What happens in our brains when we see someone we love? Or when we overcome obstacles to meet them?
We may now have an answer, thanks to a team of neuroscientists at the University of Colorado at Boulder.
"What we have found, essentially, is a biological signature of desire that helps us explain why we want to be with some people more than other people," Zoe Donaldson, associate professor of behavioral neuroscience at CU Boulder, said in a statement.
"As humans, our entire social world is basically defined by different degrees of selective desire to interact with different people, whether it's your romantic partner or your close friends," she added.
"This research suggests that certain people leave a unique chemical imprint on our brain that drives us to maintain these bonds over time."
In their study, Donaldson and colleagues investigated the neuronal pathways involved in these interactions using state-of-the-art neuroimaging technology and... prairie voles.
Now, these fuzzy animals might not seem like an obvious model for human romance, but the prairie vole has actually been extensively studied in the field of social bonding.
This is because of the strong monogamous relationships this species forms (which, humans aside, is actually pretty rare for mammals.)
The team tracked activity in a part of the prairie voles' brains that is involved in motivating then to seek rewards. Previous studies have shown that this same area in humans lights up when we hold our partners hand.
Two experiments were conducted on the voles—both of which saw one animal separated from its life partner, and having to undergo a series of challenges to reach them.
In the first test, the voles were separated by a lever-controlled door. In the second, they were separated by a climbable fence.
Fiber optic sensors were implanted in the voles' brains that "light up like a glow stick" when they detect dopamine—a molecule known to mediate reward and pleasure responses in the brain—explained paper author Anna Pierce.
And, she said, the sensors "lit up like a rave" when the voles pushed the lever or climbed over the wall and were reunited with their partners.
The same dopamine dynamics were not seen, however, when just any random vole was on the other side of the barrier.
"This suggests that not only is dopamine really important for motivating us to seek out our partner, but there's actually more dopamine coursing through our reward center when we are with our partner than when we are with a stranger," Pierce said in a statement.
In a follow up experiment, the team separated vole couples for four weeks—basically an eternity in the lifespan of a rodent.
In the wild, voles separated for this long would have probably found a new partner.
When the four weeks were up, the voles were reunited. Although they still recognized each other, the dopamine surge they once felt was almost non-existent.
The desire was gone.
"We think of this as sort of a reset within the brain that allows the animal to now go on and potentially form a new bond," Donaldson explained.
More research is required to understand how these results might translate to us humans, but the team believe that the study has important implications for people struggling to form close bonds, and those getting over a bad break-up or loss.
"The hope is that by understanding what healthy bonds look like within the brain, we can begin to identify new therapies to help the many people with mental illnesses that affect their social world," Donaldson said.
The full findings of the study are published in the journal Current Biology.
Uncommon Knowledge
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Newsweek is committed to challenging conventional wisdom and finding connections in the search for common ground.
About the writer
Pandora Dewan is a Senior Science Reporter at Newsweek based in London, UK. Her focus is reporting on science, health ... Read more
