Figure 1

Social Novelty Recognition is Impaired in SRKO mice. (A) Freely behaving SRKO mice (n = 5) and WT littermates (n = 8) were tethered and placed in a three-chamber arena for a five minute habituation, a ten minute sociability stage (novel mouse “1” vs object), and a ten minute social novelty stage (novel mouse “2” vs familiar mouse “1”, see Materials and Methods for detail). During the sociability stage, both WT (white bars) and SRKO mice (black bars) spent a larger percent of time in the chamber containing the novel mouse than the chamber with the novel object (B) suggesting the sociability of SRKO mice is unchanged. There were no between-group differences during the sociability stage for either time spent exploring either chamber (B), number of entries within a 5 cm zone surrounding the novel mouse or object (C), or in the novel mouse/object ratio of these measurements (D), indicating WT and SRKO mice behaved similarly during this phase of the task. During the social recognition stage only WT mice spent more time investigating the novel mouse than the familiar mouse, measured by the percent time in each chamber (E, strong trend) and the number of entries within a 5 cm zone (F). There were significant between-group differences in the novel/familiar mouse ratio for both measurements (G), suggesting that WT animals spent a greater proportion of time investigating novel animals than familiar animals when compared to their SRKO littermates. This suggests SRKO mice demonstrate decreased social novelty recognition or impaired social novelty-related exploration. Stars represent a significant main effect (B) or a significant Holm–Sidak post hoc test following a significant interaction (F) in a two-way ANOVA. Stars in G represent a significant Mann–Whitney U test. In all figures, bar graphs represent mean values ± standard error of the mean (see Supplementary Materials B1 for these values) while boxplots represent the median and 25th–75th percentiles with whiskers that represent minimum and maximum values. Individual values are represented in D and G by hollow squares and triangles. For all experiments the number of stars represents the level of significance (*p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001).