Improving the Abilities of Bionic Arm Patients

Al writes "Tech Review has an article about the progress being made on prosthetic arms that can be controlled using nerves that once connected to the missing limb via muscles in the chest. Todd Kuiken, director of the Rehabilitation Institute of Chicago's Center for Bionic Medicine has pioneered the technique, which has so far given more than 30 patients the ability to control a mechanical prosthetic simply by thinking about moving their old arm. Those who have had the procedure report using their arm to slice hot peppers, open a bag of flour, put on a belt, operate a tape measure, or remove a new tennis ball from a container. The next step is to add sensing capabilities to the arms so that this information can be fed back to the reconnected nerves."

Comments

Any idea why they have to move the nerves?

[fuzzyfuzzyfungus]

TFA mentions that they have to relocate the remaining nerves(the chest seems to be a popular destination); but doesn't say why. Do the nerves atrophy if they are left in the stump? Is there some sort of feedback mechanism by which a nerve can detect whether or not it is still connected to a muscle?

Re:Any idea why they have to move the nerves?

[Garrett Fox]

I think what they're doing is sensing electrical signals generated by the muscles rather than directly by the nerves, and the nerve-moving is just done to route the usual mental input through that patch of (pectoral) muscle. That way you don't have to teach yourself to flex your pecs to move the robot arm; you try to control the missing arm and the signals are routed to the chest muscle, where they're read by the machine.

Not impressed with any mechanical arms

[zymano]

Something is missing still. Do we know the language of nerve impulses?

Re:Not impressed with any mechanical arms

[Anonymous Coward]

Yes, but you'd have to forfeit the control of a body part. And then you'd have to have the thing you're linked to only accept as much input as the limb you've forfeited had. So (for example), you couldn't cut off a pinkie and hook a keyboard up to it - the pinkie can only do six things (clench/unclench/"bow"/"straighten"/move-away-from-ring-finger/move-towards-ring-finger), and not very well at that. You might be able to hook a mouse up though (clench for click, unclench for right-click, the other four handling the 4 axes).

Re:Not impressed with any mechanical arms

[Anonymous Coward]

Something is missing still. Do we know the language of nerve impulses?

We actually do know quite a lot about the language of nerve impulses, like how repeated stimulating of a post-synaptic neuron in the central nervous system either increases or decreases its response depending on the frequency and amplitude of the stimulation.

The muscle, however, is much simpler than the brain. Muscle contraction is basically frequency modulated: a nerve impulse to the muscle causes a single depolarization of the muscle cell membrane, resulting in a short twitch. Repeated high-frequency impulses (say, 100 Hz) result in the fusing of twitches into a continuous contraction called tetanus. Because these twitches are brief and numerous, and because different muscle cells contract at slightly different times (depending on their innervation), the muscle contraction is perceived as smooth.

Re:Born 50 years too early.

[Garrett Fox]

Do you want to prevent that? If so, work to protect human freedom. More tech-toys that way, too.

Still a Kludge / Pay Attention to the Low End Too

[Garrett Fox]

This is good progress, but still a kludge because it uses muscles rather than a direct nerve attachment.

It's also worth following the attempts that've been made on the extreme low-end of the budget scale, to upgrade traditional prosthetics. (What is that one type called? Troutman Hook?) I'm more interested in the bionic ones because they're versatile and cool, but it's also important to consider who can afford the tech and to make it as widely available as practical.

Re:Born 50 years too early.

[Weedhopper]

I spend 9/10 months of the year working for a very well regarded humanitarian aid NGO.

If I am in your country on an assignment, it's likely because it's because there is either a war, massive natural disaster or a public health emergency beyond the capability of the locals to handle.

So yeah, most of the year, I don't have electronics, gadgets, internet, TV, electricity, running water, hot water, trash collection or city water/sewage.

So yes, please tell me again how to appreciate the things I have now.