NMDA is composed of (1) receptor R for glutamate and (2) ion channel (for no specific ion, often Ca2+, sometimes Na+)
This is on the post synaptic neuron. 

Channel opening:
	1. 2 molecules of glycine (Gly) or D-serine bind GluN1 subunit on R. Gly normally abundant in synaptic cleft.
	2. 2 glutamates (Glu) bind GluN2 subunit on R. Glu released by presynaptic neuron.
	3. Cell membrane is depolarised
	4. Mg (or Zn) which normally block the ion channel are dislodged by depol to ~0 mV, and Ca (or Na) can flow into neuron