Whether you’re naturally good at finding your way around town or need to check in with Siri to make sure you’re in the right plane, you’re experiencing your environment. It’s an experience that changes over time as you learn a neighborhood, and now scientists have figured out how. The brain has a sort of internal GSP system, and the three scientists who discovered it just won the Noble Prize.
The Prize has been split between John O’Keefe, director of the Sainsbury Wellcome Centre for Neural Circuits and Behaviour at University College London, and Trondheim-based husband and wife team May-Britt Moser, director of the Centre for Neural Computation, and Edvard Moser, director of the Kavli Institute for Systems Neuroscience.
O’Keefe discovered the first part of the brain’s GPS system in 1971. Working with rats, he recorded signals from individual nerve cells in the rodents’ brains as they moved around a room. He found that a specific cell in the hippocampus would signal each time the rat passed through a specific area in the room. He also found that different cells reacted to the rat being in different locations in the space. These results combined to show that “place cells,” as O’Keefe calls them, allow the rats to construct a mental map of their surroundings. Multiple maps stored in the hippocampus account for familiarity with different surroundings.
But recognizing your location is only part of what makes a GPS system work. The other part is finding your destination and knowing how far away it is and how long it will take you to get there.
This is the part of the brain’s GPS that the Mosers discovered. After learning how to map brain activity from O’Keefe, the couple discovered that another set of cells exists in a neighboring part of the brain called the entorhinal cortex. These cells are more like a grid than a map; think the latitude and longitude coordinates that give sailors a sense of where they are and where they’re going on the vast open oceans. In the brain, these grid-like cells give the us its ability to judge distance and navigate from starting point to destination.
The combination of grid and place cells effectively makes up the constitutes of a comprehensive positioning system within the brain.
But the discovery of place and grid cells doesn’t just explain how we know where we are and where we’re going, it might help explain how we lose that ability. Diseases like dementia and Alzheimer’s affect the brain functions that allow us to experience our environment. Understanding how these systems work could change the ways these diseases affect us, maybe even stemming these devastating disorienting effects.
Featured image: V.J. Wedeen and L.L. Wald, Martinos Center for Biomedical Imaging at MGH [via Discover Magazine]