For humans, rats are often the stuff of nightmares, but it seems that the rodents may be as likely to experience bad dreams themselves as they are to star in ours. In a new study in Nature Neuroscience, researchers placed rats in a maze and allowed them to explore. At a certain point in the maze the scientists blasted the animals in the face with a bit of compressed air from a keyboard cleaner—a harmless but uncomfortable experience for the rats. Later, as the researchers monitored the animals sleeping, they could see patterns of connectivity in the animals’ hippocampi corresponding to their mental map of the maze. For the first time, however, the scientists saw activity in another region of the brain involved in emotion—the amygdala—whenever the rats’ brains recalled the location of the scary air puff, New Scientist reports. Whether rats actually experience this phenomenon as fear in the context of a dream is impossible to know without asking them, however.