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Séminaire - Dominique DebanneFunctional plasticity in the axon

Abstract :

In most neurons, information is transmitted to the postsynaptic neuron as discrete amounts of neurotransmitter released by the presynaptic neuron in an all-or-none or digital mode. However, subthreshold activity in the presynaptic element also determines the flow of neuronal information in an analog mode. In the first part of my talk, I will discuss recent results showing two modes of analog-digital enhancement of synaptic transmission at excitatory connections established between CA3 pyramidal neurons.

Synaptic plasticity is not the exclusive mode of memory storage, and persistent regulation of voltage-gated ionic channels also participates to information storage. This plasticity may occur in the dendrites but recent results also indicate that voltage-gated ion channels might be regulated in the axon. In this latter case, it generally corresponds to homeostatic plasticity (i.e. compensatory plasticity). Intrinsic plasticity has been reported in principal cells but the contribution of voltage-gated channels in the adaptation of inhibitory circuits remains unclear. In the second part of my talk, I will discuss a form of long-lasting potentiation in intrinsic plasticity in a subset of hippocampal GABAergic interneurons (Campanac et al., Neuron 2013). This plasticity can be considered as homeostatic for hippocampal circuits and involves the regulation of Kv1 channels located in the axon and the cell body.

Selected publications

2013 - Debanne D, Bialowas A, Rama S.
What are the mechanisms for analog and digital signaling in the brain?
Nature Reviews Neuroscience, 14 : 63-69

2013 - Tapia M, Del Puerto A, Puime A, Sánchez-Ponce D, Fronzaroli-Molinieres L, Pallas-Bazarra N, Carlier E, Giraud P, Debanne D, Wandossell F, Garrido JJ.
GSK3 and β-catenin determine functional expression of sodium channels at the axon initial segment
Cellular and Molecular Life Sciences, 70 : 105-120

2013 - Campanac E, Gasselin C, Baude A, Rama S, Ankri N, Debanne D.
Enhanced intrinsic excitability in basket cells maintains excitatory-inhibitory balance in hippocampal circuits. Neuron, 77 : 712-722

2011 - Debanne D, Rama S.
Astrocytes shape axonal signaling.
Science Signaling, 4 : pe11

2011 - Gastrein P, Campanac E, Gasselin C, Cudmore RH, Bialowas A, Carlier E, Fronzaroli-Molinieres L, Debanne D.
The role of hyperpolarization-activated cationic current in spike-time precision and intrinsic resonance in cortical neurons in vitro.
Journal of Physiology (London), 589 : 3753-3773

2011 - Debanne D.
The nodal origin of intrinsic bursting
Neuron, 71 : 569-570

Valentin Nägerl (valentin.nagerl @ u-bordeaux2.fr)

UMR_S 1072

L'Unité de Neurobiologie des canaux Ioniques et de la Synapse (UNIS UMR_S 1072, directeur D. Debanne) est une unité de recherche mixte sous la tutelle de l'INSERM et de l'Université d'Aix-Marseille.

Elle est composée de trois équipes dirigées par D. Debanne, O. El Far et JM. Goaillard dont l'objectif principal est de comprendre les mécanismes moléculaires de la neurotransmission et le rôle des canaux ioniques dans la communication neuronale, la plasticité et les maladies du cerveau. Elle abrite également une plateforme technologique dirigée par Michael Seagar qui vise à développer et proposer des outils moléculaires pour le diagnostic et le pronostic de maladies neurologiques.