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Nov 16 2011

Our Ever-Plastic Brains

One point of critical importance in the debate over how much our genes account for variability in intelligence (current status: no effect demonstrated in normal cognition) is that human brains are ridiculously plastic. As would be expected in an organism that can create and function in a wide variety of social structures, our brains can and do structure themselves on the fly. When you see a headline that says, “XYZ Rewires Our Brains!” the only appropriate response is, “Duh.”

A very recent study suggests that this plasticity may be more radical than we already knew.

McConnell has been exploring this phenomenon for more than a decade. In a 2001 paper, he and his colleagues found that individual mouse cells destined to develop into neurons contain substantial chromosomal changes called aneuploidy. A few years later, he showed that neurons with these changes are active in the mouse brain.

Because humans are born with most of the neurons they will use throughout life, genetic variability among them could have a long-lasting effect on how people behave, McConnell says.

To see if human brain cells are genetic mosaics, McConnell turned to induced pluripotent stem (iPS) cells. They are created by treating adult cells with a suite of reprogramming factors that transform the cells into an embryonic-like state in which they can form other tissues.His team transformed iPS cells from two people into neuron cells and then examined the genomes of individual neurons, looking for places where the a huge chunk of the genome is missing or duplicated.

No brain cell’s genome looked the same. They all contained numerous duplications and deletions, but never the same pattern. His team also examined the genomes of the adult cells that were reprogrammed into iPS cells and then neurons, and these cells contained numerous insertions and deletion, but not the same ones as the neurons. McConnell says that this suggests that cells acquire their own genomes as they turn into neurons.

We’re talking mouse brains, and we don’t know how active these changed regions are in brains, but if this pans out, it could explain how we start to generate plasticity and why fetal development appears to be so critical in these systems that change through our lives. In the meantime, however, just try not to use any brain tissue for DNA matching.

19 comments

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  1. 1
    David

    This blockquote said that iPS cells were from humans. But you seem to think that it was mouse cells.

  2. 2
    Stephanie Zvan

    Actually, I seem to think they’ve seen mosaic cells be active in mouse brains, and that we haven’t yet seen this result in human brains. The iPS cell results look promising on this front, but the whole area of brain genetics is touchy enough politically that I’m not going to overclaim.

  3. 3
    Bryan

    Would there be individual differences in the rate and amount of plasticity? I wonder if this might be g. At any rate, how does finding plastic brains rule out genetics? And how much literature are you ignoring by claiming no effect of H on normal cognition?

  4. 4
    Stephanie Zvan

    Oh, Dr. Bryan Pesta, if you had only clicked on that link before commenting instead of after, you could have saved yourself that embarrassing suggestion that I’m ignoring part of the literature. I fully stand by the SciAm guest blog post and the conversation with one of the researchers in the comments. It still wouldn’t have saved you from asking me how brains in which each cell has a different genome makes it less likely that any direct genetic influence will be found on intelligence, though.

    You should perhaps reconsider commenting on blog posts where your obsessions are involved.

  5. 5
    Bryan

    I read it. I’m confused though. You make strong claims with authoritative tones on no less than Scientific American’s website.

    Casual readers would be forgiven to assume you might be expert in the area.

    But then you state:

    “The only credentials I claim in writing about IQ are being familiar with the literature.”

    So you’re not an expert? What privilege did you enjoy then that allowed you to publish an amateur (non peer-reviewed?)opinion on SA? Have a cake or eat it here…

    My IQ-gate challenge: Submit a review to an elite APA journal (i.e., not the journal, Intelligence, but a true A– something like American Psychologist) wherein you claim that there is no evidence for any genetic contribution to IQ. Use the logic from your SA post.

    It likely won’t survive a desk reject, but if it does, post the blind reviewer comments here?

  6. 6
    Stephanie Zvan

    Bryan, do you know what an argument ad hominem is?

    If you want to argue with my post on the SciAm guest blog, by all means, do so, though I suggest you refer to the literature to do it. Don’t try to tell me you think it got published high enough that you think there’s hanky panky but not so high that you’ll take it seriously. Address the argument.

  7. 7
    Bryan

    Also, it’s odd to claim I am obsessed over something I do for a living. How many people might that apply to (how many have an incredibly strong interest in what they do for a living?)?

