The rewarding properties of safety signals established by a two-way active avoidance task in male rats

Actively avoiding threatening stimuli or situations is an adaptive defensive strategy that minimizes the risk of potential harm. Despite the prominent role avoidance plays in our daily lives, the mechanisms that reinforce avoidance behavior remain incompletely understood. Accumulating evidence implicates the mesolimbic dopamine reward system in the acquisition of avoidance, suggesting that the omission of an aversive event may acquire rewarding properties and function as a positive reinforcer of avoidance behavior. In a series of six experiments (N = 246 male Wistar rats), we examined whether safety signals that coincide with successful avoidance responses in a two-way active avoidance (2WAA) task facilitate avoidance acquisition and acquire reward-like properties, by assessing whether they elicit approach behavior and support the acquisition of a novel instrumental response. Although the presentation of a safety signal accelerated avoidance learning in some experiments, the effect was not consistent. Furthermore, the safety signal neither elicited approach behavior nor supported the acquisition of a novel instrumental response. Together, these findings question whether safety signals in avoidance learning acquire rewarding properties detectable through behavioral measures.