This is seen, for example, in the placebo effect, when simple sugar pills or inert salves taken by unwitting subjects are seen to ease pain or have some other beneficial physiological effect. How the brain processes this faked input and prompts the body to respond is largely a mystery of neuroscience.
Now, however, scientists have begun to peel back some of the neurological secrets of this remarkable phenomenon and show how the brain can be rewired in anticipation of sensory input to respond in prescribed ways. Writing in the current issue (March 1, 2006) of the journal Brain, Behavior, and Immunity, a team of University of Wisconsin-Madison scientists reports the results of experiments that portray the brain in action as it is duped.
The new work, conducted by a team led by UW-Madison assistant professor of psychology and psychiatry Jack B. Nitschke, tested the ability of the human brain to mitigate foul taste through a ruse of anticipation. The work, conducted at the UW-Madison Waisman Center using state-of-the-art brain imaging techniques and distasteful concoctions of quinine on a cohort of college students, reveals in detail how the brain responds to a manipulation intended to mitigate an unpleasant experience.
"There is a potent impact to expectancy," says Nitschke, who, with his colleagues, exposed 43 undergraduate subjects to potions of quinine, sugar water or distilled water while undergoing magnetic resonance imaging (MRI).
The subjects, Nitschke explains, were asked beforehand to associate a prescribed set of cues with a taste. A "minus sign" flashed through fiber optic goggles to subjects undergoing MRI, for instance, was to be an anticipatory signal that a liquid subsequently dripped into the mouth would have a very bitter taste. A "zero "cue corresponded with a neutral taste, and a "plus sign" with a pleasant
Contact: Jack B. Nitschke
University of Wisconsin-Madison