This Is Your Brain on Love

By Susan Brink
Los Angeles Times, July 30, 2007

Edited by Andy Ross

Science is just beginning to parse the inner workings of the brain in love, examining the fall from a medley of perspectives: neural systems, chemical messengers, and the biology of reward.

In 2000, two London scientists selected 70 people, all in the early sizzle of love, and rolled them into a functional magnetic resonance imaging scanner, or fMRI. The images they got are thought to be science's first pictures of the brain in love. The pictures showed that romantic love is a lot like addiction to alcohol or drugs.

The dance that leads, if we're lucky, to a stable commitment moves through several key steps. First comes initial attraction, the spark. Next comes the wild, dizzying infatuation of romance. The brain uses its chemical arsenal to focus our attention on one person, forsaking all others.

The passion lasts at least for a few months, two to four years tops, says relationship researcher Arthur Aron, psychologist at the State University of New York at Stony Brook. As it fades, something more stable takes over: the steady pair-bonding of what's called companionate love.

For years, scientists have known that attraction is more likely to happen when people are aroused. "People are more likely to feel aroused in a scary setting," Aron says. "It's pretty simple. You're feeling physiologically aroused, and it's ambiguous why. Then you see an attractive person, and you think, Oh, that's why."

Key to this state of seeing a person as a soul mate instead of a one-night stand is the limbic system, nestled deep within the brain between the neocortex and the reptilian brain. Altered levels of dopamine, norepinephrine and serotonin wield their influence.

But people in the early throes of passionate love can think of little else. They describe sleeplessness, loss of appetite, and feelings of euphoria. Brain areas governing reward, craving, obsession, recklessness, and habit all play their part.

In an experiment published in 2006, Helen Fisher, an evolutionary anthropologist at Rutgers University who studies human attraction, found 17 people who were in relationships for an average of seven months. She put these lovesick, enraptured people in an fMRI to see what areas of their brains got active when they saw a photograph of their beloved ones.

"We found some remarkable things," she said. "We saw activity in the ventral tegmental area and other regions of the brain's reward system associated with motivation, elation and focused attention." It's the same part of the brain that presumably is active when a smoker reaches for a cigarette or when gamblers think they're going to win the lottery.

Lucy Brown, professor of neuroscience at the Albert Einstein College of Medicine, has also taken fMRI images of people in the early days of a new love. In a study reported in 2005, she too found key activity in the ventral tegmental area. "That's the area that's also active when a cocaine addict gets an IV injection of cocaine," Brown says. Your ventral tegmental area uses chemical messengers such as dopamine, serotonin and oxytocin to send signals racing to a part of the brain called the nucleus accumbens with the good news, telling it to start craving.

Biologically, the cravings and pleasure unleashed are as strong as any drug. Surely such a goal is worth taking risks for, and other alterations in the brain help ensure that the lovelorn will do just that. Certain regions, scientists have found, are being deactivated, such as within the amygdala, associated with fear.

Sooner or later, excited brain messages reach the caudate nucleus, a dopamine-rich area where unconscious habits and skills are stored. The attraction signal turns the love object into a habit, and then an obsession. According to a 1999 study in the journal Psychological Medicine, people newly in love have serotonin levels 40% lower than normal people do, just like people with obsessive-compulsive disorders.

The front brain certainly gets involved as it ponders all of life's experiences and past mistakes, but not just the front brain. The nucleus accumbens holds memories. Its quest for reward is influenced by childhood experiences, friends, or previous failures.

Love's rush can happen at any age, whether people are 20 or 70, says Elaine Hatfield, psychology professor at the University of Hawaii and relationship researcher. But the older people get, the more memories they harbor of joy and trust, rejection and disappointment. And the front brain probably gets a greater say.

AR  (2007) Ah, sweet science! As love object, it beats the inconstant female of the species any day. Pity about its utter failure on the more urgent matter of slaking raw lust.