Reward Cues Turn Repulsion into Desire, Study from University of Michigan Confirms

Who would have guessed that you can actually turn feelings of disgust into feelings of desire?

Feelings such as hunger, thirst, stress and drugs can create a change in the brain that transforms a repulsive feeling into a strong positive "wanting," according to a new University of Michigan study.

Using salt appetite, the research showed just how powerful natural mechanisms of brain desires can be instantly cued to always predict a repulsive Dead Sea Salt solution into an eagerly wanted beacon or motivational magnet.

Mike Robinson, a research fellow in the U-M Department of Psychology and the study's lead author, said that the findings help explain how related brain activations in people could cause them to avidly want something that has been always disliked.

This motivation is based on the ability of events to activate particular brain circuitry-a structure called the nucleus accumbens, which sits near the base of the front of the brain and is also activated by addictive drugs.

These cues for rewards can often trigger intense motivation, such as the smell of food making a person feeling suddenly hungry when they may not be or were not so earlier. Drug cues may also prompt relapse in addicts trying to quit. In some cases, desires may be triggered even for a relatively unpleasant event.

In a study, researchers looked at how rats responded to metal objects that represented either plesant sugar or disgustingly intense Dead Sea saltiness. The rats soon learned to jump on and nibble the sweetness cue, but avoided and turned away from the saltiness cue.

However, one day the rats woke up by a new state of sodium appetite induced by drugs given to them the night before, and on the first chance when introduced to the saltiness cue, they jumped on it and left the sugar cue.

"The cue becomes avidly 'wanted' despite knowledge the salt always tasted disgusting," Robinson said.

The sudden brain changes help explain how an event, such as taking an addictive drug, could become "wanted" despite a person's knowledge of the negative and unpleasant consequences of the drug.

"Our findings highlight what it means to say that drugs hijack our natural reward system," said Robinson, who authored the new study with Kent Berridge, James Olds Collegiate Professor of Psychology and Neuroscience.

The findings appear in the current issue of Current Biology.