Figure 1.

Disorganized phase coding of hippocampal place cells produces disordered theta sequences in maternal immune activation (MIA) animals. The upper cartoon illustrates phase coding occurring as an animal crosses a place field, with phase color-coded. As the animal enters the place field, the cell spikes at late phases of the theta cycle, but spiking processes towards earlier phases as the animal traverses the field. The lower cartoon demonstrates how theta sequences emerge as a result of phase precession in several cells with overlapping place fields. In the control example, the starting phase of precession is coordinated at the network level, resulting in ordered theta sequences that are concentrated along a portion of a theta cycle. Here cell A fires first during the theta cycle because the animal is exiting this place field. In contrast Cell D fires last, because the animal is entering this field. In the MIA example, starting phase varies from cell to cell, resulting in disordered sequences that are also spread further across the theta cycle.