First brainwide map shows how rodents find love. What does it mean for humans?

AUSTIN (KXAN) — What can humans learn about love from other species?

A fuzzy little prairie vole led researchers from the University of Texas at Austin to more answers on how to find lasting relationships.

The researchers created the first map of the vole's brain that shows regions that are active during mating and pair bonding.

"I don’t think folks appreciate just the extent to which this strange little fuzzy creature has shaped our understanding of human love," said Steven Phelps, a professor in the Department of Integrative Biology at the University of Texas.

Prairie voles are as small as hamsters. They are monogamous, which means the males and females will form a bond and raise their young together. Like humans, they build long-term attachments. 

To go further in-depth on how this research can be related to human love, KXAN spoke with an expert on relationships and intimacy. 

What humans seek

"Humans relate to the vole in the way of wanting to seek partnership," Senior Associate Dean for Faculty Affairs and Graduate Education Professor at UT Austin Dr. Anita L. Vangelisti said.

"Most social science researchers will agree that that sense of belonging and connection is important. Most people also almost say now as a sense of belonging, human contact is sort of a basic human need," Vangelisti said.

Vangelisti explained that the argument for this research is that it is "literally bred into us."

"We're hardwired for that need to belong, because we know it's basic, and in our lizard brains, we know it's basic to our survival," Vangelisti said.

Matchmaking the voles

Morgan Gustison is a former postdoctoral researcher at UT Austin and is now with the University of Western Ontario. She worked alongside Phelps, Rodrigo Muñoz-Castañeda of Weill Cornell Medical College, and Pavel Osten of Cold Spring Harbor Laboratory on this study.

To create the brainwide map, the researchers tracked 200 voles with brain sensors. They separated them into different groups to measure how they looked for a partner. 

"What we essentially did was play Cupid," Gustison said. "We looked at what their brain expression profiles were at different points within forming a pair bond, and with prairie voles, we are actually quite lucky because we can essentially get them to form a pair bond within 24 hours."

Over the course of the day, the partnered-up voles mated continuously. The team captured brain activity during this time. They used this data to develop a map of the brain, while also discovering three stages of brain activity: mating, bonding and finally developing a stable relationship.

"Prairie voles are really social," Gustison said. "In the lab, we house them, and they actually hang out with their siblings before we do any kind of pair bonding experiments."

"We had the group that would form a pair bond, and then we'd watch how that bond emerged. And then there were animals that were essentially reunited with their sibling, their cage mate, and then we could see what happened when they're just in a social context, like a meeting context," Gustison said.

In this map, the prairie vole and mouse are compared to see how the brains react after blood flows through them, a process called perfusion. The researchers conducted a detailed study of the time during the mating and bond formation to examine the immediate early gene induction across the brains to test their hypotheses.

Alone and single

"We did have a group where they were solo, but this was before animals were acclimated to the chamber, and so they'd be in this chamber by themselves for a couple hours," Gustison said.

"During that session, they pretty much just sort of sat kind of in a corner. They didn't really do too much. It wasn't until they got exposed to a social partner that you start to see a lot of active behaviors," Gustison said.

In this research, they found the bonded pairs of voles would groom each other, console each other when stressed, defend their territory and protect their young. Vangelisti said humans do the same.

When measuring the voles' mating, the researchers were able to identify which parts of the brain are communicating with one another on intimacy and partnership. Once the voles mated, they stayed together as a pair.

"Our results suggest a novel model in which the BST [bed nucleus of the stria terminalis] is a key node connecting sexual experience to the neuroendocrine functions," the research study said.

By measuring different parts of the brain like the hypothalamus, preoptic area, and the amygdala, the results found changes in hormones including body temperature, mood and emotions.

"Manipulations of these circuits and their behavioral consequences offer rich new opportunities for research into the mechanisms of bonding and their contributions to well-being," the study said.

Next steps in research

Gustison said people have studied the voles for male sexual behavior before.

"We found the same circuit popping up in the female brain," Gustison said. "Something we've been trying to really understand is, why is it that this circuit that's been studied in males' sexual behavior, also showing up in the female brain?"

She explained that there is a correlation that happens between the males and females.

"One thing that Steve and I have speculated is that it might actually be related to an orgasmic response," Gustison said. "This is something where people study with male sexual physiology, but females have not really been part of that story. So we do wonder if this sexual circuitry is really important for the female brain. And wondering if that experience of sexual behavior for the female is also a really key part for the pair bond formation."

This brainwide map shows how the voles found partnership and paved the way for future studies to identify how humans can do the same.

While humans have a greater social exchange through communication and awareness, this research found that fundamentally, humans seek partnership the same way the voles do.

"In humans, it's different degrees. But oftentimes, we're not necessarily able to look at kind of the molecular side of the stories, we're often focused on fMRI, which is really looking at blood flow, and sort of an index of brain activity," Gustison said.

"But here, we're kind of seeing that in a different format. So it gives us confidence that a lot of the networks that are popping up in humans were in a variety, different social contexts are also being recruited during the pair bonding process," Gustison said.

The researchers will continue to look for new findings in their biology fields. As this was the first brainwide map of its kind, Gustison has more research questions she is eager to find answers to with her team.

"This study just goes to show that you can find out some really interesting phenomena like brain to brain similarity, that seems really important for the pair bonding process and for social bonding in general," Gustison said.