Fig. 1.

Monoamine oxidase (MAO)A knockout (KO) and MAOA/B KO mice display social and communication impairments. (a) Schematic diagram of the social interaction paradigm. (b, c) MAOA- and MAOA/B-deficient mice exhibit a significant reduction in social approaches and reciprocal interactions towards the foreign conspecifics compared to wild-type (WT) mice. (d–i) MAO mutant genotypes also displayed a marked decrease in overall sniffing behaviour in both number and duration in comparison to their WT counterparts. While this decrease was most pronounced in anogenital sniffing, MAOA/B-deficient mice also spent significantly less time in frontal sniffing than WT animals. (j–l) In the social investigation paradigm, both MAO mutant genotypes displayed a significant decrease in number and duration of social approaches. (m–p) Maternal separation-induced ultrasonic vocalizations (USVs) were markedly lower in MAOA KO and MAOA/B KO pups than WT pups. Values are displayed as means±S.E.M. *p<0.05, **p<0.01 and ***p<0.001 compared to WT mice. For social interactions n=7–10; social investigation n=8–10; maternal separation-induced USVs n=13–20.