Neuroecology - How little we know about the neuroscience of fatherhood

Neuroecology offered this brief research review on Father's Day weekend - it's a little late, but it's still good information on the neuroscience of being a dad. The study looked at the two primary hormones/neuropeptides associated with paternal behavior - prolactin and oxytocin. The results revealed different behaviors associated with each chemical:

Each were associated with a specific paternal behavior: prolactin with facilitation of a child’s exploratory behavior and oxytocin with how much the fathers matched their facial emotions with that of their children.  Since this is only a correlational study, we cannot say for sure whether or not these neuropeptides are directly causing these behaviors.

Interesting - and we know that each of these chemicals is associated with lower testosterone levels, which can lead to post-natal depression and other health issues. On the other hand, we want men to engage in these paternal behaviors, especially mirroring, which was correlated with oxytocin.

The trick, then, is to balance paternal hormones with enough T to prevent depression and other health issues.

How little we know about the neuroscience of fatherhood

June 19, 2012

 

Fathers caring for their children is the general rule across most vertebrates; almost all nonmammalian vertebrates use fathers as a prime caregiver.  And yet, the world of neuroscience knows little about paternal care. This is partly because the males of our common laboratory species, the lab mouse and rat, are more likely to eat their young than show any special care for them.  The resulting deficit in knowledge is obvious with any cursory look through a textbook on the neurobiology of parental behavior: after ten chapters detailing maternal behavior, there might be one perfunctory chapter detailing how little we know about paternal behavior.  But here’s a cool fact I learned from one of those chapters: did you know that male Djungarian hamsters assist in delivering pups by tearing away the membranes just after birth.  They play midwife!

It seems like the precise neural circuitry for maternal and paternal care are different; lesioning the amygdala decreases paternal care and increases maternal care.  Likewise, many neurohormones that cause maternal behavior have little effect on males.  But some of these pathways are likely to be the same.  I’ll quickly discuss a paper which describes the influence of the neuropeptides prolactin and oxytocin on paternal care.  Oxytocin is the ‘love hormone’ and strongly stimulates pair-bonding, influences social recognition, and has strong effects on general sociality.  Although it is typically thought of as having a pro-social influence, the reality is a bit more complicated (of course!).  Prolactin is a bit of a sex hormone, providing the body with sexual gratification after intercourse and counteracting the effects of testosterone, estrogen, and dopamine.  It clearly has a stronger social effect as well or I wouldn’t be talking about it in relation to child-rearing!

In order to assess the relationship between these two neuropeptides and fatherhood, Gordon et al. first measured  their concentration in fathers across time and found them to be fairly stable.  When they compared the of these neuropeptides to the propensity of the fathers to play with their children, they found them to be strongly related.  Each were associated with a specific paternal behavior: prolactin with facilitation of a child’s exploratory behavior and oxytocin with how much the fathers matched their facial emotions with that of their children.  Since this is only a correlational study, we cannot say for sure whether or not these neuropeptides are directly causing these behaviors.  However, these are similar to what are seen with maternal behaviors, allowing the researchers to compare their results to the richer maternal literature in the future.  It will be interesting to see if future work can relate receptor variants for these neuropeptides to differences in paternal behavior.  Perhaps we can get a genetics of daddyhood?

Reference
Gordon I, Zagoory-Sharon O, Leckman JF, & Feldman R (2010). Prolactin, Oxytocin, and the development of paternal behavior across the first six months of fatherhood. Hormones and behavior, 58 (3), 513-8 PMID: 20399783

NPR - What Do Women Really Want? Oxytocin

A little post from NPR's health blog, Shots. on what women really need - women who release more oxytocin are happier. They are also more interested in sex. So, you might be wondering, how do we increase oxytocin levels in our girlfriends or wives? Answers below this article.

What Do Women Really Want? Oxytocin

November 15, 2010

by Jon Hamilton

This woman's body is probably pumping out a lot of oxytocin.

A male scientist says he's discovered what makes women happy.

It's a hormone called oxytocin, says Paul Zak, a researcher at Claremont Graduate University. Zak presented evidence to back his case today at the Society for Neuroscience meeting in San Diego.

Produced naturally in the body, oxytocin can trigger labor contractions and lactation in women. It's also been shown to boost feelings of trust and empathy in both men and women.

Zak, trained as an economist, was part of a team that studied oxytocin levels in college-age women before and after they received a $24 gift from a stranger.

Acts like this, which show kindness and trust, are known to cause oxytocin levels to rise. But the amount of increase varies widely from person to person.

In this study, women filled out surveys about their satisfaction with life before they received the gift. And comparing the survey results with oxytocin changes revealed a clear pattern.

"Women who release more oxytocin are happier," Zak told the audience at the neuroscience meeting. "They like being around other people more, they have more sex per month, and they have more resilience to adverse events."

The reason for these differences probably has to do with oxytocin's ability to encourage people to form relationships, trust other people, and empathize, he says.

Many studies have shown that people with strong relationships are happier.

Women in this study confirmed the link between oxytocin levels and efforts to bond with another person. Those who released the highest levels of oxytocin were also most likely to send some money back to the stranger who gave them the original gift.

OK, then, so I'm sure you read the article before you got down to this part, right? Because what really matters is that the woman you love is happy, right?

Seriously, if she feels that you are manipulating her, you might as well get a blanket from the closet and set up camp on the couch for the next few days.

Here are ways to naturally boost your body's oxytocin production:

• Walk this way. Just linking arms, holding hands, or draping an arm around your significant other, child, or person you care for can produce an increase in oxytocin. Don't be afraid to show affection, and if you want to stop and hug during the walk, hug! Really, it's that simple.

• Daydream about your significant other. Research out of the University of North Carolina at Chapel Hill discovered that happily married women quickly released a dose of oxytocin when asked to think about their husbands. But of course, try not to spend too much time apart. "While absence is said to make the heart grow fonder, from a neurophysilogical perspective there is little doubt that regular intimate contact with a loved one is preferable," says Crook.

• Count on your cat. Husbands and wives can be moody and go through affectionate dry spells, but it always seems like a loyal pet is there to make owners feel good. And because the release of oxytocin is triggered by touch, petting a dog or cat you love can also increase oxytocin levels, explains Crook.

• Find comfort in familiar favorites. The smell of your mother's signature chocolate chip cookies, hearing kind words from someone you care about, waking up early to hear the dawn choir chirped by chickadees and other backyard birds—these are all ways to boost oxytocin. Crook says immersing yourself in familiar and comforting smells, sounds, music, and even pleasant thoughts and memories can coax your oxytocin meter higher.

So there were five ways to increase oxytocin naturally - the fifth one is making love. The "cuddle hormone" increases quite a bit during sex, then peaks at double the normal levels at orgasm (one of the reasons having sex triggers birth contractions in pregnant women). It also generates the emotional intimacy and bonding of the post-coital bliss - unless you fall asleep right away.

• Have (good) sex. Adults seeking an oxytocin surge should head for the bedroom. The hugging and touching during foreplay fires up the love chemical, and orgasm spikes the hormone level to two times the normal amount. This opens the door to a relaxed feeling and a greater opportunity to bond with your partner.

Interestingly, among premenopausal women, oxytocin is naturally higher during ovulation because estrogen intensifies the love hormone. This may partially explain why women seem to be more prone to touch and other displays of affection during ovulation.

Tags: psychology, brain, oxytocin, relationships, happiness, sexuality, NPR, Shots, Jon Hamilton, Paul Zak, neuroscience, women, touch, intimacy, bonding, orgasm, daydreaming, pets, comfort scents