The 'chemical fingerprint' of desire discovered. The engine of love, the reason that pushes us to overcome every obstacle for a passionate encounter, lies in the levels of dopamine: the same hormone at the basis of addiction to sugar, nicotine or cocaine. This was revealed by an American study by a group of neuroscientists from the University of Colorado in Boulder. The work, published in 'Current Biology', demonstrates on the one hand that dopamine keeps feelings alive. But on the other hand he agrees with the saying that time cures all evils, healing even the most lacerating wounds of the heart.
The research was conducted on prairie voles, large-eyed, furry rodents, among the 3-5% of mammals that form monogamous pair bonds. Like humans, voles tend to choose a mate for life, someone to share a home and raise children with, and they feel pain when they lose a loved one. By studying them, “we essentially discovered a biological signature of desire, which helps explain why we want to be with some people more than others,” says Zoe Donaldson, senior author of the research.
The which is why we are ready to climb a mountain to join those who make our hearts beat, while we remain 'cold' if it comes to making too much effort for less interesting encounters, is that “some people – underlines Donaldson – leave a unique chemical imprint in our brain, which pushes us to maintain these bonds over time”. And in the neurological mechanisms that power them, the scientists concluded, dopamine plays “a fundamental role.”
The experiment
Using cutting-edge neuroimaging technology, Donaldson and colleagues measured in real time what happens in the brain of a vole as it tries to bond with its partner. In one test the rodent had to press a lever to open the door of the room where the companion was; in another, he had to climb over a fence to do so. All this while a tiny fiber optic sensor monitored, millisecond by millisecond, the activity of the animal's nucleus accumbens, the area of the brain that motivates us to seek rewarding experiences: from food to drugs. In the past, neuroimaging studies conducted in humans have indicated that when we hold our partner's hand, the nucleus accumbens lights up.
The sensor used to 'photograph' how voles behave detects dopamine. Well, when the rodents pushed the lever or climbed over the wall to meet their life partner, “the fiber lit up like a rave”, is the expression used by Anne Pierce, first author of the study. And the 'party' continued as, reunited, the lovers cuddled and smelled each other. Conversely, if a random vole was on the other side of the door or fence, the light dimmed. “This suggests that not only is dopamine really important in motivating us to seek out our partner, but also that more dopamine flows in our brain's reward center when we are with our partner rather than with a stranger.”
But that is not all. In addition to understanding what drives romantic relationships in our brain, scientists also aimed to understand how, from a neurochemical point of view, we manage to overcome the pain of a breakup. The new research also answers this question.
In another experiment, in fact, a pair of voles was kept separated for 4 weeks, an eternity in the life of a rodent and long enough for these animals in nature to console themselves with another partner. Well, when the couple reunited after a month, the two exes remembered each other, but the increase in dopamine that previously 'lit up' their encounters had almost vanished. Essentially, the 'fingerprint' of desire was gone. To their neurons, the ex-partner was indistinguishable from any other vole. “We consider it a sort of 'reset' of the brain – interprets Donaldson – which allows the animal to move forward and, potentially, to form a new bond”. Translated: time heals everything, even broken hearts, because a mechanism inherent in our brain protects us in the long run from the torments of unrequited love.
The authors point out that further research will be needed to determine to what extent what they observed on prairie voles also applies to humans. But they believe their study could have “important implications for people who have difficulty building intimate relationships or those struggling to get over a loss.”
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