Children's effect on fathers' brains

As a man spends more time caring for his firstborn child, his brain responds to the rigors and pleasures of child care more and more like that of a woman who is a child's primary caregiver. (Susannah Kay / Los Angeles Times / July 12, 2013)

Parenting a small child requires the forethought of a crisis planner, the reflexes of a professional goalkeeper, the energy of a cheerleader and the empathy of a therapist.

After eons of practice at such caregiving, it's clear that mothers have evolved some brawn in those parts of the brain that weave together these many skills, and that practice strengthens them. But fathers can clearly develop the same cognitive and emotional muscle, and a new study finds that the more he cares for his offspring, the more a father's brain looks and behaves like that of a mother engaged in the everyday care of a child.

In fact, say the Israeli authors of the study, the very practice of caregiving, whether by a mom who is her child's primary caregiver, a dad who steps in to help or a gay father raising a child with no woman in the picture, activates a recognizable "parental caregiving' neural network."

Their research was published Tuesday in the journal Proceedings of the National Academy of Sciences. The researchers said they may be the first to take advantage of an unprecedented cultural shift. Changing cultural mores have given modern men a larger role in the care of their offspring, and in instances of gay male couples who have chosen to raise children together, at least one of the men takes on the role of primary caregiver and no mother figure is present at all.

In a series of experiments, the researchers, led by Eyal Abraham of Bar-Ilan University, visited and videotaped 89 first-time parents as they interacted with their babies. They took measurements of the parents' levels of oxytocin, a hormone that mediates behavior related to nurturing, trust and affection. And later they scanned the brains of the parents as they watched video of themselves with their babies, and of other parents interacting with their own children. The aim of the functional magnetic resonance imaging (fMRI) was to discern patterns of brain activation associated with parental caregiving.

Whether their direct caregiving role is full or part time, men have a pattern of activation that is just a little different from women's. But caring for one's baby prompts activity in and communication among the same brain circuits, whether a man or a woman is doing it.

Key components in the parental caregiving neural network are circuits that are central in attaching emotional importance to experience (the amygdala, the ventral anterior cingulate cortex, the inferior frontal gyrus and insular cortex, and the ventral tegmentum), as well as others that help us impute needs, intentions or mental state to other people (the ventromedial prefrontal cortex, the superior temporal sulcus). The circuits that came alive with caregiving involve emotional processing, reward and motivation, and in developing a smooth exchange of give-and-take known as parent-child synchrony.

In mothers, the brain's emotional processing circuit was most activated by watching videos of their interaction with baby. In fathers who were not full-time caregivers, the largest activations were seen in regions involved in interpreting and responding to another's social cues. Among gay fathers who were full-time caregivers, both regions were greatly activated, with much cross talk between them.

In females, as luck would have it, the brain structures from which these motivations and behaviors spring are rich in receptors for the hormone oxytocin, a chemical copiously released by females in the wake of giving birth. Although men make oxytocin and are sensitive to its effects, this hormone has not always been seen as a central driver of nurturing behavior.

In this study, researcher found that a woman's oxytocin levels were a good predictor of activation of her brain's emotional processing centers -- and of affectionate behavior. But in men, higher oxytocin levels predicted more activation in the brain's centers of social cognition and were associated with better parent-child synchrony.