American-British scientist John O'Keefe and Norwegians May-Britt Moser and Edvard Moser won the 2014 Nobel Prize for medicine for discovering the brain's "inner GPS" that makes it possible to orient ourselves in space and help understand diseases like Alzheimer's, the award-giving body said on Monday.

"The discoveries...have solved a problem that has occupied philosophers and scientists for centuries," the Nobel Assembly at Sweden's Karolinska Institute said in a statement when awarding the prize of 8 million Swedish crowns ($1.1 million).

"How does the brain create a map of the space surrounding us and how can we navigate our way through a complex environment?" the body added.

The Mosers join an exclusive club of married couples to win a Nobel Prize that includes scientific greats Pierre Curie and Marie Curie.

"Knowledge about the brain's positioning system may, therefore, help us understand the mechanism underpinning the devastating spatial loss that affects people with this (Alzheimer's) disease," the body added.

O'Keefe is director of the Sainsbury Wellcome Center in Neural Circuits and Behavior at University College London. The Mosers are both based in scientific institutes in the Norwegian town of Trondheim

Medicine is the first of the Nobel prizes awarded each year.

Prizes for achievements in science, literature and peace were first awarded in 1901 in accordance with the will of dynamite inventor and businessman Alfred Nobel.