Nanoscopy of Filamentous Actin in Cortical Dendrites of a Living Mouse

We demonstrate superresolution fluorescence microscopy (nanoscopy) of protein distributions in a mammalian brain in vivo. Stimulated emission depletion microscopy reveals the morphology of the filamentous actin in dendritic spines down to 40 mu m in the molecular layer of the visual cortex of an anesthetized mouse. Consecutive recordings at 43-70 nm resolution reveal dynamical changes in spine morphology.