Supplementary Figure 5: Reversible inactivation of the medial septum does not block dmPFC 4-Hz oscillations.

(a, b) Experimental strategy and location of injections sites in the medial septum (MS) and composite transmission light and epifluorescence micrograph showing the MS targeted injection of muscimol covalently bound to a fluorescent tag (bottom, dipyrromethene boron difluoride (BODIPY), red). (c) Power spectra of dmPFC LFPs before (Day 2: Test 1), following (Day 3: Inact.) and after (Day 4: Test 2) MS inactivation (n = 6). (d) Top, Quantification of dmPFC LFP 4 Hz power (2-6 Hz) before, during, and after MS inactivation. (n = 6 mice, One-way repeated measure ANOVA: F_(2,5) = 2.167, P = 0.165. Bottom, Quantification of dmPFC LFP theta power (6-12 Hz) before, during, and after MS inactivation. MS inactivation significantly reduced dmPFC theta power (n = 6 mice, One-way repeated measure ANOVA: F_(2,5) = 19.245, P < 0.001, paired t-test Bonferroni corrected, Test 1 versus Inact.: t(5) = 6.155, *** P < 0.001; Inac. versus Test 2: t(5) = 4.173, ** P = 0.006). (e) Representative spectrograms of dmPFC LFPs before (Test 1), during (Inactivation) and after (Test 2) MS inactivation (red tick represents single CS⁺ pips). White lines on the spectrogram indicate immobility/freezing episodes. (f) Percentage of dmPFC neurons phase-locked to 4 Hz (top), or theta (bottom) oscillations (6-12 Hz). (Test 1: n = 80 neurons; Inact.: n = 100 neurons; Test 2: n = 120 neurons. 4 Hz: One-way repeated measure ANOVA: F_(2,5) = 1.245, P = 0.329; theta: One-way repeated measure ANOVA: F_(2,5) = 9.858, P = 0.004, Bonferroni corrected t-tests; Test1 versus Inactivation: t(5) = 2.956, P = 0.043; Inactivation versus Test 2: t(5) = 4.347, P = 0.004). a.u.: arbitrary units. Shaded areas and error bars: mean ± s.e.m. For the representative examples in (a, e), similar results were obtained for the 6 animals used in these experiments.