{"id":19176,"date":"2018-03-20T14:32:18","date_gmt":"2018-03-20T13:32:18","guid":{"rendered":"https:\/\/neurodev-ng.u-bordeaux.fr\/ronan-chereau-valentin-nagerl-et-al-in-pnas\/"},"modified":"2018-03-20T14:32:18","modified_gmt":"2018-03-20T13:32:18","slug":"ronan-chereau-valentin-nagerl-et-al-in-pnas","status":"publish","type":"post","link":"https:\/\/www.bordeaux-neurocampus.fr\/en\/ronan-chereau-valentin-nagerl-et-al-in-pnas\/","title":{"rendered":"Ronan Chereau, Valentin Nagerl et al. in PNAS<\/em>"},"content":{"rendered":"
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Janaury 23rd, 2017<\/p>\n

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STED imaging reveals activity-dependent plasticity of axon morphology linked to changes in action potential conduction velocity<\/strong> by Ronan Chereau, Ezequiel Saraceno, Julie Angibaud, Daniel Cattaert and U. Valentin N\u00e4gerl Publication date: January 23, 2017 in Proceedings of the National Academy of Sciences (PNAS)<\/em><\/p>\n

Valentin Nagerl<\/strong> : Group leader Synaptic Plasticity and Super-Resolution Microscopy\/ IINS
\nRonan Chereau<\/strong>\u00a0: HOLTMAAT LAB \/ Universit\u00e9 de Gen\u00e8ve (ancien doctorant Nagerl’s lab)<\/p>\n

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Axons convey information to nearby and distant cells and the time it takes for action potentials to reach their targets governs the timing of information transfer in neural circuits.<\/strong> In the unmyelinated axons of hippocampus, the conduction speed of action potentials depends crucially on axon diameters, which vary widely. However, it is not known whether axon diameters are dynamic and regulated by activity-dependent mechanisms. Using time-lapse super-resolution microscopy in brain slices, we report that axons grow wider after high-frequency action potential firing: synaptic boutons undergo a rapid enlargement, which is mostly transient, while axon shafts show a more delayed and progressive increase in diameter. Simulations of action potential propagation incorporating these morphological dynamics predicted bi-directional effects on action potential conduction speed. The predictions were confirmed by electrophysiological experiments, revealing a phase of slowed down action potential conduction, which is linked to the transient enlargement of the synaptic boutons, followed by a sustained increase in conduction speed, which accompanies the axon shaft widening induced by high-frequency action potential firing. Taken together, our study outlines a novel morphological plasticity mechanism for dynamically fine-tuning action potential conduction velocity. which potentially has wide implications for the temporal transfer of information in the brain.\u00a0
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\"Valentin
Valentin Nagerl<\/figcaption><\/figure>\n

Valentin N\u00e4gerl : Les axones transmettent des informations aux neurones proches ou tr\u00e8s \u00e9loign\u00e9s.<\/strong> Le temps de propagation des potentiels d\u2019action g\u00e9n\u00e9r\u00e9s d\u00e9termine le temps de transfert de l\u2019information dans les circuits neuronaux. Dans les axones d\u00e9pourvus de my\u00e9line, la vitesse de conduction des potentiels d’action d\u00e9pend fondamentalement du diam\u00e8tre des axones, qui est tr\u00e8s variable. Or, nous ne savons pas si les diam\u00e8tres des axones sont dynamiques et r\u00e9gul\u00e9s par des m\u00e9canismes d\u00e9pendants de l\u2019activit\u00e9 neuronale. En utilisant la microscopie de super-r\u00e9solution par intervalles de temps dans des tranches de cerveau, nous montrons que les axones deviennent plus larges suite \u00e0 une d\u00e9charge de potentiels d\u2019action \u00e0 haute fr\u00e9quence: les boutons synaptiques s\u2019\u00e9largissent rapidement d\u2019une mani\u00e8re transitoire, tandis que le diam\u00e8tre de l\u2019arbre axonal augmente tardivement plus progressivement. Des simulations num\u00e9riques de la propagation des potentiels d’action incorporant ces dynamiques morphologiques ont pr\u00e9vu des effets bidirectionnels sur la vitesse de conduction des potentiels d’action. Des exp\u00e9riences d\u2019\u00e9lectrophysiologie confirment ces pr\u00e9dictions. En effet, elles montrent dans un premier temps que la conduction des potentiels d’action ralentit lorsque les boutons synaptiques s\u2019agrandissement de mani\u00e8re transitoire. Puis, qu\u2019une augmentation prolong\u00e9e de la vitesse de conduction accompagne l\u2019\u00e9largissement de l\u2019arbre axonal induit par une d\u00e9charge de potentiels d\u2019action \u00e0 haute fr\u00e9quence. Globalement, notre \u00e9tude d\u00e9crit un nouveau m\u00e9canisme de la plasticit\u00e9 morphologique qui explique la r\u00e9gulation fine de la vitesse de conduction des potentiels d\u2019action. Ces r\u00e9sultats sont potentiellement importants pour comprendre la r\u00e9gulation temporelle de la propagation de l\u2019information neuronale dans le cerveau.<\/em><\/p>\n

