How does calcium through NMDA receptors make a synapse stronger? · Grey Matter

Calcium entering a dendritic spine through NMDA receptors binds calmodulin, which activates the kinase CaMKII; CaMKII then phosphorylates its own neighbouring subunits and stays active after the calcium has gone.

How does calcium through NMDA receptors make a synapse stronger?

Calcium entering a dendritic spine through NMDA receptors binds calmodulin, which activates the kinase CaMKII; CaMKII then phosphorylates its own neighbouring subunits and stays active after the calcium has gone. Active CaMKII phosphorylates AMPA receptors so that each one conducts more current, and helps capture additional AMPA receptors at the synapse, so the same release of glutamate produces a larger response. This early phase lasts an hour or so; keeping the change for days needs new proteins and growth of the spine. The direction depends on the calcium signal: a large, fast rise drives this potentiation, a modest, prolonged one drives depression instead.