A region deep inside the brain dictates how quickly people make decisions about love, according to new research from the University of Chicago.
The findings stem from an examination of a 48-year-old man who suffered a stroke, which provided the first evidence that an area of the brain called the anterior insula "plays an instrumental role in love," said neuroscientist Stephanie Cacioppo, lead author of the study.
In a prior paper, Cacioppo and colleagues defined love as "an intentional state for intense [and long-term] longing for union with another" while lust is the desire for a short-term, pleasurable goal.
In the study, recently published in the journal Current Trends in Neurology, the patient's decisions about lust were unaffected, but decisions about love had a slower reaction time, when compared to neurologically typical participants matched on age, gender and ethnicity.
"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," said Cacioppo, a research associate and assistant professor in psychology. "The new data suggest that the posterior insula, which affects sensation and motor control, is implicated in feelings of lust or desire, while the anterior insula has a role in the more abstract representations involved in love," according to a press release announcing the findings.
In their earlier paper, "The Common Neural Bases Between Sexual Desire and Love: A Multilevel Kernel Density fMRI Analysis," Cacioppo and colleagues examined brain scans to note differences between love and lust.
The studies showed correlational evidence that the anterior insula was associated with love, and the posterior insula was associated with 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," she said.
In the current study, the 48-year-old stroke victim had suffered damage to the function of his anterior insula. He was matched with a control group of other similar men, each of whom had a healthy anterior insula.
"The patient and the control group were shown 40 photographs at random of attractive, young women dressed in appealing, short and long dresses and asked whether these women were objects of sexual desire or love. The patient with the damaged anterior insula showed a much slower response when asked if the women in the photos could be objects of love," according to the release.
"The current work makes it possible to disentangle love from other biological drives," the authors wrote.