Aggressiveness can become a “transmissible” social behavior between (mice) males who know each other well: its neural trigger has been found.
Aggressiveness infects more easily, if we witness aggressive behavior in people we know well. A group of scientists from the southern university of Illinois (United States) studied the neural and environmental bases of aggressive behavior in the mice that had previously witnessed scenes of violence.
The research, published on the Jneuroscishows that being witnesses of episodes of aggression in friends and family has a-accounting effect that the aggression observed in simple strangers does not have.
Learn the worst
The researchers created an experimental setup that forced some male mice to observe family or unknown mice while attacking another “invader” mouse, which they did not know. They studied the aftermath that this experience had, on the aggression of the mice, half an hour later, and since only the rodents who had witnessed the attack by a family member showed themselves aggressive in turn.
Neural trigger
To mediate this reaction is a group of amigdala neurons, a crucial brain structure for the management of “primitive” emotions, such as fear and aggression. These neurons had already been recognized in the past as the “fuse” of triggers of repeated aggressive behavior: those caused by the trail of anger and frustration that remain on them after an aggressive first episode and that facilitate the repetition of an action of the same tenor. This group of neurons was active in the mice that had witnessed aggression in family members, but not in those who had seen it in strangers.
When the neurons in question were inhibited by researchers, no other episodes of aggression have occurred, even after observing known mice that behaved like bullies. When the “trigger” neurons were activated, even the mice that had seen violent strangers were later aggressive. The experiment provides an extra element of reflection on the episodes of aggressiveness learned, namely the fact that the proximity is not enough to ensure the contagion effect: violence is rampant above all if it is observed to perpetrate from those who know well.
