Fig. 3: Prefrontal gamma oscillations are modulated by hippocampal and parietal 4-Hz and theta oscillations according to task requirements.

a, d Simultaneous LFP recording from the HPC (raw and 4-Hz filtered), the PPC (raw and 4-Hz filtered), and the mPFC (raw and gamma filtered) when 4-Hz oscillation was predominant. d Same as a, but when theta oscillation was predominant (HPC; raw and theta filtered; PPC: raw and theta filtered; mPFC: black; raw and gamma filtered). b, e Example of comodulograms of prefrontal gamma oscillations with respect to the phase of hippocampal 4-Hz (c) and theta (e) according to task stages and navigation strategies. c, f Box plot of modulation index of prefrontal gamma oscillations with respect to the phase of hippocampal 4-Hz (d) and theta (f) according to task stages and navigation strategies. ***P < 0.001; Sidak’s multiple comparisons test after two-way ANOVA. g Example of raw (upper, black traces) and gamma-filtered (lower, red traces) simultaneous LFP recordings from mPFC, HPC, and PPC. The panel on the right is a magnification of the dotted area from the left panel. Representative gamma events are pointed by black triangles. h Example of colorplot spectrograms of gamma oscillations of LFPs recorded from mPFC (left), HPC (middle), and PPC (right) according to task stages and navigation strategies. i Box plots of the incidence of gamma events in the mPFC (left), HPC (middle), and PPC (right) with respect to task stages and navigation strategies. *P < 0.001 Sidak’s multiple comparisons test after two-way ANOVA. For all box plots, the middle, bottom, and top lines correspond to the median, lower, and upper quartiles, and the edges of the lower and upper whiskers correspond to the 5th and 95th percentiles.