In 1971, Dr. O'Keefe discovered specific cells in the hippocampus that record location. These place cells, as they are called, register the locations of specific landmarks, such as the laboratory, or the corner deli. While recording the firing of neurons in rats as they moved from one location to another, he found that each location was logged by its own unique set of nerve cells in the CA1 region of the hippocampus, suggesting that the cells form a virtual map of the animal's location. The firing location of each cell was stable over time, and moving the animal to another location caused it to form a new map, using some of the same cells, in addition to new ones. When the animal was returned to its original location, it replayed the initial map that it had formed.
In 1996, Drs. Edvard Moser and May-Britt Moser, longtime collaborators who are married to each other, worked with Dr. O'Keefe, who became their mentor, to learn how to record the activity of cells in the hippocampus.
Nearly a decade later, the Moser team discovered cells, in the entorhinal cortex region in the brains of rats, which function as a navigation system. These grid cells, as they are called, are responsible for the animals' knowing where they are, where they have been, and where they are going; they are constantly working to create a map of the outside world. Constructed in the nervous system from tactile, visual, and other sensory input, grid cells have provided fundamental insights into how spatial location and memory are computed in the brain. The mapping information flows from the entorhinal cortex to the hippocampus and then back, and scientists are now working to understand how the grid cells inform place cells, and vice versa.
Because the entorhinal cortex, which contains the grid cell navigation system, is often damaged in the early stages of Alzheimer's disease, the work by the Mosers and Dr. O'Keefe on how memo
|Contact: Elizabeth Streich|
Columbia University Medical Center