Deep in the brains of bats, rats and monkeys, tiny neuronal cartographers called grid cells map external environments. The cells fire off messages when animals arrive at regular grid points in space. Now, scientists have found similar cells at work in the brains of people.
Joshua Jacobs of Drexel University in Philadelphia and colleagues enlisted 14 people who already had electrodes implanted in their brain as part of treatment for severe epilepsy. These electrodes picked up neuronal messages that repeated themselves regularly as the people used a computer to ride a virtual bike through a large, open arena. These grid cells were located in the entorhinal cortex and hippocampus, brain areas that are important for navigation and memory.
In the real world, one grid cell may fire every time a person walks one to six meters, the researchers write August 4 in Nature Neuroscience.
