Just Say No
If you can, that is. Caltech researchers are finding that people with self-control in the face of tempting treats experience different brain activity from the rest of us.
By Gary Dretzka 07/01/2009
It’s not the devil who demands picnickers ask for seconds and thirds, when they know full well the extra calories could add inches to an already overflowing waistline. Blame a previously uncharted region of the brain — the dorsolateral prefrontal cortex (DLPFC) — according to recent research by a team of Caltech scientists. When activated, the DLPFC modulates the more primal instincts of the stomach, heart and libido. When it fails to kick in, as is the case with people with low self-control, well, there’s hell to pay.
The full explanation is quite a bit more complicated than that, of course. For laymen, though, it’s a start.
“A very basic question in economics, psychology and even religion is why some people can exercise self-control but others cannot,” says Antonio Rangel, a Caltech associate professor of neuroeconomics. “From the perspective of modern neuroscience, the question becomes, ‘What is special about the circuitry of brains that can exercise good behavioral self-control?’ We studied this question in the context of dieting decisions and provided an important insight.”
Their findings, published in the May 1 issue of Science magazine, revealed that while everyone uses the ventromedial prefrontal cortex, or VMPFC, to make value-laden decisions, an active DLPFC allows people with good self-control to reject negative impulses. It allows them to weigh all factors when making a decision about, say, that extra helping of ribs, and override such basic urges as experiencing the taste.
Conversely, the research demonstrated that the study subjects who exercised little restraint in their food choices were also the ones whose DLPFC was the least active. The team was able to measure the activity in both regions using functional MRI technology.
“This was a completely new insight,” Rangel explains. “As neuroeconomists, our goal is to determine how the brain computes its way through different situations and how it implements activity. This study involved food, but it could have applications in any area where self-control is important.”
To make a long study short, around 40 volunteers who described themselves as dieters were shown photos of 50 foods, ranging from Snickers bars to cauliflower. The participants were asked to rate each food based on how good they thought that food would taste. Afterwards, they were shown the same slides again and asked to rate each food based on its perceived health benefits.
From each volunteer’s responses, an “index food” — roughly in the center of their own particular taste-health spectrum — was selected for that person. Using the index item as a median, the participants were asked to take another look at the same 50 photos and choose which one they’d prefer. Then they were required to eat some of foods they’d picked.
The researchers found that 19 volunteers demonstrated a significant amount of dietary self-control in their choices, preferring mostly healthy foods, regardless of taste. Eighteen members picked the tastier food, regardless of its nutritional value.
Those of you, who, right now, are considering running down to the local MRI clinic to check out your self-control modulators should know there are currently no remedies for a lazy DLPFC. Indeed, it may not even prove to be the primary factor controlling obesity and such addictions as smoking, gambling and unreasonable risk-taking.
“Unfortunately, we’re still a long way from a practical application for these findings,” Rangel said. “Diet and exercise remain the best ways to control weight.”
According to Todd Hare, a postdoctoral scholar in neuroeconomics and primary author of the Science paper, it might be possible to activate the DLPFC by making the health benefits of foods more obvious to consumers. “If we highlight the fact that ice cream is unhealthy just before we offer it,” he argues, “maybe we can reduce its value in advance, giving the person a head start in making a better decision.”
The study, co-authored by Colin Camerer, the Robert Kirby Professor of Behavioral Economics, was funded by grants intended to support “pure research,” not by pharmaceutical companies looking to turn fat into gold, Rangel noted.
As the picnic season is upon us, bon appétit to those of you with active DLPFCs. As for everyone else, you might want to put a little effort into skipping dessert.
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