https://www.scientificamerican.com/article/neural-switch-flips-on-aggression-in-male-mice/

When a male mouse senses a territorial threat from another male, an aggressive reaction toward the invader instinctively kicks in. When the same mouse detects a sexually receptive female, however, his reaction tends to be a mating attempt, not an attack. The messages may both begin with the smell and sight of another mouse. But where does the mouse brain sort out the options for the appropriate social reaction?

Research has already identified two areas in a region called the hypothalamus that are involved in mice’s aggression and mating responses. The hypothalamus, though, is just one stop in a circuit that channels the internal signals that switch on these social behaviors. In results published on July 27 in Nature Neuroscience, investigators show that two other populations of cells in a brain region called the amygdala send out projections, or axons, to two target hypothalamic areas and can switch them on or off, depending on the circumstance.