The brains of fathers who become the primary caregiver for their children show similar patterns to those seen more regularly in mothers, according to a study testing the neurological basis of parenting.
The amygdala, responsible in the brain for vigilance and reward, becomes more engaged for fathers involved in caregiving, in much the same way as it is for mothers, research published Monday in the Proceedings of the National Academy of Sciences found. Similarly, an area responsible for interpreting a child's needs also shows an increase in activity.
The report follows previous research in animals that found similar changes, said Ruth Feldman, the study author. The more the brain was activated, the more sensitive the parents were to their infants' needs, she said.
"Fathers should engage in child care activity because this is their pathway to brain changes and attachment," said Ms. Feldman, a professor of psychology and neuroscience at Bar-Ilan University in Israel. "When mothers are around, fathers' amygdala can rest and mothers do the worrying. When mothers are not around, fathers' brains need to assume this function."
Changes in the amygdala occur in women from hormones in pregnancy and childbirth, said Ms. Feldman, who is also an adjunct professor at Yale University in New Haven, Conn. In men, the brain area responsible for interpreting their child's needs recruits the amygdala to activate only when a mother isn't around, she said in an email.
More studies are needed to determine if there are cultural differences in parental brain responses and what happens when there is maternal postpartum depression and poverty, she said.
The research included 20 primary caregiving heterosexual mothers, 21 secondary caregiving heterosexual fathers and 48 primary caregiving homosexual fathers raising infants in a partnered relationship. They found there is a "parental care" network in the brain, the report said.
The mothers had the highest activation of the amygdala while fathers who were secondary caregivers had higher activation in the part of the brain that enables planning and understanding infant messages. The fathers who were primary caregivers had brains that blended both, Ms. Feldman said.
The researchers also tested the bonding hormone oxytocin and found no differences among the three groups suggesting that all are biologically prepared to attach to their infants to a similar degree, she said.
Monday's research is "the first large study on the parental brain, the first to compare brain, hormones and behavior in mothers and fathers and the first to test the brain of primary care-giving fathers," Ms. Feldman said. More study is needed "in order to better understand when things go wrong, and to devise better interventions in such cases."