The roots of empathy: Through the lens of rodent models

Abstract

Empathy is a phenomenon often considered dependent on higher-order emotional control and an ability to relate to the emotional state of others. It is, by many, attributed only to species having well-developed cortical circuits capable of performing such complex tasks. However, over the years, a wealth of data has been accumulated showing that rodents are capable not only of sharing emotional states of their conspecifics, but also of prosocial behavior driven by such shared experiences. The study of rodent empathic behaviors is only now becoming an independent research field. Relevant animal models allow precise manipulation of neural networks, thereby offering insight into the foundations of empathy in the mammalian brains. Here we review the data on empathic behaviors in rat and mouse models, their neurobiological and neurophysiological correlates, and the factors influencing these behaviors. We discuss how simple rodent models of empathy enhance our understanding of how brain controls empathic behaviors.

Keywords: Animal empathy; Emotional contagion; Mouse; Neuronal correlates; Rat; Rodent; Vicarious experience.

Fig. 1. Immediate (upper panel) and remote (lower panel) danger models

In the model of vicarious fear learning the animals are put into the cage usually divided into two compartments by a perforated transparent partition allowing the rats to see, hear and smell the neighbor, but not to contact him physically. One of the animals (“demonstrator”) is subjected to either subjected to fear conditioning or exposed to the conditioned stimuli that evoke fear. The observer rats are not subjected to any training. The observer animal is conditioned for context-dependent fear by observing the behavior of the demonstrator animal receiving aversive stimuli. In the model of socially transferred fear “demonstrators” are subjected to fear conditioning alone. When the demonstrators are trained, their cohabitants (observers) are kept in the home cages in a different sound-attenuating room. Immediately after the training, the demonstrators are placed back in their home cages and allowed to interact with the observers.