By: Karl Leif Bates, UM College of Literature, Science, and the Arts
Monday, May 07, 2012
The pleasure we get from eating is less about the mouth and more about the mind.
A slab of double-chocolate cake, for example, triggers a cerebral hotspot, a little clump of neurons about two inches behind the nose, right in the middle of the brain.
This pea-sized area in the forebrain, not the tongue or palate, is the source of pleasure one derives from experiencing a fluffy fork-full of cake, says Kent Berridge, the James Olds Collegiate Professor of Psychology and Neuroscience in LSA.
"The pleasure of that sweetness and creaminess isn’t in the food itself, it’s in the brain," Berridge says.
We’re actually born with an innate sense of yummy and yucky. Scientists have studied how various taste samples are recognized by newborn infants, who smack their lips to sweetness but cringe in disgust at bitterness.
Starting from this basic set of preferences, taste rewards or aversions then change through a lifetime of learning and can be shaped by culture. That is to say, part of why you love chocolate cake is because your brain rewards you with a little tingle of joy every time you encounter it. Your brain wants you to repeat the experience. Who are you to say no?
"Taste is a natural key to pleasure," Berridge says. It triggers a thin circuit of connected hotspots in the forebrain that amplify the sensation by putting out neurochemical signals of pleasure, including opioids, orexins, and endocannabinoids. These are the rewards that become key to learning to like a particular food.
"In a sense, culture does what orexin does," he adds. Cultural cues, like everyone around the table oohing and aaahing over that first sip of 2007 Chateauneuf du Pape, can set the reward circuits to trip. "Reward circuits are very sensitive to learning."
"Neural systems paint the desire or pleasure onto the sensation as a sort of gloss painted on the sight, smell, or taste," Berridge says. (No word yet on sexual sensations, but the Dutch are working on it, he says.)
To read the entire news release, see the College of Literature, Science, and the Arts website at http://www.lsa.umich.edu/lsa/ci.letthemeatcake_ci.detail.