From the midwest of North America comes a tiny little rodent with a great big heart: the prairie vole. Described as “stocky,” “furry,” and “grizzled,” they live in the grasslands and feed mostly on vegetation.

Researchers have noticed some peculiar things about prairie voles that have made them a favorite for studies. Nests are built by the male partner and lined by the female partner. Both male and female share in parenting the young. Most importantly, prairie voles, unlike other rodents, form monogamous bonds that can endure for a lifetime, which is 12-16 months if not picked off by a hawk, an owl, a coyote, a cat, or a dog, among other predators.

In about 1970, researchers noticed that one kind of rodent always showed up in gender pairs in traps: the prairie vole. Brain studies of prairie voles showed a huge dopamine spike upon being reunited with their partner. It is believed that this dopamine burst causes the voles to become “addicted” to each other.

“The dopaminergic reward system contributes to the formation and maintenance of maternal and passionate love,” says a group of researchers from Taiwan in a meta-analysis of neuroimaging studies of love. The addictive properties of love come from a familiar workout of the brain’s reward system, including anticipation, indulgence, and withdrawal.

Through the repeated dosing of dopamine grows attachment, speculate the researchers:

[M]ammals achieve safety by developing attachments with others. An indispensable part of developing attachment is motivation, a driving force that utilizes the dopaminergic system.

An analysis of functional MRI studies involving maternal and passionate love brought this conclusion from the researchers:

[A]lthough different types of love were found to have unique cerebral networks, all of them activated goal-directed motivation, dominated by a reward system and corresponding regions full of dopamine and oxytocin receptors.

Oxytocin and dopamine are the one-two punch of pair bonding. Research shows that the loss of a prairie vole partner leads to considerable suffering for the surviving partner. “Losing the partner suppresses oxytocin signaling in the nucleus accumbens,” say the researchers. But the voles do, eventually, shake it off.

Prairie voles that have been away from their partners for more than a month are able to form new pair bonds, according to new research by behavioral neuroscientist Zoe Donaldson at the University of Colorado, Boulder. “This is similar to what happens to us humans: we don’t forget those we love after they’re gone, although what they mean to us — their place in our daily lives — has to be relocated,” says Donaldson.

Donaldson’s research shows that the initial dopamine surge of pair bonding is never forgotten in prairie voles. Even when the oxytocin wears off after prolonged separation, they can still recognize their old mate, but it doesn’t deliver the same jolt.

Written by Steve O’Keefe. First published February 14, 2024.

Sources:

“The Neurobiological Basis of Love: A Meta-Analysis of Human Functional Neuroimaging Studies of Maternal and Passionate Love,” Brain Sciences, June 2022.

“How to get over a breakup, according to the most monogamous animal,” El País English, February 1, 2024.

Image used under Creative Commons 2.0 license.