Talk:Neocortex

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search
WikiProject Neuroscience (Rated C-class, High-importance)
WikiProject iconThis article is within the scope of WikiProject Neuroscience, a collaborative effort to improve the coverage of Neuroscience on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.
C-Class article C  This article has been rated as C-Class on the project's quality scale.
 High  This article has been rated as High-importance on the project's importance scale.
 

This nugget belongs with Brain, with a redirect there.

I think that there's plenty of information about the neocortex that could be added here instead. For example, an overview of the different types of neocortical cells (pyramidal, chandelier, spiny stellate, aspiny stellate, etc.-- Some good overview papers came out a few years ago, and I'll post some links if anyone is interested.) Also, a note about the evolution of the neocortex (is it sometimes called the "new mamallian brain" because some mammals don't have one?) MisterSheik 22:58, 8 August 2005 (UTC)
I think all mammals have neocortex. Here's[1] an article that mentions "the neocortex of various species, representative of the major subdivisions of mammals". Afaik it's called "new" just because its structure differs from that of the areas of cerebral cortex that are similar in all vertebrates.dsws 20:41, 14 December 2005 (UTC)
  • All mammals have neocortex, and some non-mammals do as well maybe. Neocortex is called "new" because it is phylogenetically newer than the rest of the CNS. Neocortex refers to any 6-layered cortex. Semiconscious 21:39, 15 December 2005 (UTC)
Cetacean intelligence#Brain structure claims that the dolphin only possesses 5 layers of the neocortex, but that layers I and VI are present among those. Is one of the six layers then missing in the dolphin? —The preceding unsigned comment was added by Wdfarmer (talkcontribs) 05:00, 29 April 2007 (UTC).

Neocortex still viable?[edit]

Is the notion of a neocortex still viable? In The Emotional Brain, Joseph LeDoux writes, "Anatomists like Harvey Karten and Glenn Northcutt were showing that so-called primitive creatures do in fact have areas that meet the structural and functional criteria of neocortex...As a result of these discoveries, it is no longer possible to say that some parts of the mammalian cortex were older than other parts. And once the distinction between old and new cortex breaks down, the whole concept of mammalian brain evolution is turned on its head." (100). --Mediaphd 02:00, 18 May 2006 (UTC)

I think the distinguishing characteristic of the neocortex is the six-layer sturcture and presence of neocortical columns, and while earlier mammals may have functional equivalents, they lack these specific structural details Tarcieri 02:20, 10 July 2006 (UTC)
Is neocortex so named because it is assumed to have developed later because it was not (thought) to be found in more 'primative' animals? Or can its devlopment actually be traced back? Perhaps neocortex is new, but both mammals and other animals have seperately developed structures which could be considered isocortex, and may be considered 'neocortex' for their respective classes. Consequently, the implication in the definition of mammalian neocortex as being evolutionarily newer than all non-mammalian cortex may be misleading, and the the comparison between mammalian and non-mammalian cortical 'ages' is misguided.Keepstherainoff (talk) 15:57, 18 July 2010 (UTC)
Isocortex and neocortex mean essentially the same thing. Neocortex is supposedly "new" in comparison to paleocortex (olfactory cortex) and archicortex (the hippocampus). Paleocortex has a similar form across the full range of vertebrates. Archicortex has changed its appearance dramatically in mammals but can be matched up with the "medial pallium" zone in nonmammals, as explained in our hippocampus article. Neocortex, however, doesn't clearly match up with anything in non-mammals. The deep layers of neocortex match up with a zone called the dorsal pallium, but the superficial layers seem to come out of nowhere.
What makes it difficult is that when we trace back the evolution of mammals, we face a huge "missing link" problem. Mammals are synapsids, which diverged from diapsids (birds, reptiles, dinosaurs) over 300 million years ago. There are no existing synapsids other than mammals, but the earliest mammals come from 120-150 million years ago. Furthermore, all mammals have a neocortex with essentially the same structure. Thus, the neocortex took shape during a period from 300-150 million years ago about which we have no useful information -- fossils are useless for understanding this. Looie496 (talk) 18:26, 18 July 2010 (UTC)

80% of the brain's weight[edit]

I'm going to go ahead and flag this with {{Fact}}. According to the article:

"In humans [the neocortex] accounts for about 80% of the brain's weight."

