Poetically speaking, the heart usually takes the blame for our human propensity to face-plant into love. Sure, your ventricles may pump a hefty pulse of hemoglobin, but years of neuroimaging research show what lies above your aorta controls that sweetly sore longing to gaze into [insert name here]'s eyes.
Our brains are by-and-large responsible for hurtling us into consistently craving a certain someone. And a recent study from Concordia University finds that a specific group of structures within our cortical folds are uniquely geared to process these intensely passionate inclinations. Intriguingly, the study also finds that these regions are the same neuronal locales that process sexual desire.
Researcher Jim Pfaus and colleagues waded through 20 studies examining the brain activation patterns of subjects looking inside fMRI machines at either snapshots of significant others or at erotica. Pfaus was struck by the significant ties that lovin' feelin' shared with the circuitry of sexual desire—particularly the similar activation of the brain's insular cortex and striatum. These structures lit up when subjects looked at images of their loved ones as well as when subjects viewed suggestive photos or sultry videos. The difference lay in the the precise portion of these regions where the stimulation occurred. More posterior regions of the insular cortex, for instance, appeared to be involved in processing sexual desire, while more anterior regions appeared to respond more strongly when subjects ogled loved ones.
This parallels a number of studies that have found more abstract, "bigger picture" concepts, thoughts, and decisions to be represented towards the front of the brain. More concrete, immediate, or visceral inklings—i.e. horniness—tend to be localized deeper and towards the back.
The shared wiring between love and desire suggests that our more immediate urges provide the basis and roots for the development of longer-term connection. Pfaus likens this process to the steps of habit formation commonly attributed to substance abuse and other compulsive behaviors. "One could argue that addiction is really bonding, except to a drug," he says. "If you've broken up with someone, you know what a drug addict feels like—as far as withdrawal is concerned."
In the best of scenarios, Pfaus explains, desire initially prompts you to (at least attempt an) interact(ion) with another individual. If they reciprocate favorably, your brain registers the ensuing social (or, fingers crossed, physical) exchanges as rewards. Should things continue to go smoothly, you start solidifying what you'll later refer to as love, including that unique, fuzzy-feeling-inducing mental representation of your desired other—the way their lips curl in a smile, the cadence of their laugh, that mole on their back, the wrinkle between their eyebrows when they're pondering what to cook for dinner. Eventually, you'll likely develop some degree of possessiveness over this person, notes Pfaus. Plus, you start to behave in a very particular way with and around him or her.
While physical pleasure alone won't suffice to lock down that more lasting version of longing, it's certainly a start. "It's not just the ecstasy of an orgasm that leads you to the more abstract experience of being in love. It's the bonding mechanisms that come after," says Pfaus. Your conscious awareness of what you're feeling as love is born out of desire—where that went, and how it was reinforced." Basically what you're dealing with, he adds, is a brain-based system originally laid down for maternal bonding that just so happens to be similarly stimulated by sex, drugs, and pretty much anything else that evokes a sense of pleasure and connection (including but not limited to rock n' roll and cocoa puffs).
Most of the structures involved in processing sexual desire as well as love are also involved in mediating emotion and motivation, as well as integrating somatosensory feedback and visceral signals. Plus, they've been known to become active when we're picking up on social cues and mirroring other people's body language. So it makes sense that these key areas of the brain would also be involved in the initial tickle of desire, the development of attachment, and other fuzzy-yet-occasionally-frustrating feelings related to partners and potential pleasure.
One lesson we can learn from all of this: From the initial stages of sexual desire to the final hurdles of consistent commitment, love's many stages act on the brain like a drug. But that may not be a bad thing. Sure, the consequential release of chemicals can cause us to do things we wouldn't normally do under more rational circumstances (see: scary, scarier, amusing, accomodating). But this brain-based system of bonding is what enables us humans to connect, maintain social ties, and ultimately ensure our own survival.