Schematic time line of the procedure for the acquisition and retrieval of object location memory (OLM). The data show the effect of contextual novelty after weak encoding on long-term memory (LTM) sessions. In the training session, aged rats were allowed to freely explore the sample objects (A and B) for 5 min (weak training [WT]), and the mean discrimination index (DI) and recognition index (RI) of the sample objects were evaluated in rats of the WT groups or in rats subjected to contextual novelty 30 min after weak training (WT + novelty; n = 7 per group). The DI (A) and RI (B) of the moved and sample objects were evaluated for 5 min in the object location memory testing (OLM) 24 h after training (LTM)) in rats of the WT or WT + novelty (n = 7 per group) groups. All individual values are shown. The values are presented as the means (±SEMs). Lines represent the chance value for the DI (0.0) and RI (0.5). Intragroup comparisons (testing vs. training sessions) used a paired t-test. Comparisons between the ratio discriminations from the group above chance level used one-sample t-tests. There was no difference between any experimental group (for details, see Table 1).
