Mirror neurons responsible for aggression found in mice

Scientists at Stanford University have found mirror neurons in mice that are located in the “rage center” part of the brain and are activated during a fight or when watching a fight. This is reported in an article published in the journal Cell .

Previous work by scientists has shown that aggression in male mice is associated with the accumulation of brain cells in part of the ventromedial hypothalamus. These neurons could activate aggression, but also turned out to be sensitive to socialization – mice kept together with relatives were less aggressive.

Using precise imaging techniques, the researchers captured activity in the rage center of male mice participating in the fight and those animals that were witnesses to the fight. The discovery of mirror neurons in mice came as a surprise, as these cells had previously been found in the primate cerebral cortex.

In addition, mirror neurons associated with aggression were activated in observers only at the sight of a fight, while in fighting mice they were activated by the smell of pheromones. Mirror neurons fired only when the observer was facing the fighters, and not when he was looking the other way. When the researchers turned off the lights, the observers’ mirror neurons were completely unresponsive to noise in the neighborhood. Also, a similar phenomenon was observed in mice that had never before observed a fight and did not show aggression.

When mirror neurons were overactivated, mice exhibited indiscriminate aggression. Not only did they initiate three times as many attacks on males as usual, they even attacked females with whom they usually mated playfully. According to the scientists, the results may indicate that mirror neurons could potentially be responsible for manifestations of aggression in humans as well.