Neurosurgeons at the University of Pittsburgh School of Medicine in Pennsylvania implanted a grid of electrodes, about the size of a large postage stamp, on top of Hemmes’s brain over an area of neurons that fire when he imagines moving his right arm. They threaded wires from the implant underneath the skin of his neck and pulled the ends out of his body near his chest.
The team then connected the implant to a computer that converts specific brainwaves into particular actions.
As shown in this video, Hemmes first practices controlling a dot on a TV screen with his mind. The dot moves right when he imagines bending his elbow. Thinking about wiggling his thumb makes the dot slide left.
With practice, Hemmes learned to move the cursor just by visualizing the motion, rather than concentrating on specific arm movements, says neurosurgeon Elizabeth Tyler-Kabara of the University of Pittsburgh in Pennsylvania, who implanted the electrodes.
After this initial training, Hemmes navigated a ball through a 3D virtual world and eventually controlled the robotic arm, all with his mind. The electrode grid was removed after the 30-day trial.
The team is now recruiting people for a trial of a more sensitive electrode grid that detects messages from individual neurons, rather than a group. They plan to implant two electrode patches, one to control arm movements and another for fine hand motion. The ultimate goal is to allow paralysed people to move individual fingers on a robotic hand.
If you enjoyed this video, watch the first practical demonstration of a mind-controlled robot arm, used by a monkey to feed itself marshmallows.