Ever fallen madly in love? Researcher Helen Fisher has spent her academic life trying to figure out what's going on in the brains of those who are in the heady, butterflies-in-the-stomach throes of passionate romantic love. Fisher has scanned the brains of young paramours and found that when they're focusing on the object of their affection, a whole host of brain parts start lighting up. One of the two most important regions was initially a little surprising to Dr. Fisher. First, she found that the caudate nucleus—part of the primitive reptilian brain—is highly active in these amorous individuals. As expected, she also saw the brain areas associated with dopamine and norepinephrine production light up. Both are brain chemicals associated with pleasurable activities and excitement.Fisher puts it best when she says, "No wonder lovers talk all night or walk till dawn, write extravagant poetry and self-revealing e-mails, cross continents or oceans to hug for just a weekend, change jobs or lifestyles, even die for one another. Drenched in chemicals that bestow focus, stamina and vigor, and driven by the motivating engine of the brain, lovers succumb to a Herculean courting urge."