Research Group Leader - Faculty of Medicine
The Valtcheva laboratory is interested in the neurohormonal adaptations during the postpartum period. Dr. Valtcheva and her research group investigate the neural pathways and synaptic mechanisms involved in relaying sensory cues from the offspring in the postpartum brain, and the functional consequences for maternal physiology and behavior.
Our research: Becoming a mother is a developmental milestone which can lead to life-long transformations in female physiology. The postpartum period is among the most critical stages in adulthood, where many functions adapt to maintain lactation and infant care. This is characterized by changes in hormonal release, and heightened sensitivity to different sensory cues from the offspring.
Our lab investigates the synaptic and circuit mechanisms during the postpartum period which gate reactivity to cues from the newborn and promote hormonal release and maternal behaviors in mice. An important player in maternal physiology is the neurohormone oxytocin. Release of oxytocin from the hypothalamus occurs during nursing but can also be triggered by other offspring signals (such as cries) to enable maternal care. We are exploring the neural pathways and plasticity phenomena controlling the activity of hypothalamic oxytocin neurons in maternal mice; and how different sensory cues from the newborn affect neural responses, oxytocin release and maternal behavior.
Our goals: Gaining mechanistic understanding about what infant cues and sensory pathways recruit the oxytocinergic system in new mothers can provide new therapeutical avenues for a variety of postpartum conditions which are often characterized by abnormalities in oxytocin signaling and impaired maternal behavior. In addition, deciphering what aspects of postpartum adaptations in hypothalamic homeostatic circuits are reversible or long-lasting will inform us about the life-long consequences of motherhood on hormonal release and sensory processing in females.
Our central questions are: What are the postpartum adaptations in oxytocin release and maternal behavior? What anatomical pathways and synaptic mechanisms relay infant sensory cues to the hypothalamus? What aspect of these mechanisms are reversible or long-lasting?
Our successes: We are using a variety of synaptic, circuit, and behavior approaches to uncover the neurocircuits controlling oxytocin release and maternal care. Our current investigations are based on Dr. Valtcheva’s previous work uncovering a noncanonical circuitry in the postpartum brain which gates oxytocin release and maternal behavior in response to infant vocalizations.
Our methods/techniques: To study how different sensory cues from the newborn affect neural responses, oxytocin release and maternal behavior, we combine multiple state-of-the-art approaches including in vivo and in vitro electrophysiology, fiber photometry, mouse behavior, viral tracing approaches, opto-/chemogenetics, molecular and pharmacology tools, and newly-developed oxytocin sensors.
Figure 1: Confocal image of oxytocin neurons in the paraventricular nucleus (PVN) of the hypothalamus and electrophysiology trace showing in vivo whole-cell recording of one oxytocin cell in awake maternal mouse.
Figure 2: (Above) Fiber photometry recordings of PVN oxytocin neurons expressing GCaMP6s. (Below) Rhythmic elevations of fluorescent activity are observed during nursing in awake maternal mice.
Figure 3: (Left) Channelrhodopsin-assisted circuit mapping of synaptic inputs to oxytocin cells in paraventricular nucleus (PVN) of the hypothalamus. (Right) Electrophysiology traces showing synaptic currents evoked in oxytocin neurons or transporter currents evoked in astrocytes in response to light stimulation of channelrhodopsin-expressing axons from the posterior intralaminar thalamus (PIL) in acute brain slices.