Brains of Sex-Having Voles Show How Love Looks in Real Time

Scientists really want to know what gets prairie voles going. The chubby gray rodents form life-long, monogamous relationships like many humans, so they’re considered great models for studying how individuals pair off and stick together. The latest vole research suggests they may also someday help humans make new friends.

Researchers recently probed the relationships of the furry little couples, known as pair bonds, to see what love actually looks like in the brain. In a new paper published Wednesday in Nature, Emory University researchers measured the dynamic behavior in the parts of the vole brain that are responsible for pair bonding in real time, marking the first time scientists have done so in an experiment. By examining the underlying neural basis of pair bonding, these scientists got a better understanding of exactly what happens in the brain when people socialize and form new bonds with loved ones.

Because if there’s one thing that will help people make new friends, it’s learning exactly which neurons make rodents want to fuck.

And that’s pretty much what they did. The new findings build on existing data showing that regions of the brain tied to a feeling of reward and satisfaction, particularly the nucleus accumbens, are directly related to pairing behavior in voles. The team behind the study found that the prefrontal cortex, the part of the brain responsible for the most advanced levels of cognitive and social behavior, actively controls the nucleus accumbens’ involvement in pair bonding.

Voles with a stronger connection between these two brain regions also experienced stronger and more rapidly formed social bonds, adding a sexy twist to the old neuroscience adage that “those that fire together wire together.” Physicist-turned-neuroscientist Robert Liu, Ph.D., who led the study, tells Inverse that some voles seemed predisposed, given their brain’s structure, to make stronger social connections.

Liu and his colleagues also searched for a causal relationship between prefrontal cortex activity and closer couples. The team found that voles whose neural activity had been boosted by a focused beam of light had an above-average preference for individuals they’d been courting compared to voles they hadn’t met before.

What has yet to be determined, however, is how this research can make good on the idea that this work can, as was claimed in a suspiciously speculative press release, “promote better neural communication to boost social cognition in disorders such as autism.”

Humans also have a nucleus accumbens and a prefrontal cortex, but both regions are far more developed than they are in voles, with more complex connections and networks of neurons. While there’s a structural analogy that may someday give rise to medical interventions, this research is way too far removed from human relevance to make any sort of claim, especially when it comes to something as contentious as treating people with some degree of autism spectrum disorder.

Liu concedes that these applications are speculative, but he also points out that there’s a good amount of data showing that similar connections between the prefrontal cortex and the nuclear accumbens could work the same in humans as it does in prairie voles, albeit in a more complex way.

By understanding how this system works in a neurotypical brain, Liu imagines that someday down the road — with further research and improved technology for targeting specific neural connections — doctors may be able to manipulate the brain activity of people with social dysfunctions in a way that might help them form new social relationships. But “that’s more speculative and down the line,” says Liu.

“What we think might translate is that there’s this cortical area related to executive function exerting control over this reward area,” he says. He describes existing human research that says that the nucleus accumbens actually activates when humans look at photos of their loved ones. “What our research is trying to do is look at how that comes to be.”

Abstract:

Adult pair bonding involves dramatic changes in the perception and valuation of another individual. One key change is that partners come to reliably activate the brain’s reward system, although the precise neural mechanisms by which partners become rewarding during sociosexual interactions leading to a bond remain unclear. Here we show, using a prairie vole (Microtus ochrogaster) model of social bonding, how a functional circuit from the medial prefrontal cortex to nucleus accumbens is dynamically modulated to enhance females’ affiliative behaviour towards a partner. Individual variation in the strength of this functional connectivity, particularly after the first mating encounter, predicts how quickly animals begin affiliative huddling with their partner. Rhythmically activating this circuit in a social context without mating biases later preference towards a partner, indicating that this circuit’s activity is not just correlated with how quickly animals become affiliative but causally accelerates it. These results provide the first dynamic view of corticostriatal activity during bond formation, revealing how social interactions can recruit brain reward systems to drive changes in affiliative behaviour.