A drop in dopamine below baseline occurs when a predicted positive event does not happen.

“Then, there's also the case in which we predict that something good will happen, when that happens, there's an increase in dopamine just as it was before, but then if that thing doesn't happen, for instance, our friends don't show up for dinner, then there's a drop in dopamine below our initial baseline. That drop in dopamine, is the chemical essence of what we call, disappointment.”

“But then if that thing doesn't happen, for instance, our friends don't show up for dinner, then there's a drop in dopamine below our initial baseline. That drop in dopamine is the chemical essence of what we call disappointment.”

“it's going to send signals to alter the circuitry in a way that says whatever you did to get there don't do it again it's going to discourage you”