[caption id="attachment_17368" align="aligncenter" width="500"] fMRI images show regions of the brain lighting up at thoughts of love or lust.[/caption] If the $2 billion Americans spend on online dating sites is any indication, most adults have no idea where to find love. Researchers at the University of Chicago don't know, either, but think they've found the part of the brain we use to make decisions about it. MRI and Functional MRI studies of the brain show that a particular segment of the cerebral cortex, called the insula or insular cortex, becomes active whenever patients are asked to think about or make decisions about loved ones. The anterior section of the insula, particularly, lit up when a patient's thoughts turned to love. (The posterior insula lit up when they thought of lust.) "We reasoned that if the anterior insula was the origin of the love response, we would find evidence for that in brain scans of someone whose anterior insula was damaged," according to University of Chicago neuroscientist Stephanie Cacioppo, lead author of a study called "Selective Decision-Making Deficit in Love Following Damage to the Anterior Insula," which was published in the current issue of Current Trends in Neurology. Even fMRI studies, which produce live images of activity in the brain while the patient remains conscious and is asked questions or shown pictures by researchers, only provide circumstantial evidence of what's actually going on. Previous studies identified the anterior insular cortex as being important to how the brain perceives the condition and position of the rest of the body (a process called interoception), while also implicating it in "a wide range of conditions and behaviours, from bowel distension and orgasm, to cigarette craving and maternal love, to decision making and sudden insight," according to a 2009 paper in Nature Reviews Neuroscience. Being able to tell for certain which parts of the insula were dedicated to bowel distension, and which to feelings of romantic love, would require that researchers find an ethically acceptable, temporary way to impair the function of a specific patient's anterior insula. A stroke that damaged the anterior insula of a 48-year-old Argentinian man provided the opportunity to help a patient recover from a serious stroke while testing the theory. Cacioppo's team rounded up a group of seven heterosexual Argentinian men with healthy anterior insular regions and were about the same age as the stroke victim. The patient and members of the control group were shown 40 pictures of attractive young women dressed in a variety of styles and were asked to say whether each was the object of sexual desire or love. The stroke victim responded just as quickly as the other men when the answer was "lust," but far more slowly when deciding he might feel love rather than lust about one of the women pictured. In a previous paper, Cacioppo et al. identified love as an intentional, intense, long-term longing for union with someone else and defined lust as sexual desire, or an intentional state of longing for a short-term pleasurable goal. "This distinction has been interpreted to mean that desire is a relatively concrete representation of sensory experiences, while love is a more abstract representation of those experiences," she said in a statement announcing the more recent paper. The anterior insula, she concluded, isn't the only part of the brain that makes decisions about love, but appears to play a key role in allowing the brain to access information about abstract emotions such as love. Knowing all this won't actually assist anyone in finding love, but should help other researchers come up with a model that will let them identify love from lust just by looking at the images of living brains and identifying patterns of neurological activity, indicating an abstract, long-term longing for connection rather than for something a little sweatier. Who says science isn't romantic?   Image: Chris Frum and James Lewis/West Virginia University; Robin Weiss/University of Chicago