The development of the hippocampal neural representation of space

•We review the development of spatially tuned neurons in the rat hippocampal formation.•Head direction cells are already present at 15 days old, before exploration begins.•An adult-like grid cell network emerges later, at around three weeks of age.•The place cell network matures slowly, but some cells are adult-like at 16 days old.•Temporal organisation of neural activity is present at the onset of spatial firing.

The hippocampal formation (HF) contains a neural representation of the environment, based on the activity of several classes of neurons whose firing is tuned to an animal's position and orientation in space. Recently, work has begun on understanding when and how this neural map of space emerges during development. Different classes of spatially tuned neurons emerge at different ages, some of them very early during development, before animals have started exploring their environment. The developmental timeline thus far uncovered has yielded insights into both the mechanisms of the ontogeny of the neural code for space, as well as how this system functions in the adult.