Does learning new things give you dopamine due to instant gratification?
Sometimes I feel great and euphoric when I learn random things, usually the basics of something I've never studied before. I download a bunch of books and make quick progress and I feel great for a while. But I once I try to learn the subject deeper I usually get suck and feel burned out and realize that I know nothing. That results in a huge release of some negative stuff, like maybe cortisol.

What's the exact brain chemistry in this case?