Theta Rhythms Coordinate Hippocampal–Prefrontal Interactions in a Spatial Memory Task
(A) Mean running speeds, CA1 firing rates, and mPFC firing rates were comparable during forced-turn (grey, epoch 5), choice-correct (red, epoch 2), and choice-error runs (hatched red) across the central arm.
(B) Example cross-correlogram (bin size 10 ms, maximum time lag ± 1,000 ms) for a single CA1–mPFC neuron pair (referenced to the CA1 firing at time 0), showing that correlated activity was higher during choice runs (red) than forced-turn runs (grey). The width of the central peak at 50% of its maximum value is 120 ms. This compares with a mean peak width of 156 ± 41 ms for 29 neuron pairs with peak cross-correlation coefficients (bin size 10 ms) of at least 0.0005. For comparison across task epochs, peak cross-correlation coefficients were quantified at the ± 200-ms time range with a bin size of 100 ms (inset to the right).
(C) Mean correlations for all neuron pairs that fired at least 50 spikes each during the three run types. CA1–mPFC correlation coefficients were significantly higher during choice runs (72 pairs) than during forced-turn (72) or error runs (49 pairs; ** p < 0.01, * p < 0.05 Wilcoxon rank sum test for grouped animal means).