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."

Re:nerve signals / muscle signals

[Alrua]

There is some research being done into bidirectional prosthetics. Kevin Warwick from Reading University in the UK has successfully implanted a chip in his own arm allowing him to control an external robotic arm and receive sensory input from it.

Some of Warwick's work is pretty controversial (see e.g. various articles from The Register [theregister.co.uk]), but he does do some solid research.

Wikipedia has more details [wikipedia.org]

Re:You win

[Ultra64]

You must have missed Taco's website [animefu.com]

Covered on Radio

[phcrack]

Quirks and Quarks [www.cbc.ca] covered this a couple of weeks ago in a pretty good interview. You can find the show here [www.cbc.ca] (in mp3 and ogg =).

Muscle vs Nerve signals

[spineboy]

The nerves in the body are usually buried somewhat deep, and are insulated usually by a layer of fat, and by their insulation(fatty Schwann cells). Since the nerves innervate the muscles, the signal becomes amplified, thus making it much easier to pick up the signal (stronger, and just under the skin, not insulated).

Another reason is that many different nerve fibers run together in a nerve, especially up in the brachial plexus (shoulder are). If this prosthesis is meant for people who have lost their are high up, then the nerves in this location, are somewhat big (between a pencil and strand of linguinni thickness), and contain many different fibers. There are about 30 different muscles in the forearm/hand, and another 20 in the shoulder and arm (and don't forget all the sensory fibers too). It might be just too hard to pick out usable signals from that mess, If some of the fibers are re-routed to a superficial muscle (chest wall pectoralis major), then it's much easier for the person to choose discrete movements, and have control over the prosthesis.

I am an orthopaedic surgeon, so I'm just posting this part to squelch any criticism about the facts above.