A monkey controls his robotic arm with a brain-machine
interface. If this monkey can eat marshmallows with his robotic
arm, mind-controlled prosthetics for humans can’t be far off,
right? Well, that’s true if all you ever wanted to do with your
prosthetic was sit strapped in a chair reaching for
marshmallows. But as Michael Chorost explains in a recent
feature for Wired, challenges abound when building an arm that
works in everyday life. Over the course of a day, you might use
your arm to pick up a chair, unzip your jacket, or scratch your
neck—each one of these actions are unique. But statistical
algorithms used now can translate the firing of neurons into
only a few stereotyped motions. And it’s not just about writing
better algorithms; it’s an input problem too. Getting electrodes
to pick up signals from the same neurons over time is a
continuous battle against the body’s natural defenses: