Fig. 3.

Silencing the medial prefrontal cortex (mPFC) altered phase locking. Polar plots are shown for all recorded mPFC and hippocampal cells phase locked to theta and gamma oscillations. A and B: silencing the mPFC with clozapine N-oxide (CNO) altered mPFC cells phase locking to hippocampal theta (A) and local low gamma (B). C and D: similarly, silencing the mPFC altered hippocampal place cell phase locking to local theta (C) and local low gamma (D). E–H: we measured phase precession for individual trials for vehicle (Veh; E and F) and CNO (G and H) days for hippocampal place cells. The correlation between theta phase and spatial location was similar between Veh (I) and CNO (J) days as were the slopes between Veh (K) and CNO (L) days. The theta phase ranges (see methods) were also similar between Veh (M) and CNO (N) days. O: disrupting mPFC impairs the initiation of a sequence. We measured the theta phase relationship of the first and P) last spike of a run through a place field for Veh days (blue) and CNO days (red). mPFC disruption had no effect on the phase locking of the first spike to the theta oscillation; however, it altered the phase locking relationship of the last spike of the field.