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Atomic Bombs Help Solve Brain Mystery

Soulskill posted about a year ago | from the microscopes-are-for-squares dept.

Science 59

sciencehabit writes "The mushroom clouds produced by more than 500 nuclear bomb tests during the Cold War may have had a silver lining, after all. More than 50 years later, scientists have found a way to use radioactive carbon isotopes released into the atmosphere by nuclear testing to settle a long-standing debate in neuroscience: Does the adult human brain produce new neurons? After working to hone their technique for more than a decade, the researchers report that a small region of the human brain involved in memory makes new neurons throughout our lives — a continuous process of self-renewal that may aid learning."

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lol (-1)

Anonymous Coward | about a year ago | (#43935291)

lol

Interesting... (4, Informative)

Black Parrot (19622) | about a year ago | (#43935309)

I just read this in a neuroscience textbook published last year [amazon.com] .

Re:Interesting... (5, Informative)

AlecC (512609) | about a year ago | (#43935853)

According to TFA, the research which originally showed this could not be repeated since the chemical given to trace growth was found to be poisonous. Therefore it was based on a probably correct but unrepeatable experiment, something people in the hard sciences do not like. This new experiment has provided confirmation of the earlier result by a different method.

Re:Interesting... (3, Interesting)

Black Parrot (19622) | about a year ago | (#43936069)

Actually I posted too fast. I went back and looked at what I read (just a few nights ago, by chance), and the book does not include the new result. It just said that the isotope ratios observed in the brain confirm the conventional view that neurons aren't being created. TFA reports that a small region of the brain has been found that does not conform to the conventional view.

One more textbook becomes outdated...

Actually it explains... (2)

NotQuiteReal (608241) | about a year ago | (#43936367)

all these toxic memories locked in my head (goatse, tubgirl...) - oh, wait, they are not radio active.

Well, one problem down. (1)

Impy the Impiuos Imp (442658) | about a year ago | (#43935311)

"New neurons -- it's learning! What's it saying? Shhhhh!"

"The only winning move is not to play."

Re:Well, one problem down. (4, Funny)

SJHillman (1966756) | about a year ago | (#43935439)

Not to be confused with T Rex, in which the only winning play is not to move.

Re:Well, one problem down. (1)

Sponge Bath (413667) | about a year ago | (#43936065)

Bang a gong!

Neurons regenerate you say? (5, Funny)

lxs (131946) | about a year ago | (#43935383)

I'll drink to that!

Re:Neurons regenerate you say? (0)

Anonymous Coward | about a year ago | (#43935811)

I thought my brain was adding lots of extra neurons; but when I asked the doctor to check, he said something that sounded like "just two more."

Re:Neurons regenerate you say? (1)

hermitdev (2792385) | about a year ago | (#43940797)

I always enjoyed the Cliff Clavin explanation of natural selection:

Well ya see, Norm, it's like this. A herd of buffalo can only move as fast as the slowest buffalo. And when the herd is hunted, it is the slowest and weakest ones at the back that are killed first. This natural selection is good for the herd as a whole, because the general speed and health of the whole group keeps improving by the regular killing of the weakest members.

In much the same way, the human brain can only operate as fast as the slowest brain cells. Excessive intake of alcohol, as we know, kills brain cells. But naturally, it attacks the slowest and weakest brain cells first. In this way, regular consumption of beer eliminates the weaker brain cells, making the brain a faster and more efficient machine! That's why you always feel smarter after a few beers.

For those that don't know, Cliff Clavin was a character on the TV sitcom "Cheers".

Re:Neurons regenerate you say? (0)

Anonymous Coward | about a year ago | (#43952477)

Fuck you man. I drink to forget... and now you're telling me it regrows.

God dammit.

This isn't a mystery (4, Informative)

hedwards (940851) | about a year ago | (#43935437)

It's been known since at least the '60s that brain cells regenerate, the question was whether that applied to the grey matter or just the glial cells.

