Conditions such as postpartum depression and psychosis can lead to alterations in the neuronal circuits of new mothers, disrupting the mother-child bonding process, according to research from MedUni Vienna.
The study, led by Daniela Pollak from MedUni Vienna’s Center for Physiology and Pharmacology, found that neuronal circuits in the brain are activated during the learning of maternal behaviour. By identifying which circuits are in use, the researchers hope to provide a basis for developing new treatments for postpartum depression.
The study has been published in The EMBO Journal.
What is postpartum depression?
Postpartum depression refers to low mood felt in mothers after giving birth. Most mothers experience ‘baby blues’ in the weeks after having a child, symptoms of which commonly include mood swings, crying spells, anxiety and difficulty sleeping. However, postpartum depression can have longer-lasting and more severe symptoms which can lead to difficulty in mother-child bonding, severe anxiety and thoughts of death and suicide.
During their preclinical investigation, the researchers analysed the maternal behaviour of female mice towards newborn pups.
The neural processes involved in the development of maternal care behaviour in female mice after birth have already been explored. However, the question of which circuits in the brain are activated during the learning of care behaviour has been up for debate.
The researchers set out to answer this question by examining nulliparous female mice that have not been impregnated.
The team found answers in the anterior cingulate cortex (ACC), a region in the prefrontal lobe that is with the recognition and evaluation of social processes and the development of emotional awareness.
Through the mouse model, the researchers found that in females who have not been pregnant or given birth, the ACC was activated when they acquired maternal behaviour upon first contact with pups.
Maternal behaviour can be learned
“Our observations have demonstrated that, through repeated experience with pups, the virgin females are capable of learning maternal behaviour that fully resembles those of mothers after delivery,” explained project leader Daniela Pollak.
The results revealed that during the learning process ACC activity was controlled by an excitatory feedback circuit involving a specific group of neurons in the central brain region, the thalamus.
The researchers defined maternal behaviour as ‘sensitivity and responsiveness to signals of infant needs’. The team say maternal behaviour is instinctively displayed in virtually all mammals and upon first contact with newborns immediately after delivery.
In many species, including rodents, animals that have never given birth themselves will still show signs of maternal behaviour towards newborns. The researchers observed maternal behaviour in the mice models, such as returning displaced pups from outside the nest area into the nest where they are protected from predators and kept warm. They noted that his behaviour was acquired through repeated experiences with the pups.
Previous research has established through observations of adoptive parents, that humans can also learn parental behaviours. However, conditions such as postpartum depression and psychosis can easily disrupt this process.
“By showing that maternal behaviours can be acquired and identifying the underlying neuronal circuits in the brain that control this acquisition, we are creating a potential basis for developing therapeutic options to treat people with postpartum depression and psychosis,” explained Pollak.
