16 January 2007

Pleasure chemical controls bee dance

Cosmos Online
The dance bees use to communicate flower locations is controlled by a relative of the brain chemical that makes humans feel happy, researchers say.
Pleasure chemical controls bee dance

When a honey bee finds a new flower patch, it gives other bees the location by performing a specific figure-of-eight pattern called a 'waggle dance'. According to researchers, the brain chemical that controls this dance is similar to the one that controls pleasure in humans. Credit: Wikimedia

CANBERRA: The dance bees use to communicate flower locations is controlled by a relative of the brain chemical that makes humans feel happy, researchers say.

After worker bees find a location rich with flowers, they fly back to their hive and report the find to other bees using a series of gyrations. Their dance tells other bees the direction and distance to the flowers and the quality of the patch. But until now, the brain chemistry underlying the dance remained a mystery.

A joint U.S. and Australian study published today in the U.S. journal Proceedings of the National Academy of Sciences suggests that a brain chemical called optopamine, closely related to the human reward and pleasure regulator dopamine, controls the bees’ judgment and expression of the patches’ quality.

“[This study] is the first step in exploring the neural basis of dance behaviour,” said lead author Andrew Barron from the Australian National University in Canberra. “It sets the stage for mining deeper into the neural mechanisms.”

The ‘waggle dance’ that the bee performs is a small figure-of-eight pattern. First, the bee runs forward, while shaking its wings and thorax. This is known as the ‘waggle phase’. The bee then turns left and runs back to the starting point. Again the bee goes through the waggle phase, this time turning right to return to its starting point.

The bee’s speed and vigour during the dance, as well as the number of times the figure-of-eight is performed, conveys the quality and location of the flower patch.

In the study, optopamine was given to North American and Australian bees either orally or by painting it directly onto their thoraxes. To analyse the effect on their dances, the researchers filmed the bees from the time they returned to their hive and played the footage back frame by frame.

Returning from the same patch, bees that had been given optopamine waggled more vigorously (indicating better patch quality) than bees who had not received the chemical, reported the paper.

As a result of the findings, Barron and his colleagues now believe that a reward system similar to the system found in mammalian brains must exist in honey bees.

In all mammals, including humans, when a reward stimulus such as food, safety or sexual gratification is experienced, the nerve cells in the middle of the brain release the chemical dopamine. The release of dopamine acts to reinforce the behaviour that led to the reward stimulus, helping the brain learn which actions are beneficial.

Some narcotics produce a pleasurable sensation by artificially stimulating the release of dopamine. The cravings associated with drug abuse can be caused by the brain learning to seek out this artificial dopamine release and the high that goes with it.

According to Barron’s theory, optopamine controls learning of reward in honey bees in the same way. If he’s right, honey bees may one day become test subjects for studies on drugs with the potential for abuse.

If a drug artificially stimulates the release of optopmine, the effects could be measured during the bees waggle dance: drugs that produce a more vigorous dance could be tagged as substances of concern.


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