Overwhelming feelings of wanting and liking.

• Position: YOUR LIFE - How our brains affect our human tendencies - Brief article

Wanting and liking are separate urges controlled by different cerebral circuits and, when combined at once, the impact on the brain is especially powerful, relate researchers from the University of Michigan, Ann Arbor.

The brain divides wanting and liking into separate circuits for the same sweet reward. Natural heroin-like chemicals (opioids) in a few brain "pleasure hot spots" make individuals want to eat more of a tasty sweet food, and make them like its sweet taste more when they eat it. The same thing happens with addictions to drugs, sex, gambling, and other pursuits involving "brain reward" circuits.

Researchers Kyle Smith and Kent Berridge show that two different brain circuits carry out the wanting and liking for the sweet reward, even when both are triggered in the same brain pleasure hot spots. "We typically want what we like, and like what we want," Smith explains, "but these results suggest that wanting and liking are processed by distinct brain circuits and may not always go hand-in-hand." Adds Berridge, "The brain seems to be more stingy with mechanisms for pleasure than for desire."

A single looping circuit between hot spots always...