Experience-dependent, asymmetric expansion of hippocampal place fields

Theories of sequence learning based on temporally asymmetric, Hebbian long-term potentiation predict that during route learning the spatial firing distributions of hippocampal neurons should enlarge in a direction opposite to the animal's movement, On a route AB, increased synaptic drive from cells representing A would cause cells representing B to fire earlier and more robustly, These effects appeared within a few laps in rats running on closed tracks, This provides indirect evidence for Hebbian synaptic plasticity and a functional explanation for why place cells become directionally selective during route following, namely, to preserve the synaptic asymmetry necessary to Encode the sequence direction.