Talk:Brain/Archive 1

Archive 1

Archive 2

Archive 3

Brain growth/brain size

When does the brain stop growing?

Basically, when it meets the skull<G>... I know that's not what you're asking. For about the last century it's been taken as doctrine that new neurons were produced up until birth, and that there would be no new neurons produced after birth. Learning might result in denser cross-linkages, but no new neurons. (The increase in the size of the brain from birth to adulthood was thought to be through enlargement of existing neurons, and proliferation of non-neuronal cells.) However, that theory is wrong. It has been demonstrated (after 1999) that neurogenesis occurs in several regions of the brain cortex well into adult life, and especially as a result of learning experiences. So the answer now would have to be "we don't know if or when growth of new brain cells occurs, but it's later than we thought."

--- Someone else 12:02 Dec 7, 2002 (UTC)

White matter of human brains, which are the most slow to mature of all animal brians, is not fully formed until after adolescence. Until recently researchers poorly understood the role of glial networks that comprise white matter, but recent research indicates they contribute much more to cognitive and behavioral functions than previous theories, which suggested they merely provide nourishment and structural support for grey matter. Late developing white matter is associated with imature behavior of late adolescents who enjoy reasonably well developed computational abilities without the more generalized ability to form associations facilitated by the ATP and Calcium mediated networks of the glial cells. Poor white matter development, and concomitant poor judgement and impulsive behavior, often presents in young adults who may excel at academic tasks but perform poorly in functions requiring social skills or leadership. Well nourished adolescents exposed to meaningful socialization and leadership experiences often perform better at these functions than late developing young adults. RaymondByrd 02:19, 15 Apr 2004 (UTC)

This sounds like pseudoscience. Do you have any references? Thanks. Alex.tan 08:46, 15 Apr 2004 (UTC)

This is a talk page. The information was freely provided. References for information on talk pages might be nice, but you are only likely to get the best contributions if you show some positive regard for contributors. Your response is vague and accusatory. What part of what you read "sounds" like pseudoscience to you? What recent reading have you done in neuroscience to provide a basis to advance allegations that a free contribution sounds like pseudoscience? How about "when the brain meets the skull" sounds like psuedoscience? How about asking which part is hypothetical, who advanced the hypotheses, and which of the hypotheses are widely recognized based on repeated experiments and which are analytical based on application of hypotheses? I have references that support this information, and can offer reasonable analysis of the parts of the contribution that are derived from analysis of the laboratory research applied to behavioral phenomena. But your one word "thanks" does not in my mind balance your accusatory approach, so I have no ambition to contribute or to bring Jim Wales proposed for-profit compact-disk up to date with the latest reliable information on neuroscience.

Do you even read the popular scientific publications available at your local library, such as Nature or Scientific American? Your reply indicates you do not, and if you don't, there is no reason for you to expect the people who do monitor those and other periodicals to share with you what they learn if you don't bother to educate yourself before telling others what they learned "sounds" wrong. I suggest if this encyclopedia is based on what "looks funny" and what "sounds like" pseudoscience, something here "smells bad".

'll give you a couple of hints, but I will also tell you won't find any of this at any one source, and such analysis requires understanding and integrating data from paid publications and careful reading of scientific journals. Marian C. Diamond started advancing the study of glial cells with a study of what was left of Einstien's brain. The role of late-forming glial connections is widely available from other sources that you will only find if you find some respectful way to approach somebody who reads that literature. Judging from what I read here, the last contributor who added substantive information on this matter was driven off by know-it-alls who were more concerned about what looks funny than they were with sharing what they knew from books they claimed to have on their shelf.

And if you had bothered follow the sources already on this page, you would see that "when the brain meets the skull" is not even pseudoscience, it is just plain wrong. The source provided : http://faculty.washington.edu/chudler/dev.html plainly shows neural mass developing at a same rate as the skull. So if you are interested in learning something, maybe somebody will help, regardless Jim Wales' intent to exploit for personal profit other's charitable contribution to the world knowledge bank. But if you are interested in playing kill the trolls, you can expect people to show just enough information to demonstrate how little you know, with focus on theories that suggests causes of ignorant behavior.

