Fig. 4: CA3 NRs-dependent reverberation by single stimuli in the hippocampal network under head-fixed conditions.

a Left, experimental design. Right, schema for head-fixed imaging. The same footshock grid and light bulb were used in free-moving and head-fixed imaging experiments. b Imaging data analysis scheme. In each cell, Ca2⁺ data are classified into four sessions, and the calculated mean z-score, considered to represent responsiveness, is sorted into CS- and US-responsive subpopulations. c-f Left, peri-event raster plots during single (c) CS presentation session in CA1 (two-tailed unpaired Wilcoxon rank sum test for CA1 CS cells: CS, P = 0.019; ITI-1, P = 0.013; ITI-2, P = 0.00001), (d) US presentation session in CA1, (e) CS presentation session in CA3 (two-tailed unpaired Wilcoxon rank sum test for CA3 CS cells: ITI-1, P = 0.00003; ITI-2, P = 0.021), and (f) US presentation session in CA3 of (left) control and (right) KO mice (two-tailed unpaired Wilcoxon rank sum test for CA3 US cells: ITI-2, P = 0.0003). Each short vertical tick represents a 1 s change of mean z-score across baseline, and CS or US presentations. Ca2⁺ activities are aligned at the time at which stimuli were delivered. The color code indicates mean z-score. Middle, averaged z-score plots over ten CS or US presentations. Right, box plots comparing mean z-scores between genotypes in each session. Numbers in parentheses denote the number of cells in each group used for the study. Data were acquired from Ctrl (n = 2 mice) and KO (n = 2 mice) groups for CA1 imaging, and from Ctrl (n = 4 mice) and KO (n = 2 mice) groups for CA3 imaging. P values were determined using (c-f) a two-tailed Wilcoxon rank sum test (*P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001). N.S., not significant (P > 0.05). Box plots represent the median, first, and third quantiles, and minimum and maximum values. Graphs represent means ± SEM. Detailed statistics are shown in Supplementary Data 1.