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MIT Researchers Explore How Rats Think

Posted by Zonk on Mon Feb 13, 2006 02:24 AM
from the i-think-backwards-all-the-time dept.
Science
Ant writes "A Nature News article explains that, after running a maze, rats mentally replay their actions backwards." From the article: "As the rats ran along the track, the nerve cells fired in a very specific sequence. This is not surprising, because certain cells in this region are known to be triggered when an animal passes through a particular spot in a space. But the researchers were taken aback by what they saw when the rats were resting. Then, the same brain cells replayed the sequence of electrical firing over and over, but in reverse and speeded up. 'It's absolutely original; no one has ever seen this before at all,' says Edvard Moser, who studies memory at the Norwegian University of Science and Technology in Trondheim."
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  • Move over CS grads (Score:5, Funny)

    by hobotron (891379) on Monday February 13 2006, @02:27AM (#14704087)

    If a rat knows the difference between a Stack and a Queue, you better start updating your resume.

  • If this idea proves true in people, it could have many implications for human learning. It suggests that those idle times, perhaps spent gazing into space, are actually crucial for our brains to replay, and learn from, recent experiences.
    Are dreams there only to help the learning process? Is there something more to them?
    • If this idea proves true in people.

      I'd be surprised if this proves true in people. Most people can't even remember where they parked their car.

    • Re:interesting... (Score:5, Insightful)

      by Skreems (598317) on Monday February 13 2006, @04:03AM (#14704406)
      Most creative thinkers already understand, at least intuitively, that the human brain will continue working on a problem even when a person is actively thinking about something else. How many programmers know that when you're beating your head against a problem, a good way to solve it is to go do something physical or repetitive, like play sports or video games or even sleep? Then when you come back, your brain has an answer for you, or at least has conceptualized the problem so you can get a better handle on it.

      I don't know how much there is to officially back this up, but I think this is why OOP caught on so well, at least with some people. If you have a system made of interacting modular components, your brain doesn't have to conceptualize sections of some messy lines of ASM or C code... it can just use the constructs you've actually built into the system, so the "processing cost" of groking the system is much cheaper.
      • Yeah, that's spot on. I can still remember dreaming visually with Java object during a particularly heavy project.

        I thought at the time one could make a good VR programming environment - none of this silly lines of code stuff, instead you move classes and objects as visual structures (blocks if you like) so you can see exactly what is interacting with what.
      • ... a good way to solve it is to go do something physical or repetitive, like play sports or video games or even sleep...

        Yeah, I guess that's why I keep coming back to /. at work.

  • Interesting (Score:5, Insightful)

    by Belseth (835595) on Monday February 13 2006, @02:35AM (#14704122)
    Sounds like it's a way of setting important memories. Being able to navigate a course is important to a rat's survival. It'd be interesting to see if this happens with all memories or just the most important for the rat to recall. Stress causes memories in humans to become more perminate. There was a study where people held their hand in ice cold water to see how it affected memory. The shock of the cold water increased retention dramatically. I'd be curious if the levels of stress hormones went up as well. Rerunning the memory may be a stress reaction to important information.
    • An interesting observation I made when studying for bigger exams:

      a) There are "key days", where I panic about not being able to learn stuff in time and those are the days when I remember/understand stuff far better than on self-confident days. On "panic days", I learn 3x-5x more effiently than on self-confident days.

      b) I might study a whole day long and dont understand or at least not being able to explain the formulas/problems/algorithms/whatever in my own words. And then I panic. When I have gone to sleep
    • The only reason to do temporally reverse processing is, of course, error back propagation. The rat's logic and sensory data does not match 100%, and the difference is stored into special locations for later processing. When resting, rat uses this data, back propagates it through its network and adjusts the synaptic weights (weighted by the gradient of the neural responce) to obtain maximal behavioral change with minimal synaptic changes, ensuring locality of the behavior change. This is so obvious that I wo
    • Food...food...food...fuck...food...water...sleepy. ..food...food...sleepy

      -Eric

  • Evidence finally found to support conspiracy theorists' claims of rats plotting world domination.
    • Evidence finally found to support conspiracy theorists' claims of rats plotting world domination.
      But Brain, where are we going to find 500 dancing girls and a cubic meter of Silly Putty at this time of the night?
    • Evidence finally found to support conspiracy theorists' claims of rats plotting world domination.

