

It would be more accurate to say that the LGN is more than a relay nucleus. That's been believed for a long time, actually, if nothing else based on the fact that there are substantially more back-projections from cortex to LGN than forward projections from LGN to cortex. The problem is to pin down those additional functions -- the new studies seem to be a step in that direction. In any case it's quite clear that relaying is at least part of the LGN's function -- without it, visual signals would not get to the primary visual cortex. Looie496 (talk) 03:52, 13 December 2009 (UTC)

Changed introduction

I've modified the definition in the introduction. First, the definition of constructing a 3D world from a 3D one is simply wrong; the visual system creates the "2D" world, as previously mentioned. Also, it does not create a 3D one; It creates a binocular one. But more importantly, it does far more than that. The visual system is not limited to V1; there are higher order visual regions in parietal and temporal cortex that are without question part of the "visual system," however it is to be defined. Feel free to make more modifications. —Preceding unsigned comment added by Thesoxlost (talk • contribs) 02:28, 18 November 2008 (UTC)

Well, in Marr's terminology it creates a "2 1/2 D" world. Anyway, good changes, please more. looie496 (talk) 02:38, 18 November 2008 (UTC)

But we also need the citations and references from which this new information stems. It may be possible to insert more material in the red link in "Based on selective damage to parts of the brain and the functional effects this would produce (lesion studies) ...". If formatting is an issue, then just add what you know on the talk page, and another editor will pick up the ball and format it in WP style. --Ancheta Wis (talk) 11:27, 18 November 2008 (UTC)

I found a url for Defining the cortical visual systems: “What”, “Where”, and “How” , but to dive in to the article requires a subscription. Thesoxlost, a specific citation would be in order here, for your changes. --Ancheta Wis (talk) 12:53, 7 December 2008 (UTC)

Which part do you want a reference for? The "What"/"Where" pathway? or the more recent reformulation of the "How" pathway? Each has a number of academic references. I'll track some down in the near future and add them. This is more of an issue for the main articles dorsal stream and ventral stream, which make the same statements without citation. --Thesoxlost (talk) 20:16, 7 December 2008 (UTC)

The casual reader might have missed the fact that there is now a citation: Ungerleider and Mishkin in the Two Streams hypothesis. History for 6 Jun 2009 --Ancheta Wis (talk) 19:11, 14 December 2009 (UTC)

Fact and Citation Check

== History Section

-The citation of Gross (1994) leads to an article in Cerebral Cortex that cannot be accessed without having a subscription to the journal--a good alternate citation for the discovery of Broca's area would be http://books.google.com/books?id=vAY0v7F4JYEC&pg=PA12&dq=discovery+of+broca%27s+area&cd=7#v=onepage&q=discovery%20of%20broca%27s%20area&f=false from page 12 in the book Essentials of neural science and behavior

-The citation of Schiller (1986)leads to an article in Cerebral Cortex that cannot be accessed without having a subscription to the journal--a good alternate citation for the discovery of the motor cortex would be http://books.google.com/books?id=Ii8gnn04a-AC&pg=PA77&dq=discovery+of+motor+cortex+fritsch&cd=1#v=onepage&q=discovery%20of%20motor%20cortex%20fritsch&f=false from page 80 of the book A Hole in the Head: More Tales in the History of Neuroscience

-An accessible reference for Hermann Munk's discovery of the primary visual cortex is http://books.google.com/books?id=_GMeW9E1IB4C&pg=PA87&dq=hermann+munk&cd=2#v=onepage&q=hermann%20munk&f=false from page 87 of Origins of neuroscience: a history of explorations into brain function

== Biology of the visual system

Retina

-Citation needed to the claim that melanopsin is not involved in vision. One possible source is http://books.google.com/books?id=GOxrtYzmixcC&pg=PA945&dq=melanopsin&cd=1#v=onepage&q=melanopsin&f=false on page 945 of Fundamental neuroscience

-Citation needed in the discussion of rod and cone distribution. A potential source is http://books.google.com/books?id=2tW91BWeNq4C&pg=PA50&dq=rods+cones&cd=1#v=onepage&q=rods%20cones&f=false on page 50 of Sensation and Perception by E. Bruce Goldstein

