Congratulations to John O’Keefe, May-Britt Moser and Edvard Moser for receiving the 2014 Nobel Prize in Medicine. The prize is for discovering “the brain’s navigation system”: place cells, cells in the hippocampus which are active whenever a rat is in a particular place, and grid cells, cells in the entorhinal cortex which are active when the animal is at multiple locations in a grid pattern.
Former Yerkes researcher Beth Buffalo and herÂ graduate studentÂ Nathan KillianÂ were the first to directly detect, via electrode recordings, grid cells in the brains of non-human primates. Buffalo is now at the University of WashingtonÂ and Killian is at Harvard Medical School.
A significant difference about theirÂ experiments was that theyÂ could identify grid cellsÂ when monkeys were moving their eyes, suggesting that primates don’t have to actually visit a place to construct the same kind of mental map. Another aspect of grid cells in non-human primates not previously seen with rodents is that the cells’ responses change when monkeys are seeing an image for the second time.
Following that report, grid cells were also directlyÂ detected inÂ human epilepsy patients. The Mosers themselves notedÂ in a 2014Â review, “It will be interesting to see whether the same cells that respond to visual movement in monkeys also respond to locomotion, or whether there is a separate system of grid cells that is responsive to locomotion.”