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- 1 Untitled
- 2 Discrepancy?
- 3 Discrepancy 2
- 4 Convert Sections To Bullet Points
- 5 repair after injury
- 6 No references?
- 7 integrating into the table
- 8 Glia in Information Processing
- 9 New information?
- 10 Glial Capacity to Replicate
- 11 The human brain contains <10% neurons?
- 12 Function of fibrous and protoplasmic astrocytes
- 13 History section needs work
It seems citation is a general problem: The reference to modulation of electrophysiology is from 2008, but I know a reference to the "Tripartite synapse", which includes glia a neuromodulator, and is much earlier. —Preceding unsigned comment added by 188.8.131.52 (talk) 12:34, 5 October 2009 (UTC)
Added "Greek for 'glue'" 184.108.40.206 12:17, 3 July 2007 (UTC)
Ok, this is most of all I got. please add somebody. GrazingshipIV 04:41, Mar 11, 2004 (UTC)
In the introduction, it is stated that glia outnumber neurons by as much as 50 to 1. In the history section, it is stated that glial cells are 9 times as numerous as neurons.
- I would assume that "as many as" is the limit, and the 9 to 1 is the normal ratio. That's a guess, and I'm not a neurophysiologist. --G3pro 15:28, 9 Apr 2005 (UTC)
There's a lot of inaccuracy in these numbers...
"In some parts of the nervous system they outnumber the neurons by a ratio of 10 to 1!"
"In the human brain glia outnumber neurons by a ratio of 10 to 1."
From: Neuroscience, third edition, published by Sinauer (http://www.sinauer.com/detail.php?id=7250)
"Glia are more numerous than neurons in the brain, outnumbering them by a ratio of perhaps 3 to 1."
Glydia Pokoli 04:02, 12 December 2005 (UTC)
Whatever is displayed, it should be mentioned where the number comes from. I happened to see the figure 3 to 1 in a book I was reading, so I changed it to that and cited the source. The source is a work of philosophy, though, not science, so if someone has another it might be nice to change it. Or maybe it is worth saying more if the number estimated is all over the place in different sources. JordanDeLong 05:39, 18 August 2006 (UTC)
It appears there may be a number of reasons for the discrepancies that appear here. I suspect that one of the main reasons for this is the lack of information available. Human Autopsies dissecting the brain are rare and few people have donated their brains for scientific purposes to enhance understanding of this topic. I also suspect that the number is considerably variable, dependent on the individual. Also, as neurons die, do Glial cells die also? A 'new' brain of a youth may have a lot of neurons and will have a low ratio of glial to neurone cells, whereas the 'old' brain of a pensioner will have fewer neurons, and therefore a higher glial cell to neurones ratio. I also add that I would expect the number to be less variable than the values quoted here. In reference to the Einstein article, it was found that he had 73% more glial cells than average. This would make the 500% variabilities between 10x and 50x glial:neurons to be outside reasonable bounds. However, the extra Glial cells posessed by Einstein have not been proven conclusively to have a significant effect on his intellect. I also suspect that different regions of the human brain contain more glial cells than others. For example, does the cerebellum contain more than the thalamus ? Does non-brain neuronal tissue contain glial cells ? The figure in the introduction quotes the figure for the brain, whereas the later figure may relate to the whole nervous system, ie. Brain and spinal chord etc. Does non-brain nervous tissue such as the spinal chord contain glial cells ? I suspect it does if it undergoes neuronal impulses with axons and myelanation. These are just some of my ideas, however it must be noted that I am not an expert in the field of Neuroscience, or even a distinguished scientist who can provide accurate answers to the question. --Minotaur500 18:47, 6 February 2007 (UTC)
"The human brain contains roughly equal numbers of glial cells and neurons with 84.6 billion glia and 86.1 billion neurons.", and
"The amount of brain tissue that is made up of glia cells increases with brain size: the nematode brain contains only a few glia, a fruitfly's brain is 25% glia, that of a mouse, 65%, a human, 90%, and an elephant, 97%."
The first says that the glia/neuron ratio is roughly 1:1, but for the second for a human it is 1:9. According to "Are there ten times more glia than neurons in the brain?" (Claus C. Hilgetag & Helen Barbas, Brain Struct Funct (2009) 213:365–366), the first is more correct, although many sources cite the second. In any case, the two statements are inconsistent with each other.
