The Nobel Assembly at Karolinska Institutet awards the prize annually to "the person who shall have made the most important discovery within the domain of physiology or medicine." It is one of five Nobel Prizes established by Alfred Nobel, inventor of dynamite, in his will in 1895.
The trio received the award for their discoveries of cells that constitute a positioning system in the brain, which was described as an "inner GPS."
O'Keefe, who holds both American and British citizenships, is a professor of cognitive neuroscience and the director of the Sainsbury Wellcome Centre in Neural Circuits and Behavior at te University College London. He discovered the first component of the positioning system in 1971.
May-Britt Moser is a professor of neuroscience and the director of the Centre for Neural Computation at the Norwegian University of Science and Technology in Trondheim. Her husband Edvard Moser is also a professor at the university, and the director of the Kavli Institute for Systems Neuroscience.
The Mosers are the fifth married couple to be awarded a Nobel Prize. In 2005, they discovered a type of nerve cell that generates a coordinate system and allowing for precise positioning.
Together, these discoveries explain how the brain creates a map of space and how we navigate our way through a complex environment.
Between 1901 and 2013, more than 560 Nobel Prizes have been awarded to 876 people and organizations. Nobel laureates receive the title, a diploma, a gold medal and about $1.2 million in award money. If two winners are chosen for a single category, the prize is split in half. When more than two people or organizations are selected, the prize is distributed at the judges' discretion.
Click here for a complete list of past laureates in this category.