Reversed theta sequences of hippocampal cell assemblies during backward travel

Cei and colleagues used a model train to transport rats forward or backward on a circular track while the animals walked on a miniature treadmill. The authors found that the firing fields of hippocampal place cells remained stable across travel directions and that, when the train transported the rat backward, theta sequences of hippocampal cell assemblies and theta phase precession still represented the trajectory and the distance traveled through place fields.