The Brain Signature of Love

by Kayt Sukel

February 10, 2011

Study the literature of the world and you will find one theme that transcends both time and culture: that of love. Whether you are reading Shakespeare or Rumi, the manner in which love is described shows remarkable similarity. Those similarities go far beyond the page: Neuroscientists are now demonstrating that romantic love is also represented by a unique pattern of activation in the brain.

The neuroimaging of love

In the past six years, several groups of researchers have sought to localize romantic love in the brain using functional magnetic resonance imaging (fMRI) techniques. Though some have criticized the attempt as nothing more than modern day phrenology, those who seek the neural correlates of love believe it an essential avenue of study.

“The study of love is important so we might bring some rationality to a complex and emotional phenomenon,” says Stephanie Ortigue, a neuroscientist at Syracuse University. “These studies allow scientists to show that love is not a drug or a pathology but something that has a unique signature in the healthy brain.”

In the November 2010 issue of The Journal of Sexual Medicine, Ortigue and colleagues published a meta-analysis of the six fMRI studies looking at both romantic and maternal love to date.

“We put together all the studies on love that had been done in fMRI to see if there was any consistency and reliability in the findings,” says Ortigue. “We found there was one common brain network specific to love regardless of the different conditions and populations used in the different studies. So we can confirm, yes, love really exists in the brain. There is scientific proof.”

The group found twelve distinct brain areas across these love studies and hypothesized that all were part of a global neuroanatomical network involved with the feeling, act, and expression of love. Most of these areas were in the sub-cortical portion of the brain, including the ventral tegmental area, caudate nucleus, and hypothalamus, with tissues rich with dopamine and oxytocin receptors. But the group also demonstrated that cortical brain regions involved with social cognition and self-representation were involved, too.

Love knows no boundaries

Semir Zeki, a professor of Neuroesthetics at University College London, was the first to publish a neuroimaging study of romantic love, back in 2005. In the years since, he has continued to study love and the brain. His most recent study, published Dec. 31, 2010, in the journal, PLoS One, compared cerebral blood flow of passionate love in both male and female participants, as well as heterosexual and homosexual ones.

“Love is often written about in literature,” says Zeki, also a member of the European Dana Alliance for the Brain. “When you read these texts, you see it is irrelevant if the author was a man or a woman, or heterosexual or homosexual. The same sentiments have been appropriated to express love. No matter whom you are or whom you love, it all comes back to the idea of being united through love.”

Zeki and his colleague John Paul Romaya measured brain activation while participants viewed photos of their significant other as well as an age-matched acquaintance. The researchers replicated their original romantic love study, demonstrating significant activation in a core group of brain areas including the caudate nucleus, putamen, ventral tegmental area, and the hypothalamus. They also replicated a signification deactivation of the frontal cortex. What they did not find was a significant difference in activation patterns between the two genders or between heterosexual and homosexual groups. This led the duo to conclude that the experience of love is universal, regardless of one’s sex or sexual orientation.

Love can last

Not only is love a universal phenomenon but it is also one, in some people at least, that can stand the test of time. Most of the early studies on romantic love focused on the early days of relationships in order to best tap into passionate feelings and behaviors. It was unknown, however, whether the same patterns of love-related brain activation would be seen in couples involved in long-term relationships.

“It’s an age-old question: going back to ancient times, people have wondered whether love can last,” says Bianca Acevedo, a researcher at Stony Brook University. “Even now that relationship research has really started to blossom, people have very different ideas about whether it can or not.”

In a study published in the January issue of Social Cognitive and Affective Neuroscience, Acevedo and colleagues offer evidence that couples can remain passionately in love even decades into their relationship. The group also measured cerebral blood flow as participants viewed photos of their long-time partners as well as opposite sex friends they’d known for about the same length of time. The scientists found no significant differences between people who are newly in love with those who claim to still be passionately in love after many years together.

“Seeing that people who are intensely in love after many years show a pattern of activation that’s similar to individuals who are newly in love confirms the idea that love has a unique pattern in the brain,” says Acevedo. “It also tells us something more—it tells us about what attachment looks like in the brain and confirms the idea that there are overlapping biological systems used for parent/infant bonds and romantic ones.”

The future of love

Ortigue is very optimistic about the fact that different research groups continue to replicate fMRI results concerning where love resides in the brain. Still, she cautions that a lot more work is necessary to understand how that global neuroanatomical network actually works not only in romantic love but other forms, such as parental love. Zeki concurs.

 “There is a huge amount to cover in the study of love,” says Zeki. “We now have an idea of where love resides in the brain, but need to study it at the molecular level and understand how chemicals like oxytocin, vasopressin, and serotonin are working. And, with such a high divorce rate in Western societies, it would be a good thing to understand how love might change, what happens to those chemicals over time or with other factors. There is still a great deal of work yet to be done.”