pavlov’s humans

Not unlike Pavlov teaching dogs to associate food with the sound of a bell, Jay Gottfried and colleagues from London’s Wellcome Department of Imaging Neuroscience have taught humans to associate pictures with peanut butter or vanilla. As reported in the Aug. 22 Science, 13 hungry human volunteers’ brains were scanned during and after a training session where abstract computer images were paired with the smell of peanut butter or vanilla. The researchers found that activity in the amygdala and orbitofrontal cortex — part of the brain’s reward center — went up for images associated with food scents. Then the volunteers ate as much vanilla ice cream or peanut butter sandwiches as they wanted, and their brains were scanned again to gauge their response to the same images: brain activity in the reward center decreased for the food just consumed, but stayed the same for the other. The study shows that not only can we mentally connect food to abstract images, but that our brains can dampen that connection when sated, a type of “brake system” to stop people from eating when full. The researchers speculate that a faulty brake system may be behind Kluver-Bucy syndrome, a brain disorder that makes people eat huge amounts, including even non-foods. Stated Gottfried in a press release, “You could conjecture that a similar thing may be going on in certain eating disorders, where the routine brakes on the whole system are tweaked somehow, so they’re no longer responding to normal cues.”

This news brief appeared in the Random Data column of the Boston Globe’s Health/Science section on 9/02/2003.