A brain-computer interface has been developed that enables monkeys' brain activity to navigate wheelchairs.
Electrodes implanted into the brain of a monkey allows scientists to decode their neural activity and use it to steer the chair via a brian-computer interface (BCI).
The micro electrodes – smaller than the diameter of a human hair – were buried deep into the frontal and parietal lobes of two female rhesus macaque monkeys. One monkey received 96 electrodes, and the other 320.
Frontal areas of the brain were chosen because they are known to be involved in producing multiple output commands to control complex muscle movement.
In a study, scientists first recorded activity in the motor and sensory cortices of monkeys riding around in the chair. The computer decoder then correlated this brain activity with the director of movement of the chair. After training, the BCI worked in reverse, using the neural inputs to steer the chair.
The Duke University study was conducted by observing the behaviour of two monkeys who learned to steer the chair across a room towards a grape dispenser.
"They can reliably steer the wheelchair to get a grape," Duke University neuroscientist Miguel Nicolelis said in a National Geographic report. "They like grapes."
Further studies include understanding how monkeys navigate the terrain of jungles and climb around trees. This could ultimately help people with spinal cord injuries, such as Superman actor Christopher Reeve.
"The most amazing result, though, was that 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 the 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."
According to the scientists: "Research findings suggest possible new approaches to treat chronic spinal cord injuries, which have long been considered untreatable.
"Scientists report successful efforts to overcome or circumvent seemingly irreparable and long-standing damage at the site of the original injury using a variety of methods, from implantation of early-stage brain cells to brain-machine interface."
Each year 130,000 people suffer spinal cord injuries worldwide, and for more than a decade, researchers have sought to help these patients using robotic interfaces with the brain.
The findings of the research were presented to the Society for Neuroscience (SfN) conference in Washington, DC.