And AFAIK, it's been accepted for years that neurogenesis applies to grey cells. Arguing that it doesn't apply would require one to have an alternate explanation for why and how memory and learning occur after the brain supposedly doesn't create new neurons. Or how precisely all that development happens in the brain after birth.

Re:This isn't a mystery (2)

MozeeToby (1163751) | about a year ago | (#43935599)

Arguing that it doesn't apply would require one to have an alternate explanation for why and how memory and learning occur after the brain supposedly doesn't create new neurons.

I was under the impression that the standard explanation was that learning and memory were based on connections, not generation of new cells.

Re:This isn't a mystery (5, Informative)

Black Parrot (19622) | about a year ago | (#43935743)

Arguing that it doesn't apply would require one to have an alternate explanation for why and how memory and learning occur after the brain supposedly doesn't create new neurons.

I was under the impression that the standard explanation was that learning and memory were based on connections, not generation of new cells.

Your impression is correct. You are born with (almost) all the neurons you will ever have. The density of synapses in your brain increases until you are ~18-20, then decreases somewhat and stabilizes. But the strength of the signal transmitted at any given synapse is subject to change at any time in your life, and is thought to be the mechanism for learning.

Re:This isn't a mystery (4, Informative)

Black Parrot (19622) | about a year ago | (#43936693)

BTW, the mention of learning in the article & summary isn't pure spin. The region they found that produces new cells is the hippocampus, which plays some kind of role in memory consolidation.

You'll have to ask an expert whether this is going to make us rethink anything about the mechanism for learning.

(Hope this isn't a dupe... I posted it earlier, but must have forgotten to click the Submit button.)

Re:This isn't a mystery (5, Funny)

werewolf1031 (869837) | about a year ago | (#43935903)

I was under the impression that the standard explanation was that learning and memory were based on connections, not generation of new cells.

That would strongly imply a zero sum game, which would be like, for example, learning a new programming language but in the process forgetting how to talk to wom...

Wait, you might be onto something.

Re:This isn't a mystery (0)

Anonymous Coward | about a year ago | (#43936733)

Actually, it's not really a zero sum game in this case. It's a little bit like some of the fuzzy logic computing (though vastly more complex) in that you essentially store a formula that given an approximate input will determine an answer. Or in other words you can remember if you've seen something before by seeing it again.

This works not by storing the original input by itself, but creating a mosiac image that contains pieces of everything and then modifying the formula to include the new information. It's not a perfect storage system, so it tends to lose little details, but it can store a little bit, or a lot of information in a very uniform amount of space.

Re:This isn't a mystery (0)

Anonymous Coward | about a year ago | (#43936903)

...and makes eyewitnesses quite unreliable as they fill in missing details and don't even realize they are doing it.

Re:This isn't a mystery (0)

Anonymous Coward | about a year ago | (#43939355)

Yet studies show that there is neurogenesis going on in hippocampus. Those who have lower neurogenesis also have issues with memory. So of course new neurons are created in some localized areas of brain, which is something science has shown for quite some time.

Re:This isn't a mystery (2)

sribe (304414) | about a year ago | (#43935619)

And AFAIK, it's been accepted for years that neurogenesis applies to grey cells.

Exactly. You'd have to be totally ignorant of at least the last decade of research in neuroscience to deny they regenerate. So I expect that the so-called "debate" was not among neuroscientists, but between people outside the field who insisted on clinging to outdated unfounded dogma, and those who had at least a single fucking clue.

Re:This isn't a mystery (1)

phantomfive (622387) | about a year ago | (#43936457)

Or it could be you started your study over a decade ago, and it took that long to perfect your measurement techniques. That's hardcore science.

Re:This isn't a mystery (2)

ceoyoyo (59147) | about a year ago | (#43935949)

The majority of the development of the brain after birth is myelination and growth of axons, not new neurons. In fact, neurons are drastically pruned in young children so their numbers decrease.

Storing memories can also be adequately explained by existing neurons growing new and reconfiguring existing connections among themselves.

