New fathers’ brains adapt to become more like those of mothers’ when bringing up a child making them more emotionally responsive to their baby’s cries, a study has found.
Men who are primary carers become hyper-sensitive to their infants’ verbal and physical signals due to heightened activity in certain areas of the brain only previously seen in mothers, scientists found.
Fathers who are not the primary carers demonstrate increased activity in cognitive – or ‘mentalizing’ – circuits which interpret a baby’s cries and non-verbal cues such as whether a squirm means “I’m about to scream” and which means “change me.”
But men who bring up children without female involvement, such as gay couples who adopt, demonstrate both maternal and paternal changes in their brain activity as they perform the dual role of mother and father.
The findings could fuel the debate over whether gay men should be allowed to adopt children, particularly in the US where many adoption agencies will not work with same-sex couples and some states have banned them from adopting.
Published in Proceedings of the National Academy of Sciences, the study conducted by Eyal Abraham of Bar-Ilan University, Israel, builds on previous work which mapped the changes in the brains of new mothers.
It was not clear if that pattern is a result of the hormonal and other changes that accompany pregnancy or a response to the experience of motherhood.
To find out, Mr Abraham, working with Ruth Feldman of Bar Ilan and Professor Talma Hendler of the Tel-Aviv Sourasky Center, filmed 89 new mothers and fathers interacting with their infants at home.
They then measured the parents’ brain activity while watching these videos in an MRI tube, as well as watching videos their children did not star in.
For the 20 mothers in the study watching their babies triggered heightened activity in the brain’s emotion-processing regions, particularly in a structure called the amygdala, which was five times more active than when watching other videos.
“These are regions that respond unconsciously to signs of an infants’ needs, and that derive deep emotional reward from seeing the baby,” study co-author Ms Feldman said.
For the 21 heterosexual fathers, who were very involved in raising their baby but whose wives took the parenting lead, watching their infant increased activation of cognitive circuits, particularly a structure that interprets a baby’s cries and non-verbal cues.
The 48 gay fathers raising children with their husbands mirrored both mothers and fathers in terms of the changes to brain activity.
Their emotional circuits were as active as those of the mothers and the interpretive circuits showed the same extra activity as that of heterosexual fathers.
The more time a man spent as primary caregiver to a child, the greater the connectivity suggesting playing both parental roles caused the brain to integrate the structures required for each.
Ms Feldman said: “In all fathers, the overlap, or connectivity, between the two brain systems – emotional processing and mentalizing or amygdala and STS – is greater the more the father is involved in childrearing responsibilities. That is, the mentalizing network recruits the emotional network.”
She added: “Fathers’ brains are very plastic.
“When there are two fathers, their brains must recruit both networks, the emotional and cognitive, for optimal parenting.”
The next stage will be for scientists to perform neuroimaging on men and women before and then after they became parents, to check that any heightened activity followed junior’s arrival and was not present before.
But Feldman is confident that the brain activity results from parenting.