John O'Keefe (born 18 November 1939) is an American-British neuroscientist and a professor at the Institute of Cognitive Neuroscience and the Department of Anatomy at University College London. He is known for his discovery of place cells in the hippocampus and his discovery that they show a specific kind of temporal coding in the form of theta phase precession. In 2014, he received the Kavli Prize in Neuroscience "for the discovery of specialized brain networks for memory and cognition", together with Brenda Milner and Marcus Raichle. He shared the Nobel Prize in Physiology or Medicine in 2014 together with May-Britt Moser and Edvard Moser.