Dubious 17:18, 15 Apr 2004 (UTC)

Look, I didn't insult what you do or do not read, nor did I insult your intelligence so why do you start on mine? If I was a little accusatory, so what? Why is the reply out of proportion? Do trolls like you really need constant attention to survive? Alex.tan 17:59, 15 Apr 2004 (UTC)

An edit summary that says "strange comments" insults anyone who considers the comments not strange. A physician's claim that information from scientific literature he has not read "sounds like pseudoscience" is an insult.

You are a physician. Do no harm. Physicians know troll is no part of any biological taxonomy. Calling a person troll in the same paragraph as one claiming not to be insulting is preposterous. Your presumptions of my motivation are ill-informed and unproductive. I do not need attention. I spent several minutes of my otherwise valuable time attempting to compose a statement that explained what appears to me to be chronic behavioral problem that is insulting the world knowledge base. I considered your behavior symptomatic of that problem, even if only by the same subjective standard you consider Dr. Diamond's work to be pseudoscience even though you apparently have not examined her work. If I have to hold your hand and show you how go obtain patient information, Okay, step one ... assess the patients interest in sharing information. Step two ... acknowledge the patient is the one who can either offer information or not. Step three ... explore reasons giving the information might support the clients interest.

If "so what" for your initial post, then "so what" for my reply. Or does some presumtion of your superior status afford you unusual rights in conversation? Jim Wales said some people who contribute to Wikipedia are complete and total assholes. You can't be all that, but do wonder about proportions of your anatomy, and attempted to reply as one of your kind. The high ground is still wide open if you care to solicit contributions of knowledge. Dubious 18:31, 15 Apr 2004 (UTC)

---

Thanks - someone told me it stopped growing in size between the ages of 9-12. Is that true?

sounds about right. Adult size head = adult size brain. There's a nice graph at [1]. At birth the brain is about 400 grams, at 18 months 800 grams, at 3 years 1100 grams, and adult is about 1350 grams. -- Someone else 00:12 Dec 8, 2002 (UTC)

Reorganization

The neuroscience/brain material could do with a bit of reorganization.

In my view, some of the material in this article ought to be moved to a new one on the Human brain, with this article being kept for brains in general.

We also need some navigation resources. E.g., List of regions in the human brain (which should be hierarchical).

Washington irving 22:10, 16 Feb 2004 (UTC)

---

agreed. Descriptive problems relating to animal/vertebrate/mammal/human distinctions plague much of Wikipedia's current anatomy and physiology content. My hope is that inclusion of precise distinctions here and there will eventually inspire someone to better develop comparative anatomy/physiology in appropriate articles.

Also agreed on the need for navigation resources, both vertically as you recommend and horizontally toward functionality and systems-related articles relevant to each region at each level. Brodmann areas might provide a useful list, too.

I agree about the Brodmann areas (BA 23 is already defined), perhaps you did it. Probably best not to add BA's to the List of regions in the human brain until the articles are ready (otherwise there will be too many dead links). Washington irving 09:24, 17 Feb 2004 (UTC)

I hadn't seen this comment when I added all of those. I wanted to see how they fit in mostly. After looking at it, I see there are so many per lobe, each lobe could be summarized on a single line - as in Brodmann Areas 1, 2, 3, 4. I advocate filling in as much as possible on this list, even with lots of red wikilinks, mostly because it avoids misleading conclusions based on incomplete work. SoCal 05:29, 18 Feb 2004 (UTC)

This seems like a very good idea Washington irving 08:02, 18 Feb 2004 (UTC)

BTW by hierarchical, I meant to include both vertical and horizonal navigation in the same list (i.e., like a tree, with indent levels). See List of regions in the human brain for an example. Washington irving 09:33, 17 Feb 2004 (UTC)

I see. I couldn't clearly define for myself how to create the horizontal spread I was advocating - anatomy is anatomy and physiology is physiology. Some of that will need to be linked out from the articles, such as "vision" links on the "occipital lobe" page. That's probably why I thought of Broddman areas, because they bring functional descriptions to an otherwise anatomical list. SoCal 05:33, 18 Feb 2004 (UTC)

I think the regions in the list should be anatomically defined, but the articles they link to should include disussion of function. They could in turn link back to more general articles such as vision...Washington irving 08:02, 18 Feb 2004 (UTC)

That seems to be the conventional approach, the more I study the thing. Broddmans are really anatomical distinctions, but most of their cytoarchitecture conveniently coincides with functional distinctions. SoCal 17:05, 18 Feb 2004 (UTC)

