It's after dark on a warm Monday night in April, and I'm lying face-up in a 13-ton tube at the Henry H. Wheeler, Jr. Brain Imaging Center at the University of California at Berkeley. The room is dimly lit, and I am alone. A white plastic cage covers my face, and a blue computer screen shines brightly into my eyes. I'm here because a neuroscientist named Jack Gallant is about to read my mind. He has given me strict instructions not to move; even the slightest twitch could affect the accuracy of what he's about to do. As I stare straight up, I notice an itch on my thigh.