They are eerie sensations, more common than one might think: A man describes feeling a shadowy figure standing behind him, then turning around to find no one there. A woman feels herself leaving her body and floating in space, looking down on her corporeal self. Such experiences are often attributed by those who have them to paranormal forces. But according to recent work by neuroscientists, they can be induced by delivering mild electric current to specific spots in the brain. In one woman, for example, a zap to a brain region called the angular gyrus resulted in a sensation that...