I notice you removed brain/csf barrier. That came from a neuroanatomy text but I at least will need to review that source before I can make any intelligable comment about it. SoCal 02:45, 17 Feb 2004 (UTC)

ependyma and glial cells present a structural barrier between CSF and interstitial fluids but it is an insignificant barrier as far as I can tell. SoCal

I have reverted the original edit. I had misread it as a typo. If it is an insignificant barrier as you say, then perhaps you can delete it again. Washington irving 09:30, 17 Feb 2004 (UTC)

Oh, my it seems I was no better at sorting out those Broddman areas than I was in organizing that list, which had the rabbits olfactory bulb described as a telencephelon. if that list is not locked, I would just as soon remove them. In fact, I would rather restore all of these brain pages to the condition they were before I edited them, becuase I have little confidence in the way I went about validating my work and several obvious errors remained posted for weeks while apparently qualified editors failed to catch them. I am glad everyone valued my opinion of how the human brain works, but I think it would be better to take it from an expert who knows what he is talking about. I certainly wouldn't try to sell writing of this low caliber, and I really don't know why I got on a kick of giving it away for free. I don't think it is fair to young people to allow such poorly researched information to stand in an environment where they might perceive it as factual. SoCal 01:39, 9 Mar 2004 (UTC)

I'm glad somebody tried to fix it, but I don't have much confidence in the fixed list either. And I don't know what the idea is splattering those brain images all over the page. There are tasteful ways to present an image of human organs, and that's just not it.

____ fixed image Bird

---

I reverted images to the original placement that I selected after I located the images, changed the backrounds, toned them, uploaded them, tried several layouts and then placed them on the appropriate page. I don't know of any objective basis for the assertion that the images were placed in a "strange" manner. There are style guidelines for images, which I reviewed, but I found nothing to support a contention that anything should be one way or another. If there is discussion of style, I would encourage use of a style that allows flexibility so that each page is not identical, and that accomodates unique images.

After considering several placements and arrangements, I selected one which seemed to best use the lines of the images to both attract a reader's eye to the text and to encourage comparison of the relative shapes of the two primary images.

In this case, if the mouse brain were to be on the right side, it needs to be away from the margin by at least 20px, and it should not be the actual size mouse brain but rather one that is sized to attract appropriate interest to that far edge of the page. But at that size, the relative (though not to scale) sizes of the human brain and mouse brain are lost. Also the dangling brain stem of the smaller image above and left of the larger images best encourages appreciation of the similartities of the two organs. Bird 04:30, 8 Mar 2004 (UTC)

OK, but can we please have not have the first image next to the first paragraph? You're right that there is no "rule" saying this in Wikipedia, but it is a fairly consistently applied. In fact, if it isn't in the Wikipedia:MoS, I'll suggest that it should be. If there is an image floated next to the first paragraph it is almost always floated to the right, the eye normally looks for the first paragraph to be left justified, and it is inconsistent to find an image there (magnified by the presence disambiguation block above it, which confuses the reader about where the left margin really starts). I only care about the first paragraph, subsequent paragraphs, left aligned is fine. --Lexor|Talk 04:47, 8 Mar 2004 (UTC)

In image layout, dominance is important. If the first image is large enough to be dominant, it floats to the right fine - it pulls an eye to an otherwise dead area of the page. But if the image is icon sized, it is lost in right field. Caligraphic images at the upper left of a text area enjoy a long history in lithography because of the value of a visual cue in pulling the eye to the corner of a page - everything points to that corner. Otherwise, the eye is left to flit back and forth, perhaps to choose neither. In this case, the icon is an actual-size image of the subject at hand, it serves to resolve the textual clutter of the disambiguation notice, and it makes the standard title, the disambig graph and the lead graph into a stairstep that leads to the next image in the series, and toward the article. The eye is encouraged to scan quickly down the page toward the the visual center, which in this case remains white, across the bottom, up the table of contents, back to interesting little picture and into the first paragraph.

I don't want to sign off here on an agreement that says any image floated to the left of a first paragraph is always out of bounds. There are not many images that hold up at that size, but I can imagine other small, especially actual size images that bring visual intrique to an otherwise heady subject.

