'Love Hormone' Experiment Shows How the Brain Tricks Us Into Making Friends

"What is more important than understanding what allows us to feel good about each other?"


Oxytocin is famously known as the “love drug” because it’s associated with the intimate bonds between lovers and family members. Scientists know it’s a neuropeptide that’s secreted into a person’s bloodstream from a gland at the base of the brain during moments of physical intimacy, but how exactly it affects our behavior — and our relationships with others — is unknown.

On Thursday, Stanford University scientists came a step closer to figuring it out. In a study published Thursday in Science, they revealed that as bursts of oxytocin coincide with positive social interactions, our brains are overwhelmed with a feeling of reward.

In an interview with Inverse, study co-author Dr. Robert Malenka said his team’s discoveries about oxytocin are especially timely. “At a time when there is enormous tension between individuals and societies with different worldviews, what is more important than understanding what allows us to feel good about each other?”

In their study, they came to an understanding of where oxytocin works in the brain, which led them to understand how it makes social interaction feel so good. “The findings of this paper suggest that one factor contributing to social behavior deficits may be abnormal modulation of the brain’s reward circuitry by oxytocin,” says Malenka.

VTA is the brain's ventral tegmental area. 

With his team, Malenka, the co-director of the Stanford Institute for Neuro-Innovation and Translational Neurosciences, found that positive social interactions cause neurons to release oxytocin into the brain’s ventral tegmental area (VTA) — a region rich with dopamine and serotonin receptors, which are established parts of the brain’s reward system. The flood of oxytocin into the VTA after a social experience is what they think leads us to experience those interactions as positive and rewarding moments.

In experiments with adult male mice, they used a virus to knock out the mouse VTA’s oxytocin-releasing neurons so they could artificially manipulate the amount of oxytocin they released, in hopes of discovering what happened to mouse friendships when the hormone couldn’t do its job. After each mouse went through manipulations to either inhibit or excite the oxytocin-producing neurons, it was introduced to a younger juvenile mouse.

The scientists discovered that when oxytocin neuron activity was increased in the VTA, the subject mouse “spent more time hanging out with its younger buddy.” When those neurons were inhibited, the mouse avoided its potential pal.

When oxytocin was released in a mouse's VTA, it became sociable.

Wikimedia Commons

It’s important to understand how oxytocin works in the brain, Malenka explains, so scientists can understand how to mediate its potential therapeutic effects. While future experiments on humans are needed to see if the same, feel-good reactions happen the exact same way in our brains, this study is a step in developing therapeutic drugs, with fewer side effects, that can help individuals whose brain disorders cause them to exhibit social behavior deficits.

“These deficits in social behavior profoundly affect these individuals’ quality of life and thus it is critical to understand the underlying abnormalities in brain function that cause the deficits in social behavior,” Malenka says.

But besides informing exciting therapeutic possibilities, oxytocin research gives us a much-needed look into the things that make the human experience a positive one.

“I would argue for the survival of the species, we need to delve into the brain mechanisms that facilitate and promote warmth and empathy toward our fellow human beings,” he says.

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