Damn this is cool. The New York Times has an article on an innovative technology that allows people to naturally use mechanical prosthetic arms.
While most of the media attention has been focused on implanting electrodes directly into the brain as a form of ‘neuroprosthetics’, this technology takes a novel and remarkably ingenious approach with impressive results.
The technique, called targeted muscle reinnervation, involves taking the nerves that remain after an arm is amputated and connecting them to another muscle in the body, often in the chest. Electrodes are placed over the chest muscles, acting as antennae. When the person wants to move the arm, the brain sends signals that first contract the chest muscles, which send an electrical signal to the prosthetic arm, instructing it to move. The process requires no more conscious effort than it would for a person who has a natural arm.
Researchers reported Tuesday in the online edition of The Journal of the American Medical Association that they had taken the technique further, making it possible to perform 10 hand, wrist and elbow movements, a big improvement over the typical prosthetic repertoire of bending the elbow, turning the wrist, and opening and closing the hand.
It’s an inventive technique because it takes a whole chunk of the hard work away from the technology.
With neural implants, the major obstacle is developing the technology to reduce the noisy neural information into simpler signal channels. The patient then needs to be trained to generate the right brain activity to funnel the activity into the broad channels of the digital signal processor.
This technology takes advantage of existing healthy nerves but just reassigns them to other muscles and the activity in these is just converted into mechanical actions.
Of course, it isn’t useful for people who are completely paralysed, but the results are quite spectacular.
The article has an embedded video which illustrates the remarkable dexterity that the woman with the prosthetic arm is able to achieve.
The scientific article describing the technology has just been published in the Journal of the American Medical Association and describes five prosthetic limb patients who were asked to complete a number of manual dexterity tests.
The study found that they completed tasks only marginally less well than comparison participants who had no damage and were using their original arms.
UPDATE: Mo has reminded me that Neurophilosophy covered an single case of the same procedure earlier in its development cycle. Mo also notes that the technology has the potential to feed-back touch information to the phantom limb!