A monkey can direct a robotic arm to pluck a marshmallow from a skewer and stuff it into its mouth using only its brainpower, US researchers have announced.
The monkey guides the robot arm the same way it does its natural limbs, through brain signals.
"They are using a motorised prosthetic arm to reach out, grab and bring the food back to their face," said Andrew Schwartz of the University of Pittsburgh School of Medicine, whose study will appear in an upcoming issue of the journal Nature.
Mr Schwartz's team picks up those signals through an array of microelectrodes half the size of a thumbtack that has been implanted in the monkey's brain. These signals are amplified and relayed to a computer that operates the robotic arm.
Mr Schwartz said the technology behind this feat may lead to brain-powered prosthetic limbs for people with spinal cord injuries or disabling diseases that make such simple tasks impossible.
Until now, such brain-machine interfaces have been used to control cursor movements on a computer screen. Mr Schwartz and colleagues wanted to apply the technology to real-world tasks.
Mr Schwartz said his team has learned that certain motor neurons fire rapidly when the monkey wants to move a certain way. "What is important is each neuron seems to have a preferred direction," he said.
"We record those patterns of action potential, interpret them with a computer and extract the monkey's intention to move. That serves as a control signal to the robot."
He added it takes about three days for a monkey to learn to operate the arm, and they continuously improve.