The brain pathway that leads to heightened levels of aggression when two male mice are put together has been elucidated.
In many animals, males tend to become more aggressive when they spend time with rival males.
A brain region known as the dorsal raphe nucleus controls aggressive behaviour and it receives a signalling molecule called glutamate when male mice become aggressive in the presence of rivals. But where the glutamate was coming from was unclear.
Now, a team led by researchers from the University of Tsukuba in Japan has traced the source of glutamate to a region called the lateral habenula.
When the researchers blocked communication between the dorsal raphe nucleus and the lateral habenula, male mice didn’t exhibit heighten aggression when placed together. But this blocking did not affect other forms of aggression, implying that the pathway is specific for aggression between rival males.