Marie, a sixty-three-year old Belgian woman, has been totally blind since the age of fifty-seven. But now, thanks to electrodes implanted around her right optic nerve, she can see lights, shapes, and colors again. Marie is one of a handful of people around the world who have had computer chips implanted in their bodies to extend, enhance, or repair their senses. The idea of actually melding man and machine still seems futuristic, unlikely and a little...