Yoky Matsuoka grew up dreaming of becoming a top-ranked tennis pro,
but she wasn’t your average jock. She spent a lot of on-court time
pondering how her brain was controlling her hand, allowing her to
smoothly swing her racket at just the right time and angle. More than a
decade and several mechanical hands later, Matsuoka is still chasing
the same question. But now she’s pursuing it by trying to build the
ultimate prosthetic—a fully functional replica of the human hand,
controlled directly by the brain.

Matsuoka, who in graduate school built the hands for MIT’s famous
humanoid robot COG, is a trailblazer in brain-machine interfaces, the
still-experimental effort to control external devices through brain
signals. Her new project aims to teach a monkey how to use a
three-fingered version of the human hand. The prototype has artificial
versions of all the tendons and muscles controlling our thumbs and
middle and ring fingers.

In the first experiment, the monkey will be seated before a bottle
containing food. Its own arms will be strapped to its sides, and
electrodes inside its brain will be wired through a computer to a
robotic arm with Matsuoka’s artificial hand on the end. The computer
will interpret the monkey’s brain signals and move the artificial arm
and fingers accordingly. If all goes well, the monkey should be able to
control Matsuoka’s creation with its thoughts, opening the bottle and
procuring its snack.

Other scientists are working on mind-controlled prosthetics that would
translate these signals into basic actions, like grasping an object,
but Matsuoka wants all the coin-rolling-over-the-knuckles capabilities
of the real deal. Her eventual goal is to create a pop-it-on-and-go
prosthetic for humans—like the kind that Luke Skywalker receives at the
end of The Empire Strikes Back.
She points out that for the average amputee, the hand might be lost,
but the neural signals dispatched to control it are still flowing fine.
“Your brain could still do exactly the same thing it had been doing,”
she says, “but naturally control this new mechanical hand.”—Gregory Mone