The neural circuitry underlying the responses of mouse mothers to calls from their pups has now been studied by researchers. The results were published in Nature. This mechanism may be important for sustaining mouse maternal care over time, the authors suggest.
The hormone oxytocin is known to be important for maternal physiology and behaviour; for example, it has roles in childbirth and in milk ejection during nursing. In humans, baby cries are a powerful signal of infant distress, and most nursing mothers respond to cries with oxytocin release, increased hypothalamic activity, comforting behaviours towards the infant and occasional milk ejection. However, the neural circuitry that routes auditory information about infant distress calls to oxytocin neurons is unclear.
To investigate the neural circuitry for maternal oxytocin release induced by infant cries, Robert Froemke from the New York University School of Medicine, New York, and colleagues recorded the neural activity of oxytocin neurons in maternal mice whilst their pups were calling. They found that these neurons responded via input from a region of the brain called the posterior intralaminar thalamus. This circuit was found to control oxytocin release and pup retrieval, providing a mechanism for the integration of sensory cues from the offspring into maternal hormone networks to promote efficient parenting.
“We found that oxytocin neurons responded to pup vocalizations, but not to pure tones, through input from the posterior intralaminar thalamus, and that repetitive thalamic stimulation induced lasting disinhibition of oxytocin neurons,” they write.
The findings help us to understand how sensory cues from offspring are processed by neural circuits to activate the release of neuromodulators such as oxytocin, which alter maternal behaviour.
