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Authors & Affiliations
Kaya Melissa Baumert, Charlotte Burns, Silvana Valtcheva
Abstract
Naturalistic behaviors in mammals are triggered by specific sensory cues and strongly influenced by internal states such as hormonal levels. Infant-oriented motor actions in maternal mice are enabled by sensory stimuli from the pups (such as vocalizations, somatic touch). Some maternal behaviors, like nursing and searching for isolated pups outside of the nest, further depend on the release of the hypothalamic neurohormone oxytocin (Menon & Neumann, 2023). However, pup stimuli are often aversive to virgin females (Lecca et al., 2023; Schiavo et al., 2020), who also exhibit different patterns of motor behavior transitions compared to mothers (Ammari et al., 2023), and fail to activate the virgin oxytocin system (Valtcheva et al., 2023; Carcea et al., 2021). What experience-dependent changes in the postpartum hypothalamus contribute to the integration of sensory cues from the offspring to enable infant-oriented behaviors in new mothers remains unexplored. Here, we investigate the synaptic and circuit mechanisms underlying the sensory-hormonal coupling in the maternal hypothalamus necessary for infant-directed maternal motor actions. We specifically tested experience-dependent synaptic plasticity at different sensory inputs (auditory and somatosensory) to hypothalamic oxytocin neurons in virgin and maternal mice to define the molecular and synaptic underpinnings which actively participate in refining maternal sensitivity to infant stimuli during the postpartum period. We combine in vitro whole-cell recordings coupled with optogenetic activation of different synaptic inputs in transgenic mice, viral tracing approaches and immunohistochemistry to study this.