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Biotech Robotics Science

Brain Interface Lets Monkeys Control Prosthetic Limbs 208

himicos was one of many readers to point out one recent success of scientists working to develop working brain-machine interfaces, writing "A team at the university of Pittsburgh has finally advanced a 2002 technology enough for use in prosthetic limbs, the targeted application all along. Training computer models to the firing patterns of the neurons in the parts of the brain that control motion, they are able to project the intentions of a monkey to a robotic arm, which follows the will of the animal. The sad thing about the articles is that the beauty of the mathematics used to create and train the models is totally ignored." Reader phpmysqldev adds a link to coverage at the BBC, and writes "This of course brings significant hope to amputees and other other people with physical disabilities." (Note that this research has been going on for quite some time.)
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Brain Interface Lets Monkeys Control Prosthetic Limbs

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  • by dezert_fox ( 740322 ) on Thursday May 29, 2008 @10:57AM (#23586437)
    Shannon entropy has been a standard tool in data communications for a very long time--telcos use this math to make your phones work. It's effectively a way of quantifying the informational content of a signal, which can be used to determine exactly what kind of bandwidth you need in a bandwidth-limited environment. I'm uncertain what it's used for in the context of a brain-machine interface.
    Any good data communications textbook would have some nice examples in it, and actually that wikipedia article posted is very readable and informative.
  • by Molochi ( 555357 ) on Thursday May 29, 2008 @11:41AM (#23587075)
    As I recall, direct electrical stimulation, eventually killed the nuerons. Though I don't know why they couldn't eventually have a mechanical-to-biological interface that duplicated the natural one non destructiveness.
  • Re:Monkey's opinion (Score:2, Informative)

    by street struttin' ( 1249972 ) on Thursday May 29, 2008 @12:05PM (#23587493)

    He/she might be thinking "I wish this @#$@ing robot arm thing would quit stuffing those @%#$ed marshmallows in my mouth!"
    I'd think it'd be more like The Terminal Man [wikipedia.org]. In it, they discuss the addiction to the stimulation. If you could have a marshmallow whenever you wanted (a good thing) just by thinking about it, eventually you'd just never stop thinking about it.
  • by Anonymous Coward on Thursday May 29, 2008 @01:06PM (#23588487)

    Anyone have the straight dope on this research? Because if it does work it stands to reason that if a person could control an artificial limb with their thoughts controlling real limbs would also be possible.
    I work directly in this field and can tell that the science underlying this work is actively looked down upon and has been largely rejected. What remains are some 'neat' videos that do not shed much light on how the brain actually controls movement, if anything, it actively obscures reality. In the long-term, technology based on this science is going nowhere.

    A common argument is that although scientifically questionable, such devices pose an interesting engineering problem that has a very useful purpose (i.e. helping paralyzed people). That is fine, but if you ask a paralyzed person, what they want is to control their bowels, blatter and sexual function far more than their arms.
  • by smellsofbikes ( 890263 ) on Thursday May 29, 2008 @04:10PM (#23591291) Journal
    >Though I don't know why they couldn't eventually have a mechanical-to-biological interface that duplicated the natural one non destructiveness.

    That's a difficult engineering problem because it's a complicated chemical process. Nerves talk along their length by depolarization, which is essentially an electrochemical process. A nerve pumps sodium and potassium ions in opposite directions across its cell membrane to form a gradient -- think potential energy, like an anvil sitting on a table -- and when they propagate a signal along themselves, they open pores and let diffusion happen so the gradient vanishes. That signals adjacent pores to do the same thing. (A side-note: nerves are covered with something called a myelin sheath, a cell that is wrapped around like a scroll, to minimize the volume of liquid outside the nerve so it doesn't have to pump as hard to get a good gradient. Many neurodegenerative diseases, like MS, involve this sheathing cell to break down. It's not insulation, but it's sort of related.)
    But when nerves talk to each other, they do so across synaptic membranes, which are points where the nerves are almost in contact, separated by a narrow cleft. One nerve extrudes a bunch of bubbles of protein, filled with neurotransmitters, which diffuses across the cleft and joins/merges with the other nerve. At that point, as the bubble merges, it basically bursts, dumping all the neurotransmitters into the other nerve and starting it depolarizing in that area, which then propagates down the nerve.
    Neither of the processes -- depolarization or neurotransmitter diffusion -- are easily built by anything we can create. We can simulate depolarization by abusing the nerve (there is an electrical field that changes as the sodium and potassium flow back to their baseline concentrations) but that's apparently not good for the nerve in the long-term.
    (I may be wrong in some of the details: it's been fifteen years since I took neurobiology courses.)
  • by j_166 ( 1178463 ) on Thursday May 29, 2008 @04:18PM (#23591439)
    Wow, you don't have to be such a dick about it. Maybe people would take your insanity a bit more seriously if you weren't so frothing mad about it.

