a, Schematic representation of the entorhinal-hippocampal circuit in the rat. Sensory information reaches the three regions of the hippocampus (dentate gyrus [DG], CA3, and CA1) via the superficial layers of the entorhinal cortex (EC-L2). In turn, the output station CA1 and subiculum (SUB) project back to the deep layers of the entorhinal cortex (EC-L5), which broadcasts the hippocampal output to multiple cortical areas. b, A comparative timeline delineating relevant milestones in the structural and functional maturation of the hippocampus-dependent memory system of rodents.