However, according to this site:

http://faculty.washington.edu/chudler/facts.html

 Average number of neurons in the brain = 100 billion
 Number of neocortical neurons (females) = 19.3 billion
 Number of neocortical neurons (males) = 22.8 billion

How is it that the neocortex could comprise approximately 20% of the brain's neurons but 80% of its weight?

I'll also go ahead and incorporate that information into the article. Tarcieri 02:20, 10 July 2006 (UTC)

Never write "go ahead and" again! Useless. Dumb. —Preceding unsigned comment added by 70.181.119.79 (talk) 23:33, 2 April 2010 (UTC)

RE: 80% of the brain's weight[edit]

Neurons are not the heaviest part of the brain... Glia weigh a lot too, and there is a great deal of myelination in the neocortex. but citation is still needed.

changed form percent to total number[edit]

I changed the part under anatomy from percentage of neurons in male and females to total number. Writing it as percentage assumes that the average man and the average woman have the same total number of neurons. The citation only talks about the average brain and does not specifiy whether men and women have the same total number of neurons. Correct me if I am wrong.


Images[edit]

Folks, it would be nice if someone could add an image here. I myself always wanted to see what really the neocortex is, but never found an image! —The preceding unsigned comment was added by 200.196.125.95 (talk) 02:52, 15 February 2007 (UTC).

I added a few images and hope to rouse myself up to expanding the article a bit.Colincbn (talk) 02:30, 12 November 2009 (UTC)
That would be great, this is a pretty important article. Looie496 (talk) 04:47, 12 November 2009 (UTC)

male and female brain differences[edit]

could we remove this reference to different numbers of neocortical neurons in males and females? it is a silly fact (men are larger, and therefore have greater numbers of almost every cell type), and without context could come across as needlessly provocative (especially with the silly comment about "what effects this might have"). —Preceding unsigned comment added by PhineasG (talkcontribs) 06:25, 29 January 2008 (UTC)

This is what Feminism does to science. It is fact and not pointless that number of neurons is different for men and women. Difference being in brain it might have (most likely has) some effect on something.

Fact that men have more cells in general because they are larger is completely pointless and misleading. Mwn might have more muscle mass aswell ? what you seem to imply is that it does not make any difference ?

It is sad that we need to add "context" so women and some men would not be provoked by a simple scientific fact, when political correctness starts affecting how we write wikipedia articles then all is lost ? — Preceding unsigned comment added by 88.113.20.137 (talk) 09:57, 3 July 2014 (UTC)

Image redux[edit]

Thanks Traveler100 for adding an image, but, well, um, I don't like that image. Can I look around for a different one, showing the cell layering structure or something? Looie496 (talk) 19:10, 13 February 2011 (UTC)

File:Neocortex.jpg Nominated for Deletion[edit]

Icon Now Commons orange.svg An image used in this article, File:Neocortex.jpg, has been nominated for deletion at Wikimedia Commons in the following category: Deletion requests July 2011
What should I do?
A discussion will now take place over on Commons about whether to remove the file. If you feel the deletion can be contested then please do so (commons:COM:SPEEDY has further information). Otherwise consider finding a replacement image before deletion occurs.

This notification is provided by a Bot --CommonsNotificationBot (talk) 02:43, 12 July 2011 (UTC)

Gyrification[edit]

Gyrification does not occur only because of spatial demands. This has been changed. Further illustration for doubters is the following: Macaques have partly and inhomogeneously gyrified cortex, which means there are other demands than spatial which determine the gyrification, because if space was the only demand, the cortex would be homogeneously gyrified. Furthermore, although I can't find the article, there exists a report on the consequence of removing part of the developing sheep cortex. This supposedly does not lead to altered gyrification, whereas selective severing of specific short distance white matter tracts does.