Re:This isn't a mystery (0)

Anonymous Coward | about a year ago | (#43936511)

Beyond that, adult zebrafish are I believe the highest order vertebrate to have been shown that neurons are born in adulthood and integrate into circuitry. And there was a study a couple years ago in Science I think that showed that fear conditioning (thought to depend on memory) can be modulated by intracellular mechanisms (i.e., GPCRs). GP's comment about "of course" there have to be new neurons for learning and/or memory is bullshit. This is a BIG FUCKING DEAL (tm). And yes, I'm a neuroscientist FWIW.

Re:This isn't a mystery (0)

Anonymous Coward | about a year ago | (#43937819)

Re:This isn't a mystery (1)

phantomfive (622387) | about a year ago | (#43936669)

The majority of the development of the brain after birth is myelination and growth of axons, not new neurons.

Axons, and dendrites.......

Given that more about the brain is unknown than known, it's dangerous to say that the majority of brain development is anything.

Storing memories might not be adequately explained by existing neurons growing and reconfiguring existing connections, because we still don't know what the brain is doing. We don't know how to take what we think it's doing and turn that into a Turing machine, for example.

For all we know there is some magic fairy dust in the brain that we haven't discovered yet (although after we discover it, of course it won't be 'magic' anymore).

Re:This isn't a mystery (2, Funny)

Anonymous Coward | about a year ago | (#43936987)

If only the Intelligent Designer had used the waterfall method and left behind requirements specs, functional specs, architecture specs, and design specs.

Unfortunately, based on results, it seems she used agile and we get random bits of this and that from whatever hare brained idea someone came up with at each morning standup and don't even have a documentation trail to help us figure out the black box.

Re:This isn't a mystery (1)

mcswell (1102107) | about a year ago | (#43947471)

It's self-documenting code. We've been documenting it for thousands of years.

Re:This isn't a mystery (1)

ceoyoyo (59147) | about a year ago | (#43946107)

The brain culls more connections than it makes during childhood and adolescence. But long range axons do increase in calibre, which takes up space and accounts for some of the growth of the brain. It probably accounts for some of the behavioural development as well because bigger axons carry signals long distances more effectively (even more so when they're myelinated).

Very little is known about the functional development, as it relates to the physical development, but we know quite a bit about both behavioural development AND physical development of the brain. Both of them you can, you know, watch.

Storing memories is adequately explained by reconfiguring existing connections. That doesn't mean that's all that's going on, but there doesn't have to be something else happening. The poster I replied to said that obviously the brain is growing new neurons because it develops after birth and we're able to learn. Neither of those things need to involve new neurons.

Re:This isn't a mystery (1)

phantomfive (622387) | about a year ago | (#43946677)

. That doesn't mean that's all that's going on, but there doesn't have to be something else happening. The poster I replied to said that obviously the brain is growing new neurons because it develops after birth and we're able to learn.

Good point.

Re:This isn't a mystery (2)

Baloroth (2370816) | about a year ago | (#43936129)

Two things. First, it's one thing to be "accepted" that it happens, and totally another to prove that it happens. Secondly, this experiment allowed them to trace how much it happened, which wasn't really known before, and allows you to say much more about how much of a role neurogenesis plays in the adult brain.

Atomic bombs?? (1)

gmclapp (2834681) | about a year ago | (#43935517)

It doesn't sound to me like nuclear weapon research had anything to do with this. If the link between nuclear research and this has anything to do with carbon-14 vs. carbon-12 then you can link this "brain discovery" to nearly any branch of research using carbon-14 dating...

Re:Atomic bombs?? (2)

Dins (2538550) | about a year ago | (#43935533)

Shhh, you're ruining the narrative...

Re:Atomic bombs?? (2, Informative)

Anonymous Coward | about a year ago | (#43935695)

I confess I RTFA (I'm sorry!), and you're wrong. It was the large increase in carbon-14 due to weapon testing that produced the measurable differences in the cadavers' brain tissue.

Re:Atomic bombs?? (1)

NoNonAlphaCharsHere (2201864) | about a year ago | (#43935809)

And you know where that [wikimedia.org] leads...

