



Video: Monkey brainwaves control avatar

Monkeys have feelings too. In a mind-meld between monkey and computer, rhesus macaques have learned to “feel” the texture of virtual objects without physically touching a thing. In the future, prosthetic limbs modelled on similar technology could return a sense of touch to people with amputations.

Using two-way communication between brain and machine, the monkeys manoeuvred a cursor with their minds and identified virtual objects by texture, based on electrical feedback from the computer.

Miguel Nicolelis of Duke University Medical Center in Durham, North Carolina, and his colleagues implanted electrodes into the brains of two monkeys. The electrodes recorded activity in the motor cortex and somatosensory cortex (SSC) – brain areas that orchestrate voluntary movement and sense of touch. Electrical activity from the motor cortex was sent to a computer, which translated the neural chatter into instructions that moved a cursor on screen. The monkeys learned what patterns of thought reliably changed the cursor’s position.


The team then assigned a unique texture to each of three identical circles on the screen. When the cursor hovered over each circle, the computer zapped the monkeys’ SSCs with the same electrical impulses that occurred when they touched each texture in real life. Finally, the team taught the monkeys to associate a particular texture with a reward.

Random circles

When the circles were randomly moved on the screen, the monkeys were able to identify the circle associated with the reward with around 90 per cent accuracy.

“Amazing stuff – you can take information from the brain, analyse it outside, bring it back to the brain and affect computation,” says psychobiologist Matti Mintz of Tel Aviv University in Israel. “That’s the model vision of brain-computer interfaces.”

“It really is novel,” says Paul Marasco, who works on neuroprosthetic limbs at the Advanced Platform Technology Center of the US Department of Veterans Affairs. Marasco says he does not know of a prosthetic limb that not only can be controlled by a patient, but also allows them to pick up and respond to sensory information from the limb itself – an ability he calls “user-inclusive sensory feedback”.

Whereas typical brain-machine interfaces return some motor control to people who are paralysed or who have had amputations, brain-machine-brain interfaces could return lost sensory experience to them as well.

Journal reference: Nature, DOI: 10.1038/nature10489