Social avoidance of mice in pain in naturalistic conditions

Pain and social behavior are subject to reciprocal modulation. Both humans and rodents experience emotional contagion from afflicted conspecifics, and may act to relieve the afflicted state of these. Little has been done to investigate the motivation of such prosocial behavior in rodents in naturalistic conditions. Here, we analyzed social interactions in mice group-housed in a seminatural environment (SNE). Social buffering reduced nocifensive behavior in formalin-injected mice. These mice were also both socially withdrawn and avoided by other mice. These findings appear counter to those showing empathy in mouse pain models. It is possible that in naturalistic conditions, healthy mice simply avoid individuals in pain and the cost associated with emotional contagion. Interestingly, behaviors involving direct body contact were not different between saline- and formalin-treated mice, and thus may carry a prosocial, altruistic component. These findings unveil new patterns of social modulation by pain in a naturalistic laboratory setting holding high translational value. TeaserIn a new, ethological assay, mice in pain are socially withdrawn and avoided by others, challenging findings of empathy in rodent models.