Do we understand the emergent dynamics of grid cell activity?

Single neurons in the dorsolateral band of the rat entorhinal cortex (dMEC) fire as a function of rat position whenever the rat is on any vertex of a regular triangular lattice, that tiles the entire plane (Hafting et al., 2005). Even in the dark, the pattern refreshes correctly with rat movement, and maintains its coherence over paths whose accumulated length exceeds 200 m (Hafting et al., 2005). For dMEC activity to be a precise function of the rat’s changing position in the dark, it must have access to an accurate estimate of position based on selfmotion cues, suggesting that dMEC may be involved in idiothetic path integration.