NEURONAL CIRCUITS AND NEURONAL MEMBRANE PROPERTIES INVOLVED IN EMPATHY

Abstract Empathy is a cognitive and emotional response that occurs in individuals who observe the experiences of others. In this study, we aimed to understand the neural circuit mechanisms involved in empathy by using the observational fear learning (OFL) test, immunohistochemical (IHC) and patch-clamp (PC) analyses in mice. We labeled pyramidal cells in the dorsal medial prefrontal cortex (dmPFC) that project to the basolateral lateral amygdala (BLA) or periaqueductal gray (PAG) and control fear and its associated behaviors, respectively, and analyzed the neuronal activity induced by OFL using c-fos expression as an indicator for IHC analysis. PAG projection neurons were both activated by about 15%. PC analysis of the membrane potential properties of dmPFC pyramidal cells under normal conditions revealed that BLA- or PAG-projecting pyramidal cells fired action potentials more frequently than did non-projecting pyramidal cells. These results suggest that BLA- or PAG-projected dmPFC pyramidal cells express empathy by suppressing their excitability.