The Institute of Navigation Satellite Division looked deeply inward for its keynote speaker at this year’s ION GNSS+ conference, held Sept. 12–16 in Portland, Oregon.
Nobel Laureate John O’Keefe provided insight into how our brains determine position. In 1971, O’Keefe recorded signals from individual nerve cells in the hippocampus of rats roaming about a room. He found that a type of nerve cell in the hippocampus was always activated when a rat was at a certain place, and other nerve cells were activated when the rat was at other places.
O’Keefe concluded that these “place cells” formed a map of the room. The place cells were not just registering visual input, but building an inner map of the environment. The hippocampus generates numerous maps, which can be seen by the activity of place cells activated in different environments. The memory of an environment can be stored as a specific combination of place-cell activities in the hippocampus.
In 2005, co-laureates May-Britt and Edvard Moser discovered another key component of the brain’s positioning system. “Grid cells” generate a coordinate system and allow for precise positioning and pathfinding. Their research showed how place and grid cells make it possible for rats — and presumably us — to find our way around, determining where we are in the world and which way to go.
Recent investigations show that place and grid cells also exist in humans. In patients with Alzheimer’s disease, the hippocampus is frequently affected, causing those afflicted to lose their way. Knowledge about the brain’s positioning system may help us understand the mechanism underpinning the disease.