In a general way, most people think of love as living in the heart. And why not, when being with a person you love causes your heart to beat faster, and breaking up with a person you love makes your chest hurt? Science, however, tells us that love lives not in the heart but in the brain. And when I say brain, I do, in fact, mean the blood-and-guts organ between our ears. In fact, thanks to functional magnetic resonance imaging (fMRI) techniques, we even know where in the brain this wonderful emotion resides.
One neurobiological study of people who said they were "intensely in love" compared test subjects' brain activity as they viewed photos of their beloved interspersed with photos of familiar but not beloved individuals, to see how the brain reacts to love versus a neutral stimulus. Later, other scholars replicated that study, but they did so with pornographic imagery tossed into the mix. This research was done in an attempt to separate physical attraction (sexual arousal) from romantic connection (love). Taken together, these studies give three primary findings:
1. Sexual attraction/arousal consistently activates the dopamine-rich nucleus accumbens, which is sometimes referred to as the brain's "pleasure center."
2. Intense feelings of love also consistently activate the nucleus accumbens, creating a sensation of pleasure.
3. In addition to the brain's pleasure center, intense feelings of love activate regions of the brain that "give value" to life-sustaining activities (to make sure we continue to engage in them). Sexual attraction/arousal without love does not activate these other parts of the brain.
This means that our brains view love not only as pleasurable but also as a life-sustaining necessity, while sexual arousal merely gives us pleasure. As such, people who are strongly in love feel a powerful desire to be with their beloved because it gives them pleasure and because their brains are actually telling them this is part of the human survival process. This is also why we can feel real, physical pain after a breakup with someone we truly love. Basically, the "value" parts of our brain cause our bodies to react to the loss of love in a way that reminds us how important it is.
So, how can we accurately define love? Perhaps we could state that love is a pleasurable feeling that our brain values more than most other pleasurable feelings. For instance, eating a chocolate ganache gives us pleasure, but our chests don't ache when the treat is gone because our brain doesn't place the same value on chocolate as on love. So perhaps the 1970s rock band Sweet got it right when they sang, "Love is like oxygen." As with oxygen, without love we ultimately can't survive.