    "When did I ever say I didn't want experiments on humans, or "because they might die"? I don't remember saying either of those things."

    You said "If this technology ever makes it to humans, it will only be after HUMAN experiments are done. Of course, the frauds who call themselves vivisectionists will say that "We couldn't have achieved the human version without first torturing - sorry - 'experimenting' on monkeys", but the first human version will fail, guaranteed. They will be EXPERIMENTING on humans, until they find out what works, as simple as that."

    I drew the conclusion that you were against experiments on both humans and animals because it is the equivalent of torturing both. You your self say "first torturing - sorry - 'experimenting' on monkeys" and then in the same thought "they will be EXPERIMENTING on humans". Was this the wrong conclusion to draw from this paragraph? Perhaps you could provide a little clarification for what you originally meant then.

    "Did you not read the part where I stated "92% of drugs that pass animal 'tests' FAIL human 'clinical trials' (AKA human EXPERIMENTS)"?????

    In what way are 'clinical trials' NOT human experiments?"

    Yeah, I get you are against animal testing for whatever reason. But you consistently link that idea to the idea of human EXPERIMENTS. What am I supposed to think then? Maybe you can work on your paragraph structuring or something. Learn how to link coherent thoughts together?

    "Jesus. Where do I begin? Animal research has been touted as the CURE for all our ills."

    Touted as the CURE for all our ills by whom?

    " You yourself stupidly stated above that if we don't have animal research, we don't have ANY research!""

    No I didn't. I just happen to think that animal research is a very important part of basic science and medicine.

    Man, you are fucking batshit crazy! Hit me with some more of your colorfully worded 'wisdom'. Its entertaining to me.
  • The Real Sad Thing (Score:4, Informative)

    by DynaSoar ( 714234 ) on Thursday May 29, 2008 @04:58PM (#23592055) Journal
    "The sad thing about the articles is that the beauty of the mathematics used to create and train the models is totally ignored."

    The sadder thing is that the discovery of response patterns of amputated limbs being mapped to other parts of the body is totally ignored.

    A man had his arm removed. A psychiatrist attending happened to note that the man claimed to "feel" things in his missing hand when other parts of his body were touched. After careful mapping, three different response maps were found -- one each on his arm, chest and back. Each was so sensitive that individual fingers could be stimulated and he could correctly tell which.

    This major discovery in neural plasticity makes it totally unnecessary to try to decode signals from electrode either drilled through the skull, or else placed on the surface and reading signals though the scalp, skull and dura mater, which reduces the signal by 3 orders of magnitude. Either way, these signals require some massive processing because a significant command/response signal (ie. an electrical response representing a single Hebbian cellular assembly that can be clearly decoded to an intent as stated in the article) comes from 0.3% to 3% of the neurons in the region being detected, the vast majority of the signal needing rejection as false positive or noise. Using the mapped response regions allows for signal analysis based on EMG patterns that are not expected at all in the area under the electrodes, making detection and analysis trivial.

    TFA and most such research is not about giving amputees mobility. It is about decoding and using neural signals. If it were about the former, easier ways would have been used and the job already accomplished. It is about the latter because such things make more news, get more recognition, and therefore result in more grant application success.

    The resulting technology will only be applied to prosthetics as a secondary result. Its primary use will be in such as hands-off controls for fighter pilots (see Clint Eastwood's "Firefox" for your obligatory Slashdot sci-fi/movie reference), tank crews and mobile missile launchers. Maybe this is the saddest part of all, but ignoring a more certain path to success as far as prosthetics is a sad piece.

    Also sad, with a touch of irony, is the fact that the weaponry applications will be untenable because of the heuristic nature of neural processing -- getting it close but error prone will be fast, getting it right will be no faster or require less effort than hand operated controls. The slow speed and so the ability to use real-time perceptual feedback with prosthetics will make that far more successful. It remains to be seen whether after the war applications fail the research continues (ie. there is adequate funding offered) with respect to prosthetics. If someone like the US Veterans Administration picks it up when DARPA drops it, it might. I'm not hopeful.

    The portion of the above that's assertion or opinion is based on the same professional experience as the portion that's not. That experience includes development of some of the "beautiful" maths decried as being ignored. Having been prosthetic-wrist deep in the research and from both directions, I find that a minor point to consider as "sad".

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