Conformity-like behaviour in mice observing the freezing of other mice: a model of empathy

Abstract

Background: Empathy refers to the ability to recognise and share emotions with others. Several research groups have recognised observational fear in mice as a useful behavioural model for assessing their ability to empathise. However, in these observation systems, it remains unclear whether the observer mouse truly recognises the movements of, and empathises with, the demonstrator mouse. We examined changes in the behaviour of an observer mouse when a demonstrator mouse was anaesthetised, when the demonstrator's activity was increased, and when the interval of electrical stimulation was altered. If mice exhibit an ability to empathise, then the observer should display empathic behaviour when the demonstrator experiences pain or discomfort under any circumstances. Results: Relative to low-frequency stimulation, frequent electrical stimulation reduced immobility time among observer mice. Moreover, when demonstrators exhibited excessive activity, the activity of the observers significantly increased. In addition, the proportion of immobility time among observer mice significantly increased when demonstrator mice exhibited fear learning and excessive immobility. Conclusion: Although our results indicate that observer mice change their behaviour based on the movements of demonstrator mice, increases in immobility time may reflect conformity-like behaviour rather than emotional empathy. Thus, not only visual but also auditory and odour information additionally influenced the conformity-like behaviour shown by observer mice. Thus, our findings suggest that methods other than the fear observation system should be used to investigate rodent empathy-like behaviour.

Anterior cingulate inputs to nucleus accumbens control the social transfer of pain and analgesia

“…Our results provide additional evidence that mice can rapidly and reliably adopt the sensory-affective state of a social partner, regardless of the valence of the information (pain, fear, or pain relief). Although it is conceivable that the behavioral responses of our BY mice reflect “imitative” or “mimicry” behavior ( 45 ) rather than “empathy,” several findings suggest that at least for the social transfer of pain and analgesia, the BY mice manifest changes in their behavior because they are experiencing an altered sensory-affective state. Importantly, the BY mice were tested using several different behavioral assays and did not always have direct visual access to their social partners during testing.…”

Emotional contagion in nonhuman animals: A review

“…However, in the experiment of Rice (1964), it was not clear whether this effect and the observers' fear‐related responses were due to the features of the apparatus or triggered by the sight of the distressed conspecific.Some recent and more controlled studies have provided mixed results on the response of rodents to the exposure of conspecifics being subjected to physical stressors. Four studies showed that neither the visual (Sanders et al, 2013) nor auditory (Atsak et al, 2011; Chen et al, 2009; Ueno et al, 2020) exposure to familiar or unrelated conspecifics receiving foot‐shocks or to videos of foot‐shocked cagemates elicited freezing responses in observer rodents. However, another series of studies provided positive evidence of this phenomenon.…”

“…(Allsop et al, 2018; Atsak et al, 2011; Carrillo et al, 2015; Chen et al, 2009; Gonzalez‐Liencres et al, 2014; Jeon et al, 2010; Jeon & Shin, 2011; Keum et al, 2016; Keum et al, 2018; Pisansky, Young, et al, 2017; Pisansky, Hanson, et al, 2017; Sanders et al, 2013; Ueno et al, 2020; Ueno et al, 2020 ( video) ) (Sehoon Keum et al, 2018)…”

“…However, another series of studies provided positive evidence of this phenomenon. Mice ( Mus musculus ), degus ( Octodon degus ) and rats displayed freezing behavior in response to the sight of a familiar or unrelated demonstrator receiving electrical shocks (e.g., Allsop et al, 2018 ; Atsak et al, 2011 ; Carrillo et al, 2015 ; Gonzalez‐Liencres et al, 2014 ; Han et al, 2020 ; Jeon et al, 2010 ; Jeon & Shin, 2011 ; Keum et al, 2016 ; Keum et al, 2018 ; Lidhar et al, 2017 ; Pisansky, Hanson, et al, 2017 ; Pisansky, Young, et al, 2017 ; Sanders et al, 2013 ; Twining et al, 2017 ; Ueno et al, 2020 ; Yusufishaq & Rosenkranz, 2013 ). Besides, in rats, the demonstrators' behavior was modulated by the behavior of the observers: they froze more if witnesses froze more (Atsak et al, 2011 ; Han et al, 2020 ).…”

Effect of simultaneous testing of two mice in the tail suspension test and forced swim test

“…In an experimental environment without dividers, we investigated whether the nature of the demonstrator in the adjacent transparent cylinder changed the depressive-like behaviour of the test subjects, since it has been shown that mice change their behaviour by imitation of other individuals 34 – 39 . However, in this experiment, the behaviour of the cage mate in the adjacent cylinder, irrespective of whether they were hyperactive or immobile, did not change the behaviour of the observer.…”