      Plotting? They have already acieved it! the species is called Rattus Politicianus, you it infests senate, parlieamentary and other government buildings world wide. There is also a lesser species called Rattus Lawyeriensis it is usually found chasing after ambulances or monitoring peoples internet connections looking for evidence of illegal music downloads.

  • the learning possibilities (Score:4, Interesting)

    by TubeSteak (669689) on Monday February 13 2006, @02:39AM (#14704140) Journal
    The discovery could also help to explain why people tend to learn a new task quicker when they take short rests between each practice round. It suggests that eliminating such breaks could actually interfere with learning, and perhaps even explain why hyperactive children often have learning difficulties.
    This may be less about ADD/ADHD kids than about teaching style in general.

    Any teaching style that will appeal to a hyperactive child, will more than likely be engaging for a 'normal' student.

    Though it might be a stretch to suggest this could be extended to understanding hyperactive kids. AFAIK, they usually have abnormally low levels of dopamine and/or seratonin in their brains, while the article posits that "The rerun [for mice] could coincide with a burst of the reward chemical dopamine, which is released in the brain when the animal finds food."

    Maybe they can find some hyperactive mice to run the tests on?
    • Back when I was I kid there was a very good treatment for ADHD. You lack attention in school and your mother opens a large can of whoop-ass on you. Voila! You don't lack attention anymore (until your ass stops hurting at least). To me this seems like a better alternative to stuffing kids with psychotropic drugs.
    • You do realise that hyperactivity is just one optional symptom of ADD/ADHD? Using the word "hyperactive" is missleading, since it's the attention span issues that are the hallmark of the disorder. I assume you already know this, since you used the term ADD, but many others don't know.
      • It's an old problem (you do remember what Socrates was accused of, don't you?) that people who grow up idealize their behavior as kids (and the behavior of their contemporaries), and then blame the current generation for not matching their (false) memories. If you don't think this means you, watch the movie "Blackboard Jungle"* about kids in the 1950's (or find some movie made contemporaneous that DOESN'T idealize kids).

        "Blackboard Jungle" was a "Be afraid! The kids are revolting!" movie. It's no more re

  • How they think? (Score:5, Funny)

    by neoform (551705) <djneoform@gmail.com> on Monday February 13 2006, @02:40AM (#14704144) Homepage
    It's pretty simple, once they get the juice on someone, they squeal to the nearest narc.. obviously.
  • "It's absolutely original; no one has ever seen this before at all," says Edvard Moser.

    Except for the rats, of course.

  • Real political science. (Score:4, Funny)

    by www.sorehands.com (142825) on Monday February 13 2006, @03:13AM (#14704266) Homepage
    MIT is studying politicians. They use rats since the rats won't pick the scientist's when they turn their backs.
  • The researchers found that some of the rats thought more about the maze than others. Here [cartoondepot.com]'s a picture of two mice. The one on the left thought much more about his performance than the one on the right.
  • I read this article twice and tried to come up with a good comment. But all that happened was that the words kept repeating themselves in my mind...

    ... and just think how many times you, my dear reader, will have to repeat this sentence in you mind. So stop resting and get back to work!

  • I suspect they will find the same true for people (Score:4, Interesting)

    by icecow (764255) on Monday February 13 2006, @04:11AM (#14704428)
    Haven't most people walked through the halls of a unfamiliar building to their destination then stopped and reviewed how to get back out a few times (a movie in reverse sorta) in order to get it in their long term memory? or is it just me? I don't always do it, just when the path seemed complicated. I'd think doing this would be much more important to a mouse considering they have rival creatures towering over them like downtown buildings.

    Whoa, I'm reading back my post and thinking WTF!
    • Thinking "backwards" always fucks me up. I get my directions flipped and just end up confusing myself even more. I've either got to start from a landmark of some sort, or right from the beginning and retrace my steps that way.

      Though I guess its worth nothing that i'm also one of those people who sucks at reading the alphabet backwards. And if i'm ever quizzed on "what letter comes before..." I generally have to pick a 'landmark' string of letters ('lmnop' seems to be easiest, dont ask me why) and quickly
    • I do that too - after going through a junction, look back and see which direction to take (two adjacent T-junctions with staircases are probably the hardest).

