Severely impaired fear memory and mild deficits in the spatial working memory in Grin1Rgsc174/Grin1+mice. (A) There were no significant differences between the genotypes in the percentage of time freezing during conditioning in the contextual and cued fear conditioning tests. Grin1Rgsc174/Grin1+ mice displayed a decreased percentage of time freezing in the contextual (B) and cued tests (C) compared to wild-type mice. Grin1Rgsc174/Grin1+ mice showed an increase in distance traveled immediately after footshock 1, but not after footshocks 2 or 3 in the training phase (D). In the eight-arm radial maze, there was no significant difference between Grin1Rgsc174/Grin1+ and wild-type mice in the number of revisiting errors (E), different arm choices (F), or latency (G) in the first eight entries during the test session without delay (1–19 blocks). No significant difference between the genotypes was detected in the number of revisiting errors (H), or latency (J) in the later session (20–22 blocks) with delays (30, 120, and 300 sec). The mutant mice showed a significantly lower number of different arm choices during the first eight entries in the trials with delay (I). The p values indicate the genotype effect in two-way repeated measures ANOVA.