Fig. 3

Dlg2^–/– mice display decreased social approach but normal social novelty recognition. a Both WT and Dlg2^–/– mice spent more time sniffing an age-matched stranger mouse (S) than a novel object (O). b The preference index (S-O) of Dlg2^–/– mice, which was calculated for group comparisons as %[(time spent in sniffing S − time spent in O)/total time spent (S + O) × 100], was significantly decreased compared to that of WT. n = 22 mice per genotype. c, d There was no difference between groups in the social novelty test, as shown by the time spent sniffing a novel stranger mouse (S2) and a familiar mouse (S1). The preference index for the S1-S2 phase was not significantly different between groups. n = 22 mice per genotype. eDlg2^–/– mice tended to spend less time interacting with an age-matched stranger (WT, 129/SvJae) than with WT mice in the test arena, where mice were allowed to freely explore and interact each other. WT, n = 5; Dlg2^–/–, n = 6. Wilcoxon matched-pairs signed rank tests were used for a and c. Mann-Whitney tests were used for b, d, and e. *p < 0.05; **p < 0.01; ****p < 0.0001; ns, not significant