How do the new prosthetics work where people can seemingly control their new limbs with just their mind?
In: Technology
There are two basic methods that can happen to achieve this.
* Method 1: The cheating way (but also the more common way)
You have to remember that the “mind” isn’t really a thing. In a healthy limb, your brain sends signals down your nerves. These nerves touch your muscles and tells them to move, which moves your limb. Nerves aren’t anything special though. You can kinda think of them like wires as they move electrical signals around. In the case of a prosthetic, we can read these nerve impulses and turn that into motion with a little bit of processing. In short, the brain and nerves send the signals still and instead of your muscles getting the signal, a computer tells a motor to run. I call this cheating because you aren’t really controlling it with your mind directly – you are just replacing your muscles.
* Method 2: The real way.
This is not used as much, mostly because it is still very much in development, but you may have seen videos of this sort of thing. This sort of prosthetic uses signals directly from your brain. Not only do they replace your muscles, but they replace your nerves. The difference between (1) and (2) is that if your arm were to be chopped off, you could use both methods to restore movement. If you wanted to control the headless body of Agnew from the safety of your jar, you would probably use this method. The essence of this method is that, while very complex, we can read signals from your brain. If you were to be jar-bound Nixon, your brain could still make the signals that tell your body to take a step, even if you don’t have the legs or spinal cord needed to execute that motion. Sensors on the head (or even directly implanted into the brain) can pick these signals up, and then just like the first method, we translate these into motion. The cool thing though, is that with enough training, you just have to think about making a movement. If I were to implant one of these devices into you, after a fair bit of training, you could get a robot arm to move just by thinking about it – as if you had a 3rd hand.
As an example of this method, here’s a pretty early video of this technology working with a monkey controlling an arm: https://www.youtube.com/watch?v=sm2d0w87wQE
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