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Science

Neuronal Learning Observed 103

Posted by Hemos from the watching-the-brain dept.
Gregg Favalora writes "According to this week's EE Times, R. Colin Johnson reports that researchers at UC San Diego have directly observed the physical changes that neurons undergo during learning. His article explains that neurons were cultured on a smooth, photoconductive silion substrate. Using optical techniques, they were able to trigger individual neurons into firing -- and were actually able to observe some of the physical changes that underly short- and long-term learning. According to the article, "[The team] tested out the theory that learning results from a physical change that strengthens the connections between selected neurons. [They showed] how short- and long-term memories result from different physical effects in the brain. Short-term memories, it turns out, result from the instant assembly of more filaments to strengthen the skin of the cell temporarily, whereas long-term memories result from the growing of a new synapse to strengthen the connection permanently." Besides the interesting cellular observations they're making, I am also intrigued by the process the article describes which uses properties of the silicon substrate to aid in firing individual neurons. "
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Neuronal Learning Observed More

Neuronal Learning Observed

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  • Don't look for neurons to hold 1's and 0's, because you'll probably take up more room with neuron+silicon substrate+implantation technology than you would in plain magnetic or CMOS storage.

    Now, silicon subsrtate technology probably does hold great wonders for helping people with sensory disabilities, but don't be looking for Nerual RAM upgrades in the near future.
    • It's the human brain's ablility to recognise patterns and small details in complex systems that seems to allow it to remember so much. It is only in fact, remembering a concept from a book or the outline of an object. Many test have been done to show that the human brain actually remembers very little of it's surroundings. Most of it is just filtered out as noise.
    • You're right on the Johnny Mnemonic thing, but hey, if I could plug a module in my head that stored an entire encyclopedia and be able to access it like it were an adjunct to my own memory think what a benefit that would be in so many environments!!
      Need to repair that aircraft engine you've never seen before? Plug the chip in! S'long as one has a foundation of basic skills and knowledge, the minutiae of many fields could be placed on a chip, saving (potentially) years of study.
      If we could interface a neuronal structure (our brain) to a silicon structure (ROM) it would totally revolutionise the way we conduct our entire existence.
      Not to mention the potential for interfacing. (DOOM the way it was meant to be! And other, er, "entertainment" :)

      • Long way off.. is it possible?? (Score:1, Insightful)

        by Anonymous Coward
        To do this kind of thing requires complete understanding of each *individual* brain. Everyone understands things in different ways, precisely because of the way that these neural connections form dynamically. To wire anything into a brain that can be understood would most likely take phenomonal brain power just to work out =)

        Although.. The current brain implants rely on the brain to figure out what it means.. do you think it's possible for a brain to just `pick up' a data stream by figuring out it's relationship to existing knowledge? Sounds a little far-fetched to me..
      • You're right on the Johnny Mnemonic thing, but hey, if I could plug a module in my head that stored an entire encyclopedia and be able to access it like it were an adjunct to my own memory think what a benefit that would be in so many environments

        Unfortunately, learning to use such an interface would likely require several years of education.

        Also, merely having access to the raw data does not bestow understanding, since understanding requires understanding the relationships of the data to each other and to the real world. That is part of what you get in a college education - you work out how things go together.

        Sadly, there may not be an easy shortcut to this aspect of the process. Otherwise you wind up with an educated idiot. And the world has enough of those already.

      • Come on, /.'ers, we all know this isn't new around here. After all, didn't Trinity learn to fly a helicopter by having a program downloaded into her brain?

        I know a few users I'd like to educate that way. Just think of the productivity gained by eliminating the learning curve.

        Oh, wait, then anyone could learn to do my job...

      • If that ever became possible the cultural implications would be staggering. For one, higher education would be abandoned by most of society, and with it college-set comedy films like Road Trip and Animal House.

        "This bra bomb better work, Nerdlinger!"
      • And other, er, "entertainment" :)
        Ah, the lady in the red dress.
  • Short-term memories, it turns out, result from the instant assembly of more filaments to strengthen the skin of the cell temporarily, whereas long-term memories result from the growing of a new synapse to strengthen the connection permanently
    Seems like the difference between WinXP and Linux programmers!
  • This is a good step towards making 'biological' computers if you ask me. Computers designed after natural minds are bound to be better adapted for some tasks, such as learning etc...

