Synapses are highly dynamic and complex structures that allow for rapid and flexible neuronal communication and hold the key to understanding higher nervous system function. Synapses constantly adjust their functional properties during development and in response to experience. Investigating the plasticity of neuronal synapses is challenging because they are densely packed in the brain and small in size - at the limit of what conventional light microscopy can resolve. As a result, a lot of our understanding of the properties of single synapses is derived from electron microscopy of fixed tissue samples, which is by definition not well suited for understanding the dynamic processes of synapses.
We propose to study synaptic dynamics with a new and ground-breaking laser-scanning fluorescence microscopy technique, STED imaging, which has vastly improved spatial resolution (at the nanoscale) compared to conventional light microscopy. Expanding our previous research, we will investigate key structural and cell-biological mechanisms of synaptic plasticity, imaging morphology and constituent proteins of synapses in living brain slices that can be properly resolved for the first time.