How the 'Love Hormone' Works Its Magic
A whiff of oxytocin lit up reward center in men's brains when they looked at their partner's face
By Brenda Goodman
MONDAY, Nov. 25, 2013 (HealthDay News) -- Scientists, and women everywhere, have long wondered exactly what keeps a man from straying with a stranger.
From a biological perspective, at least, cheating is easy to understand. The more sexual partners a man has, the more likely he'll be to pass on his genetic material.
So why do so many men settle down, get married and stick around to raise their kids?
Researchers think they may have found a clue in oxytocin, a hormone released during sex and other intimate gestures like hugging or holding hands that's been proven to strengthen social bonds in other mammals.
They found that the hormone appears to boost men's attraction to their mate -- even when presented with pictures of other women.
The findings are published in this week's issue of the Proceedings of the National Academy of Sciences.
In the study, 20 men who were in committed relationships for 28 months, on average, took whiffs of either oxytocin nasal spray or an inactive placebo spray.
For the first test, the men looked at pictures of their partner, a woman they'd never met, or a house. The photos of the women were carefully matched so one wasn't more attractive than the other.
In the second experiment, they looked at pictures of their partners or of women they knew but weren't related to, perhaps someone they saw at work every day.
Then the men rated the attraction they felt to the various faces. Men consistently rated their partners as being more attractive and arousing than the other women and, in most cases, a whiff of oxytocin boosted that effect compared to the placebo.
But what really fascinated the researchers was what happened inside the men's brains.
Under the influence of oxytocin, two areas of the brain responsible for feelings of reward and pleasure lit up when men saw their partner's faces. But the sight of other women had the opposite effect, suppressing feelings of pleasure.
"Oxytocin triggers the reward system to activate on the partner's face, the presence of the partner," said study author Dr. Rene Hurlemann, a professor of psychiatry at the University of Bonn, in Germany.