Thought-Controlled Prosthetics

Ponca City, We Love You writes "Physiatrist Todd A. Kuiken, M.D., Ph.D. has pioneered a technique known as targeted muscle reinnervation (TMR), that allows a prosthetic arm to respond directly to the brain's signals, allowing wearers to open and close their artificial hands and bend and straighten their artificial elbows nearly as naturally as their own arms. Doctors first perform nerve transfer surgery to redirect nerves that go to the amputated arm to the patient's chest muscles. Then when the chest muscle contracts, an electromyogram picks up the electrical signal to move the prosthetic arm. So when the patient thinks 'close hand,"' the hand closes. Now the team wants to see if they can extract more information from the electrical signals produced by the nerves to provide a greater number of hand and arm movements. Theyd have been able to identify unique EMG patterns with 95% accuracy for 16 different elbow, wrist, hand, thumb, and finger movements. 'We've been able to demonstrate remarkable control of artificial limbs and it's an exciting neural machine interface that provides a lot of hope,' says Dr. Kuiken."

nerve signals / muscle signals

[xristo70]

Obviously I'm not a neurosurgeon. I look forward to posts from the experts.

But what is the difference between the electrical signals from the nerves and those given off by contracting muscles? Since the nerves which carry the signals are known, why can't those nerve signals be read straight away? Is it a case of much easier signal patterns to identify with the electrical signals of muscles or just a question of signal strength or something much more complicated?

Interesting as well that they should say that when the muscles are touched, for the patient is seems like the prosthetic arm is touched. Too bad they don't mention the perceived sensitivity to temperature and pressure with this effect. Put sensors on the tip of the hand and a little device on his chest and you might give the patient movement and "feeling" as well.

Semi-serious thought...

[damburger]

The war in Iraq has created a 'market' for prostetic limbs. Given that the latest and most advanced of these are being tested on such veterans, do you think anyone is considering fielding combat cyborgs any time in the future? Go to Iraq, get an arm blown off, go back 6 months later with a submachine gun for a hand...

Re:nerve signals / muscle signals

[WarlockD]

From what I understand, the communication with nerves not only have to be bi-directional but also we arn't sure what other signals are sent (chemical, etc). We can detect the messages to muscles as those are VERY simple and only require small electrical detectors. Decoding a straight nerve seems still seems beyond our reach.

Mind you, this is much better than before. Previous robotic arms are built this same way, but it takes months and months of training to use your chest muscles to move your arm. Now it looks like you don't need that much therapy since they rout your arm nerves to your chest.

PS - I am no expert, I just looked into it a bit ago when I met someone with a claw hand.

Re:nerve signals / muscle signals

[cortex]

The signals in the nerve can be detected directly, but the are very small, and it is harder to get a micro-electrode array in the nerve. The muscle acts like a bio-amplifier, so that the small impulses from the nerve are measured as larger electro-myographic signals (EMG). I am a neural engineer on f the team at the Univ. of Utah that is working on using the signals in the nerve directly. We can already decode the movement signals from the nerve directly and are investigating how to provide sensory feedback. We have been discussing with Todd Kuiken using our array to map out the sensory and motor fibers in the nerve prior to his surgery, so that he can achieve better separation of the signals. That is, he'll know which nerve fibers carry which signals prior to implanting them on the muscle. We and other universities (Caltech, Brown, U. Pitt...) are also looking into using signals straight from the cerebral cortex to control prosthetic limbs.

Feedback

[RicardoRT]

Simple motions of a prosthetic device can be accomplished with this approach, but they will always rely on visual feedback. The problem is that it is too slow for more complicated movements, such as delicately grabbing objects of different stiffnesses. As long as no proprioceptive feedback is given to the brain, electromechanical prosthetics will remain cumbersome.

i propose the term Psionics

[AP31R0N]

i propose the term Psionics for mind controlled machines (attached or not). Avionics are electronics for aviation, psionics could be electronics related to the brain. Given that only D&D nerds would know of the word having any other use, we could replace the awkward phrases "mind controlled" and "mind machine interface".