Brain-Wired Bionic Arms used on Monkeys

Monkeys with tiny sensors wired to their brains have learned to reach, grip and eat using a robotic arm. This is an advance that foreshadows bionic limbs that could restore motion for people with disabilities, researchers said.

In the experiment, two macaque monkeys were given prosthetic arms, complete with shoulders, elbows and finger-like grippers. The arms were linked to electrodes that transmitted signals from areas of the brain that control movement. Nerve signals powered the arms to grab marshmallows and fruit, which the primates popped into their mouths “all in one natural-looking motion,'’ said the article, reported in the journal Nature.

The study documents the first successful use of a “brain- machine interface'’ to control a robotic limb for a practical function, said the authors. Before now, such experiments involved controlling a cursor on a computer screen, according to the researchers from the University of Pittsburgh and Carnegie Mellon University.

“Our immediate goal is to make a prosthetic device for people with total paralysis,'’ said Andrew Schwartz, the paper’s lead author and a neurobiology professor at the University of Pittsburgh. “The more we understand about the brain, the better we’ll be able to treat a wide range of brain disorders — everything from Parkinson’s disease and paralysis to, eventually, Alzheimer’s disease and perhaps even mental illness,'’ he said in a statement accompanying the article.

The researchers implanted a series of electrical probes, each the width of a human hair, into the monkeys’ brains. Each sensor recorded signals from 100 nerve cells. When fed through a mathematical algorithm the researchers created to plot the animals’ intentions, the monkeys quickly learned to control the robotic arms with only their thoughts. The monkeys’ real arms were restrained during the tests, the study said.

Within days, the monkeys were swinging the arms around obstacles. They learned to chew and reach at the same time and shifted their heads and eyes normally without affecting the robot appendage.

The robotic dexterity offers “a heartening example of what, in due course, may be possible,'’ John Kalaska, a University of Montreal professor, wrote in a commentary that accompanied the article. “Learning could be even quicker in human subjects, facilitated by verbal instructions from a trainer,'’ he wrote.

Obstacles remain before human-machine hybrids the likes of Robocop and Terminator come marching from the laboratory, Kalaska said. Most of the technology used by the monkeys has been tested in simpler remote devices in previous studies, some using human subjects, Kalaska noted. The reliability of the electrodes needs to be improved, he said, and people will need prosthetics that feed tactile information back to their brains, so they use the right amount of force and don’t crush or drop objects.

“We should not get carried away and leap to the conclusion that neuroprosthetic robots will soon be available at the local rehabilitation clinic,'’ Kalaska wrote.

Source: journal Nature