Dr. David Anderson

Female mice only fight when they are nurturing and nursing their pups after they've delivered a litter.

And there is a window there where they become hyper aggressive.

After their pups are weaned, that aggressiveness goes away.

So this is pretty remarkable that you take a virgin female mouse and expose it to a male and her response is to become sexually receptive and to mate with him.

And now you let her have her pups and you put the same male or another male mouse in the cage with her, and instead of trying to mate with him, she attacks him.

And we recently showed in a paper, this is work from one of my students, Mengyu Liu, that within VMH in females, there are two clearly divisible subsets of estrogen receptor neurons.

And she showed that one of those subsets controls fighting and the other one controls mating.

This gets into the whole issue of neurons that are present in females but not in males.

So this is already showing you some complexity.

The male mouse VMH has both male-specific aggression neurons and generic aggression neurons.

And then the female VMH, the mating cells are only found in females.

They are female specific and not found in the male brain.

And so we're trying to find out what these sex specific populations of neurons are doing, but that indicates that that is some of the mechanism by which different sexes show different behaviors.

I can't really speak to the issue of whether this is species specific because I'm not a naturalist or a zoologist.

I've seen like you have in the wild, for example, lions when they mate.

I've seen them in Africa.

There's often a biting component of that as well.

One of the things that surprised us when we identified neurons in VMHVL that control aggression in males is that within that population, there is a subset of neurons that is activated by females during male-female mating encounters.

There's some evidence that those female selective neurons in VMH are part of the mating behavior.

If you shut them down, the animals don't mate as effectively as they otherwise would.