Figure 3.
Impaired spatial learning of GluN1Rneo/+ mice. (A,B) GluN1Rneo/+ (n = 12) and wild-type GluN1+/+ littermates (n = 13) were trained to a fixed hidden platform position in a watermaze for seven consecutive days (acquisition, four trials a day), followed by 6 d, to a platform position in the opposite pool quadrant (reversal, after 21-d interval). (B) Identical escape latencies for both genotypes at the beginning of the experiment, as shown by the results from individual trials on training day 1. (C) (○) Wild-type GluN1+/+, (n = 13) and (●) GluN1Rneo/+ mice, (n = 12) were trained for 6 d with four trials per day to locate the platform marked by a local visual cue, prior to the training for the hidden platform. The two groups performed equivalently well at day 1 (ANOVA, P > 0.65), and by training day 6 (ANOVA, P > 0.33). The differences between the groups during days 2–5 (ANOVA, P = 0.0007, 0.005, 0.01, and 0.0002, respectively) suggest that the mutants were slower learners than their wild-type littermates during this period, but this difference was insignificant by the end of the task. (D,E) Probe tests (PT1 and PT2) were performed (without platform) after training days 7 and 13, respectively. GluN1+/+ mice spent more time in the TQ than GluN1Rneo/+ mice. (F) Representative swim paths from PT1. (TQ) Training quadrant; (AL) adjacent left; (OQ) opposite; (AR) adjacent right; (+) start of swim path; (●) training position of platform.