According to a lovely new Nature paper combining fMRI imaging with animal experiments, the human brain encodes spatial information in the form of of a hexagonal grid - Evidence for grid cells in a human memory network.
If you've ever played Chinese checkers, you'll know what a hex grid is. It's already known that in rats, the entorhinal cortex of the brain contains "grid cells", each of which fires according to where in a certain place the rat is. The diagram above left shows how one example grid cell fires more often when the rat is in certain places in a 1m x 1m box.
Doeller et al wanted to test whether grid cells exist in humans, but being unable to just stick electrodes in people's heads, they made use of two useful facts about rat grid cells. First, the orientation of the grid is fixed in all the cells ...