Re:Atomic bombs?? (3, Informative)

Black Parrot (19622) | about a year ago | (#43935969)

It doesn't sound to me like nuclear weapon research had anything to do with this. If the link between nuclear research and this has anything to do with carbon-14 vs. carbon-12 then you can link this "brain discovery" to nearly any branch of research using carbon-14 dating...

It has nothing to do with carbon dating. As the A/C partially explains in another reply, the nuclear testing during the middle of last century increased the relative amount of C-14 in the environment, but it has been falling off since the test ban treaty went into effect in 1963.

Cells consist of lots of carbon, so *new* cells will be built out of whatever is available in the environment. Thus cells created before 1945 will have the "standard" ratio of C-12 and C-14, those created in the 1950s will have an increased proportion of C-14, and those created since 1963 will also have an increased proportion, though that increase has gotten smaller every year as the excess C-14 disappears from the environment.

So for cells created in the past ~100 years you can distinguish the pre-nuclear-testing ones from the later ones, and for cells created since 1963 you can give an approximate date based on the isotope ratio, since that ratio has been decreasing on a well-known curve.

People born before 1945 have the "standard" ratio of isotopes in most of the neurons in the brain, ergo those cells were created before 1945. People born more recently have an elevated ratio in most of the neurons in their brain, depending on what year they were born.

If new neurons were regularly created throughout life, people born before 1945 would also have an elevated ratio of the isotopes.

The news in TFA is that someone found a brain region with an elevated C-14 ratio in people born before nuclear testing started, and thus conclude that that region of the brain creates new cells later in life.

Re:Atomic bombs?? (1)

gmclapp (2834681) | about a year ago | (#43937479)

Fair enough. I guess I was focusing too much on the part of TFA that talks about the later-to-be-found-toxic indicator that was used to come to the same conclusion. I stand corrected.

Re:Atomic bombs?? (1)

Smurf (7981) | about a year ago | (#43937965)

It has nothing to do with carbon dating.

[...]

Cells consist of lots of carbon, so *new* cells will be built out of whatever is available in the environment. Thus cells created before 1945 will have the "standard" ratio of C-12 and C-14, those created in the 1950s will have an increased proportion of C-14, and those created since 1963 will also have an increased proportion, though that increase has gotten smaller every year as the excess C-14 disappears from the environment.

So for cells created in the past ~100 years you can distinguish the pre-nuclear-testing ones from the later ones, and for cells created since 1963 you can give an approximate date based on the isotope ratio, since that ratio has been decreasing on a well-known curve.

Oh, so it has absolutely everything to do with carbon dating, only that instead of using the ratio of C-12 and C14 to estimate the age of the sample directly, they use it to identify if the neurons' age match the patient's age (i.e., estimate the age of the neurons in a slightly more indirect way).

archeologists will love our era (1)

peter303 (12292) | about a year ago | (#43935709)

It will be so easy to date from the poisonous chemicals and radiactivity, You figure up to a century earlier we didnt have all these chemicals. And a more than a century hence we will have finished cleaning up our pigsty.

Re:archeologists will love our era (2)

oodaloop (1229816) | about a year ago | (#43935751)

And a more than a century hence we will have finished cleaning up our pigsty.

I think it's wildly optimistic humans will still be alive in a hundred years.

Re:archeologists will love our era (0)

Anonymous Coward | about a year ago | (#43935829)

Really? You think that the kids born in 10 years will be the last generation of humans *ever*?

Re:archeologists will love our era (0)

Anonymous Coward | about a year ago | (#43936157)

Oh leave him alone, he's probably a Space Nutter. The Space Nutter religion essentially teaches that humanity is doomed (as you have pointed out, this is the last generation of humans), this planet ("rock" or "mud ball" in their liturgy) is also doomed, and the only hope is colonizing other planets, which presumably are not "rocks" or "mud balls", but are actually the Promised Land of Manifest Destiny. Their only concession to reality is that they somehow sense chemical rockets are not enough so they keep praying for warp drives, usually by invoking the Wright Brothers as some sort of template to believe that anything is possible.

