Synaptic plasticity plays an important role in the regulation of higher brain functions, and studies of its molecular mechanisms are being actively studied worldwide. Our research has been focused on uncovering the intracellular signaling mechanisms of synaptic plasticity in different brain regions and cell types. Based on these biological findings, we have developed innovative optogenetic tools to precisely control intracellular signaling for artificial manipulation of synaptic plasticity. In this project, we will further develop these tools to explore synaptic plasticity, with the goal of uncovering mechanisms that modulate emotional valence and deepening our understanding of the dynamics of empathy.