Tuesday, February 02, 2010

Angry Flies are used in the Explain Human Aggression

Recently, biologist David Anderson set out to learn whether flies, like bees, can get angry--part of a broader effort to study how animal behavior relates to genetics.

"Every time you swat a fly away from your hamburger, it seems to come back to the food more aggressively or persistently," Anderson said. "People might wonder about whether there's such a thing as an 'angry' fly, but no one would challenge the idea of an angry bee--especially someone who's been stung by one."

To test his hypothesis, Anderson--who currently has two projects funded by the National Science Foundation (NSF) and who is a Howard Hughes Medical Institute (HHMI) Investigator at Caltech--created an experiment modeled after the traditional "bees-at-the-picnic-table" scenario using Drosophila, the common fruit fly (or more accurately, the vinegar fly).

"We developed the 'puff-o-mat' apparatus, with the idea of putting some fly food at one end, and then blowing the flies away from the food with a gentle puff of air every time they got close to it," he said. "Then we measured whether the flies became more agitated and approached the food more aggressively after experiencing this frustrating experience several times."As it turned out, they didn't even need the food.

"To our surprise," Anderson said, "simply blowing the flies off their feet several times in a row was sufficient to get them riled up. So we decided to focus on that--the agitation response--because it was much simpler to set up without the food, and without starving the flies. The part with the food never made it into the final paper," he added, referring to a study published in the journal Nature in early December, 2009.

The flies showed a primitive emotion-like behavior. Prompted by a series of brisk air puffs delivered in rapid succession, the flies ran around their test chambers in a frantic manner, and kept it up for several minutes. Even after the flies had calmed down, they remained hypersensitive to a single air puff.

The research showed that Drosophila produces a pheromone--a chemical messenger--that promotes aggression, and directly linked it to specific neurons in the fly's antenna. Anderson and his colleagues believe that the findings ultimately may be relevant to the relationship between the neurotransmitter dopamine and attention deficit hyperactivity disorder.
The brain of Drosophila contains about 20,000 neurons, and has long been considered a valuable system with which to study the genetic basis of learning, courtship, memory and circadian rhythms.

In recent years, Drosophila research has also been a powerful tool with which to study emotions. Most of the genes in the fruit fly are also in humans, including neurons that produce brain chemicals associated with several psychiatric disorders.

For example, in an earlier study, the researchers demonstrated how Drosophila hunkers down and stops moving in response to a steady wind--a sensory tool that could improve how the insects navigate during flight, and could help scientists learn more about the nervous system.
Anderson came to this field of research after amassing an impressive record studying the developmental biology of neural stem cells in mice. He decided he wanted to try something new. Switching scientific directions mid-career is always risky, it takes courage and a willingness to fail, but Anderson was game.

Resource http://www.nsf.gov/discoveries/

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