Why do voles fall in love?

Like human fools, lovesick prairie voles are slaves to chemistry.

Let Cupid (or a grad student) hit the furry rodent with an arrow dipped in oxytocin, and bang, he's enraptured. Use a different dart, loaded with the antidote, and he couldn't care less.

The love drug for humans won't arrive in time for Valentine's Day, but it's coming, says Larry Young, Emory professor of psychiatry and director of the Center for Behavioral Neuroscience at Yerkes National Primate Research Center. "[R]ecent advances in the biology of pair-bonding mean it won't be long before an unscrupulous suitor could slip a 'love-potion' in our drink," he writes in a recent issue of Nature, a science journal. "And if they did, would we care? After all, love is insanity."

This is vintage Young. A compact, energetic 41-year-old who's been studying prairie voles for more than a decade, Young is adept at finding that place where human yearnings and hard science intersect. By studying the brain chemistry of pair-bonding in rodents, he's become the Dr. Love of the Emory campus, quoted not just in professional journals, but in newspaper stories, and on David Letterman's and Jay Leno's shows.

"What is lost in the [newspaper] stories," says Young, sitting in his modest office at the Yerkes center, "is that we're not looking for the neurochemistry of love, but the basic chemistry of social bonding." His desk is littered with transparencies showing slices of voles' brains. On a shelf is a bottle of "Fast Working Fidelity Spray." ("That's a joke," he says, "but it's not that far from reality.")

On his computer, one sees images of voles communing, cohabiting and caring for their young, and it becomes clear why Young studies voles to learn about affection and social behavior. Prairie voles are among the few monogamous mammals, a group that also includes marmosets and humans. Research traces bonding behavior in voles to the neurotransmitter oxytocin. Humans and voles both release the hormone during childbirth, lactation and sex. The chemical that promotes the mother-child connection also apparently prompts pair-bonding in certain species.

What Young demonstrates is that, in voles, the chemistry of pair-bonding can be played like a violin, turning the little creatures on and off at the flick of a peptide button.

Whether humans are equally mechanistic is the next big question. Other researchers are following that trail, demonstrating the chemical imperatives that control human behavior. For example, Young showed that some voles with a particular variant of the gene "avpr1a" tend to stay single. In Sweden, scientists have demonstrated that men with the same gene variant are twice as likely to remain single or, if married, twice as likely to report marital problems.

Brain chemicals definitely had an impact on Young's love life. He and his colleague, Anne Z. Murphy, associate professor of neuroscience at Georgia State University, met at a scientific conference in Italy. They married in 2005 --- second marriages each. Murphy, who studies differences in male and female sensitivity to opiates, is amused by the national press that her husband garners. "Love Doctor? Hey dude, if you're going to be the Love Doctor, I want to see some flowers," she jokes, "I want to see some chocolates."

His discoveries about love and bonding are tangential, Young says, to his research goal, "which is to understand the social brain: Why do we enjoy interacting with others? How do we possess social information? Because if we understand that, we may be able to understand what might be going wrong in disorders like autism or Asperger's syndrome."

A hallmark of autism is impaired social interaction and communication. Young envisions the use of oxytocin, or other neuropeptides, to help autistic children develop greater empathy and social cognition.

Some early studies with autistic patients are promising, he said, but "We have a long way to go."

The rest of us may also benefit from these advances. Young says he can imagine marital therapy enhanced with doses of oxytocin and vasopressin.

But the best love potions, he says, are the ones we manufacture right in our own brains. "The best way to maintain a good, loving, healthy relationship is to activate our own endogenous oxytocin and vasopressin system, our endogenous love cocktail, through natural behavior: hugging and kissing and sex."

IN YOUNG'S WORDS

On whether humans are simply large, biochemical computers: "I don't think it will come down to that. You don't think of computers as having free will, and I do think we have free will. That comes from the amazing complexity of the billions of synapses, billions of connections."

On the similarities of drug withdrawal and the lovesick blues: "Prairie voles, if you take away their partner, they show behavior similar to depression. It's almost as if there's withdrawal from their partner. I believe that evolved so that individuals will always be seeking out their partner, getting the fix they need, so they don't feel bad."

On whether humans are monogamous: "Without a doubt, humans do form very strong bonds with a single individual at a time. ... I do not think it is in our biology to stay with the same partner forever."

--- Bo Emerson

A VISIT TO THE LAB

There are no primates in Larry Young's lab at Yerkes National Primate Research Center, other than grad students and their ilk. He works with voles. The small rodents are housed separately from the radioactive dyes, microscopes and brain-slicing devices lining the shelves and cubicles where he and his colleagues look at brain receptors and measure DNA strings.

An ingenious software program remotely monitors several groups of the rodents, however, and digitizes their movements, analyzing and assigning values to their interactions.

On one shelf are jars of various sizes, holding the brains of a human, a dolphin, a chimpanzee, a rhesus monkey and a few other primates. (The dolphin brain is the largest.)

Grad student Meera Modi is looking at glutamates and other peptides that might facilitate long-term social learning. "Chocolate could work, too," Young quips.

Fellow grad student Todd Ahern is examining brain structures of voles to see how a vole raised by a single parent might develop differently than a two-parent vole.

Occasionally the entire group will take a trip to Young's South Georgia farm to eat barbecue, shoot guns and talk about neuroscience.

--- Bo Emerson

VOLES 101

> Mouse-sized, but stouter and rounder, voles are as cute as little furry buttons. There are several hundred at the Yerkes center, where their breeding population is replenished regularly with voles captured in the wild.

> Voles live two to three years and are generally monogamous. When the female goes into estrus, she and the male will copulate 30 to 40 times in a few hours, and the female will usually become pregnant within 24 hours, said Emory professor Larry Young. The two then nurture and raise their young together.

> Like humans, voles (both male and female) will stray, if separated from their significant other, but will return to their mates after the dalliance.

> And don't forget, "vole" is "love" spelled sideways.

--- Bo Emerson

CAPTION: RICH ADDICKS / raddicks@ajc.com Emory researcher Larry Young has studied prairie voles for more than a decade, but a pair of loving chimps in his office shows his sense of humor.

CAPTION: Yerkes National Primate Research Center Two voles are on a printout showing a schematic representation of their DNA. No, it's not their idea of romance, either.

CAPTION: ELIZABETH LANDT / Staff illustration

Credit: STAFF

Copy from: BO EMERSON. The Atlanta Journal - Constitution. Atlanta, Ga.: Feb 14, 2009. pg. E.1