-Same citation listed above can be used to talk about the absorbance spectra of rods and cones

-The entire paragraph starting "in the retina" needs citations for its claims. A good source is http://books.google.com/books?id=DbahEn-y6AoC&pg=PA288&dq=anatomy+retina&cd=5#v=onepage&q=anatomy%20retina&f=false from page 288 and onwards of Neuroscience: exploring the brain by Mark F. Bear, Barry W. Connors and Michael A. Paradiso

-The numbered list following that paragraph needs citations for its claims. A possible citation for the M and P cells is http://books.google.com/books?id=mfl_MLihLEoC&pg=PA20&dq=types+of+retinal+ganglion+cells&cd=6#v=onepage&q=types%20of%20retinal%20ganglion%20cells&f=false from page 20 of Stevens' Handbook of Experimental Psychology, Sensation and Perception by Hal Pashler and others

-The Zaidi et al. reference listed in the paragraph before "Photochemistry" leads to an article that cannot be accessed without a subscription to Current Biology. The paper is well summarized and explained by the next reference, which is the only reference needed out of the three listed ("Normal Responses to Non-visual..."

-The "photochemistry" section needs a reference. One that could be used is http://books.google.com/books?id=QMHQmryI82sC&pg=PA47&dq=retinal+molecule&cd=9#v=onepage&q=retinal%20molecule&f=false from page 47 of Principles and practice of clinical electrophysiology of vision by John R. Heckenlively and others

-The second paragraph in the "Optic nerve" section contains a link (Lucas et al.) to an article that is not accessible without a subscription to Science. An alternate source would be http://books.google.com/books?id=GOxrtYzmixcC&pg=PA945&dq=melanopsin+pretectum&cd=2#v=onepage&q=melanopsin&f=false from page 945 of Fundamental neuroscience by Larry R. Squire

-The last paragraph of the "Optic nerve" section again references Zaidi et al., which cannot be accessed without a subscription to Current Biology. I couldn't find an alternate source for this, so it may have to be taken out.

-The first sentence of the "Optic chiasm" section uses two extremely old (historical, really) references. It might be helpful to add a current reference, such as http://books.google.com/books?id=DbahEn-y6AoC&pg=PA311&dq=optic+chiasm&cd=3#v=onepage&q=optic%20chiasm&f=false from page 311 of Neuroscience: exploring the brain by Mark F. Bear and others

-A good reference for the "lateral geniculate nucleus" section of the article can be found at http://books.google.com/books?id=Cphm_fxwvl8C&pg=PA110&dq=lateral+geniculate+nucleus+anatomy&cd=1#v=onepage&q=lateral%20geniculate%20nucleus%20anatomy&f=false from page 110 of Ocular Anatomy and Physiology by Al Lens and others

-An appropriate reference for the "optic radiation" section would be http://books.google.com/books?id=Cphm_fxwvl8C&pg=PA110&dq=optic+radiation+anatomy&cd=1#v=onepage&q=optic%20radiation%20anatomy&f=false from page 110 of Ocular Anatomy and Physiology by Al Lens and others.

-A reference for the "visual cortex" section could be http://books.google.com/books?id=T_KNSWU4uz4C&pg=PA13&dq=visual+cortex&cd=3#v=onepage&q=visual%20cortex&f=false from The perception of visual information by William Hendee and others

-The first paragraph of the "Visual association cortex" section could have the following reference added: http://books.google.com/books?id=d0D0ghp2fSAC&pg=PA185&dq=visual+association+cortex&cd=6#v=onepage&q=visual%20association%20cortex&f=false from page 185 of the book Neuroscience for the study of communicative disorders

-The "two streams hypothesis" could be referenced with the following: http://books.google.com/books?id=pbhnSGojUt0C&pg=PA243&dq=two+streams+hypothesis&cd=4#v=onepage&q=two%20streams%20hypothesis&f=false from page 243 of Vision and Goal-Directed Movement: Neurobehavioral Perspectives

-The last paragraph in the wiki cites an article that cannot be accessed without a subscription to that journal.

