Abnormal social behavior of M
R KO mice. (A) No significant difference in total duration of contacts was detected between genotypes. (B) The number of contacts was slightly but not significantly increased in M4R KO mice. (C) M4R KO mice displayed a significant decrease in the mean duration of each contact compared to wild-type mice. (D) The distance traveled by M4R KO mice was significantly increased compared to that of wild-type mice. (E) Scatter plot of distance traveled against mean duration per contact. M4R KO mice, n = 14 pairs; wild-type mice, n = 14 pairs.