nonhuman Article 5 controlled study 5 Animals 4 Conditioning, Classical 4 animal 4 animal experiment 4 conditioned reflex 4 drug effect 4 Male 3 animal behavior 3 animal tissue 3 male 3 metabolism 3 physiology 3 Avoidance Learning 2 Behavior, Animal 2 Hippocampus 2 Rats 2 Signal Transduction 2 adult 2 article 2 avoidance behavior 2 catalepsy 2 hippocampus 2 human 2 memory 2 muscimol 2 rat 2 saccharin 2