If the human organ were to be placed on the left of the page, though, I would have used human_brain_NIH.jpg, which is the same image flipped. And I am not always impressed with a left image at the top left of a text area, even if it is under a second or third heading. Images make nice lead boxes if they are small but if they are wider than 200px or so, they move the start of the text toward the middle of the page. A dominant image on the left can pull the eye to the image, down to the caption and on to the next block, never to return to the start of the text wrapped right of the image. I generally prefer a larger left-floating image in the middle of a text area rather than at the beginning. In my experience, upper left images they tend to work when they reveal details about the text block and pull the eye in to examine intricacy of the image.

The mouse brain could be between the index and the human brain, if it were near the top of that space, rather than near the bottom. It would be along the same lines suggested by the nerve bundles in the brains and by the Wikiglobe in the upper left. That would be a more convetional layout, but I'm reluctant to consent now to appeals to convention when my consent might add to the foundation of a yet unestablished convention I might otherwise find arbitrary.

I think the current layout encourages better cognitive apprecation of the images in the context of the text, and I think well orchestrated novelty encourages learning, but if the lead image bothers you, I wouldn't be too disturbed if it were in the middle of the page, between the index and the image of the hominid organ. I would probably more appreciate help sorting out the history of conventions in neurological nomenclature. "Bird"

There is another image I planned for this page. That might be why it looked askew. I am working it up now.Bird

Suggestion: Combine mouse and Human Brain images into a single picture (arranged vertically or horizontally) which is nicely layed out. Then put this below the first paragraph. This will help show the difference in scale and similarities in structure nicely. That way the layout on the page can be controlled better. Whatever the history of Calligraphy and Lithography, I think the mouse brain looks funny in its current position. Washington irving 07:47, 8 Mar 2004 (UTC)

Insects are not vertebrates

Im new to Wikipedia and did not wan't to try editing the page myself. However, there is a sentence in the brain article that begins, "Small vertebrates, like insects...". Im not a zoologist. But, I'm almost certain insects do not have vertebra.

Good point. You should go ahead and fix this error. Washington irving 10:01, 8 Mar 2004 (UTC)

I actually just went ahead and did this (the report above was made by an anon IP). --Lexor|Talk 10:04, 8 Mar 2004 (UTC)

Someone should also check the "million billion" figure quoted. I'm pretty sure I have read smaller estimates for the human brain (one of the larger ones). Google search shows 100 billion is a common figure. I don't know how many cells there are in the cetacean brains (which are even bigger). Sometimes these estimates include cerebellum, sometimes not (which may account for some of the variation). Some may include glial cells. Probably best to express large numbers as powers of ten as billion means different things to different people. Washington irving 10:37, 8 Mar 2004 (UTC)

Billion means one million times 1,000. What does it mean to you? Did you bother to check the term in Google before you started telling people what they should do? Try it. Among other sources, you will find Mozart's Brain and the Fighter Pilot, which uses the number. And that author was able to garner a hefty payment for his ability to convey messages in concepts in terms people understand. Perhaps you would be more comforatable with the term 100 trillion? To explain computational science of the human brain, the commonly used term is 20 million billion computations per second. Frankly, the only people who understand numbers in powers of 10 are the few employed in computational sciences.

Actually, there's some ambiguity on the matter. In American English usage, a billion is 10^9, but european countries often use the milliard as 10^9 and thus a billion is 10^12. In fact, the 10^12 definition predates 10^9 by about 65 years. The power of ten notation is not just restricted to computer science, it's also widespread in mathematics and science, often in the form of scientific notation. If it bothers anyone, just use the age-old technique of saying: 10^9 (1,000,000,000). -FunnyMan3595 02:02, 15 Apr 2004 (UTC)

What experience can you offer presening cogent analysis to a mass audience? Or are your skills more limited to declaring when image placement appears "funny"? User:Jimbo Wales said some people who contribute to Wikipedia are complete and total assholes. Are you one of those? Or is only Jimbo Wales empowered to determine who is a complete and total asshole? RaymondByrd 01:47, 15 Apr 2004 (UTC)

Well, those errors have been there for days and nobody bothered reading the copy until I began using images to encouragre readers to pay attention to the article. Since the lead says brains refer to the nervous system of vertebrates and non vertebrates, insects would be included. I don't immediately recall the source for the million-billion - that really seems like a number of synapses more than a number of cells.

