Cats can definitely be taught, as opposed to the idea of training them. My 3yr old cat Frankie has epilepsy (we have had him for one year, as his previous owners moved house and dumped him when he developed epilepsy, the likely reason being a cat's lifetime of medication at �14 per month). If a cat is going to develop epilepsy it is around the age of two years. Frankie has to have a Phenobarbitol tablet morning and evening every day for the rest of his life.
The first few days he was none too happy. But now I can say sit Frankie, and he sits. Open your mouth. and he does so. He has learned this without any encouragement . He also comes promptly to call just like a well trained dog, no matter what he is interested at the time. He also responds immediately to a quietly spoken no. I wouldn't say this was down to training, it seems more as if he has learned for himself, the things that are to his advantage, such as finding himself a safe home after he was dumped. He followed my well-fed cats home, and found a welcome. Good luck with your research.