  • pot smoking. (Score:2, Funny)

    by garcia ( 6573 )
    there have been studies upon studies of how marijuana effects short-term memory (NORML always posts messages about how it has been proven that it does not in any way effect short term memory).

    So, if the researchers start smoking will:

    A) the neurons will start firing so fast that they light up the room?
    B) the neurons die -- proving that it has a negative effect on STM
    C) the neurons have no change
    D) you don't remember any of the options -- proving for sure that marijuana does have an effect on STM

    Happy New Year everyone.
    • A more interesting question is, using this experiment technic, can they develop a way to counter the affect pot has on STM and LTM.

    • Re:pot smoking. (Score:3, Informative)

      by Zen Mastuh ( 456254 )

      This would be interesting to see. In The Natural Mind, Dr. Andrew Weil elaborates on his 1960's Harvard research which showed that short-term recall and task performance were dependent on whether the task/info was learned while the subject was in the same state of mind for the testing (learned stoned, performed straight; learned stoned, performed stoned; ...). Emperical evidence illustrated that difficulty in short-term recall was a product of the subject's anxiety about being stoned in a test situation.

      But let's see some biology in action and the physical results. Don't get your hopes up, though: Presidents Nixon and Reagan declared drug wars despite the findings of scientists they commissioned to study the effects of illegal drug usage on society.

      • My "Dr. Weil" spider-sense is tingling. Maybe off topic, but Dr. Weil is Mr. Pseudo-Science.
        While I agree with the idea that medical science should be more attuned to mental and nutritional aspects of health, Dr. Weil goes way beyond this. He basically leaves science behind. If you're just reading him because he has some interesting ideas, great. But don't treat him as a medical or nutritional authority. I don't have time to look up lots of links now, but here's [drkoop.com] a relatively benign one.
    • I smell a /. poll if I ever heard one.

      .... er maybe that's just my christmas tree on fire!

  • Reprograming. (Score:3, Funny)

    by AltGrendel ( 175092 ) <ag-slashdot@eGAUSSxit0.us minus math_god> on Monday December 31, 2001 @12:44PM (#2767907) Homepage
    Does it mention whether they have they figured out how to reprogram neurons? If so, I could use it on my cats.

    I know, I know, why not a human. I start getting all ethical when I think of that.

  • link to the lab's home page (Score:4, Informative)

    by markj02 ( 544487 ) on Monday December 31, 2001 @12:47PM (#2767921)
    Here [ucsd.edu] is a link to the lab's home page. The project is described briefly here [ucsd.edu]. It would be nice if web-based included those links. It would also be nice if people in the biological sciences followed CS and put their publications on-line.

  • This is really an important discovery (Score:4, Interesting)

    by 3ryon ( 415000 ) on Monday December 31, 2001 @12:50PM (#2767929)
    For more background info on how neurons work: see How stuff works [howstuffworks.com] sub-page on the brain. I was hoping that they would have a good discussion on how sodium and potasium ions move through the cell membranes creating a charge, but at least it's a good intro.
    • Did my graduate work in ion channels and GABA neuromodulation... here's some history, overview of ion channel function, membrane potential and action potentials.

      history:
      http://opal.msu.montana.edu/cftr/IonChannelPrime rs /ion_channel_history.htm

      overview of membrane transport:
      http://www.uiowa.edu/~c156201/PDFLecs/Schmidt/PM CB TS03h.pdf

      movie clips:
      http://www.utexas.edu/depts/pharmacology/gonzale s/ channel.html

      java demos of membrane potentials:
      http://sun.science.wayne.edu/~bio340/Applets/

      have fun!
    • I agree. I'm particularly interested in the evidence on short-term learning. This may connect to the work on microtubules, since the neurons seemed to show fast physical changes in response to Hebbian and anti-Hebbian stimuli. Unfortunately, I don't have easy access to Neuron here at Sunderland. My interest involves fast modulation of afferent signals in the early auditory system of bats, so it's probably relevant.

