The Nobel Prize for physiology or medicine has been awarded to three scientists who discovered the brain's "GPS system".
UK-based researcher Prof John O'Keefe as well as May-Britt Moser and Edvard Moser share the award.
They discovered how the brain knows where we are and is able to navigate from one place to another.
Their findings may help explain why in Alzheimer's disease patients cannot recognise their surroundings.
