A mouse model for observational fear learning and the empathetic response.

Research on observed fear and its relation to human mental disorders has been hampered by the lack of a suitable animal model. The empathetic response, which is impaired in various mental disorders, requires the ability to recognize the emotions and feelings of others. Due to the lack of a robust behavioral assay system, studies of empathy in laboratory animals have been absent from the literature. This unit describes a protocol for assessing social observational fear learning as a precursor of empathy in the mouse. In this assay, the observer animal is conditioned for context-dependent fear by observing the behavior of the demonstrator animal receiving aversive stimuli. The magnitude of the fear response of the observer is positively influenced by the animal's familiarity with the demonstrator. This indicates that the degree of familiarity, and its relationship to empathy, can be modeled in an animal system by a method relevant to human disease.