@welcome2atlantis I forget its name right now, but I had found a webcomic once that was roughly about that sort of thing. If a zombie in that setting ate enough human brains, it could regain human intelligence itself. Continued consumption to maintain that was required. The story takes place after quite an amount of zombies have basically rebuilt society for themselves, so either humans were basically cattle or they were using cloned brains to survive or something.
Naturally, the main character is a human, so he's playing on hard mode.
@NE0N3XUS Apparently, it either wasn't old enough to have been missed by my more recent method of bookmarking things, or I've updated its bookmark sometime since then, so it was actually pretty easy to find. Probably also helps that the person who wrote it hasn't abandoned the website entirely yet despite it being completed, man that happens too often with webcomics. I probably have hundreds of dead links. But yeah, here you go, The Other Grey Meat.