2.6.1. Open field test

Data from the above locomotor test were used to analyze anxiety‐like behavior as part of the OFT. The arena was divided into a center area (25% of arena) and four equal squared corners (combined, 25% of arena) (Figure 2a). The time spent in the center was calculated using the software PAS764 provided by SD Instruments. Less time spent in the center was taken to represent anxiety/fear‐related behavior.

The effect of NMDAR antagonists on locomotion in WT and GluN2D‐KO mice. (a) Schematic overview of the paradigm. Locomotor activity without drug during the first 1 h (b), and locomotor activity over 2 h following drug challenge (c–g). Average distance traveled (c) and distance traveled over time with either saline (d; n = 9 F WT, 9 F KO, 9 M WT, 10 M KO), R‐norket (e; n = 10 F WT, 10 F KO, 10 M WT, 9 M KO), S‐ket (f; 9 F WT, 9 F KO, 10 M WT, 10 M KO), or PCP (g; 9 F WT, 10 F KO, 10 M WT, 11 M KO). Further measures of ataxia (h), stereotypy (i), and catalepsy (j) were assessed in a separate cohort (n = 10 F WT, 8 F KO, 12 M WT, 12 M KO). All data presented as mean ± SEM. When a two‐way ANOVA showed a significant interaction, p‐values were calculated with the Sidak's multiple comparison test (b, c), Fisher's LSD test (d–f, g: females), Tukey's multiple comparison test (g: males, h–j); *p < .05, **p < .01, ***p < .001, ****p < .0001.