We investigate the structures and functions of biological membranes (synapses, plasma membrane, organelle membranes, transport vesicles, etc.) as well as the metabolism of lipids composing of membranes by using the combination of imaging (electron microscopy, histocytochemistry, live imaging) and biochemical analyses. Through investigating the meanings of membranes as platforms for synthesis, modification, transport, signaling, organelle contact, and cell-cell contact, we are clarifying the background mechanisms of lipid metabolism disorders including adult diseases, organization of neuronal circuits, and survival of neurons under stresses.