I also removed the part that stated that gyrification allowed for the development of working memory and speech and language. First of all, all animals have working memory. Second, there is absolutely no proof for this.— Preceding unsigned comment added by 86.89.79.42 (talkcontribs)

The last two sentences of the first paragraph under the Anatomy section state: "The mechanism by which the gyri form during embryogenesis is not entirely clear. However, it may be due to differences in cellular proliferation rates in different areas of the cortex early in embryonic development." I think the first sentence is fine, but the second sentence gives the impression that this is a singular hypothesis regarding gyri development. There are many such hypotheses, the most popular of which is probably Van Essen's (1997) theory of axonal tension. There is also the Richman (1975) theory of cortical buckling. The Ronan paper is a good one, but I don't see why we're giving this (rather new, by wikipedia standards) research special treatment in this section. If anything, this should state that there are several hypotheses. I recommend the removal of the last sentence. nben (talk) 20:53, 28 March 2014 (UTC)

Proposed merge with Proisocortex[edit]

Proisocortex is a stub and subtopic of neocortex where page would benefit from its inclusion Iztwoz (talk) 13:57, 5 May 2014 (UTC)

  • Support, seems logical and stub is over 10 years old. --Spike Wilbury (talk) 16:11, 5 May 2014 (UTC)
  • Support. I agree. --Tryptofish (talk) 00:06, 10 May 2014 (UTC)

 Done

Etymology[edit]

I believe "cortex" in Latin can also mean "outer layer" or "shell". If I'm correct, calling neocortex "new rind" seems needlessly whimsical. At least, whimsical to anyone who imagines munching on a brain as whimsy. More importantly, it's uninformative unless it's known that the coiner had that etymology in mind. TalkPageWarrior (talk) 21:48, 1 March 2017 (UTC) TalkPageWarrior (talk) 21:48, 1 March 2017 (UTC)

Layer IV lacking in motor cortex is a misconception[edit]

See: 2014: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4201116/ 2014: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4290446/ 1997 (pdf): https://watermark.silverchair.com/070178.pdf?token=AQECAHi208BE49Ooan9kkhW_Ercy7Dm3ZL_9Cf3qfKAc485ysgAAAaUwggGhBgkqhkiG9w0BBwagggGSMIIBjgIBADCCAYcGCSqGSIb3DQEHATAeBglghkgBZQMEAS4wEQQM10TPK2t1aNgelOIuAgEQgIIBWIx7xdqlL5y2HYd4WZ4HyYXY9ddzfd2sMPVwVZn66vCYK39ByqaRF4no5pkkcIzp8KIQcd5QRoGEsbMIXuNT9EbtTDKmuwhnsvZu8Wp6Sat2bFXnIYJGzQJRrshMhrtLyDAjTs1xxOE1MguOrkQSN88h3l_1wN5hacYglYY6O_IjynGP0pltuFkA4aDZ5ysrHEoaloaNvEP8pd4axvZ_0QFTaX-3jMofsZSpGH52eFy8YXNrXQzGfLI-myRZXpZ_wgK50FXLFxSXA3LjorDO-HIG2aO2VUGd06XWGzCT-8zm2P00329rneKzkA1RqzKho16mtfATWt7L0Q2bkesHSS0WKywSPEIwP7KPbKOyDdy42CrknlRuoRPQyPgupBhgFX1DJPuy5lzuwB_QyLpuOyy-Azid4I-jp2RfYLn-XblV4Kbf9jm5KlDnXX2OBjb2OhDsDi5aF4Ep — Preceding unsigned comment added by 2600:1010:B00D:F5C:BD95:65E7:73E8:1B4C (talk) 23:53, 22 April 2018 (UTC)