Neurons live longer than almost any other cell in the body. Blood cells are replaced in a period of weeks, muscle cells over years, but most neurons must last a lifetime. How do neurons prevent the molecular damage that necessitates the constant turnover of other cell types? How does a neuron live over 90 years? The molecular mechanisms that enable neuronal longevity remain unclear. We are applying cell-type-specific molecular, cellular, and genetic techniques to study individual populations of neurons and glia as they age in vivo. As part of these studies, we also seek to identify how neuronal cell identity is maintained throughout aging and how much of this maintenance is an active process.