Spatial learning correlates with hippocampal expression of NR2B: training trials. A, Spatial learning, as assessed by three trials per day for 10 d in a Morris water maze hidden platform paradigm, reveals a significant age-related deficit in cumulative distance from platform (number of animals: aged,n = 8 at 16 months, 24 at 22 months, and 8 at 23 months; young, n = 14 at 6 months;p = 0.003 by repeated measures ANOVA). Distance units shown are in a linear, calibrated arbitrary tracking unit.B, Regression analysis between performance in the Morris Water maze on days 3 and 4 and expression of the NR2B subunit reveals a significant association across animals in all age groups (p = 0.0003;R2 = 0.23). Distance units shown are in a linear, calibrated arbitrary tracking unit.C, Regression analysis between performance in the Morris Water maze on days 3 and 4 and expression of the NR2B subunit reveals a significant association across animals in the aged group (16, 22, and 23 months; p = 0.005;R2 = 0.20). Distance units shown are in a linear, calibrated arbitrary tracking unit.
