CR maintains synaptic plasticity and memory. A, Preservation of long-term potentiation by CR. fEPSPs (expressed in percentage of maximal amplitude) in hippocampal area CA1 of CON,AL, CK-p25,AL and CK-p25,CR animals (n = 3–4 slices from 3–4 mice each) before and after TBS. *p ≤ 0.05 by ANOVA for the effect of treatment. Sample traces above the line chart represent fEPSPs at 1 min before (black) and 1 h after (colored) TBS. B, Input–output relationship of comparable baseline synaptic transmission between CON,AL, CK-p25,AL, and CK-p25,CR animals. C, Cued fear conditioning. Left, Freezing responses before the onset of the tone were comparable between CON,AL, CK-p25,AL and CK-p25,CR animals 24 h after training. Right, Freezing responses after the onset of the tone show comparable memory retention between CON,AL and CK-p25,CR animals, but reduced memory for CK-p25,AL mice. One-way ANOVA (F_(2,30) = 6.29, p ≤ 0.01) followed by Tukey's post hoc tests; n = 10–12 mice each. D, Contextual fear conditioning. Freezing responses 24 h after training on a contextual fear conditioning task show comparable memory retention between CON,AL and CK-p25,CR animals, but reduced memory for CK-p25,AL mice [one-way ANOVA (F_(2,30) = 7.52, p ≤ 0.01) followed by Tukey's post hoc tests; n = 10–13 mice each]. E, Novel object recognition. Discrimination ratio 24 h after training revealing a significantly enhanced object memory in CK-p25,CR compared to CK-p25,AL animals [one-way ANOVA (F_(2,19) = 7.16, p ≤ 0.01) followed by Tukey's post hoc tests; n = 7–8 mice each]. *p ≤ 0.05; **p ≤ 0.01 for Tukey's post hoc comparisons. All values are mean ± SEM.