Theta Rhythms Coordinate Hippocampal–Prefrontal Interactions in a Spatial Memory Task
Figure 7
CA1–mPFC LFP Coherence Showed a Significant Peak in the Theta-Frequency Range and Was Enhanced during Choice Epochs
(A) Raw LFP from dorsal CA1 (black) and mPFC (blue) during consecutive single central-arm crossings in the choice (left) and forced-turn (right) directions. Thick lines show theta-filtered LFP. Horizontal scale bar 0.5 s; vertical scale bar 0.8 mV. Red lines highlight the timing relationship between CA1 and mPFC theta peaks (red circles). Numbers above raw LFP traces give coherence in the 4- to 12-Hz range during these two example trials.
(B) Trial-averaged, central-arm coherence during a single run-session (17 trials). Central-arm coherence is subdivided into forced-turn (grey) and choice (red) directions. Dashed line marks 95% confidence level, with shaded band thickness corresponding to jackknife error bars (estimated over trials and nine tapers). Significant coherence was seen only in the theta-frequency range, and only during choice epochs on the central arm.
(C) Mean coherence at delta (1–4 Hz) and theta (4–12 Hz) frequencies, pooled across animals during forced-turn (grey), choice-correct (red), and choice-error (hatched red) epochs (* p < 0.05). Like theta CA1–mPFC spike cross-correlations and theta phase-locking of mPFC units, theta-frequency CA1–mPFC LFP coherence peaked during choice-direction runs across the central arm.