Imminent vs. remote danger: emotional reactions and patterns of c-Fos expression in the rat brain

It has been shown that emotional states displayed by animals are able to infl uence their conspecifi cs’ behavior and that such transferred emotions help animals to adapt to specifi c requirements of changing environment. Animals that are not in direct danger can share fear by either observation of a conspecifi c in danger or being informed by a conspecifi c about danger. To date, relatively little is known about mechanisms by which the emotional transfer occurs. Aiming to gain more insights into the neural substrates of two types of socially transferred fear, we designed behavioral models of indirect emotional stimulation. To allow observation of a conspecifi c in danger, we placed a rat designated as an observer in a safe compartment of two-compartment conditioning box and exposed the animal to a demonstrator being fear-conditioned in the other compartment. To model a situation in which an observer cannot witness a demonstrator in direct danger, we used a rat that had previously undergone fear conditioning as stimulus source for the other individual. Witnessing conspecifi c’s distress evoked an increase in defensive responses and a decrease in exploratory behaviors. On the other hand, interaction with a stressed partner increased behaviors directed towards gaining information (sniffing and allogrooming). Activation of various brain structures following observation of a conspecifi c in danger and interaction with a conspecifi c that underwent a stressful stimulation were analyzed.