Fig. 3: Encoding-recruited acute and repeated cocaine ensembles are reactivated during the retrieval of cocaine-context associative memories.

a Experimental design for CPP ensemble tagging in Arc-CreER^T2::Ai14 mice. 4-OHT 4-Hydroxytamoxifen, 1 P 1 Pairing, 5 P 5 Pairings. b Time spent in the paired vs unpaired chamber (left) and CPP score (right). n = 7, weak; n = 6, strong. Left: Two-way RM-ANOVA: interaction conditioning x session F_1,24 = 6.23, *p = 0.0199; main effect of conditioning F_1,24 = 4.89, *p = 0.0368; main effect of session F_1,24 = 9.05, **p = 0.0061; followed by Šidák post-hoc tests. Right: Two-tailed unpaired t-test: t₁₂ = 2.791 *p = 0.0163. c Representative images of cells activated during conditioning (Tom+ , red), test (ARC+ , green) or both (arrows indicated). Scalebar, 50 µM. d Reactivation ratio (as “Recall”, over total number of Tom+ cells). n = 4, 1 P/homecage; n = 5, 5 P/homecage; n = 8, 1 P/test; n = 10, 5 P/test. Two-way ANOVA: interaction conditioning x test, F_1,19 = 3.559, p = 0.0746; main effect of conditioning, F_1,19 = 8.783, **p = 0.008; main effect of test, F_1,19 = 104.9, ***p < 0.0001; followed by Šidák post-hoc tests. e Chance-adjusted probabilities of cell activation during both conditioning (Tom+ , red) and test (ARC+ , green). n = 8595 cells in n = 4 mice, 1 P/homecage; n = 16538 cells in n = 7 mice, 1 P/test; n = 9951 cells in n = 5 mice, 5 P/homecage; n = 16130 cells in n = 7 mice, 5 P/test. Baseline-Category Logit Mixed Model (BCLogMM), equation for Tom+/ARC+ counts: interaction conditioning x test, z = −2.093, *p = 0.0363; main effect of conditioning, z = −1.002, p = 0.3163; main effect of test, z = 8.984, ***p < 0.0001; followed by Šidák post-hoc tests. f Correlation between the reactivation ratio and CPP score. 1-pairing (left): n = 7; Pearson’s r = 0.8926, **p = 0.0068. 5-pairing (right): n = 7, Pearson’s r = − 0.8912, **p = 0.0071. Bar graphs are expressed as mean ± SEM. Regression lines and probability estimates are shown with their 95% confidence interval. Source data are provided as a Source Data File. Created in BioRender. Parise, E. (2025) https://BioRender.com/voi7l54.