Brain was used in old cold cut recipes and still sees use in some specialty restaurants and such. it’s not common (i guess mostly because it spoils faster than most of the rest of the animal), but not unheard off.

My Grandmother was once very pleased to get her hands on fresh brain, which she basicaly stir fried with eggs and oinions. Me and my brother were not pleased with it, but i think it once was a fairly popular dish in germany and austria.

so if you know a butcher you trust you might be able to buy cleaned fresh brain. I still would not recommend it, but if it can be used why not?