PFC activity is coordinated with hippocampal isolated activity.

(A) Schematic illustrating potential CA1 and PFC activity around the time of isolated spiking. Changes in PFC spiking around the time of CA1 isolated spiking may reflect coordination between the 2 regions. (B) Example spike raster and spiking rate (mean ± SEM) for pairs of co-recorded hippocampus CA1 and PFC cells. Each raster shows spiking aligned to isolated hippocampal activity (cycle 0) and matched control trials. Spiking is plotted relative to the cycles of the hippocampal theta rhythm. For CA1 cells, red indicates spikes and spiking rate for intervals with isolated spiking at cycle 0. Black indicates control intervals without isolated spiking at cycle 0. For PFC cells, purple indicates spikes and spiking rate for intervals with isolated spiking at cycle 0. Black indicates control intervals without isolated spiking at cycle 0. (C) Violin plots and quantification of spike rate differences between control and actual intervals for PFC–CA1 cell pairs (n = 2,798) in time windows relative to CA1 isolated activity. Rate difference, original data (black) and permuted (gray), is expressed the z-score of the absolute observed difference relative to its own permuted distribution. The Wilcoxon signed rank test (*** p < 0.001) was used to compare the original and permuted groups: p = 4.7 × 10⁻⁸, 3.6 × 10⁻¹², and 2.2 × 10⁻¹⁰ for each group, respectively. (D) Violin plots and quantification of spike rate differences between control and actual intervals for PFC–CA1 cell pairs (n = 2,892) in time windows post CA1 isolated activity. The Wilcoxon signed rank test (*** p < 0.001, ** p < 0.01) was used to compare the original and permuted groups: p = 9.5 × 10⁻⁷, 1.8 × 10⁻³, and 2.1 × 10⁻³ for each group, respectively. PFC, prefrontal cortex.