Significance statement :<\/strong><\/h3>\n

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Recent work has called into question the classic view of axons<\/strong> as electro-anatomical cables that faithfully transmit nerve impulses in an all-or-none fashion over variable distances. Due to their small size below the diffraction barrier of light microscopy, it has not been possible to resolve their dynamic morphology in living brain tissue. Enabled by a combination of live-cell super-resolution STED microscopy, electrophysiology and mathematical modelling, Ch\u00e9reau et al. show that high-frequency action potential firing induces structural enlargement of boutons and axon shafts in hippocampal brain slices, which in turn drives changes in the conduction velocity of nerve impulses (action potentials). The findings reveal a new mechanism for tuning the timing of communication between nerve cells.<\/p>\n

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Illustration :<\/strong>\u00a0\u00a0Super-resolution imaging of axons and their plasticity. The image shows fluorescently labeled axons imaged by STED microscopy in a living mouse brain slice. Ch\u00e9reau et al. discovered that neuronal activity drives nanoscale remodeling of axonal morphology, which impacts the conduction speed of nerve impulses down the axon. See the article by Ch\u00e9reau et al. PNAS 2017. Image courtesy of Ronan Ch\u00e9reau and Valentin N\u00e4gerl. CNRS Imagerie \u00e0 super-r\u00e9solution des axones et de leur plasticit\u00e9<\/p>\n

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U. Valentin N\u00e4gerl Professor and group leader Synaptic Plasticity and Super-Resolution Microscopy Institut Interdisciplinaire de Neurosciences Universit\u00e9 de Bordeaux \/ CNRS UMR 5297<\/a><\/p>\n<\/div>\n

Derni\u00e8re mise \u00e0 jour le 23.01.2017<\/strong><\/p>\n<\/div>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

Janaury 23rd, 2017 STED imaging reveals activity-dependent plasticity of axon morphology linked to changes in action potential conduction velocity by Ronan Chereau, Ezequiel Saraceno, Julie Angibaud, Daniel Cattaert and U. Valentin N\u00e4gerl Publication date: January 23, 2017 in Proceedings of the National Academy of Sciences (PNAS) Valentin Nagerl : Group leader Synaptic Plasticity and Super-Resolution…<\/p>\n","protected":false},"author":108,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[71],"tags":[],"class_list":["post-19176","post","type-post","status-publish","format-standard","hentry","category-highlight-en"],"_links":{"self":[{"href":"https:\/\/www.bordeaux-neurocampus.fr\/en\/wp-json\/wp\/v2\/posts\/19176","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.bordeaux-neurocampus.fr\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.bordeaux-neurocampus.fr\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.bordeaux-neurocampus.fr\/en\/wp-json\/wp\/v2\/users\/108"}],"replies":[{"embeddable":true,"href":"https:\/\/www.bordeaux-neurocampus.fr\/en\/wp-json\/wp\/v2\/comments?post=19176"}],"version-history":[{"count":0,"href":"https:\/\/www.bordeaux-neurocampus.fr\/en\/wp-json\/wp\/v2\/posts\/19176\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.bordeaux-neurocampus.fr\/en\/wp-json\/wp\/v2\/media?parent=19176"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.bordeaux-neurocampus.fr\/en\/wp-json\/wp\/v2\/categories?post=19176"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.bordeaux-neurocampus.fr\/en\/wp-json\/wp\/v2\/tags?post=19176"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}