Specific neurons may cause male aggressiveness

Scientists have managed to identify certain neurons in the brain that could evoke sense of aggressiveness. This could mean that problems associated with aggression could not be understood better and perhaps prevented they hope.

Image Credit: AFPics / Shutterstock

Image Credit: AFPics / Shutterstock

The results of this study titled, “A neural network for intermale aggression to establish social hierarchy,” appeared in the latest issue of the journal Nature Neuroscience.

The researchers were studying aggressive behavior in animal kingdom that translates into humans as well. This aggressive behavior begins as school yard conflicts and occurs in large scales in global warfare. They delved into the brains of animals to seek out centres that control such aggression.

The team of researchers found that there was a group of neurons in the ventral premammillary nucleus (PMv) of the hypothalamus in the brain. The hypothalamus is one of the key zones in the brain that controls several basic functions of the body. These groups of neurons in the hypothalamus are found to play an important role in initiating as well as organizing aggressive behavior.

Lead author Christian Broberger from the Karolinska Institutet in Sweden explained that aggression and violence can lead to long term injury as well as mental trauma in people. It has financial connotations for the society and community as well he added. This study, he explained, adds to the knowledge about the origins of such aggression.

For this study the team looked at ventral premammillary nucleus neurons in mice models in the labs. The aggressive behavior of the mice could be controlled using stimulation and inhibition of the neurons in this region of the brain they find.

They activated these neurons in some mice. When a new male mouse was introduced into the cage, the activated mice showed aggression. The stimulation of these neurons was done using optogenetics – or use of light to control their switches.

By switching off these PMv using lights, the team could successfully abort an ongoing attack. They experimented by inhibiting these cells in a dominant male and switching them on in a submissive male.

The hierarchical status of the two mice were reversed, they noted. Broberger explained that this was a “role switch” that could be seen with the PMv cell manipulation.

The team noted that these neurons could specifically activate other regions of the brain as well. This included the reward and pleasure centres.

Stefanos Stagkourakis from the Karolinska Institutet explained that after these neurons were stimulated, the effects seemed to last. This can be explained in real life as well, he said. After a quarrel, people tend to feel resentful and antagonistic for a long period of time.

The effects of stimulation of the PMv cells in these mice seemed to last for up to two weeks said Broberger.



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