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Neuronal Learning Observed
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. "
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.
The next Slashdot story will be ready soon, but subscribers can beat the rush and slashdot the links early!
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.
I know, I know, why not a human. I start getting all ethical when I think of that.
The simple truth is that interstellar distances will not fit into the human imagination
- Douglas Adams
Here is a link to the lab's home page. The project is described briefly here. 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.
For more background info on how neurons work: see How stuff works 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.
Kind thoughts do not change the world
forma3
[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.
The good and new comes from no quarter where it is looked for, and is always something different from what is expected.
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"
...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.
For the lazy:
See: http://www.inc.salk.edu/
Slashdot is an anagram for Has Dolts, and I am Dolt number 468543
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.
Open Source Identity Management: FreeIPA.org
Gah.. There was a theory i read about sometime, it was mentioned in Clarke's "The light of other days" near the end, but the name of it escapes me right now. I'll have to look it up later - but i t held that your conciousness of yourself transmigrated to the new body... i wish i had the details. Buuuuuuuut I don't.
Ponderance: How long would it be possible to preserve the brain, assuming you could do a whole-body transplant, get over the immune response thing, and find a way to restore spinal cord continuity and function? In other words.. if the body could be made to maintain a brain for an indefinate period of time, how long could the brain last?
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.
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.
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.
My opinions are my own, and do not necessarily represent those of my employer.
In response to my own post below.. Leibniz's identity of indiscernibles. Its a quantum mathematical theory, but i can see how clarke may hae equivicated it to human life.