Reducing Social Stress Elicits Empathy for Pain in Mouse and Human Strangers Loren J. Martin1, Georgia Hathaway1, Kelsey Isbester1, Sara Mirali1, Erinn L. Acland1, Nils Niederstrasser1, Peter M. Slepian1, Zina Trost1,2, Jennifer A. Bartz1, Robert M. SapolsKy3, Wendy F. Sternberg4, Daniel J. Levitin1, and Jeffrey S. Mogil1,5* 1Dept. of Psychology, McGill University, Montreal, QC 2Dept. of Psychology, University of North Texas, Denton, TX 3Dept. of Biological Sciences, Neurology, and Neurosurgery, Stanford University, Stanford, CA 4Dept. of Psychology, Haverford College, Haverford, PA 5Alan Edwards Centre for Research on Pain, McGill University, Montreal, QC *To whom correspondence should be addressed: Jeffrey S. Mogil Dept. of Psychology McGill University 1205 Dr. Penfield Ave. Montreal, QC H3A 1B1 CANADA +1-514-398-6085
[email protected] Running Title: Stress and emotional contagion in mice and humans 2 Summary BacKground: Empathy is a multidimensional construct; at its core is the phenomenon of emotional contagion (state matching). Empathy for another's physical pain is well known in humans, and emotional contagion of pain has been demonstrated in mice. In both species, empathy is stronger between familiars. Using a translational approach, we investigated the effect of stress on emotional contagion of pain in familiar and stranger dyads of both species. Results: Mice and undergraduates were tested for sensitivity to noxious stimulation alone and/or together (dyads). In familiar—but not stranger—pairs, dyadic testing was associated with increased pain behaviors or ratings (i.e., hyperalgesia) compared to isolated testing. Pharmacological blockade of glucocorticoid synthesis or glucocorticoid/mineralocorticoid receptors revealed the hyperalgesia in mice and human stranger dyads, despite having no effect (or even an opposite effect) on pain sensitivity per se, as did a shared gaming experience (the video game Rock Band®) in human strangers.