Children quickly learn to avoid negative situations and seek positive ones. But humans are not the only species capable of remembering positive and negative events; even the small brain of a fruit fly has this capacity. Dopamine-containing nerve cells connected with the mushroom body of the fly brain play a role here. Scientists have identified four different types of such nerve cells. Three of the nerve cell types assume various functions in mediating negative stimuli, while the fourth enables the fly to form positive memories.