Ultrafast membrane trafficking at synapses

Project Summary Neuronal signaling events at synapses determine circuit responses and result in specific behavioral outputs. This signaling is dynamic - modulated by the history of synaptic activity and perceived stimuli. Defects in neurotransmission also play a causative role in neurological disorders. However, our understanding of this process is limited by two factors: size and speed. Over the years, we have developed several techniques in electron microscopy to visualize changes in protein localization and synaptic ultrastructure associated with neuronal activity with millisecond temporal precision. Our experiments have revealed key insights into mechanisms of the synaptic vesicle cycle as well as new parameters controlling synaptic plasticity. However, many mysteries remain. How do exocytic and endocytic proteins coordinate to mediate membrane remodeling at synapses on a millisecond time scale? How do these proteins interact with each other and membrane lipids to perform their functions? How heterogenous are these processes? To address these questions, we will develop novel approaches in electron microscopy and leverage these tools to dissect the molecular mechanisms underlying synaptic vesicle exocytosis and endocytosis.