Where dread registers in the brain
By LEE BOWMAN
Scripps Howard News Service
04-MAY-06
"The worst part of it is the waiting."
It's a sentiment shared in such varied circumstances as soldiers preparing for an assault to civilians bracing for a turn in the dentist's chair.
Now, for the first time, scientists using brain-imaging technology have locked on the corner of the brain that fills us full of dread as we anticipate pain or another bad outcome _ and often makes us act irrationally just to get it all behind us.
The research has applications for economic theory as well as for health and pain management. It found, perhaps not surprisingly, that the area of brain activity related to dread overlaps areas of the organ known to be associated with pain.
"Most people don't like waiting for an unpleasant outcome and want to get it over with as soon as possible," said Dr. Gregory Berns, an associate professor of psychiatry and behavioral sciences at the Emory University School of Medicine in Atlanta and lead author of the study, published Friday in the journal Science.
"The only explanation for this is that the dread of having something hanging over your head is worse than the thing that you're dreading. It is a commonplace experience, but standard economic models of decision-making don't deal with this issue," Berns explained.
"So, we decided to take a biological approach and see what happens in the brain that might cause people to make such rash decisions."
The study participants included 18 men and 14 women, ages 19 to 49. The volunteers had their brain activity monitored by a functional magnetic resonance imaging scanner. Each person received a series of low-voltage shocks to one foot, with different levels of intensity and time delays for each jolt.
Each participant was screened to determine his or her maximum pain threshold. While in the scanner, each person got a total of 96 shocks. But before each zap, the subject was told how painful the shock would be (as a percentage of the person's top threshold) and how long he or she would have to wait for it.
After the scanning, each volunteer was then given another round of shocks. He or she was given a choice between different intensity-delay combinations, with the choice always between more pain sooner or less pain later.
For instance, the choice might be 90 percent of the top jolt in three seconds, or 60 percent in 27 seconds. The degree to which an individual picked a higher voltage sooner served as an indicator of the dread he experienced from waiting.
Most volunteers _ 27 _ chose shorter delays more than half the time, indicating that they dreaded the wait. But nine participants dreaded the wait so much that they consistently were willing to take a lot more pain just to avoid waiting. Berns labeled these the "extreme dreaders." Those who disliked the delay but were more cautious about trading off to a worse jolt were dubbed the "mild dreaders."
In the brain scans, dread was found in areas of the brain's pain network linked to attention. That's significant, Berns said, because it suggests that dread is not as simple as fear or anxiety _ emotions controlled by different brain regions.
The mild and extreme dreaders had different patterns of brain activity associated with the pain. The extremes showed more intense and earlier activity in the attentional parts compared to the mild dreaders.
"The key factor seems to be that extreme dreaders devoted more attention toward the part of their body that was about to be shocked," Berns said. "Taken together, the anatomical locations of dread responses suggest that the subjective experience of dread that ultimately drives an individual's behavior comes from the attention devoted to the expected physical response, and not simply a fear or anxiety response."
As George Loewenstein, a researcher in human decision-making at Carnegie Mellon University in Pittsburgh, put it in an accompanying commentary: "The information that one is going to receive a shock, like the shock itself, seems to be a source of misery."
Although the time frames of seconds in the experiment may not be the same kind of interval that people normally take for making economic decisions, Loewenstein said it does challenge the economic tenets that people prefer to expedite things that are expected to have a pleasant outcome while deferring events they expect will be unpleasant.
Berns said the findings also show that dread can be lessened by diverting attention.
"The dread associated with things like medical procedures or public speaking, while real, can probably be alleviated by diverting one's attention during the waiting period," he said, citing tools that might range from meditation to exercise or even taking in a movie.
On the Net: http://www.sciencemag.org
(Contact Lee Bowman at BowmanL(at)SHNS.com. Distributed by Scripps Howard News Service, http://www.shns.com)
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