Dr. Joe Z. Tsien, co-director of Georgia Health Sciences University's Brain & Behavior Discovery Institute, says eating chocolate or falling off a building -- or just thinking of either -- can evoke production of dopamine, a neurotransmitter that can make the heart race and motivate behavior.
The finding, published in the journal PLoS One, may help explain the "thrill" of thrill-seeking behavior or maybe just the thrill of surviving.
In a study using mice, the researchers looked at dopamine neurons in the part of the brain related to reward motivation or drug addiction. They found all the cells had some response to good or bad experiences while a fearful event excited about 25 percent of the neurons -- spurring more dopamine production.
"We have believed that dopamine was always engaged in reward and processing the hedonic feeling," Tsien says in a statement. "What we have found is that dopamine neurons also are stimulated or respond to negative events."