Figure 3.

Phase–amplitude coupling (PAC) between hippocampal theta and gamma oscillations in HPC, RSC, and ACA. A, Raw and filtered LFPs recorded in HPC, RSC, and ACA during aWK and PS in one representative animal. B, Power spectra of fast oscillations during aWK and PS. C, Pseudocolor-coded averaged cross-frequency coupling maps between hippocampal theta phase and gamma amplitude in HPC, RSC, and ACA during aWK and PS (color bar is set the same for all panels, warm colors indicate strong coupling). D, PAC quantification shows that theta phase modulation of gamma (40–100 Hz) and fast gamma (100–160 Hz) is significantly higher during PS than during aWK in HPC and RSC but not in ACA. *p < 0.05, paired t test. E, PAC is similar when calculating it using theta from HPC or RSC. F, Time-frequency plot of averaged gamma amplitude (Z-score) distribution time-locked to the theta peak (0 s) in the HPC (top) and RSC (bottom) during PS (n = 10). Hippocampal averaged theta cycles during PS are superimposed on plot traces.