Animal Testing in Psychological Experiments

Lately it seems that animal testing is growing more and more controversial, but in terms of discovering how organisms function, I think its absolutely necessary. I've encountered several articles explaining how stem cells could be used in research, but they wouldn't be useful enough to understand all aspects psychology. Plant tissues have been considered for testing too, but that would hardly make sense: Plants have no brain or emotion, so whats to study? Besides, many laws and standards exist today to be sure that live animals involved in experimentation remain safe and healthy (for the most part). If we were to discontinue animal testing all together, we may as well just give up on discovering more about how brains work and why we do what we do, and that's just out of our nature.