Early Social Enrichment Improves Social Motivation and Skills in a Monogenic Mouse Model of Autism, the Oprm1^−/− Mouse

Figure 4

Mean time (+SEM) spent by female (a) and male (b) mice in social investigation of a younger same sex/genotype/standard reared intruder mouse during 5 consecutive 1 min social interaction sessions (line graph). The same intruder was used during the first 4 sessions, while an unknown one (same characteristics) was introduced in the fifth session. Histograms represent the total amount of investigation shown during the five sessions by different experimental groups. : 8–15 per group. µ-KO-L: Oprm1^−/− pups reared by their mother [10 males + 15 females]; µ-KO-L+L: Oprm1^−/− pups reared by their mother plus a second lactating female [9 males + 11 females]; WT-L: Oprm1^+/+ pups reared by their mother [10 males + 15 females]; WT-L+L: Oprm1^+/+ pups reared by their mother plus a second lactating female [8 males + 11 females]. Genotype difference: ; rearing condition difference: ^⁎; recognition of new partner (session 4 versus 5 and paired -test): (µ-KO-L and WT-L females) and (µ-KO-L+L males and females).

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