Biology: Your Brain In Love

What goes on in your head when you fall madly in love? One scientist decided to find out. In an exclusive book excerpt, she lays bare the physiology of passion

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Martin Parr / Magnum

Have you just fallen madly in love? Thus began the announcement I posted on a bulletin board for psychology students on the Stony Brook campus of the State University of New York. I had come to believe that romantic love is a universal human feeling, produced by specific chemicals and networks in the brain. But exactly which ones? Determined to shed some light on this magic, I launched a multipart project in 1996 to collect scientific data on the chemistry and brain circuitry of romantic love.

My working hypothesis was that three related chemicals in the brain — dopamine, norepinephrine and serotonin — play a role in romantic passion. I speculated that the feelings of euphoria, sleeplessness and loss of appetite as well as the lover's intense energy, focused attention and increased passion in the face of adversity might all be caused in part by heightened levels of dopamine or norepinephrine in the brain. Similarly, I believed that the lover's obsessive thinking about the beloved might be due to decreased brain activity of some type of serotonin. I also knew these three compounds were much more prevalent in some brain regions than in others. If I could establish which regions of the brain become active while one is feeling romantic rapture, that might confirm which primary chemicals are involved. Perhaps these data would help explain the evolutionary roots of romantic love, why we choose one person rather than another, even how people can find and sustain this glorious passion.

My Plan
After a conversation with a neuroscientist at the Albert Einstein College of Medicine, I developed a scheme. I would collect data on brain activity while love-smitten subjects performed two separate tasks: looking at a photograph of his or her beloved and looking at a "neutral" photograph of an acquaintance who generated no positive or negative romantic feelings. Meanwhile, I would use a functional magnetic resonance imaging (fMRI) machine to take pictures of the subject's brain. The fMRI machine records blood flow in the brain. It is based in part on a simple principle: brain cells that are active use more blood than quiescent brain parts in order to collect the oxygen they need to do their job. I had already invited Lucy Brown, a neuroscientist at the Albert Einstein school, to interpret the scanning results. But I had one concern about the design of the experiment. I knew that lovers have a hard time not thinking about their beloved. I was afraid that the lovers' passionate romantic thoughts, generated as they looked at the photo of a sweetheart, would carry over and contaminate their passive thoughts as they looked at the neutral photo. Art Aron, a research psychologist at SUNY Stony Brook, who joined our team, along with graduate students Deb Mashek and Greg Strong, recommended that we use a "distraction task," a standard psychological procedure to wash the brain clean of emotion. We settled on a particular "distraction task" that amuses me to this day. Between looking at the photo of the sweetheart and the photo of a boring acquaintance, subjects were shown a large number (like 8,421) on the screen and asked to mentally count backward in increments of seven. The point: to cleanse the mind of strong feelings.

The Experiment
Now we were ready to gather our subjects, using word of mouth and the HAVE YOU JUST FALLEN MADLY IN LOVE? poster. Just and madly were the operative words. We sought only candidates who were so intensely in love that they could hardly eat or sleep, people whose romantic feelings were fresh, vivid, uncontrollable and passionate.

They were not difficult to find. Students immediately began to call Aron's psychology lab to volunteer. Mashek weeded out those who had metal in their heads (such as lip, tongue or nose jewelry or braces on their teeth) that would affect the magnet in the fMRI machine. She also excluded those who were claustrophobic, those taking medication that could affect brain physiology, and men and women who were left-handed. Brain organization can vary with handedness, and we needed to standardize our sample as much as possible.

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