  • A few interesting articles... (Score:4, Informative)

    by instinctdesign ( 534196 ) on Monday December 31, 2001 @12:52PM (#2767937) Homepage
    Just looking around online, I was able to find a bit more info about the subject. One good read (well, actually a number of good reads) I found was from the Howard Hughes Medical Institute [hhmi.org]'s 2000 Annual Report [hhmi.org]. There are a number of articles that are worth checking out, but I would recommend the one entitled "Brain-Wiring Receptor Shows Extraordinary Diversity. [hhmi.org]" Here is a brief quote:
    Researchers have identified a new axon guidance receptor found in the tips of growing neurons that can exist in more than 38,000 slightly different forms. The unprecedented diversity of proteins derived from this single gene may offer an important hint that a fundamental code directs the precise wiring of trillions of neurons in the brain...
    Also, an interesting, abet rather short, article from Popular Mechanics [popularmechanics.com] tells how researchers were able to actually "see" neurons changing at the synapse between two of the tens of million of nerve cells in the brain of a rat.
    • Does that quote mean that some things are hard wired and others are soft wired, or that they all exist somewhere between. I kind of figured there was some hard wiring, as you just can't lump a bunch of neurons and have intelegence even if you try to teach it, it would probably take much longer. Some amount of hard wiring would also explain why some characteristics of people are the same from inheritance of genes. Anyway, I kind of wish that article about the Neurochips explained why relationships are strengthened rather then just that they are.
  • ...to being able to download our brains into computers. Not that it's something I'd want to do for a closer association with my computer, I just don't want to die.
  • [The team] tested out the theory that learning results from a physical change that strengthens the connections between selected neurons. [They showed] how short- and long-term memories result from different physical effects in the brain

    They showed physical effects that MAY be responsible for the phenomenon that we call memory. This is very good work, and it shows that these physical effects occur in the brain (there is some possibility that it's an artifact of their method but it's pretty slim.) They also occur on about the right timescale to explain memory. HOWEVER that is NOT sufficient to show that these physical effects are responsible for the phenomenon we call memory, just that they very well could be.

    The point at which you call something "proven" can be fairly subjective but in this case we haven't eliminated other potential physical effects that might play some role, possibly a crucial or pivotal one, in actual memory.

    As a scientist, I am convinced (just short of certain) that the effects that they've observed play some role in real memory. That doesn't mean that they play the definitive role.

    I suspect that the scientists responsible for the research couched there statements in a number of caveats that the reporter simply ignored.
  • ...but how can I use this to learn Ju-Jitsu?
  • Just to inject a little shoot the moon sci-fi here, it seems like this moves the concept of memory "blanking" up a few years. With a good understanding of this stuff, it seems like you could develop a treatment (or perhaps even a drug) that could wipe out someone's memory of the past 24 hours (insert X-Files / Orwellian string swell here).

    • You mean something like rohypnol? Or one of these [demon.co.uk]?

      I have heard anecdotal evidence that they've been using drugs like this for quite a while in emergency rooms to take advantage of the amnesia-inducing effect for those who have suffered a very traumatic experience - nearly burning to death, violent rape, etc.

    • seems like you could develop a treatment (or perhaps even a drug) that could wipe out someone's memory of the past 24 hours

      Great. I can see the news article now..

      "New synapse research makes frat party rape easier than ever!"

      I'm betting it shows up in Maxim, February 2002 issue.

  • ...on a Beowulf cluster of these!

    Though not an impressively large cluster...

    Oops, Blue Visual Field of Death again.
  • The chip preparation seems cool, but this experiment doesn't prove a thing about learning or memory.

    Changes in individual neurons have been observed in many ways (electrically, visually) in many preparations (live animals, brain slices, brain cultures) in response to artificially induced activity like what these guys used.

    The problem is the assertion that the artificially induced activity is anything like what happens during real learning in an intact, awake brain. This is a hard problem, and the present study doesn't address it at all.

    The study therefore has no real relevance to learning and memory.
  • It doesn't address the issue of HOW memories are stored, WHAT consists of a whole memory, and HOW memories exist in the same physical space.

    -
  • that in the future (50+ years) I'll be able to plug a jack into my head and download PDF manuals to my motherboards so that I won't have to go digging in my huge file cabinet anymore? Matrix style baby!

