2022/07/22
University of Tsukuba
Keio University School of Medicine
Tohoku University
When we perceive malice from others, we can become irritated or feel aggressive. It is also known that male mice exhibit more intense aggressive behavior than usual when provoked by a rival. So, what is happening inside the brain when provocation intensifies this aggressive behavior?
Our research group has previously shown in experiments with mice that when they experience provocation from others (social provocation), the input of glutamate, an excitatory neurotransmitter, increases in the dorsal raphe nucleus of the brain. One of the brain regions that projects glutamatergic neurons to the dorsal raphe nucleus is the lateral habenula, which is involved in negative emotions and stress. In this study, we found that the projection neurons from the lateral habenula to the dorsal raphe nucleus are activated by social provocation. Suppressing the activity of this neural projection prevented aggressive behavior even after social provocation, indicating that excitatory input from the lateral habenula to the dorsal raphe nucleus is involved in the increase in aggressive behavior caused by social provocation. Furthermore, it was shown that among the non-serotonergic neurons in the dorsal raphe nucleus, those projecting to the ventral tegmental area are involved in the increase in aggressive behavior due to social provocation.
The results of this research have revealed part of the mechanism by which aggressive behavior becomes excessive. These findings are expected to contribute to the understanding of the problem of human violence.
For the full press release, please see below.