Monkey Controls Robot Arm With Mind Power

November 24, 2009 | Leave a Comment

MONKEYS have learnt to feed themselves using a robotic arm controlled by their thoughts, in an experiment that could help paralysed people to lead more independent lives.

A brain implant that picks up patterns of neural activity has allowed the animals to manipulate the prosthetic limb with sufficiently fine control to reach for marshmallows and pieces of fruit, grab them and then pop them into their mouths.

The success is by far the best demonstration yet of a technology that promises to transform the quality of life of patients paralysed by spinal injuries, strokes or wasting conditions such as motor neuron disease.

Similar implants have been used to enable quadriplegics to move a computer cursor, giving them the ability to open emails, write messages and even to move a much simpler robotic arm.

The much more precise control achieved by the two rhesus macaque monkeys should now lead to further human trials within two years, aimed at enhancing the independence of thousands of people.

“Our immediate goal is to make a prosthetic device for people with total paralysis,” said Andrew Schwartz, professor of neurobiology at the University of Pittsburgh, who led the research. “Ultimately, our goal is to better understand brain complexity.”

In the study, which is published in the journal Nature, the monkeys’ brains were implanted with probes the width of a human hair that recorded signals from the motor cortex that controls movement. They then learnt to control the robot arm, which was placed next to the shoulder, by moving a joystick with their hands.

Once they had mastered this skill, their arms were restrained while signals from their brain implants were processed by a computer and used to control the prosthesis. They rapidly learnt to control the robotic arm.

Over two days of experiments, one monkey grabbed and ate food treats with a success rate of 61 per cent. A second monkey achieved a success rate of 78 per cent over 13 days.

“It’s a lot like sports training, where trainers have athletes first imagine that they are performing the movements they desire,” Professor Schwartz said. “The entire task is now performed with brain control.”

Writing in a commentary for Nature, John Kalaska, of the University of Montreal, said that the research might be applied eventually to human patients, though he cautioned that technical challenges remained.

The quality of signals captured from the brain has often declined over time in previous experiments, robotic arms are not very portable and it is not yet possible to make them touch-sensitive, so it is difficult to adjust the force with which objects are grasped.

Dr Kalaska said: “This is the first reported demonstration of the use of brain-machine interface technology to form a practical behavioural act – feeding themselves – via brain control of the motion of a robotic arm in three-dimensional space.”

The Times
Mark Henderson
May 29, 2008 06:14pm

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