Thus, the dual functions of the theta oscillation mechanism are to bring together and link cell assemblies into the temporal range where they can be modulated by synaptic plasticity, and at the same time segregate them within the available phase space54,60. The phase segregation of adjacent place cells may be brought about by perisomatic interneuron-mediated inhibition79–81 (Fig. 6). There are three interrelated consequences of the theta phase segregation of cell assemblies. First, the firing sequences of neurons on the descending phase, trough and ascending phase of the theta waves represent the sequences of the past, current and future positions of the animal’s journey75,82. Second, the time delays between overlapping place cells at the sub-theta-cycle scale are proportional to the time differences between their peak firing activities in physical space; that is, the time it takes for the animal to travel between the peaks of their place fields (Fig. 5a–d). As a result of this relationship, the travel distances between landmarks during navigation are expressed in the temporal domain by a time-compressed format in the theta waves75,82. Third, the oscillation frequency
