Afterwards, it’ll taste less sweet.
Truly. Tell Mom that when people are fed good food until they’re full, and then asked to eat more, they say the food still has the same "quality" and "intensity," it just doesn’t taste as "good."
Mom’s proud of her cheesecake. She wants it to taste its best . . .
She still won’t let you eat it first? She says, Not before the broccoli quiche?
Then tell her this: Researchers in Penn State’s College of Medicine recorded the activity of the neurons in the part of a rat’s brain that processes both the "Tastes Good" signals from the tongue and the "I’m Full" signals from the gut. Previously, they and other researchers had found that if they put small amounts of fat into the rat’s duodenum (the part of the gut that drains the stomach), the rats would behave as if they had just eaten a full meal. They would refuse to drink a very tasty (to a rat’s tongue) beverage. So this time, the researchers did the same thing (put fat in the rat’s gut) while recording the taste responses in its brain.
For most taste sensations, there was no change before or after the "meal" of fat.
But the rat’s responses to sugar (sucrose) were much smaller than normal. In fact, the bigger the reaction beforehand (Hey, wow! Mom, is this cheesecake good!), the greater the decrease afterwards (Yeah, it’s okay. Maybe not as good as the last one you made . . .).
Andras Hajnal, the assistant professor of behavioral science who led the study, speculates that the largest neural responses to sweets (and these responses were also the most specific ones), might be the ones that signal the "goodness" of the sucrose. The smaller ones — the ones less affected by this artificial "I’m Full" feeling — might just allow the rat to distinguish one taste from another, for instance, the difference between sweetness and saltiness. If true, then taste may operate the same way in humans.
If I eat the quiche first, it’ll wreck the cheesecake, Mom. I won’t hardly even taste it. It’ll be, like, wasted . . .
—Nancy Marie Brown
Andras Hajnal, M.D., Ph.D., is assistant professor of behavioral science in the College of Medicine, Hershey Medical Center, 500 University Dr., Box 850, Hershey PA 17033; 717-531-8521; axh40@psu.edu. Kaoru Takenouchi, Ph.D., and Ralph Norgren, Ph.D., professor of behavioral science, collaborated on this study, which appeared in the Journal of Neuroscience, 19(16): 7182 - 7190. It was funded by the National Institutes of Health. Reported by Leilyn Perri, College of Medicine.
