Mapping the brain’s GPS system has earned three neuroscientists the 2014 Nobel Prize in physiology or medicine. John O’Keefe of University College London shares the prize with husband-and-wife duo May-Britt Moser and Edvard Moser of the Norwegian University of Science and Technology in Trondheim.
“I’m delighted that three great friends and three great scientists have deservedly won this prize,” says neuroscientist Richard Morris of the University of Edinburgh, who has worked with O’Keefe and the Mosers for decades.
By discovering nerve cells that a rat uses to keep track of its location, the scientists offer a strikingly clear example of how the brain makes sense of its environment. The discovery of these navigational cells “is one of the most exciting stories in brain and cognitive sciences today,” says cognitive scientist Barbara Landau of Johns Hopkins University.
O’Keefe’s and the Mosers’ work both relied on some of the best navigators around — rats. In 1971, O’Keefe found that certain cells in the rat hippocampus, a brain region involved in memory, became active only when the animal was in particular spots. These “place cells” allowed an animal to form an internal map of its surroundings. Unlike many earlier experiments, O’Keefe’s work studied animals as they moved freely about an area. O’Keefe, who will receive half of the roughly $1.1 million prize, used implanted electrodes to record the behavior of neurons in the rats.Jonathan Dostrovsky, a University of Toronto neuroscientist who was O’Keefe’s student when he made the discovery, says he’s thrilled to hear of the prize. “Discovering the place cells with him was an amazing introduction to the world of scientific research for me as a young researcher just starting out on a career in neuroscience.”
More than three decades later, the Mosers discovered what they dubbed “grid cells” in a nearby brain area, the entorhinal cortex. These cells fired off signals when a rat passed through certain locations spaced at regular intervals, becoming active in multiple locales that correspond to a grid similar to a Chinese checkerboard or a hexagonal beehive.
Along with other cells that take note of a rat’s head position and a location’s borders, grid cells send messages to place cells in the hippocampus, the Mosers found. The resulting elaborate network of neurons allows an animal to know where it is in the world.
This work is important not just because of what it reveals about how rats find their way through space, says cognitive neuroscientist Russell Epstein of the University of Pennsylvania. “It’s one of the best examples we have of how information can be encoded in the nervous system.”
Such cells are present in people, too. With implanted electrodes, scientists uncovered place cells in the brains of people in 2003 and grid cells in 2013 (SN Online: 8/5/13). “From what we can tell, there’s quite a bit of similarity between rats and people,” says neuroscientist Joshua Jacobs of Drexel University, who helped find grid cells in people.
The brain’s navigation abilities may serve as a foundation for other processes, too. Developing a sense of where the body is in space seems to be an important step for developing babies, says neuroscientist Michael Kahana, also of the University of Pennsylvania. And many of our memories are built on a scaffold of space, says Epstein. People remembering a meal in a superb restaurant will often be able to say exactly which table they sat at, for instance.
What’s more, these brain regions are some of the first affected by Alzheimer’s disease. In the early stages of the neurodegenerative disorder, the ability to successfully navigate can slip away, perhaps because these navigational cells stop working correctly or die.
Studies in humans were enabled by the discovery of place and grid cells in rats, Kahana says: “This is a line of work we could do only because of the work of the Mosers and O’Keefe.”
— With additional reporting by Nathan Seppa