A procedure where two rats, one pregnant rat and one female rat who is not pregnant, are surgically joined to share a blood supply. This means they they both are exposed to hormones that just one secretes. The end result is that the rat who is not pregnant will show maternal behavior, because the pregnant rat secreted the necessary hormones. 

Parabiotic Exchange 

It is seen that virgin female rats do not display these maternal behaviors around newborns. Virgin females dislike the smell of pups. However, if put a female around pups for a few hours for a few days in a row, virgin females can develop some maternal behaviors; they can be trained to care for newborns. 

University of California, Davis

Behaviors that are instantly shown in the mother after giving birth. Four measurable behaviors seen in rat mothers are nest building, crouching over pups, retrieving pups, and nursing.  

Maternal Behavior

Breedlove, S. & Watson, N. (2017). Behavioral neuroscience, eighth edition. Oxford University Press.

Behavioral Neuroscience 8th Edition

One way that pregnant rats prepare for her pups is licking her nipples to clean them. This makes them more sensitive to touch and expands the sensory cortex related to the surrounding skin. An example of animals altering their brains to impact future behaviors. 

Preparing for Offspring

Virgin Females and Newborns

There is not one hormone responsible for the ignition of maternal behaviors. Many hormones that appear during and after pregnancy are required to develop maternal behaviors and allow mothers to care for their children. It is also interesting to note that some of the same brain regions are involved in both mating and maternal behaviors. 

Hormones for Maternal Behavior

Studies have shown that rats have two competing neural pathways that mediate maternal responses and aversive behaviors towards pups. In virgin females the aversive pathway is dominant and plays a strong role in suppressing maternal behavior. However, the hormones in postpartum rats ignite the opposite circuit and silence the aversive one. Studying the interplay of these two circuits in different environments and in different populations can help us discover the controls of parental care in various species. 

Neural Model of the Control of Maternal Behavior

- Breastfeeding has psychological and physical benefits for both mothers and infants
- Its immunological benefits are considered to be the most effective preventive means of reducing the death rate of children under five years old. 

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