Development of the Hippocampal Cognitive Map in Preweanling Rats

Thomas Joseph Wills, Francesca Cacucci, Neil Burgess, John O'Keefe

Abstract:

Orienting in large-scale space depends on the interaction of environmental experience and
preconfigured, possibly innate, constructs. Place, head-direction, and grid cells in the hippocampal
formation provide allocentric representations of space. Here we show how these cognitive
representations emerge and develop as rat pups first begin to explore their environment.
Directional, locational, and rhythmic organization of firing are present during initial exploration,
including adultlike directional firing. The stability and precision of place cell firing continue to
develop throughout juvenility. Stable grid cell firing appears later but matures rapidly to adult
levels. Our results demonstrate the presence of three neuronal representations of space before
extensive experience and show how they develop with age.