DURHAM, 15 October 2003 — US researchers have taught monkeys to control a robot arm using brain impulses in a series of experiments that could have far-reaching implications for the rehabilitation of people who have suffered brain or nerve damage, a study released yesterday said.
Researchers at Duke University in North Carolina were able to coach the two rhesus monkeys to manipulate a robotic arm to play a videogame — hands-free. The monkeys were able to achieve the feat thanks to a circuit that connected electrical impulses in the animals’ brains to a robotic arm.
The findings hold significant promise for the development of therapies for stroke victims, victims of neurological disorders, or people who have suffered some type of paralysis, according to the study in the journal, Public Library of Science.
The implication is “that you can take these signals in real time and use them to animate an artificial device,” said neurobiologist and the study’s lead author, Miguel Nicolelis. “You can bypass damaged parts of the brain and extract all the information you need to control human movement.”
Nicolelis and his colleagues began by implanting scores of microelectrodes in the monkeys’ brains. The electrodes were wired to a computer, which logged and analyzed the brain activity of the animals during the course of the experiments.
At first the monkeys were given a joystick, and encouraged to play a videogame that required them to hit a target on-screen.
Out of sight of the animals, the joystick was in fact hooked up to a robotic arm, complete with sensors, which controlled the computer cursor, Nicolelis explained. Then the scientists disconnected the joystick in order to test whether the animals could continue to play the game using the alternative brain machine circuit they had set up.
Initially, the simians continued to wave their arms in mid-air as if grasping for a phantom joy stick, but slowly they began to realize that they could still move the cursor by means of computer-modulated nerve impulses. “After only a few days of playing with the robot in this way, the monkey suddenly realized that she didn’t need to move her arm at all,” said Nicolelis.
“Her arm muscles went completely quiet, she kept her arm at her side and she controlled the robot arm using only her brain and visual feedback. Our analyses of the brain signals showed that the animal learned to assimilate the robot arm into her brain as if it was her own arm.”
Eventually, the two monkeys became as proficient at operating the arm with bioelectrical feedback as they had been with the joystick, according to the study. The monkeys’ relatively sophisticated manipulation of the arm is what distinguishes this study from previous studies in the field.
The North Carolina researchers are already conducting preliminary studies in humans to see whether their brain signals correlate to the animals brain activity, and they are also seeking to develop wireless devices.