American-British scientist John O'Keefe and Norwegians May-Britt Moser and Edvard Moser have won the Nobel Prize in medicine for their work in discovering the brain's inner navigation system.
The Nobel Assembly at Sweden's Karolinska Institute said Monday the laureates answered the question of how the brain maps spaces and allows beings to move through complex environments.
O'Keefe, director of the Sainsbury Wellcome Center in Neural Circuits and Behavior at University College London, discovered the mapping mechanism in 1971 by observing the way certain nerve cells activated in a rat's brain when it was in one part of a room and how other nerve cells activated in a different part.
In 2005, the Mosers, who are married, identified another type of cell in a nearby part of a rat's brain that creates a grid system and connects with the mapping cells to make up the brain's positioning system.
Further research has shown evidence these same types of cells exist in human brains.
The Nobel panel says the discoveries have opened new ways to understand other mental activities, including memory, thinking and planning.
The award comes with a $1.1 million prize, with half going to O'Keefe and the Mosers splitting the other half.
On Tuesday, the Nobel prize in physics will be awarded, followed by the chemistry prize on Wednesday, literature on Thursday and the Nobel Peace Prize on Friday.