LI in the conditioned freezing paradigm. (A), Expression of freezing behavior toward the tone-CS across the three conditioning trials immediately after pre-exposure. The amount of freezing was significantly reduced (p<0.05) in pre-exposed (PE) relative to non-pre-exposed (nPE) animals reflecting the LI effect. (B), Freezing to the context 24h after conditioning expressed as a function of 1 min bins on the left and as the overall means on the right. (C), Freezing to the tone CS 48h after conditioning. Freezing in the PE subjects tended to be lower than in the nPE subjects, which was more pronounced in the beginning of the CS-phase, which was equally seen in mutants and controls. This impression was confirmed by the appearance of a significant pre-exposure by bins interaction (p<0.05) in a 2 × 10 (pre-exposure × 1-min bins) ANOVA of the percent freezing. The histogram on the right illustrates the mean levels of freezing averaged across the entire 480s CS period. All values refer to mean ± standard error of the mean (SEM).