Description du projet
Nouvelle vision de la transmission synaptique dans le cerveau
Les neurones du cerveau communiquent par l’intermédiaire des synapses, où le signal électrique passe d’une cellule à l’autre grâce à la liaison des neurotransmetteurs aux récepteurs membranaires. Le récepteur NMDA est un canal ionique fixé au glutamate qui a été associé à la plasticité neuronale. Le mécanisme est traditionnellement connu pour impliquer la liaison du glutamate au récepteur, ce qui déclenche un flux de calcium. Les scientifiques du projet NovelNMDA, financé par l’UE, ont découvert que le NMDA pouvait fonctionner par un mécanisme de signalisation non ionique. Une étude plus approfondie de ce processus devrait améliorer notre compréhension de la signalisation synaptique.
Objectif
Long-term synaptic plasticity is an experience dependent increase or decrease in synaptic signaling between nerve cells that can last from hours to days or even longer. It is thought to represent the cellular substrate of learning and memory by providing an information storage mechanism in the brain. At many excitatory synapses, plasticity-induction processes involve NMDA receptors, glutamate-gated ion channels. I recently discovered a new form of NMDA receptor signaling during spike-timing dependent long-term depression at layer-4-to-layer-2/3 synapses in rodent somatosensory cortex, which requires glutamate binding to the NMDA receptor but not ion flux through its channel. This non-ionic signaling mechanism via the NMDA receptor represents a strikingly overlooked signaling pathway at glutamatergic synapses, and its discovery may overturn much of the long-term depression field, which has focused on calcium influx through the NMDA receptors as the relevant signal in plasticity. Indeed, the discovery of non-ionic NMDA receptor signaling in the postsynaptic membrane even calls into question our current understanding of the basic properties of synaptic signaling.
By combining electrophysiology and two-photon imaging and uncaging, we will address the fundamental properties of non-ionic NMDAR dependent plasticity at cortical layer-4-to-layer-2/3 synapses, determine in which synaptic subcompartment plasticity occurs, assess whether signaling depends on a particular NMDA receptor subtype, and examine whether non-ionic NMDA receptor signaling represents a general mechanism at other glutamatergic synapses. This work will lead to a detailed functional understanding of the novel non-ionic NMDA receptor signaling process and its role in synapse function and plasticity.
Champ scientifique
Programme(s)
Thème(s)
Régime de financement
ERC-STG - Starting GrantInstitution d’accueil
37075 Goettingen
Allemagne