The vast majority of people who've lost a limb can still feel it — not as a memory or vague shape, but in complete lifelike detail. They can flex their phantom fingers and sometimes even feel the chafe of a watch band or the throb of an ingrown toenail. What causes these phantom limb sensations? Joshua W. Pate explains how the brain reacts to a ...

In 1995, the British Medical Journal published a report about a builder who accidentally jumped onto a nail, which pierced straight through his steel-toed boot. He was in such agonizing pain that any movement was unbearable. But when the doctors took off his boot, they discovered that the nail had never touched his foot at all. What's going on? ...