Medchecker (talk) 23:22, 1 May 2010 (UTC)

My comments to the above review:

• Wikipedia does not require that sources be freely and easily accessible to everyone. Sources behind paywalls are acceptable as are rare books. Instead of suggesting alternative sources, it is appropriate to suggest additional sources. See WP:PAYWALL. A claim (your ref: "The last paragraph of the "Optic nerve" section") sourced to a paid source does not have to be taken out. I don't know if WP has a policy about using "too many" sources for a claim; the more the better in my opinion.
• Thank you so much for these helpful suggestions! While it would appear that better communication and coordination between interested Wikipedia editors and Google reviewers would be helpful, the stand-alone effort above is itself very valuable. - Hordaland (talk) 16:05, 10 May 2010 (UTC)

I would actually prefer to see the citations to the original research articles (even if they are behind a paywall), rather than lots of citations to second-hand sources and textbooks, none of which is any better than many other similar texts, JUST because they're available online. Famousdog (talk) 07:51, 11 May 2010 (UTC)

I agree that "JUST because they're available online" is not a good reason for preferring a source. However, recent reviews and textbooks are preferable to primary research results whether the sources are online or not. Qualified reviewers know to weight studies by many criteria which non-specialists may miss, and they are more likely to reflect current knowledge. - Hordaland (talk) 09:06, 11 May 2010 (UTC)

Strange image

The illustration, which is provided in the introduction, could be construed correct to represent the phenomenon of image inversion, which must be reckoned its objective. However, I should draw the atteention up to the fact that the location of the iris is obviously wrong, and that it also provides the superficious reader with the impression that light is focused inside the lens, which is also inaccurate. I would recommend modification.LEMEN (talk) 09:15, 23 May 2011 (UTC)

Thank you for your critique. Replaced the previous diagram with a newer contribution. --Ancheta Wis (talk) 11:46, 23 May 2011 (UTC)

work in progress for easy to understand table for Visual system

Question for all interested editors. See foot of this talk page.

Table moved to the next section

Wait for citations before moving to article page. --Ancheta Wis (talk) 20:19, 2 August 2011 (UTC)

Nice idea, but I would remove the reference to primary visual cortex and just refer to Visual cortex where the further regions (V2, 3, 4, 5) are also discussed. I would also remove reference to the dorsal/ventral streams, as these aren't strictly portions of the visual system - they are a hypothesised functional subdivision of cortical visual processing (and probably a gross oversimplification of the true state of affairs). Finally, I'm not sure why cerebellum is here. It is a sort of multisensory integration centre primarily involved in coordinating movement (yes, in response to sensory info) - but not really a "visual area". You could add superior colliculus to the table. It plays an important role in eye movements. And perhaps pulvinar. Famousdog (talk) 10:41, 3 August 2011 (UTC)

The anonymous IP who started this table posited that Ventral stream was related to balance and smoothness of movement. Perhaps delete this row? V. S. Ramachandran uses "What pathway" and "How pathway" but I see these are red links. Rather than anatomical areas for the last two rows, would it be fair to list functional areas?

--Ancheta Wis (talk) 10:55, 3 August 2011 (UTC)

Various vision researchers have subdivided the visual system into "dorsal/ventral", "action/perception", "where/what", or "where/how" and various variations on those. There is by no means an established segregation of function along these lines (read the Two streams hypothesis article for a taste of the debate). Personally, I think the idea of "two streams" in visual cortex is simply a conceptual hook upon which to hang various grant applications and doesn't actually reflect the reality of the visual brain at all. It should not really be included in this table at all for those reasons. I'm also confused by the emphasis upon the encoding (or not) of angular position in the table, so I've made some changes. I wonder whether we need this table at all, considering there is a "Sensory system: Visual system and eye movement pathways" infobox at the bottom of the page and the contents at the head of the article nicely subdivides the page? Famousdog (talk) 12:22, 3 August 2011 (UTC)

