CU Boulder neuroscientists identify ‘chemical imprint’ of love
One small rodent shows love leaves a mark on the brain
New research by University of Colorado Boulder neuroscientists have identified what they are calling a “chemical imprint” of love, and the findings are centered around a small rodent that forms monogamous pair bonds.
Imagine you hop in the car to meet your lover for dinner and a flood of dopamine — the same hormone underlying cravings for sugar, nicotine and cocaine — likely infuses your brain’s reward center, motivating you to brave the traffic to keep that unique bond alive. But if that dinner is with a mere work acquaintance, that flood might look more like a trickle, the authors said.
“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,” senior author Zoe Donaldson, associate professor of behavioral neuroscience at CU Boulder said. “This research suggests that certain people leave a unique chemical imprint on our brain that drives us to maintain these bonds.”
The study, published Tuesday in the journal Current Biology, centers around prairie voles, which are among the 3% to 5% of mammals that form monogamous pair bonds. Like humans, voles tend to couple up long-term, share a home, raise offspring together, and experience something akin to grief when they lose their partner.
Donaldson sought to gain new insight into what goes on inside the human brain to make intimate relationships possible by studying voles.
The University said Donaldson’s team used state-of-the art neuroimaging technology to measure, in real time, what happens inside the brain as a vole tries to get to its partner.
In one scenario, the vole had to press a lever. In another, she had to climb over a fence.
Meanwhile a tiny fiber-optic sensor tracked activity in the animal’s nucleus accumbens, a brain region responsible for motivating humans to seek rewarding things.
When the voles pushed the lever or climbed over the wall to see their life partner, the fiber — which illuminates like a glowstick in the presence of dopamine — ‘lit up like a rave’, the authors said. The party continued as the voles snuggled.
In contrast, when a random vole was on the other side of that door or wall, the glow stick went dim, the authors said.
“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,” first author Anne Pierce, a former graduate student in Dondaldson’s lab, said.
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The research team also found dopamine surges nearly vanished after the prairie voles spent significant time apart, suggesting the brain has an inherent answer or defense from endless unrequited love.
In another experiment the authors performed, the vole couple was kept apart for four weeks — an eternity in the life of a rodent — and long enough for voles in the wild to find another partner.
When the couple was reunited, they remembered one another, but their signature dopamine surge had almost vanished.
“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 said.
This could be good news for humans who have undergone a painful breakup, or even lost a spouse, suggesting the brain has an inherent mechanism to protect us from endless unrequited love, the authors said.
Read the full study here from CU Boulder.
Prairie voles are among the 3% to 5% of mammals that mate for life.