Familiarity makes the heart grow fonder, at least when it comes to the prairie vole. This rodent species is monogamous, with partners forming lifelong bonds. Until recently, no one knew why. That “why” is exactly what researchers at the Yerkes National Primate Research Center at Emory University want to understand.

“Prairie voles were critical to our team’s findings because studying pair bonding in humans has been traditionally difficult,” said Dr. Elizabeth Amadei, a co-lead author on the research. “As humans, we know the feelings we get when we view images of our romantic partners, but until now, we haven’t known how the brain’s reward system works to lead to those feelings and to the voles’ pair bonding.”

The existing research suggests an interaction between chemicals, such as oxytocin and dopamine, and brain regions, including the prefrontal cortex, leads to these lifelong bonds. That, however, wasn’t enough information for this team that wants to understand the specific neural process and neural networks.

So why do prairie voles mate for life? When a male and female vole interact for extended periods of time, the prefrontal cortex increases the activity of the nucleus accumbens, the brain’s reward system. The decision to engage in affiliative behaviors, such as cuddling and mating, strengthens the animals’ bond and increases overall pleasure for both voles.

While this research has led to additional questions about how the brain impacts the sensational and emotional components of love, it also has longer-term implications. According to Dr. Larry Young, co-author, director of the Emory Conte Center and chief of the Behavioral Neuroscience and Psychiatric Disorders Division at Yerkes, “this discovery is just part of the larger effort to understand how brain circuits works during natural social behaviors. The more we understand, the easier it is to tackle disorders, such as autism, which impair social functioning.”

Reviewed August 2019