https://www.sciencedaily.com/releases/2022/07/220722123314.htm

Aggressive behavior, especially between males, is important in many animal species and can be promoted in a number of different ways, including by social instigation. Although this behavioral effect is well characterized, the brain pathway that is responsible for it is less understood. The dorsal raphe nucleus is a brain region that controls aggressive behaviors, and it receives glutamate (a molecule that acts as a signal between brain cells) when social instigation occurs. However, the source of this glutamate was a mystery. Researchers from the University of Tsukuba decided to address this gap in the knowledge.

"Many different brain regions release glutamate into the dorsal raphe nucleus," explains lead author of the study Professor Aki Takahashi. "Because our initial experiments suggested that glutamate release from the lateral habenula might be responsible for aggression induced by social instigation, we conducted more experiments to see if this was the case."