Kirill Volynski, UCL Queen Square Institute of Neurology, University College London, United Kingdom
Differential regulation of kinetics and plasticity of glutamate release among presynaptic outputs of pyramidal neurons.
Short-term synaptic plasticity and the balance between fast synchronous and delayed asynchronous release of neurotransmitters has a major role in defining computational properties of neuronal synapses and regulation of neuronal network activity. However, how these presynaptic functional properties are tuned at the single synapse level remains poorly understood. We have recently developed a method to image quantal vesicular release in tens to hundreds of individual synaptic outputs from single pyramidal cells with 4 milliseconds temporal and 75 nm spatial resolution. We find that the ratio between synchronous and asynchronous synaptic vesicle exocytosis varies extensively among synapses supplied by the same axon and that asynchronous release fraction is elevated in parallel with short-term facilitation at synapses with low release probability. We further demonstrate that asynchronous exocytosis sites are more widely distributed within the release area than synchronous sites. Our findings are consistent with a model in which functional presynaptic properties are regulated by a synapse-specific adjustment of the active zone morphology and the effective coupling distance between presynaptic Ca2+ channels and release-ready synaptic vesicles. Together, these results reveal a universal relationship between the two major functional properties of synapses – the timing and the overall efficacy of neurotransmitter release.
Kirill Volynski is a Professor of Neuroscience at University College London. After establishing his laboratory at UCL Queen Square Institute of Neurology in 2006 (MRC Career Development Fellowship) he focused on studying the mechanisms of neurotransmitter release and synaptic plasticity. Volynski group established a powerful suite of quantitative imaging and computational modelling approaches that allow them to study the relationship between calcium entry and vesicular exocytosis, and to probe presynaptic ion channel function in individual small presynaptic terminals. His current research interests focus on how the presynaptic release machinery decodes calcium signals and translates them into the complex patterns of neurotransmitter release.