    I can't wait to have a USB jack in my head! heheh

  • For the lazy:

    See: http://www.inc.salk.edu/ [salk.edu]
  • That the mechanical guides the logical has been the basic assumption of Neural networks research for a long time. By Mechanical, I mean the physical connection between neurons, as opposed to the chemical levels in the neuron (the neuron holding state).

    I've read that neurons can feed back into themselves, kind of like latches in computer memory, but in a much more complex way. I wonder if this is how the brain knows how to do long sequences: Part of the neural net keeps the brain focused on the task at hand, Say playing a song on a piano. The combination of the steady state and the current state ( I am at measure 4, third note, held for a count of 2) Figures out what to play next (G major chord in the left hand, start the trill with the right.)

    So to learn a long sequence, the brain must start off with the short term memory of reinforcing with fibers the synapses for certain combinations...and then make new connections. That is why it is hard to learn a new song, and possible to play something you memorized in 5th grade. But since the actual playing of the instrument is common to both, it fades into the background.

    One concept that I read about that is helpful in the study of Neural Nets is Orthogonaity. The more different two things are from each other, the easeir they are to differentiate. IE, Fire either Neuron 1 or Neuron 2 type distinctions. I guess that is why two things that are very similar (two different editors with different shortcut keystroke settings) can really confuse you...at least until the short term memory fibers kick in and reinforce the current task. Over time, It should get easier to switch between the two editors...just need to kick your brain into the right editor mode. Since Typing is the same for both of them, it fades into the back ground.

    I wonder what triggers the start of the long term memory building process. Is it a threshhold of the short term memory that, once reached, kicks it into gear? Or is it a gradual process: adding more fibers will eventually build another connection.

  • Point of Interest (Score:4, Insightful)

    by rossjudson ( 97786 ) on Monday December 31, 2001 @02:14PM (#2768233) Homepage
    It's very cool to read that the basic research to verify neural models is being done. Like someone else said, it's not definitive, but it certainly does give us good evidence that certain electro-chemical situations strengthen existing synapses and even form new ones (the filaments).

    I've always felt (intuitively, not scientifically) that the brain was made up of a series of interconnected networks, each fulfilling different roles. There's a very special role, though -- our point of interest.

    If synapses are altered by the current that flows through them, then point of interest is critically important because it directs where the current goes.

    The upshot is that the things you find interesting (and think about) are the things that get strengthened. So what determines your interest?

    Well, we're very visual creatures, so a lot of what interests us is stuff we can see. We are continually interested in a great deal of the information that comes in from our five senses.

    This sort of implies that you can strengthen different points of your mind by focusing on them, directing your interest towards those points. Your interest excites those neural pathways in your mind, strengthening them.

    Want to get better at programming? THINK about it. A lot. Stop thinking about what you're seeing, and move in an abstract direction instead. Don't waste your valuable brain electricity on strengthening visual neurons that take too much already.
  • SO this means, I can shine a flashlight in my eyes and learn all kinds of crazy shiznat?
    SWEEET! My folks always said that some of my neurons weren't firing!

    Step 2, finding batteries for my maglight...

  • hebb learning (Score:2, Interesting)

    by gnujoshua ( 540710 )
    The idea that presynaptic firing and postsynaptic firing control the synaptic efficacy of a cell was proposed by Donald Hebb in 1947. However, it has also been questioned that different neurons behave differently. For instance, granular cells may act differently then cells in the lateral geniculate nucleus (they are drastically different in size and number for one). Therefore, these scientists have shown a particular case, they have not shown that Hebb learning can be generalized throughout all the brain, only that in certain cells obey Hebbian learning.
  • It's a really interesting effect and I don't doubt that it's got something to do with the mechanisms of memory, but there's a lot of evidence for the role of changes in gene expression in memory as well. Take a look at Doctor Eric Kandel's [hhmi.org] research. There's a reason he got the Nobel Prize, the Wolf prize, the Lasker Award, the Gairdner Award, the Harvey Prize, and the National Medal of Science - the man has done an immense amount to elucidate the basis of memory. I know it's more fashionable around here to think of neurons as something to hook up to electrodes, but like just about everything biological it's a little bit more complicated than that. I'd place real money on both effects being part of the process.

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