Duke University scientists have trained rhesus monkeys to move virtual arms using a brain-mind interface.
Monkeys and humans have previously controlled a single prosthetic arm using their thoughts. It is done using electrodes placed in the brain, which recognise specific patterns of electric activity that occur when a person thinks about moving. This pattern is then translated into actual movement in the prosthesis.
So far, the success of BMIs in humans has been largely limited to moving single body parts, such as a hand or an arm.
Neuroscientist Miguel Nicolelis at Duke University in Durham, North Carolina said, “No device will ever work for people unless it restores bimanual behaviors, you need to use both arms and hands for the simplest tasks.”
In 2011, Nicolelis announced on The Daily Show that he is developing a robotic, thought-controlled “exoskeleton” that will allow paralyzed people to walk again.
To achieve such bimanual movement, Nicolelis and his colleagues recorded the individual electrical activity from almost 500 single neurons in the somatosensory and motor cortex on both sides of a monkey’s brain, the areas responsible for sensing body position, touch and movement.
Among the two tested rhesus monkeys , both the real monkeys, first learned how to get the juice by moving joysticks with her real arms and hands. This practice went on during 20- to 40-minute sessions for a year. Once this was achieved, the joysticks were disconnected and the algorithm took over, and they were strapped into a padded chair so that they couldn’t move their own arms or hands, and trained to control the avatar arms just by thinking.
This part of the experiment is vital, as it demonstrates that the algorithm can be trained using thoughts alone – a crucial step if people without the use of their limbs are to use the technology. It took about 7 minutes for the algorithm to recognise the patterns of brain activity that correlated with the movement of the virtual hands. After this time, the researchers allowed the algorithm to take over – only moving the hands when the monkey thought about moving them.
Nicolelis will use the rhesus monkey findings to advance his work with the Walk Again Project.