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Assessing the mechanism and the functional impact of activity-dependent synaptic plasticity| old_uid | 20010 |
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| title | Assessing the mechanism and the functional impact of activity-dependent synaptic plasticity |
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| start_date | 2022/01/24 |
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| schedule | 14h UTC +1 |
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| online | no |
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| details | Invited by Rosa Cossart - lien de connexion : https://zoom.us/j/96798160455?pwd=TTIwT3BWZFUveWRJeGlpMU1idzBudz09 - ID de réunion : 967 9816 0455 - Code secret : KH2Y8f |
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| summary | Activity-dependent synaptic plasticity, a process by which synapses can strengthen or weaken in response to neuronal activity, is believed to be a core mechanism involved in memory formation while alterations in synaptic function are associated with brain diseases. The dentate gyrus (DG), a major input area of the hippocampus, contains two types of excitatory neurons: dentate granule cells (GCs) and hilar mossy cells (MCs). MCs and GCs form an important but under-investigated associative circuit, that is implicated in DG-dependent cognitive functions and epilepsy. Yet, very little was known about the dynamic properties of GC-MC-GC associative circuit, which we aimed to address. Remarkably, a single MC contacts about 30,000 GCs. We recently found that MC-GC synapses express a robust form of presynaptic long-term potentiation (MC-GC LTP) that increases DG output. Importantly, initial epileptic seizures trigger broad MC-GC LTP in vivo, which promotes further seizures. It is therefore crucial to understand the molecular processes underlying MC-GC synaptic strengthening. MC-GC LTP requires both postsynaptic TrkB activation and presynaptic cAMP/PKA signaling, indicating the involvement of a retrograde messenger, whose identity was unknown. To our surprise, we found that most conventional retrograde messengers were not implicated in this form of plasticity. Instead, MC-GC LTP is mediated by the novel adenosine/A2AR retrograde signaling system by which BDNF/TrkB and A2ARs may contribute to DG-dependent form of learning and epilepsy. Building up on my previous research experiences, my independent research program will investigate the role of _-containing GABAA receptors in hippocampal function (e.g. memory) and disease (e.g. epilepsy). |
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| oncancel | Cplt |
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| responsibles | Bernier |
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