Fig. 3. Emotional memory is impaired during aging in both SynI^–/– and SynII^–/– mice. Conditioned fear displayed by WT, SynI^–/– and SynII^–/– mice was evaluated in young (A), adult (B) and aged (C) mice (eight to ten mice per group). The test session was carried out 24 hours after conditioning and the percentage of time spent freezing is shown as means ± s.e.m. Statistical analysis was carried out by using the one-way ANOVA followed by the Bonferroni's multiple comparison test. Contextual test: F(2,27)_Young = 1.33, not significant; F(2,33)_Adult = 15.53, P<0.001; F(2,26)_Aged = 12.29, P<0.001. Cued test: F(2,27)_Young = 0.24, not significant; F(2,33)_Adult = 6.44, P<0.005; F(2,26)_Aged = 44.22, P<0.001. Bonferroni's multiple comparison test vs WT: ^*P<0.05; ^**P<0.01; ^***P<0.001.