Ready for motherhood. Chemosensory, socio-sexual and motivational brain networks adjust their activity during pregnancy

Résumé

Maternal behaviour is instinctively induced by pups during late gestation and postpartum, when hormonal changes elicit increased motivation towards offspring and aggressiveness towards potentially infanticidal intruders. In this thesis, we study the possible role of pup odours/pheromones in the attraction they cause in dams. To do so, we analyse the brain activation induced by pups and by non-social control objects (buttons), and the changes that occurred in this activation at the end of pregnancy. We focus on the chemosensory systems (olfactory and vomeronasal) including the vomeronasal organ, demonstrating changes in sensory processing during motherhood. We also analyse the activity patterns in the circuits of social behaviour (socio-sexual brain network) and those of motivation. The results indicate that gestation increases motivation towards pups and decreases motivation towards non-social objects (buttons).