Figure 4.

Impairments in exploratory behavior and social memory in Pja1 ^KO/Y mice. (A–C) Open‐field task. Pja1 ^KO/Y mice travelled slightly yet significantly shorter distances than their WT littermates (A) and spent significantly more time in the central area (B) suggesting a decrease in anxiety‐like behavior. The number of rearing was significantly decreased in the Pja1 ^KO/Y group (C). (D–F) 3‐chambers task. While no preference for a specific side was seen in the habituation period (D), mice from both groups spent significantly more time investigating the stranger’s side (Str) than the empty side (Em) during the sociability phase of the task (E). In the preference for social novelty phase, whereas WT mice significantly spent more time on the stranger mouse (Str) than the familiar one (Fam), this discrimination did not reach the significance level in Pja1 ^KO/Y mice (F). (G) In the tube test, the wining rate of Pja1 ^KO/Y opposed to their WT littermates did not differ significantly from the 50% random outcome. (H–L) Barnes maze task. Spatial learning was conserved in Pja1 ^KO/Y mice as they showed a similar latency (H), distance travelled (I), and number of errors (J) to reach the target hole during the primary learning (training T1 to T4) as well as the reverse learning periods (R1 to R4). In the probe test (K) as well as in the reverse probe test (L), the performance of Pja1 ^KO/Y mice was not significantly different from that of their WT littermates. Ta.: target hole; Op.: Opposite side hole. Values in (A–C) and (H–L) are expressed as mean ± standard error of the mean. Two‐way ANOVA (A–C, H–L), Chi‐square test (G) or one‐way ANOVA (D–F) with significance set at (*) P < 0.05 and (***) P < 0.001.