In this video, a scientist presents a piece of food to a monkey, who has had an array of tiny electrodes implanted into his brain. The monkey has been trained to use his thoughts to control a prosthetic arm to grab the food and bring it to his mouth. (The monkey’s arms are temporarily restrained so that he must use the prosthesis.) At the end of the video, the monkey displays how comfortable he has become using the device: he uses it for a movement he has not been trained on--pushing a piece of food that didn’t quite make it into his mouth.