In classical conditioning, animals can learn to associate a neutral stimulus (like a bell) with food, leading to anticipatory responses such as salivation and insulin release.

“So Pablo in his classical experiments in conditioning, you know, associative conditioning, he would take a bell, it will ring the bell every time he was going to feed the dog. Eventually the dog learn to associate the ringing of the bell with food coming. The dog now in the presence of the bell alone will start to salivate and we will call that you know neurologically speaking an anticipatory response. Neurons in the brain that form that association now represent food is coming and they're sending a signal to motor neurons to go into your salivary glands to squeeze them. So you release you know you know saliva because you know food is coming. But what's even more remarkable is that those animals are also releasing insulin in response to a bell. Somehow the brain created these associations and there are neurons in your brain now that no food is coming and send a signal somehow all the way down to your pancreas that now it says release insulin because sugar is coming down.”