 Then, as the rat continued to move on past the place field and the cell firing slowed, the action potentials continued to occur progressively earlier relative to the theta wave, until they again became synchronous with the wave, aligned now with one wave peak earlier than before.O'Keefe and Recce termed this advancement relative to the wave phase "phase precession".Subsequent studies showed that each time a rat entered a completely different area and the place fields would be remapped, place cells would again become phase-locked to the theta rhythm.