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. 2009 Feb 4;29(5):1496–1502. doi: 10.1523/JNEUROSCI.5057-08.2009

Figure 5.

Figure 5.

Effect of enrichment on contextual conditioning memory. a, ras-grf1/2 double knock-out mice have defective contextual conditioning memory. One-month-old wild-type mice (□) (n = 17) and ras-grf1/2 double knock-out mice (■) (n = 15) (F0) were subjected to one-trial paradigm training. There was no significant difference in baseline freezing before footshock (pre) or immediately after (post). A retention test was performed 24 h after training. The data represent the average and SEM from the indicated number of samples. The freezing response in ras-grf1/2 double knock-out mice was significantly lower than that in wild-type mice (p < 0.05, Mann–Whitney U test). b, Enrichment rescues deficient contextual conditioning memory in ras-grf1/2 double knock-out mice. One-month-old naive ras-grf1/2 double knock-out mice control (□) (n = 12) and enriched ras-grf1/2 double knock-out mice (■) (n = 12) were subjected to one-trial paradigm training as described in a. The freezing response in enriched ras-grf1/2 double knock-out mice was significantly higher than that in naive ras-grf1/2 double knock-out mice (p < 0.05, Mann–Whitney U test). c, Defective contextual conditioning memory is partially rescued in 1-month-old offspring of enriched juvenile ras-grf1/2 double knock-out mice. One-month-old offspring from two litters of either naive ras-grf1/2 double knock-out mice (□) (n = 15) or enriched ras-grf1/2 double knock-out mice (■) (n = 16) were subjected to one-trial paradigm training as in a. The freezing response in the offspring of enriched ras-grf1/2 double knock-out mice was significantly higher than that in naive ras-grf1/2 double knock-out mice (p < 0.05, Mann–Whitney U test). d, Defective contextual fear memory is not rescued in 3-month-old F1 offspring of enriched juvenile ras-grf1/2 knock-out mice. Experiments were performed as in a except that offspring of enriched knock-out mice were reared in a standard environment for 3 months before being tested for fear conditioning response (control, n = 12) (EE, n = 15). e, Defective contextual conditioning memory is not rescued in the F2 offspring of enriched juvenile ras-grf1/2 knock-out mice. Experiments were performed as in a except that 1-month-old F2 offspring of enriched knock-out mice were used (control, n = 11) (EE, n = 13).