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Nonlinear thalamic inputs mediate whisker-evoked heterosynaptic plasticity in the somatosensory cortex| old_uid | 12687 |
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| title | Nonlinear thalamic inputs mediate whisker-evoked heterosynaptic plasticity in the somatosensory cortex |
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| start_date | 2013/06/27 |
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| schedule | 14h |
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| online | no |
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| details | Séminaire impromptu. Une invitation de Yann Humeau de l'IINS |
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| summary | Long-term potentiation (LTP) of synaptic connections within layer (L) 2/3 of the somatosensory cortex is thought to underlie sensory experience-dependent cortical map plasticity. One possible mechanism for LTP involves the temporal coincidence of synaptic inputs and somatic action potentials (APs) that back-propagate into dendrites, termed spike-timing dependent (STD) LTP. Indeed, we have previously shown that experience-mediated disinhibition facilitates STD-LTP in L2/3 pyramidal neurons in the barrel cortex. However, spontaneous and sensory-evoked spiking is strikingly sparse in those L2/3 pyramidal neurons. This casts doubt as to whether repetitive and natural whisking would ever produce enough somatic APs to induce LTP. Here we show using in vivo whole-cell recordings and calcium imaging in the anesthetized mice, that repetitive whisker deflections can induce LTP of whisker-mediated synaptic inputs without generating somatic APs. This potentiation was specific to the stimulated whisker, and it required nonlinear NMDARs-dependent plateau depolarization driven by inputs that are relayed in the posterior medial (POm) higher order thalamic nucleus. These inputs are part of the paralemniscal pathway and project in a non-specific manner to the distal dendrites of L2/3 neurons. Together, our data suggest that the activation of paralemniscal somatosensory pathways facilitates the strengthening of spatially segregated synaptic inputs on barrel cortex pyramidal cells. |
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| responsibles | Deris |
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