As explanation only (I don't care whether it goes in the article or not) if we view the eye as an optical system, then positions in the field of view are measurable as angles from the optical axis. Thus objects in the field of view of the optical system subtend an angle. For example, the Moon subtends the same angle as the Sun (which we exploit in a solar eclipse). --Ancheta Wis (talk) 16:35, 3 August 2011 (UTC)

It sounds like you're talking about retinotopy. Yes? Famousdog (talk) 10:33, 4 August 2011 (UTC)

Thank you for mentioning this link. I fixed some of its links to visual cortex. --Ancheta Wis (talk) 15:03, 10 August 2011 (UTC)

I just realized that a second table, of dysfunction versus damaged area in the brain, could capture the current state of knowledge about vision. For example V.S. Ramachandran's observations of "Diane", who could not distinguish the orientation of a pencil (vertical vs horizontal) but who could tell it was a pencil. Ramachandran names the inferred pathway the "what pathway" (Diane could distinguish "what it is"). --Ancheta Wis (talk) 13:15, 3 August 2011 (UTC)

Some dysfunctions mght include hemianopia, hemineglect, denial syndrome, scotoma-induced perceptions, ... --Ancheta Wis (talk) 17:07, 5 August 2011 (UTC)

Table moved to the next section

Famousdog, as you pointed out, the superior collicus is part of another visual pathway, from the optic nerve to the brainstem and eventually to parietal lobes (I got this from Ramachandran). Might we refer to it as a 'saccadic pathway' or eye motion pathway? --Ancheta Wis (talk) 17:07, 5 August 2011 (UTC)

Hi everybody, Thanks for the input. I've done the same type of table for three other sensory systems. I won't be putting the table onto the main page until it's complete. The reason for me creating these tables is to help High School students to understand the sensory systems in a quick and accurate manor. Also, I try to put something interesting in each part in the hope of capturing young peoples attention. I see it's already almost complete. Leveni 16:43, 4 August 2011 The reason why cerebellum was mentioned is because I copied a table I created from another sense and pasted it here. You guys found it before I could complete it.Leveni 17:43, 4 August 2011

Thanks for the explanation of why this table has been suggested. This is laudable project, but I question whether Wikipedia is the right place for it. First and formost, Wikipedia is an encyclopaedia. It sounds like you are producing "cheat sheets" (just an expression, I'm not implying any cheating!) to help summarise the component parts of the different senses. That's fine, but encyclopedias don't tend to have summary tables like this for the benefit of students (of any particular age). This article should be viewed (and edited) as an encyclopedia entry on the visual system, not as a generic educational tool for a particular age group. I would read more carefully about Wikipedia because it sounds like you are trying to stretch the definition. I would also refer you to my previous comment about the sensory system infoboxes at the bottom of the article, because they already bring together the component parts of the particular systems and link to the relevant articles. As such, a table like the one you are suggesting, is at least partially redundant. Famousdog (talk) 10:17, 4 August 2011 (UTC)

I think Wikipedia is the perfect place for this. Wikipedia is not just any encyclopaedia, it is written by the masses for the masses. Many of us absorb information in different ways at different stages of our lives. What I am doing here is allowing people to absorb information clearly and precisely in an easily understood manner. I had a look at 'about wikipedia' and can't really find anything there that says I'm contradicting any policy. Please give me an actual link to the policy violation you are talking about. I would like to hear some other opinions though. Leveni 00:22 5 August 2011 —Preceding undated comment added 14:35, 4 August 2011 (UTC).

I agree that Wikipedia could benefit from something like this, but it might be better suited to a distinct article called Outline of the vertebrate visual system, analogous to Outline of neuroscience. This would give a lot more flexibility for arrangement, and leave room for all the parts that are not yet there (I could reel off at least a dozen). Looie496 (talk) 16:30, 4 August 2011 (UTC)

I was actually thinking about something along similar lines. Putting all five senses together on one page and creating a link from each page to the summary page. Anyone else think this is a good idea?Leveni 21:20 5 August 2011 —Preceding undated comment added 11:19, 5 August 2011 (UTC).

