Repeated exposure to emotional stress can lead to a variety of mental disorders. The social defeat stress model is an animal model that is frequently used to investigate the mechanisms of chronic stress-related mental disorders. In this model, however, it is difficult to study the effects of emotional stress itself since the subject animals are exposed to both physical and emotional stress at the same time. Recently, a novel psychosocial stress model has been established that exposes mice to emotional stress without physical distress by witnessing socially defeated conspecifics. It has been reported that animals witnessed social defeat scenes display behavioral and physiological changes similar to those observed in actually defeated animals.
On the other hand, we found that emotional stress activated different brain regions compared to physical stress. In this symposium, we will focus on the insular cortex, the region activated only during emotional stress, and report our findings on the roles of the insular cortex in emotional stress-induced behavioral changes.