Swedish researchers have successfully identified the neurons responsible for aggression in our brains. Based on these results, they were able to control the attacks of laboratory mice on each other.
Aggression is a behavior present in the human species since its arrival on Earth. But if it has long been established by science that this instinct is regulated by our brain, the mystery remains on the neurons involved in its activation. However, we now know a little more thanks to a new Swedish study published on May 25 in the newspaper Nature Neuroscience. According to researchers at the Karolinska Institute, the aggressiveness is put in place by a group of rarely studied brain cells, present in the ventral premamillary nucleus (PMv) of the hypothalamus.
By studying mice, the researchers found that the ones that reacted most aggressively when a new male arrived in their cage had more active PMv cells than the others. By simulating the latter using optogenetics, a technique that makes neurons sensitive to light by combining genetic engineering and optics, scientists have succeeded in generating aggression in situations where animals do not attack. not normally. On the contrary, by inhibiting the PMv cells, they were able to interrupt the attacks in progress.
In mice, the main purpose of the attacks is to determine the strongest member of the group and thus establish a hierarchy, explain the scientists in their study. Also, by inhibiting the PMv cells of a dominant male and simulating those of a submissive male, it is possible to reverse the hierarchy in the medium term.
“Fundamental biological knowledge on the origins of aggression”
“One of the most surprising results of our study was that the role change we achieved by manipulating PMv activity during a meeting lasted up to two weeks,” notes study leader Christian Broberger . Because, “we also found that the brief activation of the PMv cells could trigger a prolonged explosion, which could explain something that we all recognize – how, after a quarrel, the feeling of antagonism can persist for a long time”, adds Stefanos Stagkourakis, co-author of the study. Another discovery and not the least: PMv cells could also activate other regions of the brain such as reward centers.
This study is capital since it “provides fundamental biological knowledge on the origins of aggression”, welcome the researchers. “Aggressive behavior and violence cause injuries and mental trauma in a lot of people,” says Dr Broberger, who hopes to eventually be able to put in place strategies to help people better manage their aggression.
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