Leveni, I have to disagree with your earlier post. The first line of this policy article says clearly: "Wikipedia is an online encyclopedia". The fact that it is written by the masses does not change its core mission to be and ecyclopedia. You should also look at WP:NOTANARCHY where it says: "Wikipedia is free and open, but restricts both freedom and openness where they interfere with creating an encyclopedia" ... "Our purpose is to build an encyclopedia." Now, I accept that its democratic authorship and online format make it more than a simple encyclopedia, and there's nothing wrong per se with the type of summary tables that you are suggesting, but they need to be incorporated sensibly into the relevant articles. They can't just be dumped in the middle of an article without explanation, and if they re-iterate too much of what has already been said, then the article is needlessly repetitive. Looie496's suggestion is a good compromise and I'd look at doing that, but first I'd look at the sensory system infoboxes and decide whether doing what you suggest is needlessly reinventing the wheel. Famousdog (talk) 11:23, 5 August 2011 (UTC)

I was also thinking of doing something along looie496's suggestion. But as for reinventing the wheel, that is what Wikipedia is, Wikipedia is a total reinvention of the wheel. As for the definition of encyclopaedia: it is a summary of information. Your main objection is the repetitive nature of the table. My objective is to summarize a large amount of information into a few sentences for easy comprehension. You want people to gain information from the article in one and only one way. But tables like this are beneficial to people who have read the entire article and then read the table as a summary, and beneficial to people who don't wish to read the whole article but just wish to look at a few main points. Again the definition of encyclopaedia is: a summary of information. I can not see how a table that summarizes information goes against the definition of encyclopaedia. — Preceding unsigned comment added by Leveni (talk • contribs) 13:51, 9 August 2011 (UTC)

Outline of the vertebrate visual system

Fellow editors, I have added citations to the tables, which I envision placing into Outline of the vertebrate visual system discussed above.--Ancheta Wis (talk) 15:06, 2 October 2011 (UTC)

This Outline of the vertebrate visual system lists several of the functional areas in the visual system. The tables below summarize functions as follows:

1. A canonical optical pathway, from the eye to V1
2. A more detailed look of this pathway, from the LGN to areas within visual cortex
   1. Because visual cortex and other cortical regions are less accessible, some evidence is indirect, and based on dysfunction
3. A description of a mechanism for shifts of attention between the available sensory streams and cortical processing

Canonical optical pathway

Main article: Visual system

Name	Function
Eye	Cornea	Transparent tissue that covers the eye. Works with the lens to refract light and is responsible for two thirds of the eye's optical power.
	Pupil	An aperture located in the centre of the eye that allows light to reach the retina.
	Lens	Changes shape with contraction or expansion of the iris so as to focus light onto the retina. It works in conjunction with the cornea to do so.
Retina	Is a light-sensitive layer of photoreceptor cells, on the wall of the eye, that act as a transducer to convert light into electrical impulses. These cells contain either rod opsin proteins; which are found in the periphery of the retina for night vision or cone opsin proteins; found towards the centre of the retina for determining colours.
Optic_nerve	90% of impulses from the retina go to the lateral geniculate nucleus in the thalamus in the brain for vision and the remainder go to the superior colliculus in the midbrain, which control eye movement.
Optic_chiasm	The point at which the optic nerves meet, and partially cross over, en route to the brain. The left halves of both fields of view in each eye go to the right side of the brain. And the right halves of each eye go to the left hand side of the brain.
Canonical optical pathway	Lateral_geniculate_nucleus	Signals originating from the opposite eye are mixed here. Relays the processed signals to the visual cortex.
	Optic_radiation	Point at which nerve tracts diverge to maintain retinotopic encoding in primary visual cortex.
	Visual_cortex	V1 contains cells responsive to lines and edges of particular orientations and widths: Nolte 2002, p. 441. Higher areas encode more complex visual properties such as motion and form: Nolte 2002, p. 441.