At any rate, I am very dissatisfied with the division of labor in this project. i researched sn article, wrote it, wrote several articles to support it, found images, worked the images, tried several placements nad found one that works consisten with several years of professsional experience in publishing, only to be told someboyd would rather have white space all over the name space, or images that lead the eye off the edge of the page.

my preference is not to maintain a user name in this service, because I find people use user names to establish reputations that encourage others not to check the content of what they write. That is exactly what has happened here. I am going to place the images in a way that allows the index box, the overview heading and all three images to appear in the opening screen. If others find it ncccessary to revert them, the legacy of the user name that created the article human brain, and all the others attributed to this name, will be finished. My next effort will be to review the content of what I contributed under this name, with an eye to accuracy. There might be little left when i am done removiing all of the content I contributed but about which I now have doubts havign come to understand I have not even the intelligence to place images on a page. Bird

Hey, don't get too disheartended, the work you've been doing is great and much appreciated. Just remember not to get too attached to an article (I know it's difficult not to especially when you've spent a good deal of time on it), but remember the thing that's unique about wikipedia is that nobody owns the articles (see Wikipedia:Ownership of articles), and that goes for somebody who wrote 99% of something, as it does for somebody who fixed some typos. I know it takes some getting used to (it did for me too!). That's not to say that those who have contributed the most don't get the most respect (in general they do), but just because we have discussions about arcane formatting details, doesn't mean that the content isn't appreciated (obviously it's the most important thing, but also important are conventions). Different users contribute in different ways, the point is that people are making positive contributions (however small and however incrementally). I don't think there has been any negative contributions, at least not on this article. And if there have been, it certainly hasn't been intended, but sometimes in the rough and tumble people don't spend the time they should looking at edits. I try and assume good faith and most of the time good faith is intended. Anyway I hope you will stay with us! -

-Lexor|Talk 15:18, 8 Mar 2004 (UTC)

whoever you are, im not your friend and I don't wnat to be. YOur platitudes nausiate me. If I were you I would bother with your own actions and quit telling other poeple what to do. If somebody wrote soemthing or contributed sometyhing and they later say it was wrong and that images were not fairly used, and they retract it, it is not your mission in life to fight for their creation. You are probably going to become some overlord boss that spends his six figure salary paying cheap service workers to follow your orders. If you wanted this person to contribute, you could have watcyhed and learned, adn ADDED when you had something to ADD. You had notyhing to contribute until you smelled an opportunity to play dictator.

Just remember not to ==Please stop changing the complete article==

I don't know if the changes you are making are accurate, but they are making the article less useful by removing the markup for links, removing images and just in general changing everything. Please incorporate your changes into the article itself (without destroying everything) or talk about it on this page before doing so (with others who know more about this subject than I do). Thank you. RadicalBender 20:13, 8 Mar 2004 (UTC)

Somebody locked this page in a version that was disavowed by the very person that wrote it. I don't know what the value is of an open source encyclopedia that freezes when somebody puts up wrong information. The brain list is all wrong, and the regions, god only knows whats up. I think the earlier version before somebody tried to change it and add all those pictures was best.

Pictures: Sources and copyright status

The human brain picture appears to be an edited version of an image at [2] a US government website. The site links to an official NIMH disclaimer which reads:

• The majority of information at this site is in the public domain. Unless stated otherwise, documents and files on NIMH web servers can be freely downloaded and reproduced. Most documents on this server are sponsored by the NIMH; however, you may encounter documents that were sponsored along with private companies and other organizations. Accordingly, other parties may retain all rights to publish or reproduce these documents or to allow others to do so. Some documents available from this server may be protected under the United States and foreign copyright laws. Permission to reproduce may be required.

There is no indication that the image is copyright on the page in which it is shown. There is thus everty reason to believe it is in the public domain. Washington irving 20:58, 8 Mar 2004 (UTC)

The text you site in no way distinquishes which material is copyright and which is not. Adding the quote added nothing to the disussion except NIMH, where you beleive the images originated, says some of the materlial on its site is copyrighted adn some of it is not. You posted some vague information that makes no distinction then came off with another argument of authority that it must be public domain, because you say it is. That's really bogus. Bad faith

WEll aren't you proud. You got free pictures, toned and placed to your demands, and all you had to do is sit around and bite people in the ass. And now you not only have your free article, you have a new vandal to hate, plus one less identitie with whom your ego must contend when tending your pet flock of articles. So you've locked an article written by a vandal. Bully Bully for you.

