Thursday, Jul 24, 2008
New advances in neuroscience are explaining why people just do it, exactly as they're told to, when that commercial comes on.
Sep 30, 2002 | Pity the poor overstuffed couch potato, little suspecting that his latest turn of appetite is not the true call of hunger but a hijacking of his brain's circuitry from afar. While he waits for his favorite rerun to air, a fast-food commercial shows him images of moist, steaming meat; crisp, glistening vegetables; and taut strands of melted cheese. A cascade of neurotransmitters is set off in an ancient part of his brain, and his food cravings reawaken.
Several decades into the era of consumer capitalism, the whiz kids on Madison Avenue have learned fairly well how to attach psychic puppet strings to our minds, but they have never really known why (or often whether) their tricks worked. Enter the age of neuroscience. As investigators plumb ever deeper into the strange dynamics of the brain, they are shedding new light on many domains of human behavior, including mental illness, violence, cooperation, addiction, eating and even aesthetics.
Stock assertions like "People buy designer clothes because it makes them happy" or "Americans are overweight because they're weak-willed" are not real explanations. There are deeper reasons why comely pop stars make us desire a certain brand of fill-in-the-blank, or why billboards coax us off the expressway and into a drive-through.
"The mainstream economic theory behind advertising is just horrible," says Caltech behavioral economist Colin Camerer. "For some reason economists are reluctant to accept the idea that advertising makes you want to buy something you didn't necessarily want before ... Some of this new evidence from neuroscience could be very powerful in overturning that kind of silly, narrow conception."
Take the case of the hunger-struck couch potato. A recent brain-imaging study sheds light on the mechanism that makes the mere presence of food alluring. When people were allowed to see and smell their favorite chow, a deep-lying brain structure called the dorsal striatum was activated and the subjects reported feeling hungrier. Notably, this neural circuit was different from the pleasure pathways that are tickled when people actually get to eat.
"The dorsal striatum is being linked to addiction formation and to things that you learn and do almost uncontrollably," says Nora Volkow, the neuroscientist at the Brookhaven National Laboratory who led the study. "When it's active, it creates a very strong drive to consume food. This is a reason why [fast food] advertisements are so compelling, and why we are having an epidemic of obesity in this country."
The job of the dorsal striatum is to enhance the desirability of food automatically, says Volkow. Though it sits right next door to one of the brain's most important pleasure centers, it is not itself a generator of warm, fuzzy feelings. Indeed, being hungry in the presence of forbidden food is distinctly unpleasurable.
What this and similar research implies is that, contrary to how it may feel, the reward of eating is not the sole, perhaps not even the primary, thing motivating us to stuff our faces. The dorsal striatum draws us to food (and other objects of our addiction) in the first place, says Volkow, even when we are not hungry.
"This system was once very important for survival," she says. "It was important to want food whenever you could get it, because you never knew when it was going to be around.
"But now with refrigerators and 7-Elevens all over the place it doesn't serve any purpose anymore. Individuals are being constantly exposed to food stimulus. In an almost reflexive way, people's brains are responding to these signals, generating a biochemical change and a motivation to eat."
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