      I've also noticed that when taking a new route for the first time, such as finding a room in a campus build never visited before, the outgoing path always seems twice as long as the return path.

      There was an article about how London taxi drivers had larger hippocampi regions>/a> when compared to non-taxi drivers. [pnas.org]

    • Haven't most people walked through the halls of a unfamiliar building to their destination then stopped and reviewed how to get back out a few times (a movie in reverse sorta) in order to get it in their long term memory? or is it just me?

      I suspect there are different mechanisms at play here.

      This is morking with a documented phenomena with rats whereby they will take the same route to/from a location over and over, moreso than most other critters.

      It sounds like this goes some way to dexcribing the mechanism

  • back propagation learning algorithm (Score:5, Informative)

    by S3D (745318) on Monday February 13 2006, @05:18AM (#14704618)
    The result is also of keen interest to those who study artificial intelligence and try to teach computer systems or robots to learn through reward and punishment. Some such systems already work by playing back a sequence of moves so that the computer can identify at which point it made the trial or error.
    It's called back propagation learning [wikipedia.org] The algortihm is based on the error propagation backwards from the output nodes to the inner nodes of neural net.
    • It could also mean http://www.answers.com/topic/reinforcement-learnin g?method=22 [answers.com] (Wikipedia itself is currently down). Reinforcement Learning (RL) is about learning from reward - and about finding optimal sequences of action. Especially for learning sequences over time - like the rats - it is THE method of choice. And yes, Artificial Neural Networks (ANNs) are often used for representing the "optimal policy" in RL. The weights in those networks are then altered by the RL process.

      You could describe the proc
  • Sounds like a lovely way to learn how actions lead to rewards without the complications of the actor-critic approach. I'd like to see whether this learning is able to propagate the rewards backwards in a way that allows a change in reward to affect actions. At the same time, I'd like to know whether this can be used to learn the continuous dependence of the final rewards on the actions chosen. Finally, I'd like to know whether this reversal is more general--that is, can plans be reversed? If so, it provide
    • This kind of temporal difference learning is the job of the cerebellum (short time scales) and the basil ganglia (arbitrary time scales). I would bet that the fact that the sequence is replayed backwards in this case is just arbitrary. The idea is to re-enforce the connections between the neurons that represent the learned sequence, as well possibly to train cortical neurons in gestalt like representions of the sequence.

      You are right in that this type of sequencial inforamtion is capable of encoding causa
  • The paper is available at Nature Advance Online Publications [nature.com] - if you have access.
  • Most animals are path oriented. Could be why cats & dogs can find their way 'home'. When taking our cats for a walk (yes, on a leash) into a new area, they always stay on a path. If we turn around, they pull us towards that same route back to the car (cause they want to go home...). And when they walk back appear more confident in stride. Considering rats are more intelligent, this theory does have traction.

    Of course, it doesn't take a MIT researcher to figure that out, just funding and identification

  • Rats don't think because they don't have to, here in the UK anyway. They operate on the taxi-rank prinicple, i.e., they are compelled to take the first client who knocks on their door.

    Just a little spot on Monday morning humour...

  • New Science? (Score:4, Informative)

    by ThePopeLayton (868042) on Monday February 13 2006, @10:46AM (#14706447)
    Sorry boys, But I have been studying Neuroscience for the last 3 years. Every lecture we have had on sleep, particullary REM, has taught that when you are sleeping your neurons will all re-fire in an organized manner. This is when your memories are "consolidated" from semi-long term to long term memories. This is why if you have had a particularly stressful day you can "re-live" that day in your dreams. However it has long been shown that "place cells" or neurons that store spatial location will fire in the direct same sequence in which they fired when the test subject was presented with a spatial puzzle. You can read about this in the book Neuroscience by Kandal.
  • a) researchers wired some rats and made them run up and down a straight run and watched some nerve cells fire;

    b) researchers saw the same nerve cells activate in reverse order while the rats rested;

    c) researchers speculate either wildly or obviously that the rats are replaying the event and that maybe the rats are mentally replaying the run, and that maybe it would be the same in a maze, and maybe this coincides with dopamine release (not observed or measured), and that if maybe that were so, it would maybe
    • There was a recent Robin Williams movie like that, actually. The consequences of having such a device are quite startling. (moral responsibility) "The Final Cut" is the name of the film.

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