We use the term "falling in love" even though the first giddy days of a new romance feel buoyant, free from gravity, as if some perfectly placed wind were boosting us skyward. That sense of becoming airborne is so unforgettable that, years later, we may recall it longingly and wonder why relationships now seem so bound-to-earth. We may even gaze on our partners with some dissatisfaction, measuring them against that lost intensity.

But the gleam of infatuation may be largely the product of unexpectedly potent brain chemistry. And the primary ingredient in that chemical brew is the neurotransmitter, dopamine. When you imbibe alcohol, for instance, the brain responds by releasing more dopamine. Cocaine also seems to stimulate a dopamine rush. And with that comes a high-flying sense of pleasure, power, concentration, a jazzed-up sense of energy.

Dopamine is an essential part of infatuation, says Fisher, who is now scanning the brains of wildly infatuated people. "Dopamine," she notes, "is already associated with euphoria, sleeplessness, loss of appetite, and a rush of motivation.

Fisher suspects that the dopamine high of first love is meant to be a merely transient pleasure. Fisher theorizes that different neurochemicals influence different stages of male-female relationships, which she categorizes as lust (driven mainly by hormones), attraction/ infatuation (dopamine), and attachment. As we move into attachment, long-standing relationships- it may be that serotonin or hormones, such as oxytocin, that are associated with nurturing behaviors become more important. For partners and parents, such stability is essential.

It is those who never grow out of infatuation, who remain obsessed with love, that may eventually become dangerous lovers or stalkers, for instance, On the other hand, Fisher's theory also holds hope for those who look back wistfully, wishing they could recreate those heady days of early romance. Fisher suspects that parenting, in particular, may suppress the dopamine spark in relationships.

Suddenly, dopamine is the target of research into happiness, attention, extroversion, self-confidence, and goal-direction. In addition, dopamine appears to influence attention and the ability to concentrate. But the most intense excitement among researchers is over the role of dopamine within the limbic system, a brain region that helps regulate emotions, basically, dopamine brightens and highlights our connections with the world around.

When our dopamine system is active, we are more positive, excited, and eager to go after goals and rewards, whether it's food, sex, money, education, or professional achievement. Dopamine also works in conjunction with serotonin, the neurotransmitter linked to tranquility, reason, and calm. The best-selling antidepressants on the market — the Prozac family keeps serotonin levels high. There's nothing Zen-like about dopamine however; it calls up breathless images like that of a teenager standing up in a plummeting rollercoaster car.
In short, there's much about the power of dopamine that we're still finding out.