The Nobel Prize in Physiology and Medicine, awarded today, recognizes discoveries that help us understand the brain’s “place sense” and “navigation sense.” Together, these abilities constitute a built-positioning system, a kind of internal GPS.
Half of the prize goes to British-American researcher John O’Keefe, Ph.D., who discovered that certain nerve cells in the hippocampus become activated in rats when the rats occupy particular locations. These “place cells” not only register visual input, Dr. O’Keefe concluded, they also build up an inner map of the environment.
The other half of the prize is shared by May-Britt Moser, Ph.D., and Edvard I. Moser, Ph.D., for identifying another type of nerve cell in rats that allows for precise positioning and pathfinding. Nerve cells of this type—“grid cells”—are found in the entorhinal cortex. Together with other cells of the entorhinal cortex that recognize the direction of the head and the disposition of perceptible landmarks, such as the borders of a room, grid cells form circuits with hippocampal place cells.
Networked together, the grid cells and place cells form a comprehensive positioning system—the aforementioned brain-based GPS.
Dr. O’Keefe, a professor of cognitive neuroscience and the director of the Sainsbury Wellcome Center in Neural Circuits and Behavior at the University College London, discovered place cells in 1971 on the basis of work he initiated in the late 1960s. Drs. May-Britt Moser and Edvard I. Moser, spouses and scientific collaborators at the Norwegian University of Science and Technology in Trondheim, made their discoveries decades later. After identifying grid cells in 2005, they continued their work to show how place and grid cells make it possible to determine position and to navigate.
According to a press release issued by the Nobel Foundation, recent investigations with brain imaging techniques, as well as studies of patients undergoing neurosurgery, have provided evidence that place and grid cells exist not only in rats, but also in humans.
“In patients with Alzheimer’s disease, the hippocampus and entorhinal cortex are frequently affected at an early stage, and these individuals often lose their way and cannot recognize the environment,” the release explained. “Knowledge about the brain’s positioning system may, therefore, help us understand the mechanism underpinning the devastating spatial memory loss that affects people with this disease.”
The Nobel Foundation asserted that the discovery of the brain’s positioning system represents a paradigm shift in our understanding of how ensembles of specialized cells work together to execute higher cognitive functions: “It has opened new avenues for understanding other cognitive processes, such as memory, thinking, and planning.”