More detailed pathways

Name	Function
M pathway (largely magnocellular laminae of LGN)	Pathway beginning at lateral geniculate nucleus and emanating into posterior parietal cortex.	Processes spatial and motion information:Tovee 1996, p. 64.
P pathway (largely parvocellular laminae of LGN)	Pathway beginning at lateral geniculate nucleus and splitting into P-B pathway) and P-I pathway) in upper layers of V1, both projecting into inferior temporal cortex.	P-B pathway seems to be associated with color, while P-I pathway seems to be sensitive to orientation of the stimulus, mediating high acuity perception: Tovee 1996, p. 64.
	P-B pathway	Layers of striate cortex form 0.2mm columns (as found by Hubel et.al.) that extend through layer 2 and 3, and 5 and 6, at a spacing of 0.5mm. These columns are called blobs, and deal with color: Tovee 1996, p. 65.
	P-I pathway	The region between the blob columns is denoted inter-blob and respond to lines or bars of a particular orientation, but not color: Tovee 1996, p. 65.

Dysfunction The following table lists dysfunction in the visual system, along with the implicated area of the brain. Thus the implicated area of the brain is necessary for that visual function.

Dysfunction	Damaged area
Blindsight	Nonfunctional V1	Although a patient can unconsciously see, there is no conscious awareness of sight: Tovee 1996, p. 72. Ramachandran & Blakeslee 1998, pp. 75–76 cites Weiskrantz, L (1986) Blindsight Oxford:Oxford University Press.
Akinetopsia (Motion blindness)	V5, the middle temporal visual area	Although patient can see static images, Ramachandran & Blakeslee 1998, p. 72 describes her perception of motion as stroboscopic, leaving her unable to estimate speeds of approaching cars, etc.
Hemineglect	Cerebral hemisphere	Damage to a single hemisphere of the brain, for example by stroke, can manifest as behavioral or perceptual dysfunction.
	Parietal lobes	The parietal lobes participate in the perception of spatial layout. Ramachandran & Blakeslee 1998, p. 115 discusses a patient who accurately perceived the right side of the visual field (such as the right side of her face in the mirror) and neglected the opposing side of her face when, for example, applying makeup.
Prosopagnosia (inability to identify faces)	Fusiform gyrus	"I can see the eyes, nose and mouth quite clearly. They all seem chalked in, like on a blackboard. ... I cannot recognize people in photographs, not even myself." -- Pallis CA (1955), J Neurol Neurosurg Psychiat 18:218 as referenced by Nolte 2002, pp. 444–445
Capgras syndrome	Hippocampus and amygdala	Although a patient can recognize people, there is a loss of emotional connection to those people: Sacks 2010, pp. 104–5
Musical alexia (condition) (loss of ability to read music)	Visual cortex	Concert pianist Lillian Kallir lost the ability to read music while giving a concert in 1999: Sacks 2010, pp. 1–31, especially pp 16-17 cites a slowly developing posterior cortical atrophy.
Filling-in of a blank spot	Scotomas in eye	In compensation for a blank spot, a loss in the extent of the visual field, our mind's eye fills in the scene: Sacks 2010, pp. 170–184
Charles Bonnet syndrome	Enabled by surgery or scar tissue in the visual cortex	Although patient can see in much of the visual field, in the scarred area, there is conceptual filling-in. The patient sees remembered or imagined images, or perhaps cartoons: Ramachandran & Blakeslee 1998, pp. 106–112.
Visual perseveration, also called paliopsia	Loss of central vision in right eye due to laser surgery on an ocular melanoma	Sacks 2010, pp. 144–201 describes a panoply of hallucinations, ranging from remembered or inferred images of clouds, and city lights, to reconstructed memories of the bookshelves in his home. Sacks cites Critchley, Macdonald (1951) "Types of visual perseveration: paliopsia and illusory visual spread." Brain 74:267-98.

Shifts of attention The brain is "never at rest": Sacks 2010, pp. 144–201, and multiple sensory and memory processes are occurring simultaneously. Attention shifts among these processes in the brain, giving rise to emergent conjectures and hypotheses which are variously disproven or confirmed, depending on the evidence available to the brain.