Bird/brain Affair Information

To whom it may concern: User talk:Bird/Brain and stuff holds information regarding the conduct of Wikipedia contributors (including User:Bird) and of system administrators regarding the content of this and other articles.

---

Scale

Shown approximately to scale That's cute. Who made that up? one of the lead science editors? It seems they quit listening to the artist earlier today and they don't know anything about the scale. Anybody who knows their stuff knows that is a right lobe, anyway. Artist probably thought nobody around here cared if it was right or not. If I recall, the artist had considered including a neccessary reference to specify that the images are not to scale. From what I know, there was developing a collection of literature on relative brain sizes to enhance accuracy of these grossly anthrocentric stubs. For my part, I wouldn't want to write about it in an environment where allegiance to group process is more important than allegiance to factual accuracy.

They are not to scale. What kind of cat is that, anyway? A lion? Panther? Is kitten? Is that a rat? Or a lab mouse? That would be one big mouse with a brain that size, compared to the human brain. Probably a rat?

pinky and the brain.. :D

Overview

I deleted this paragraph from the overview section:

Along the phylogenic scale three distinctive regions emerged in the chordate neural scheme. Sensory faculties organized around the regions. Olfactory senses were associated with the forebrain, visual senses with the midbrain, and other senses developed pathways in the hindbrain. Grey matter developed from each of the sections forming the cerebrum, the tectum, and the cerebellum.

Although the intent was good, the information here is not entirely correct. The midbrain has little to do with visual processing and the hindbrain is mostly involved in autonomic function. Grey matter can be found throughout the brain and in the spinal cord. Although a short overview of anatomy and phylogeny is important in the overview, I think it should be a bit more accessable to a general audience. Sayeth 19:32, Aug 13, 2004 (UTC)

Merge from Mind Myths

In this edit I merged the contents of Mind Myths here, per that page's VfD result. I haven't checked the accuracy of that information. dbenbenn | talk 21:12, 23 Jan 2005 (UTC)

I really think that information may find a better home on human brain, since it is closer to that subject area. This article should focus more on the brain in general. Sayeth 18:24, Jan 24, 2005 (UTC)

"iter", the medical term

Ah, good... From the start of this page, i thought i'd come to the wrong place. Finally, it became clear that this could be a good place to ask my question.

I was refered to Wikipedia while looking up the word "iter." Wikipedia's only referance i could find so far is:

... "ITER is a proposed international experiment designed to show the scientific and technological feasibility of a fusion power reactor. It builds upon research conducted on devices such as TFTR, JET, JT-60 and T-15, and will be considerably larger than all of them....... "

Other sources told me it is also a medical passage in the brain.

My Question is: Where should the medical terms be put?

I would be happy to do it if someone suggests where to put it.

I've never heard of such a thing. A quick check of my neuro textbooks turned up nothing on "iter" and a PubMed search for "iter brain" turned up a bunch of false positives. If it really is a tract in the brain, it may be a antiquated or extremely uncommon term. Sayeth 05:27, Feb 14, 2005 (UTC)

Unexplained Reversion

Hi. Um... Wikibob reverted an edit of mine without explanation. Except in cases of obvious vandalism, I think an editor should explain their reverts, either in their edit summary, or on the talk page. All that I did was:

1. Italized the myths, so that they are differentiated from their explainations
2. added a few explainations

If my explainations were incorrect, I think they should be corrected, but not removed. Thanks. func(talk) 16:28, 13 Apr 2005 (UTC)

food

Is it true that people used to eat animal brains for food? I think that's disgusting! Scorpionman 18:17, 23 May 2005 (UTC)

Folks still do, especially in the South. Ain't you ever heard of brains & scrambled eggs? It's typically squirrel brains or hog brains. Some people love it. See [3]. Sayeth 18:39, May 23, 2005 (UTC)

mental abilities

The sentence that mental abilities do not decrease with age because our mental abilities depend (only) on how much we use brain seems like a politically correct slogan. Where did the author get it? And what does he mean "how much we use brains"? We use brains 24 hours a day, unless we are in a coma. Does he mean that brains of all people are absolutely the same? It is simply not true. Or does he mean that the differences in brain weight/structure of people has nothing to do with mental abilities? Or that they are entirely because some people "use brains more" than others?

So I reverted this.

See also following link: http://my.webmd.com/content/article/75/89828.htm