STOCKHOLM - U.S.-British scientist John O'Keefe and Norwegian scientists May-Britt Moser and Edvard Moser won the Nobel Prize in medicine on Monday for discovering the "inner GPS" that helps the brain navigate through the world. Their findings in rats — and research suggests that humans have the same system in their brains — represented a "paradigm shift" in the knowledge of how cells work together to perform cognitive functions, the Nobel Assembly said, adding that could help scientists understand the mechanisms behind diseases like Alzheimer's. "This year's Nobel Laureates have discovered a positioning system, an 'inner GPS' in the brain, that makes it possible to orient ourselves in space," the assembly said. New York-born O'Keefe, 75, of University College London, discovered the first component of this system in 1971 when he found that a certain type of nerve cell was always activated when a rat was at a certain place in a room. He demonstrated that these "place cells" were building up a map of the environment, not just registering visual input.

A giant screen displays the image of (from left) British-American researcher John O'Keefe and Norwegian duo May-Britt Moser and Edvard Moser at a press conference announcing the winner of the 2014 Nobel Medicine Prize on Monday in Stockholm, Sweden. JONATHAN NACKSTRAND / AFP - Getty Images

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- The Associated Press