Re:archeologists will love our era (0)

Anonymous Coward | about a year ago | (#43936209)

I think it's wildly pessimistic that you feel humans will not be alive in a hundred years.

Re:archeologists will love our era (1)

cellocgw (617879) | about a year ago | (#43937271)

I think it's wildly optimistic humans will still be alive in a hundred years.

Well, certainly most of the ones we can currently confirm exist won't be.

hmm (1)

superwiz (655733) | about a year ago | (#43935805)

I thought keeping the Cold War cold was the silver lining. Unless, we all of a sudden think that peace is bad thing?

Lemonade from lemons . . . (2)

Idou (572394) | about a year ago | (#43935815)

But I really think we could have done this more cheaply, more ethically, and more humanely through a controlled experiment. Call me jaded, but I have absolutely no romantic feelings of nostalgia towards the cold war. It was a time when the timeless "mine is bigger than yours" human defect almost destroyed human civilization.

Re:Lemonade from lemons . . . (1)

Anonymous Coward | about a year ago | (#43935927)

Crikey, next you'll tell us that just because we can't know the future long term benefits we shouldn't blow up the Moon.

Re:Lemonade from lemons . . . (0)

Anonymous Coward | about a year ago | (#43937235)

Crikey, next you'll tell us that just because we can't know the future long term benefits we shouldn't blow up the Moon.

If we blew up the Moon, we wouldn't be able to use it as a nuclear waste dump [wikipedia.org] .

Re:Lemonade from lemons . . . (0)

Anonymous Coward | about a year ago | (#43936257)

But I really think we could have done this more cheaply, more ethically, and more humanely through a controlled experiment. Call me jaded, but I have absolutely no romantic feelings of nostalgia towards the cold war. It was a time when the timeless "mine is bigger than yours" human defect almost destroyed human civilization.

I charge that you didn't read the article before commenting, or you have incredibly poor reading comprehension.

Re:Lemonade from lemons . . . (1)

TeknoHog (164938) | about a year ago | (#43940539)

If life gives you lemons, then shut up and eat your damn lemons!

Re:Lemonade from lemons . . . (1)

jelizondo (183861) | about a year ago | (#43954385)

Man, have you got it wrong!

If life gives you lemons, find some TEQUILA!

Adult mammalian neurogenesis observed in the 40s? (1)

seminumerical (686406) | about a year ago | (#43936161)

My very elderly Canadian neighbour, at one time associated with Cold Spring Harbor Laboratory and retired from teaching at an American medical school more than 15 years ago, told me that a scientist at her university came up with photo micrographic evidence of of adult mammalian neurogenesis in the late 1940s. This caused some eye rolling and denial of tenure for heresy, and the fellow eventually disappeared. It had to wait 'til the sixties to be rediscovered by Altman.

Maybe just radioactive brains? (1)

hughbar (579555) | about a year ago | (#43936351)

Sir, my brain is getting BIGGER! [cut to tanks, artillery etc. etc.]

Old news (1)

idbedead (2196008) | about a year ago | (#43936371)

This is old news. Using an old (and fun but not novel) technique to confirm what has been known and studied for 20+ years is barely headline news.

Re:Old news (1)

iggymanz (596061) | about a year ago | (#43937771)

indeed, not just brain neurons but peripheral nervous system too. known for even longer time period than you mention, it's 30+ years.

Every cloud has a silver lining... (0)

Anonymous Coward | about a year ago | (#43936887)

(except for the mushroom shaped ones, which have a lining of Iridium and Strontium 90.)

capcha=oblivion!

Every cloud has a silver lining... (1)

TeknoHog (164938) | about a year ago | (#43940509)

except for the mushroom shaped ones, which have a lining of iridium and strontium.

As a result of the experiment (0)

Anonymous Coward | about a year ago | (#43941633)

People turned into Mars Attacks like creatures.

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