Name	Function
Reticular activating system	RAS neurons arouse selected areas of the brain, depending on situation	Monotonous repetition leads to habituation; arousal and attention can be effected by activation of single neurons in the RAS: Luciano, Vander & Sherman 1978, pp. 326–7.
Hippocampus	The hippocampus is the seat of new memories; long term potentiation can be triggered from the hippocampus	New information can lead to emotional response and possible action: Luciano, Vander & Sherman 1978, pp. 330–333
Brightness detection pathway	Photoreceptive ganglia	Certain photoreceptive ganglia in humans also have a role in conscious and unconscious visual perception: Nolte 2002, p. 445 states "central nervous system automatically implements the pupil size that is the best compromise for a given target distance and illumination".
Head & eye motion pathway	Superior colliculus	Some of the fibers from the optic nerve attach to the superior colliculus, then to the brainstem, playing.a role in directing visual attention and eye movements.
	Brainstem	Eye motion is effected from the brainstem.

Notes

Sources

• Luciano; Vander; Sherman (1978), Human Function and Structure, ISBN 0-07-038942-X
• Marr, David (1982), Vision: A Computational Investigation into the Human Representation and Processing of Visual Information, San Francisco: W. H. Freeman.
• Nolte, John (2002), The Human Brain: An introduction to its functional anatomy, ISBN 0-323-01320-1 5th edition.
• Ramachandran, V. S.; Blakeslee, Sandra (1998), Phantoms in the Brain : Probing the Mysteries of the Human Mind, ISBN 0-688-17217-2
• Sacks, Oliver (2010), The Mind's Eye, ISBN 978-0-3072-7208-9
• Tovee, Martin J. (1996), An introduction to the Visual System, Cambridge: Cambridge University Press, ISBN 0 521 48339 5

looie496 and other editors, would any of you object if we placed Outline of the vertebrate visual system in article space in the near future? Comments and improvements are welcome, of course. --Ancheta Wis (talk) 11:31, 4 October 2011 (UTC)

This article really needs a section (or a link) for non-mammalian vision

This entire article reads very human-centric, while the title is simply "Visual system", not "human visual system". That may be all you care about if you're a medical doctor. But what about all the aspiring entomologists? I would change it myself, but I know very little about non-human vision systems.129.63.129.196 (talk) 20:45, 11 December 2012 (UTC)

Or, you could read the eye article. --Ancheta Wis   (talk | contribs) 02:02, 12 December 2012 (UTC)

"Visual categorization fMRI studies" section

I've deleted the section headed "Visual categorization fMRI studies". In my opinion, this section was no more than a (poor) summary of a single study. Although the study in question (Huth et al., "A Continuous Semantic Space Describes the Representation of Thousands of Object and Action Categories Across the Human Brain", Neuron (2012)) is certainly interesting and does bear some relevance to the topic of this article, it does not warrant the special attention it was given through being allotted its own section (which was also oddly crowbarred into the narrative in a way that clashed with the article's general structure). If the study is to be referenced, it should be in the context of a broader section on, for example, (fMRI-based) parcellation of visual cortex, including a proper interpretation of the study's results and their relevance. --Rubseb (talk) 17:01, 1 November 2013 (UTC)

Here is a record of the change for reference. --Ancheta Wis   (talk | contribs) 10:24, 2 November 2013 (UTC)

Define 'visual'

"As someone wrote above several years ago (in 2007): "You are right that the projections to the SCN, the VLPO, and the Edinger-Westphal nucleus are not part of the visual system per se. They use the visual system to regulate other functions."

Since the discovery of the third photoreceptor in the retina, it has bothered me that "visual system" sometimes refers only to seeing and sometimes includes the various functions of those 3rd photoreceptors. Is it futile to wish for an easy way to differentiate the two in English? --Hordaland (talk) 15:02, 10 December 2014 (UTC)

