Among the editors’ picks of yesterday’s Science issue was a paper published in PNAS and entitled “Father’s brain is sensitive to childcare experiences”. Brain imaging is not my area of expertise, so in such a case, I would usually just read the paper’s abstract (which sums up what was done in the study and what was found), and move on. This time however, I also looked at the metrics linked to the paper (how much the study was relayed in newspapers, blogs, social networks, etc.).
I expected that such a topic would have been picked up by many news outlets. It turns out that it had not (at least not yet), but there were a few tweets about the study that bothered me. One of them said something to the point that hands-on childcaring could rewire a father’s brain the same way a pregnancy did a mother’s brain. While the first part of this sentence corresponds to what the study shows (the activation of certain neural circuits is associated with caregiving experiences in fathers), I wondered where the second part of the sentence came from (“the same way a pregnancy did”).
The study looked at mothers who were primary caregivers, fathers who were secondary caregivers (both of those in heterosexual couples), and fathers who were primary caregivers (in homosexual couples). In all cases, parents were raising their firstborn infant. The researchers videotaped parents and children together and submitted the parents to functional magnetic resonance imaging brain scanning (using the videotapes as stimuli). They found that parenting integrated two neural networks, one involved in emotional processing, and another implicated in social understanding and learning. Primary caregiving fathers showed a degree of activation in the emotion, attention, and reward processing network that was similar to that observed in primary caregiving mothers, but which was greater than that seen in secondary caregiving fathers.
The point of this post is not to go deep in the study (which is available in open access here), but to react to the tweet that said that childcaring could rewire a father’s brain the same way a pregnancy did a mother’s brain. This study did not compare brain activity in women before and just after pregnancy, and did not look at brain activity right after delivery, before any childcaring activity had taken place (true, getting into an fMRI machine might not be high on your list of things you want to do right after delivery). So where does this idea of “pregnancy rewiring the brain” come from ? Other studies ? Because from this particular paper, all that I would be able to say is that being a primary caregiver is associated with a greater activation of certain neural networks compared to being a secondary caregiver, independently of whether the primary caregiver is male or female.
What I did not like in that tweet is the assumption that, while caregiving experiences can modulate a father’s brain activity pattern, a mother’s brain is already wired the way the father’s brain ends up to be after some time of hands-on childcaring experience. Why wouldn’t the activity pattern of the mother’s brain also be a result of her childcaring experiences? So that there would not be a “maternal instinct” activated solely by hormones, but rather a “parental brain pattern”, activated by hands-on childcaring experience?
It would be interesting to see a study comparing brain activity pattern in primary versus secondary caregiving mothers, just like this study looked at primary versus secondary caregiving fathers. However, it would probably be difficult to find enough mothers who take on as little childcaring activities as “traditional” secondary caregiving fathers do from the moment the child is born and onwards to conduct such a study. Alternatively, what about a study looking at brain activity pattern in mothers caring for an infant they delivered versus mothers caring for an infant they adopted, and comparing brain activity on the first day of caregiving with a day some months later, to try and dissect the effects of pregnancy versus bonding and childcaring activities on the activation of parental neural networks?
A side (and personal) note: while looking at news article that relayed this study, I found that some of them built on the idea that mothers knew (by instinct?) what their baby needed, whereas fathers learned it. Yet, among all my friends who have children, I have not yet witnessed such a thing: I have only heard both mothers and fathers say that figuring out what their babies needed when they cried was a learning, trial-and-error process. By contrast, “mothers know and fathers don’t” is something I have heard from women belonging to my mother’s generation, women who had taken on the bulk, not to say the whole, of infant caregiving activities.
Father’s brain is sensitive to childcare experiences. Abraham E, et al. PNAS May 27, 2014. doi: 10.1073/pnas.1402569111