When he started the video, the paw began to twitch—and, with each twitch, musical notes resounded from different neurons in the brain. The effect was like a church organ playing underwater; chords rolled then subsided. An electrode readout made the order of events clear: first the pup moved, then the brain responded. Bursts of activity in the sensorimotor cortex, which coördinates movement and sensation, followed the twitches. The body and brain weren’t disconnected. The brain was listening to the body.