Rats display empathic behavior independent of the opportunity for social interaction.

Empathy, the capacity for shared emotional valence with others, can allow for cooperativity and social bonding between individuals. However, clinical studies indicate it is dysregulated in neuropsychiatric disorders like autism and addiction, making a translationally relevant model of empathy extremely important. The evolutionary basis of the empathic behaviors observed across numerous species can be described using the Perception Action Model (PAM), in which shared affect can promote an action that eliminates the distress of both the "Target" and, by extension, the "Observer". Increasing evidence suggests rodents will work to reduce the distress of a conspecific, but current models of helping behavior are unable to completely parse apart whether the reported behavior is driven by empathy or social reward. The current study demonstrates, using a novel behavioral model, rats learn to aid a distressed conspecific in the absence of social reward, retain the task over time, and previous experience increases the rate of task acquisition. Further, our model suggests that empathic behavior is subject to low effort as compared to a social reward. We next validated the specificity of this model to study empathic processes, characterized the importance of both the Target's level of distress and the impact of the Observer's familiarity with the Target on empathic behavior. Overall, we believe this model adheres to the PAM of empathy by eliminating the influence of social interaction. Importantly, it can be used to directly evaluate the neurocircuitry of empathy and explore the interplay between blunted empathic behavior and neuropsychiatric disorders.