Ten years ago, after a shooting incident, Erik Sorto became paralysed from the neck down. But now he can drink beer again, thanks to this prosthetic limb, recently developed in the US. It is attached to the posterior parietal cortex, the part of the brain that controls not movement itself, but the patient’s intention to move.

Erik Sorto explained: “I start thinking about the robot arm, I close my eyes just like this and I start imagining the robotic arm and what I want it to do.”

Surgeons at the University of Southern California implanted two small electrodes in the patient’s brain, which were then connected via cables to computers that could process and decode brain signals. These decoded signals were then sent to a cursor and a robotic arm. After the surgery, Erik Sorto learned to use the cursor and the arm. The scientists said it was a big surprise that he could control the limb on day one.

Charles Y Liu, a neurosurgeon, said: “Now we have an entirely new brain-machine inter