Cell Circuitry Can Explain Aggression, Scientists Find

A study done with fruit flies could explain how aggression is controlled in the brain.

Fruit fly

You have more in common with flies than you thought. Photo via Shutterstock

For those of you who thought aggression was just a personality trait, not so fast. Harvard Medical School researchers have identified cell activity in fruit flies that they believe causes and regulates aggressive behavior, findings they believe could someday be applied to humans.

The researchers, who published their findings in the journal PNAS, observed the dopamine-producing (dopaminergic) neurons of 200 genetically engineered fruit flies as the flies acted out different types of behaviors, including aggression. Dopaminergic neurons were chosen because dopamine is a neurohormone closely associated with behaviors and how organisms act. Eventually, the researchers identified two sets of dopaminergic neurons that were connected to aggressive behaviors and traced those neurons back to the central complex of the fly’s brain, leading them to hypothesize that this part of the brain controls aggression. A report from Harvard quotes Edward Kravitz, a professor or neurobiology and the senior author of the study:

“We don’t know how complex this modulatory circuit is, but we now have a key element of it. If we eliminate or increase the function of that dopaminergic neuron, it affects the circuit of the brain responsible for controlling aggression,” Kravitz said.

And though it seems impossible that research done in fruit flies could have any bearing on humans, the Harvard report says that flies actually have many neurological similarities to humans and it’s conceivable that a similar process could be happening in our brains, too. This parallel means the results could be used to better understand people with aggression problems and find ways to more effectively target therapies. The Harvard article says:

The goal will be to establish fundamental principles for how dopaminergic neurons work in the fruit fly system, with the hope that the research will one day translate to how these neurons work in higher species. This may ultimately aid in the development of new dopamine-targeted medications for humans.

“We can now relate these two pairs of neurons specifically to one behavior, and that is aggression,” Kravitz said. “That means we have one piece of the puzzle.”