I Was a Fast-Food Worker. Let Me Tell You About Burnout.

If you had to make a rat depressed, how do you think you'd go about it?

(Okay, you can't technically make a rat “depressed” — a scientist would ask how to “create a model of depression” in rats. Actually being depressed is exclusive to humans. But the drugs used to treat depression in humans are developed and tested using rodents.)

So to test your new antidepressant, you need an efficient method of making a lot of rats exhibit anhedonia — that is, making them lose interest in things they used to enjoy, like sugar.