Serotonin release in the habenula during emotional contagion promotes resilience

• DOI: 10.1126/science.adp3897
• Publication Date: 2024-09-05T18:00:11Z
• Authors: Sarah Mondoloni; Patricia Molina; Salvatore Lecca; Cheng-Hsi Wu; Léo Michel; Denys Osypenko; Fanchon Cachin; Meghan Flanigan; Mauro Congiu; Arnaud L. Lalive; Thomas Kash; Fei Deng; Yulong Li; Manuel Mameli
• Keywords: Male; Neurons; Mice; Habenula; Serotonin; Neuronal Plasticity; Adaptation, Psychological; Emotions; Animals; Raphe Nuclei; Female; Resilience, Psychological

Negative emotional contagion—witnessing others in distress—affects an individual’s emotional responsivity. However, whether it shapes coping strategies when facing future threats remains unknown. We found that mice that briefly observe a conspecific being harmed become resilient, withstanding behavioral despair after an adverse experience. Photometric recordings during negative emotional contagion revealed increased serotonin (5-HT) release in the lateral habenula. Whereas 5-HT and emotional contagion reduced habenular burst firing, limiting 5-HT synthesis prevented burst plasticity. Enhancing raphe-to-habenula 5-HT was sufficient to recapitulate resilience. In contrast, reducing 5-HT release in the habenula made witnessing a conspecific in distress ineffective to promote the resilient phenotype after adversity. These findings reveal that 5-HT supports vicarious emotions and leads to resilience by tuning definite patterns of habenular neuronal activity.