When American psychiatrist Mark S. George stepped into the elevator of a London hospital in 1990, he had no idea the short ride would transform his research career. A fellow passenger was having a giggling fit for no apparent reason. When George inquired about the outburst of merriment, the man replied that a doctor had held a magnetic coil against his head and that it had made his thumb twitch uncontrollably.
Even though the tale sounded a bit like quackery, George was curious. He contacted the doctor, who said he had stimulated the man's motor cortex, located at the top of the head, in hopes of seeing whether it would spark