Figure 6.

Both juvenile and adolescent MAM animals exhibit learning deficits in the Morris Water Maze. (a₁ and b₁) Summary line graphs show the average latencies (s) to the escape platform across training on the Morris Water Maze for juvenile (a₁) and adolescent (b₁) saline and MAM animals. Training began on P17 for juveniles and P40 for adolescents. (a₁) Juveniles exhibited learning deficits with a significant effect of day (F=9.49, p=0.001), treatment (F=20.04, p=0.002), and an interaction (F=2.73, p=0.034) by repeated measures ANOVA (n=11 for each group). Post-hoc analysis revealed a significant difference in escape latencies on training days 3, 4, and 5 between saline and MAM animals (*p<0.05). (b₁) Although adolescent MAM animals learned the task better than juvenile MAM animals, they still exhibited certain level of learning deficits, with a significant effect of treatment ANOVA (F=23.1, p=0.02) and an effect of day (F=24.2, p=0.0001), but no interaction (F=1.52, p=0.56) by repeated measures ANOVA (n=7 for each group). Post-hoc analysis revealed a significant difference in escape latencies on training days 2, 3, and 5 for MAM animals compared with saline (*p<0.05). (a₂ and b₂) Summary histograms show the time spent in searching the target quadrant during a probe trial for juvenile (a₂) and adolescent (b₂) animals, respectively. (a₂) During a probe trial conducted post-training, juvenile MAM-exposed animals spent significantly less time swimming in the previous target quadrant, indicating low memory for the previous platform location (p=0.01, n=11). (b₂) In contrast, there was not a significant difference in the amount of time adolescent MAM animals spent swimming in the target quadrant compared to saline animals (p=0.41, n=7). This indicates that adolescent MAM animals have a memory for the previous platform location.