Larry Young and Brian Alexander explain how heartache begins in the brain in The Chemistry Between Us

By Larry Young and Brian Alexander

Image: Current, a member of Penguin Group (USA), Inc.

Editor's Note: Neurobiologist Larry Young studies a monogamous species of rodent, the prairie vole, to understand the behavior and chemistry behind relationships. In The Chemistry Between Us, Young teams up with science journalist Brian Alexander to describe science's progress in illuminating the neurochemistry behind our experience of love. In this excerpt, the authors describe the work of neurobiologist Oliver Bosch, a specialist in maternal behavior, who worked with Young's prairie voles to study the bitter price of bonding.

Excerpted from The Chemistry Between Us: Love, Sex and the Science of Attraction, by Larry Young, PhD, and Brian Alexander, by arrangement with Current, a member of Penguin Group (USA), Inc., Copyright Larry J. Young and Brian Alexander, 2012.

To investigate the rodent version of getting hugs, and what happens in the absence of hugs from a bonded partner, Bosch took virgin males and set them up in vole apartments with roommateseither a brother they hadn't seen in a long time or an unfamiliar virgin female. As males and females are wont to do, the boy-girl roommates mated and formed a bond. After five days, he split up half the brother pairs, and half the male-female pairs, creating what amounted to involuntary vole divorce. Then he put the voles through a series of behavioral tests.

The first is called the forced-swim test. Bosch likens it to an old Bavarian proverb about two mice who fall into a bucket of milk. One mouse does nothing and drowns. The other tries to swim so furiously the milk turns into butter and the mouse escapes. Paddling is typically what rodents will do if they find themselves in water; they'll swim like crazy because they think they'll drown if they don't. (Actually, they'll float but apparently no rodent floaters have ever returned to fill in the rest of the tribe.)

The voles that were separated from their brothers paddled manically. So did the voles who stayed with their brothers and the voles who stayed with their female mates. Only the males who'd gone through vole divorce floated listlessly as if they didn't care whether they drowned.

"It was amazing," Bosch recalls. "For minutes, they would just float. You can watch the video and without knowing which group they were in, you can easily tell if it's an animal separated from their partner, or still with their partner." Watching the videos of them bob limply, it's easy to imagine them moaning out "Ain't No Sunshine When She's Gone" with their tiny vole voices.

Next Bosch subjected the voles to a tail-suspension test. This test uses the highly sophisticated technique of duct taping the end of an animal's tail to a stick and suspending it. As in the swim test, a rodent thus suspended will usually flail and spin his legs like a cartoon character who's run off the edge of a cliff. Once again, though, while the other males did just that, the divorced males hung like wet laundry.

Go here to see the original:
Love Hurts: Brain Chemistry Explains the Pangs of Separation [Excerpt]