- This discrepancy is due to the changing knowledge in the field, I think. The newest research on number of glial cells and the ratio of glia to neurons is here, and here is a Scientific American article clarifying the misconception the field has had for a while. Indeed, most if not all textbooks will soon have to change their coverage of this topic.
- I would suggest that all the numbers be updated to reflect this, but I'm pretty new to the wiki scene and I'm not quite sure of the process. Just thought I'd try and clarify for everyone...
A fundamental difference with neurons is their ability to duplicate through mitosis.
- At least some neuroglia retain mitotic ability for at least several years after development, although I don't know which exactly... --Username132 (talk) 09:53, 21 May 2006 (UTC)
90% are glia, 10% are neurons. And indeed, astrocyts regenerate well. Good mitosis capacity. (gliosis). Neurons normally don't do mitosis I think, since they last a lifetime, and after one is born there is no need to generate more neurons. (even though neuron tumors do occur, but seldom)
Source: My histology course (Gent University).
Neurons do not undergo mitosis after they differentiate. There are neural stem cells in certain parts of the brain (like the olfactory bulb) that can lead to neurogenesis.
220.127.116.11 18:46, 11 January 2007 (UTC)Source: My cellular Neurobiology class (Harvard University)
Convert Sections To Bullet Points
I propose that the "function of the glial cell" section is turned to bullet points with the main body of information contained within the subsequent sections on individual receptor types. --Username132 (talk) 15:36, 20 May 2006 (UTC)
repair after injury
i've added some information about glial repair under the functions of glia cells. i think this counts as one of their primary functions that deserves a mention. the information is from neuroscience 3rd edition purves et all isbn 0-87893-725-0. not really sure how to put the references on properly yet... --Dylan2106 20:04, 17 April 2007 (UTC)
Who added that? Did you try scrolling to the bottom of the page. --IceHunter 17:32, 12 September 2007 (UTC)
- Whoever added that, I changed to a "refimprove" tag. There are some references right now but certainly not enough for such an important article in the biology field. Keith Galveston (talk) 01:35, 28 February 2008 (UTC)
integrating into the table
I think the following content is supposed to be integrated into the table. Does everyone agree?
- star shaped with many processes
- connect to neurons; help anchor them to nearby blood capillaries
- control the chemical environment of the neurons
- range in shape from squamous to columnar; many are ciliated
- line the dorsal body cavity housing the brain and spinal cord
- form a barrier between the neurons and the rest of the body
- have few processes
- line up along neurons and wrap themselves around axons
- form the myelin sheath – an insulating membrane
- form a semi stiff connective tissue around the neurons in CNS
- oligodendrocytes form myelin sheath of neurons in CNS
Glia in Information Processing
Seems like there is evidence for their involvement in information processing. http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&uid=17202478&cmd=showdetailview&indexed=google May want to add something to the article about this. —Preceding unsigned comment added by 18.104.22.168 (talk) 03:57, 14 March 2008 (UTC)
I know Discover magazine is not a peer review journal, but this article seems to point to new information about glial cells. i notice that the ratio in the article of glial to neuronal is not consistent with this article (or at least someone is summarizing perhaps more than necessary), and there is some debate in the past about the ratio. is the article accurate, or does it gloss over different ratios in different nervous system structures? I would like to have this referenced, but i have not done much editing of relatively advanced science articles, so im starting with this query.Mercurywoodrose (talk) 17:41, 22 August 2009 (UTC)
- Glial cells are kind of a hot topic nowadays, and lots of new information has been coming out. I'm a neuroscientist, but unfortunately glial cells are one of my weakest areas, so there's not a lot I can do to help. Regarding the numbers, it seems that estimates have been changing recently, but lots of journalism-level articles don't know that and go with the old numbers. There has been some editing relating to this in the Brain article -- PMID 19226510 is the reference used to justify the numbers currently given there. Looie496 (talk) 16:26, 23 August 2009 (UTC)
Information on Glial cells in other species? The following article suggests Glial cell ratios are 1.4:1 for humans, but 7.7:1 for Minke whales. See: Scientific American - Are whales smarter than we are?
