The Science of Attraction and Love: In Matters of the Heart, the Brain Reigns Supreme

— -- In matters of love, the conventional wisdom is to follow your heart. But you might want to consider following your brain instead this Valentine's Day.

When you meet The One, your brain releases a cocktail of three chemicals that make you fall in love, said Larry Young, a psychologist who studies love at the Emory University School of Medicine in Atlanta. The chemicals are oxytocin, dopamine and opiates, he said.

"All of those act together in the brain's reward system," he said. "Our reward system now becomes wired to be especially tuned to our partner -- the space, the sound, maybe the smell of our partner."

Oxytocin, not be confused with the drug oxycodone, is sometimes called the "cuddle hormone," and is responsible for the bonding between mother and baby and between partners.

Dopamine is involved in exhilaration and excitement, Young said. Cocaine and sex both cause the brain to release dopamine.

Opiates cause feelings of warmth and pleasure. Heroine and sex both cause the brain to release opiates.

"The next time we see the partner, our reward system is activated," Young said, adding that love can also be like addiction. "Once the bond is formed, we stay together not only because we're attracted to our partner but the other part because of the negative feeling when we're away from our partner."

Although humans rely less on pheromones to pick their mates than animals, scientists know that finding that special someone has something to do with chemicals that the person releases, said organic chemist George Preti, who works at the Monell Center in Philadelphia. But they haven't been able to isolate the specific attraction chemical, or pheromone, he said. They have, however, determined that chemicals produced in a man's underarms can alter a woman's neuroendocrine levels, which alter their menstrual cycles.

Romantic, right?

"We didn't study attraction," Preti said. "We studied something we could measure quantitatively."

The chemicals enter through the nose, but what happens next isn't entirely clear, Preti said. He said he thinks they enter the hypothalamus and the amygdala, two parts of the brain that deal with emotion, mood and sex drive.