Neural circuit remodelling by pregnancy and social experience

Social behaviour is shaped by internal states and experience. Both processes can produce similar behavioural changes, but it remains unclear whether they act on the same neural circuits and via similar plasticity mechanisms. We propose to use parental behaviour in mice as a paradigm to address this fundamental question. Female mice can become highly parental via two distinct routes: hormone-mediated remodelling of the brain during pregnancy, and sensitisation through repeated exposure to pups. We have recently shown that pregnancy hormones act on specific hypothalamic neurons to enhance parental performance, but little is known about how sensitisation affects parenting circuits. This proposed programme will therefore investigate whether pregnancy hormones and social experience promote parenting via shared neural mechanisms. We will (1) characterise how pregnancy and sensitisation affect pup-directed behaviour, identify the sensory cues critical for sensitisation, and determine which brain areas are affected by both processes; (2) uncover the neural plasticity mechanisms through which pregnancy and sensitisation enhance parental performance; and (3) determine which forms of plasticity are critical for the highly parental states induced by pregnancy and sensitisation. This programme will reveal how hormones and experience remodel neural circuits to produce equivalent behavioural outcomes.