Synchronous hippocampal and thalamic theta oscillations. A, Color-coded 3 s power spectrograms, representing simultaneous recording of LFP from hippocampal area CA3 (left panels), anteroventral theta (middle panels), and anteroventral nontheta (right panels) signal. The black dashed line indicates the frequency level of 8 Hz. B, Coherence plot between hippocampal LFP and anteroventral theta (red trace) and nontheta (gray trace) LFP (mean ± SEM). C, Sample LFP traces for the simultaneously recorded hippocampal (black), anteroventral theta (red), and anteroventral nontheta (gray) LFPs. D, Cross-correlation between hippocampal and anteroventral theta (top, red trace) and nontheta (bottom, gray trace) signal (mean ± SEM). Time lag 0 is denoted by the dashed vertical line. E, Phase plots between hippocampal LFP and anteroventral theta (top) and nontheta (bottom) LFP (mean ± SEM).