2.1. Mice and housing

C57BL/6N mice were bred in house and maintained on a 12 h:12 h light cycle (lights on at 7AM) with ad libitum access to food and water. Mice were housed in 31 × 12 × 14 cm cages with cob bedding and 4 × 4 cm cotton nestlet. Litters were composed of both male and female pups and ranged from 4 to 8 pups per litter. A total of 16 litters were used for the maternal behavior recordings (control:6, LBN:5, MS:5) and a total of 23 separate litters were used for brain extraction at either PD8, PD16 or PD21 (control:8, LBN: 7, MS, 8). Virgin dams were not used for the current studies. Pups were weaned and sex segregated at postnatal day (PD) 21. All animal procedures were approved by the Brown University Institutional Animal Care and Use Committee and consistent with the guide for the care and use of animals in research.