Supplementary Figure 6: dmPFC local theta resetting and 4-Hz oscillations are independent phenomena.

(a, b) Averaged raw (a) and Z-score normalized (b) LFP spectrogram in the 2-12 Hz frequency band around CS⁺ pip presentations during freezing episodes. CS⁺-associated theta was observed as a single burst occurring right after CS⁺ and spanning ~300 ms with frequency between 8 and 12 Hz (b). On the contrary 4 Hz oscillation was present throughout the triggered spectrogram, due to the co-occurring freezing behaviour and was not modulated by CS⁺ presentation (a). (c) Overlaid dmPFC local theta and 4 Hz phases of CS⁺-triggered LFP traces from a representative animal, illustrating theta but not 4 Hz phase resetting induced by CS⁺ pip presentations during freezing episodes. (d) LFP phase spectrogram in the 2-12 Hz frequency band around CS⁺ pip presentations from the same animal as in (c) revealing a sharp and stable versus a broad and unstable CS⁺-evoked phase for local theta and 4 Hz oscillations, respectively. (e) Color coded mean resultant length (MRL) of phases across animal for each time-frequency bin in the 2-12 Hz frequency band around CS⁺ pip presentations during freezing episodes (n = 13 mice). A low MRL value indicates an unstable phase (no modulation nor resetting of 4 Hz oscillations) whereas a high MRL value relates to a consistent phase (8-12 Hz theta burst and resetting). (f) Mean MRL for dmPFC 4 Hz (blue line) and 8- 12 Hz theta (red line) revealing the changes in phase stability triggered by CS⁺ pip presentations during freezing episodes (n = 13 mice). Inset: Averaged MRL after (0 to 300 ms) CS⁺ pip onset (n = 13 mice, 12 CS⁺, paired t-test, 4 Hz versus Theta: t(12) = 4.417, *** P < 0.001). Shaded area and error bars: mean ± s.e.m. Spectral power in log scale. For the representative examples in (c), similar results were obtained for the 13 animals used in these experiments.