Research backs theory that insects' brain reward system activates pleasure centers
THURSDAY, Dec. 25 (HealthDay News) -- Give a foraging honey bee cocaine, and it will dance to reap and share the rewards of success, a new study says.
The finding, published in this month's issue of the The Journal of Experimental Biology, supports the theory of a reward system in an insect's brain and altruism in the bee world.
Cocaine affects the transit of octopamine, a neurochemical that's abundant in the brains of foraging honey bees. A previous study showed octopamine causes the bees to increase their dancing even when it is not warranted. Octopamine affects the reward systems in mammals, including humans, by influencing the chemically related dopamine system. Dopamine plays a role in the human ability to predict and respond to pleasure or reward.
Foraging honey bees perform a "round" or "waggle" dance in the hive when they have found high quality nectar or pollen when the hive is in need of it. The dance directs the other bees to find the food. Such an altruistic act, in people, excites the pleasure centers of the brain.
When treated with cocaine, the foraging honey bees are more likely to dance regardless of the quality of or need for food, the study authors reported.
"It's not like they're gyrating wildly on the dance floor out of control," study leader Gene Robinson, an entomology and neuroscience professor at University of Illinois, said in a news release issued by the school. "This is a patterned response. It gives distance information, location information. That information is intact."
It's just that bees are communicating about a food source they normally would ignore because of poor quality or lack of need. The cocaine causes the bees to dance more -- an altruistic behavior, which supports the researchers belief of a reward system in the insect brain.
The bees on cocaine do not dance every time they go foraging, and when they do dance, their movements are not distorted.
"This study provides strong support for the idea that bees have a reward system, that it's been co-opted, and it's now involved in a social behavior, which motivates them to tell their hive mates about the food that they've found," Robinson said.
In a separate experiment, the researchers found that withholding cocaine from honey bees on the drug caused them to experience withdrawal symptoms. This, along with the other findings, may mean honey bees would be good subjects for substance-abuse research, he said.
The U.S. National Institute on Drug Abuse has more about how the brain reacts to drugs.
-- Kevin McKeever
SOURCE: University of Illinois at Urbana-Champaign, news release, Dec. 23, 2008
All rights reserved