The medial entorhinal cortex (MEC) is part of the brain’s circuit for dynamic representation of self-location. The metric of this representation is provided by grid cells, cells with spatial firing fields that tile environments in a periodic hexagonal pattern, like holes in a bee hive. Grid cells were identified first in rats but were then found in mice, bats, monkeys and humans, with particular adaptations in primates, suggesting that grid cells arose early in mammalian evolution.
