Two lovers reuniting on the silver screen as the curtain closes – the most cliché climax of romance movies. But why does the audience love a plot involving a character pining for a loved one? Perhaps, it would be better if we ask what makes us long to be together with our partners in the first place? And how does this longing to be with the other shape relationships?
Driven by an urge to answer these questions, researchers at the University of Colorado set off by studying brain images of prairie voles — which belong to the 5% of mammals, including humans, inclined towards monogamy. This is not the first time the furry rodents have been studied to draw parallels with humans. Voles are an ideal choice for scientists when studying the underlying neural chemistry of human interactions. Scientists can not tinker with the human mind or other higher primates, so far studies at the molecular level have been limited to the laboratory mouse. But years of inbreeding for medical research has made them much removed from nature.
What sets prairie vole apart from other rodents are monogamous tendencies. The male courts the female and once babies are born, the male rather than taking off sticks around to raise them. The voles experience a life long bond with their partners after mating and when one partner dies the other shows signs of grieving.
These remarkable characteristics are what made scientists choose this species to study neural circuitry involved in building relationships. In the study published in Proceedings of the National Academy of Sciences the researchers used tiny cameras and sophisticated technology called in vivo calcium imaging to note brain activity when the voles met, after they had mated and 20 days after living together. Brain activity, while the voles interacted with other voles whom they did not share a close relationship with, were also studied.
The results show that when voles are together with their partner or strangers brain activity remains more or less the same. However, when they meet their partners after being separated from them for some time, a unique set of cells in the reward center of the brain called the nucleus accumbens fire off. The scientists noticed that the more the prairie voles spent time with their partners; the stronger bond they shared therefore a larger number of cells show activity in the nucleus accumbens upon reuniting with their partners.
The researchers speculate that hormones such as oxytocin, vasopressin, and dopamine may also be involved in establishing trust and closeness. However, the exact role of the cluster of cells observed to be active remains a mystery and more research is underway to crack the code.
“These negative feelings so many of us are experiencing right now (in light of the pandemic) may result from a mismatch: we have a neuronal signal telling us that being with loved ones will make us feel better, while practical restrictions mean this need is going unmet,” lead author of the paper Zoe Donaldson commented.
The research in context to these extraordinary times gives rise to an interesting question; while it is agony yearning to be together with our beloved, will the restrictions imposed to keep us apart intensify the love partners share for one another? Or will the heartache associated with social distancing become too much to handle?
