A monkey has successfully fed itself with fluid, well-controlled movements of a human-like robotic arm by using only signals from its brain, researchers from the University of Pittsburgh School of Medicine report in the journal Nature.
This significant advance could benefit development of prosthetics for people with spinal cord injuries and those with conditions such as Lou Gehrig's disease or amyotrophic lateral sclerosis.
"Our immediate goal is to make a prosthetic device for people with total paralysis," says Andrew Schwartz, Ph.D., senior author and professor of neurobiology at the University of Pittsburgh School of Medicine. "Ultimately, our goal is to better understand brain complexity."
Previously, work has focused on using brain-machine interfaces to control cursor movements displayed on a computer screen. Monkeys in the Schwartz lab have been trained to command cursor movements with the power of their thoughts.
Using this technology, monkeys in the Schwartz lab are able to move a robotic arm to feed themselves marshmallows and chunks of fruit while their own arms are restrained. Computer software interprets signals picked up by probes the width of a human hair.
The probes are inserted into neuronal pathways in the monkey's motor cortex, a brain region where voluntary movement originates as electrical impulses. The neurons' activity is then evaluated using software programmed with a mathematical algorithm and then sent to the arm, which carries out the actions the monkey intended to perform with its own limb.
Movements are fluid and natural and evidence shows that the monkeys come to regard the robotic device as part of their own bodies.
The monkey learns by first observing the movement, which activates his brain cells as if he were doing it. "It's a lot like sports training, where trainers have athletes first imagine that they are performing the movements they desire," Dr. Schwartz says.
He says that "the more we understand about the brain, the better we'll be able to treat a wide range of brain disorders from Parkinson's disease and paralysis to eventually Alzheimer's disease and perhaps even mental illness."