It would involve further disambiguating seeing, which can refer to multiple meanings, including the mechanism, painstakingly discovered over the course of several millennia (beginning at the optics end, which I denote the 'front end', also called 'early in the chain'), and which remains a work in process at the neuroscience end of the visual chain (which I denote the 'back end', or 'later in the chain'). I suggest that the words 'visual perception' be reserved for those processes which refer to the back end (the functions occurring after signal input into V1, V2, etc.). Thus the 'seeing' disambiguation page needs more entries, for example, those which more precisely describe the front end (including the optics of vision), as well as the processes behind an optical illusion, which lie in the back end. --Ancheta Wis   (talk | contribs) 18:08, 10 December 2014 (UTC)

Human development merge

Today I found two articles in states of disrepair:

• infant vision — mainly problems with excessively formal tone
• visual development with age — as constituted, barely qualifies as a Wikipedia article

There certainly does need to be a treatment of human visual development and age-related degeneration. I'm not sure these articles are the right way to cleave the carcass. I'm using the merge proposal as a way to attract general attention to the nature of the problem. I'm not at all sure a merger is the right approach. This article itself is rather poor in clearly demarcating the sections pertaining to animals in general, and those pertaining to human particulars. That also could use a rethink. — MaxEnt 01:46, 19 September 2014 (UTC)

As this article purports to discuss vision from a systems perspective, I added the parenthetical to the following sentence:

This article mostly describes the visual system of mammals, although other "higher" animals have similar visual systems (see bird vision, vision in fish, mollusc eye, reptile vision).

It might be better if this article decided to call itself mammalian visual system with perhaps an "as compared to" sub-section to contrast the other "higher" animals. I think there should be a sub-section devoted to human vision (or, more generally, primate vision), and that human/primate vision should have its own proper article, portions of which (concerning humans) can perhaps defer to ophthalmology (e.g. degeneracy and disease). I don't think the weak delineation of this article is doing any favours to any other article concerning vision in various animal species. — MaxEnt 02:39, 19 September 2014 (UTC)

I think that the article should be retained but requires significant modification in orientation to the topic. The methods to identify visual abnormalities among infants and children as in 1 and 2 need to be delineated. Diptanshu^Talk 06:32, 10 December 2014 (UTC)

Which articles are we talking about, please?

My source for the concepts in visual system is Tovee 2008, Introduction to the visual system, which is already in the article. Would you please clarify which articles you are referring to? If you have suggestions for other citations for Visual system, that would be helpful for the article. --Ancheta Wis   (talk | contribs) 08:31, 10 December 2014 (UTC)

Don't merge. My opinion is that the articles infant vision and visual development with age should be merged with one another and developed, but kept separate from this article (visual system). I found this article helpful and interesting when I was seeking to understand the science underlying (human) vision. The other two articles deal with a different type of science, which though important in its own right, would imo make this article less readable. Apuldram (talk) 21:44, 10 December 2014 (UTC)

Update

1. Visual development with age appears in the history to already be merged (not by me) so I've removed the tag.
2. I agree with the above... the infant vision article is too big in my mind to be merged. We can however move it to "Development of the visual system" (this format "Development of..." is used in almost all other related anatomical articles) and that way use it as the parent article for that topic, to which it relates. Please comment on the proposal here: Talk:Infant_vision#Requested_move_20_November_2015.

Cheers --Tom (LT) (talk) 23:15, 20 November 2015 (UTC)

Kudos to editors

A big shout out to the many editors who've worked on this page. I just applied some general structure like we do with most anatomical articles (see WP:MEDMOS#Anatomy). The quality of the information here is great and I think that is covers technical topics that, with a bit of attention from the reader, are accessible even to lay readers. So well done to the editors, this is a great article.

--Tom (LT) (talk) 23:17, 20 November 2015 (UTC)

New section System overview

Have placed this at the end of the page before Clinical significance. This section was recently added by a new editor who clearly hadn't looked into the Wiki guidelines. The references provided are not entered up correctly and some may not even be suitable; there is a repetition of certain bits of information; there is a lot of content completely uncited. Have placed this section further down, still keeping the heading but treating it more as a summary. The section is in real need of attention. No links at all are provided and it is quite badly written up. But there may be useful content to retrieve. Let's see if it can be made good. Or it may be felt that it needs to be removed first for improving.--Iztwoz (talk) 21:22, 31 March 2016 (UTC)