Emotional contagion in FVB mice
INTRODUCTION: Lately, we can observe a steady increase in the number of autism spectrum disorder (ASD) diagnoses every year. ASD is often connected with empathy impairments, a phenomenon thought to be limited only to humans, yet the simplest form of empathy, emotional contagion, can be examined also in rodents. AIM(S): In our previous study we have shown that C57BL/6 mice are capable of transferring the emotional information, but Keum and colleagues (2015) reported that strain is a major factor influencing empathic fear responses. They showed that FVB mice are not capable of Observational Fear Learning. In the current study, we tested if exposure to a stressed Demonstrator in the safe environment of the home cage (providing remote information about the stressor) elicits emotional contagion in the FVB mice. METHOD(S): Between subject transfer of emotional information paradigm was used, in which mice are housed in pairs for three weeks, one of them labelled as a Demonstrator, and the other as an Observer. In the test session, the Demonstrator is subjected to a series of aversive stimuli outside of the home cage, while the Observer remains there undisturbed. Then, the Demonstrator is returned to the home cage, where it can freely interact with the Observer. The following interactions are recorded and then analysed using BehaView software. RESULTS: Here we report that FVB mice display emotional contagion in the between-subject transfer of emotional information paradigm. Observers exposed to stressed Demonstrators show increased social behaviours towards the Demonstrators. Results are similar to these obtained on C57BL/6 mice, albeit the behavioural response was slightly different. CONCLUSIONS: Confirmation of empathic abilities in the FVB strain allows for further studies of genetic influence on empathic responsivity. FVB mice lacking Fmr1 gene, encoding the fragile X mental retardation protein, are considered a strong animal model for autism spectrum disorder (ASD). FINANCIAL SUPPORT: This study was supported by NCN Sonata BIS grant no. 2015/18/E/NZ4/00600 to Ksenia Meyza.