    Given– by your own admission– that your are not an expert on this topic, whom is obsessed?

  8. 8
    Bryan

    Was it peer reviewed?

    I was asking about your status as expert or not in this area. I did not claim that you were wrong because of your status, I think that would be an ad hom.

    I’d like to publish my opinions there on quantum mechanics. Can you hook a brother up?

  9. 9
    Bryan

    re my qualifications for a guest blog on QM: Like you, I’m sure I’ve written some science fiction (just not on purpose in my case).

  10. 10
    Stephanie Zvan

    Bryan, when I talk about obsessive, I’m talking about getting into it so deeply with Greg and me on the topic two years ago that you were afraid the argument would jeopardize your tenure review. Remember that? When your wife was contacting Greg asking him to stay away from you–on Greg’s blog? Not a healthy time for you. You’re not working on heading down that path again, are you? Your comments are getting a bit disjointed.

    As for peer review, when Paul Thompson called the post “thought-provoking,” I’m pretty good with that–unless you want to add a review of your own. Ready to do that yet, or do you want to sneer at my qualifications some more?

    If you want to post at the SciAm guest blog, I suggest you query the editor. That’s what I did. Pretty standard for mainstream publications.

  11. 11
    Bryan

    So, who was the editor you queried? Name?

    Suppose I had wrote exactly the blog that you did and submitted under my name. Do you think SA would have published it? Just trying to understand the privilege system at work here.

  12. 12
    Stephanie Zvan

    I’ll take that as a “Nope, only interested in smearing.”

  13. 13
    Greg Laden

    Bryan, you are being a complete dick. Do I have to contact your wife and ask her to get on you to take your meds? Again?

    Or, if Stephanie does not get in line and agree with you uncritically, are you going to threaten her with a law suit like you did to me a while back?

    Please go back and carefully reread what you’ve written here, critically and thoughtfully.

    Then apologize.

  14. 14
    Bryan

    SZ:

    I posted a reply addressing some of your comments re IQ. Did I screw up clicking “send,” or is it being held in moderation?

    G: Why the fascination with my prescription for SSRIs? I imagine some people you know and care about use them. If your cute little kid ever happens to need them, how would you feel about other people mocking him?

    You strongly disagree with me, and so stereotype me as “off my meds”. Is this the moral high ground (and is it consistent with an elite education in cultural anthropology)?

    I did consider getting a lawyer, is that always a default “win” for the other side? Can you point me to some type of internet rule (e.g., Godwin) that describes this?

    You guys have many threads where you discuss outing / exposing / alerting authorities about people who post here. You want to out them because you perceive they have committed criminal or civil wrongs against you.

    Does exercising your rights to use of the legal system make your arguments wrong by default?

  15. 15
    Stephanie Zvan

    Bryan, there’s nothing in moderation or the spam filter here from you. And you’re not wrong because you’re acting obsessive on the internet again where it’s preserved for posterity. You’re being asked about your mental state because you’re being wrong in a rather ugly way in full public view again. Nor is it an unreasonable question from someone you threatened to sue over an argument you had with him on his blog. If this is going to be that bad for you all over again, maybe you should walk away now.

    Or don’t. Implode again instead. I can’t really get that worked up over what happens to someone whose response to an article is to ask me how I managed to get my work into a publication.

  16. 16
    Bryan

    Asking about how this got published is ugly, and shows me spiraling into insanity? Comments on the SA blog raise the same issue.

    How was it published?

    The gist of my missing post:

    I need some clarification on what you claim before I can comment further:

    1. Do you think Cognitive Ability and Motivation are:

    completely independent
    correlated but in a spurious way
    correlated where IQ causes motivation
    correlated where motivation causes IQ
    co-causal.

    2. Do you grasp and accept the distinction between systematic and random error?

  17. 17
    Stephanie Zvan

    Bryan, if you need more from me than is in the post before you can comment, you aren’t commenting on the post. Did you have any comment on the post itself?

  18. 18
    Jason Thibeault

    Oh Doctor Pesta. No wonder you’re worried about your tenure. You do so love to melt down repeatedly.

  19. 19
    Bryan

    My questions were based on the first link in your blog above– your SA article. Trying to raise one criticism at a time, starting from the top.

    No need to reply if you don’t feel like it.

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