Glial Capacity to Replicate
"However, detailed studies found no evidence that 'mature' glia, such as astrocytes or oligodendrocytes, retain the ability of mitosis." I don't specialise in glia, but I do know that astrocytes replicate after injury to fill the gap, quite famously so in the field of CNS injury. One famous paper (http://www.ncbi.nlm.nih.gov/pubmed/16825202) selectively killed proliferating astrocytes only and left and gaping hole instead of scar tissue after injury. The evidence is pretty conclusive that astrocytes divide, and the current article provides no citation to its claimed study suggesting otherwise. Wee Jimmy (talk) 22:54, 30 June 2011 (UTC)
- Please feel free to fix the article in whatever way seems correct to you. Looie496 (talk) 00:25, 1 July 2011 (UTC)
The human brain contains <10% neurons?
According to the article, the tissue of the human brain is 90% glial cells. That means that neurons, blood vessels etc. make up only 10% of the brain, either by mass or volume. Since the article has already established that the brain has roughly equal numbers of glia and neurons, this also means that glial cells are >10x the volume or mass of neurons. Neither of these claims seems plausible to me. Can someone confirm these figures. Mark Marathon (talk) 07:44, 27 February 2012 (UTC)
- Most glial cells are in fact a lot smaller than the average neuron, but even so the 90% number is out of date. The currently most widely accepted value for the human brain is that the numbers of neurons and glial cells are roughly equal -- the brain article gives a reference for that finding. Looie496 (talk) 18:15, 27 February 2012 (UTC)
If glial cells are in fact a lot smaller than neurons, the claim makes no sense at all. The article states that there are approximately equal numbers of glial cells and neurons, and that glial cells comprise 90% of the mass/volume of the brain. That simply isn't possible. It's like a claim that women are much smaller than men, and there are equal numbers of men an women in New York, but women make up 90% o the human biomass of New York. There's just no way such claims can be correct. You can't have equal numbers in two categories, yet the category with the smaller average size have a larger aggregate size.Mark Marathon (talk) 20:41, 27 February 2012 (UTC)
- Okay, I see what you are talking about now. Unfortunately the reference for those numbers is a "News and Views" piece from Nature that does not specify the sources of its information, so it isn't clear whether the authors were simply using out-of-date figures. I am not terribly knowledgeable about glia myself, but I agree with you that it looks like there must be a discrepancy somewhere. Looie496 (talk) 22:37, 27 February 2012 (UTC)
It depends on different areas of the brain, I have seen brain slices from monkey and from mice and the difference in the cerebellum is evident. Being the ratio in mice 1:1 and in monkey around 5 :1 astrocytes per neurons. I do not think they the statement 90% refers to volume and mass, or I always thought it must 90 % of cells in number, that could make more sense since astrocytes are in general smaller than neurons. — Preceding unsigned comment added by Bruno Pascal (talk • contribs) 20:11, 10 March 2012 (UTC)
- But the article states explicitly that the brain has roughly equal numbers of glia and neurons, so the 90% figure can't be referring to numbers of cells. Something about this figure is wrong, since any way we look at it, it contradicts the rest fo the article. I suggest we remove it until someone with access to that article can confirm the figure. I suspect a misunderstanding. Mark Marathon (talk) 11:57, 21 March 2012 (UTC)
Function of fibrous and protoplasmic astrocytes
History section needs work
I don't have time at the moment to find appropriate references, but let me at least flag some issues in the "History" section:
- "Einstein's brain was discovered to contain significantly more glia than normal brains in the left angular gyrus": there is no citation for this observation, and overall, so what? One person and one brain area prove nothing. "Einstein was smart and he had more glia, so he must have been smart because of the glia" is quite a leap of logic.
- "The ratio of glia to neurons increases with our definition of intelligence." Brain size would be perhaps more appropriate, and is far more quantifiable than "intelligence." The correlation of brain size to proportion of glia is strong when comparing species across the animal kingdom, but I'm not aware of evidence that it's a major factor when comparing among different individual human beings.
- The final paragraph contains many myths, and reads more like a polemic. The main source seems to be an article in ScientificBrains, which is not a peer-reviewed journal, and that article contains several inaccuracies.