Dr. David Anderson

emotions tend to outlast often the stimulus that evoke them if you're walking along a trail here in southern california you hear a rattlesnake rattling you're going to jump in the air your heart is going to continue to beat and your palms sweat for a while after it's slithered off in the bush and you're going to be hyper vigilant if you see something that even remotely looks snake-like a stick you're going to stop not all states have persistence

So, for example, you think about hunger.

Once you've eaten, the state is gone.

You're not hungry anymore.

But if you're really angry and you get into a fight with somebody, even after the fight is over, you may remain riled up.

for a long time and it takes you a while to calm down.

And then generalization is an important component of emotion states that make them, if they have been triggered in one situation,

they can apply to another situation.

My favorite example of that is you come home from work and your kid is screaming.

If you had a good day at work, you might pick it up and soothe it.

And if you had a bad day at work, you might react very differently to it.

First of all, the word aggression

in my mind, refers more to a description of behavior than it does to an internal state.

Aggression could reflect an internal state that we would call anger in humans, or could reflect fear, or it could reflect hunger if it's predatory aggression.

The work that Dayu did when she was in my lab, she found a way to evoke

aggression in mice using optogenetics to activate specific neurons in a region of the hypothalamus, the ventromedial hypothalamus, VMH, following first the famous Nobel Prize-winning work of Walter Hess.

In Hess's original experiments, he describes two types of aggression.

that he evokes from cats depending on where in the hypothalamus he puts his electrode.

One of which he calls defensive rage.

That's the ears laid back, teeth bared, and hissing.