Your Brain On Love

Join science writer Kayt Sukel at SCI on Saturday for a special Cafe Scientifique presentation, "Your Brain On Love." Details at www.sciowa.org/brainonlove

Join science writer Kayt Sukel at SCI on Saturday for a special Cafe Scientifique presentation, "Your Brain On Love." Details at www.sciowa.org/brainonlove

Guest post by: Kayt Sukel, science writer and presenter of SCI's "Your Brain On Love"

Why is love so complicated?  Your brain may be to blame.

Helen Fisher, an evolutionary biologist from Rutgers University, hypothesized that there are three distinct yet intersecting brain systems that correspond to sex, romantic love, and long-term attachment (like a mother-child bond or the comfortable relationship you might see in a couple who have been married for sixty years). These three separate systems, she argued, could cover all facets of love: romantic, parental, filial, platonic, and that old bugger, lust.

Scientists have long known that the seat of the sex drive is the hypothalamus. When it is removed, folks lose all interest in sex, as well as the ability to perform sexually. This almond-size brain area is linked to the pituitary gland, which produces the hormones necessary to fuel the desire to "get it on."

Humans are more than just their sex drives, however. With romantic love, Fisher and her colleagues observed brain activity in areas outside the hypothalamus, including the right ventral tegmental area (VTA) and the right caudate nucleus. These are both part of the basal ganglia, a brain area connected to both the cerebral cortex and the brain stem. The basal ganglia, along with the hypothalamus and amygdala, is implicated in reward processing and learning. It’s a little like bribery: when we experience something that feels good, such as satiating our hunger, having a sexy romp, or spending time with the object of our affections, these areas of the brain give us a little extra boost to encourage us to do it again. If we are talking about deep emotional attachment, the ventral pallidum, a different part of the basal ganglia circuitry, is activated. All these areas are very sensitive to the neurochemicals dopamine, oxytocin, and vasopressin, which are thought to be pleasure-inducing and critical to forming pair-bonds in socially monogamous animals like prairie voles and Titi monkeys. But they each work a little differently.

The two regions that seemed most important to romantic love in Fisher’s research were the caudate nucleus and the VTA. These areas reside in what is called the "reptilian brain" — a cluster of subcortical regions near the brain stem that have existed since before we evolved to walk upright — and are strongly implicated in both reward processing and euphoric feelings. They are also part of an important dopamine-fueled circuit called the mesocortical limbic system, a pathway critical to motivational systems; unsurprisingly it’s a circuit that has been implicated in addiction. These study results led Fisher and her colleauges Arthur Aron and Lucy Brown to conclude that romantic love is not an emotion but a drive. According to Brown, "Love is there to help fuel reproduction, to help us psychologically by connecting with others. It is distinct, yet related to lust and attachment."

Think of it this way: Lust may be the simplest of the three hypothesized systems, an almost reflex-like process that keeps us getting busy. Certainly if it were a more involved process, we would not find ourselves so interested in individuals like Pamela Anderson in all her glory or, like one of my girlfriends who is too embarrassed to be named, totally hot for the ’s resident Lothario, Mike "The Situation" Sorrentino, right? At the same time, we also have a system for attachment. Feeling connected to someone is a rewarding behavior, hence that ventral pallidum activation; it is nice to have someone to come home to, even if you are no longer inclined to jump his or her bones 24/7. Somewhere in the middle is the romantic love system, connected to both lust and attachment. It hits on areas involved in attachment and lust, as well as those implicated in reward processing and learning. It is no surprise that romantic love feels good and helps us to bond with another person (and consequently promotes procreation).

"These brain systems often work together, but I think it’s fair to say they often don’t work together too," Fisher told me when I asked whether these three systems overlapped in other ways. "One might feel deep attachment for one partner, be in romantic love with another partner, and then be sexually attracted to many others. There’s overlap, but like a kaleidoscope, the patterns are different."

It is also possible that these systems work on a bit of a continuum: one’s physical attraction for a person can develop over time into romantic love and then into a deep-seated attachment. It might even work the other way: a good friend to whom you are deeply attached may one day, inexplicably, seem physically irresistible. A quick flick of the wrist, a change in circumstance or age, and that love kaleidoscope may offer you a completely different configuration. 

With these kind of systems in play, is it any wonder that love can drive us so crazy?

Kayt Sukel is a passionate traveler and science writer, she has no problem tackling interesting (and often taboo) subjects spanning love, sex, neuroscience, travel and politics. Her work has appeared in the Atlantic Monthly, the New Scientist, USA Today, Pacific Standard, the Washington Post, ISLANDS, Parenting, the Bark, American Baby, National Geographic Traveler and the AARP Bulletin. She is a partner at the award-winning family travel website Travel Savvy Mom and is also a frequent contributor to the Dana Foundation's many science publications.

Category: General SCI