The NMDA receptor (NMDAR), a glutamate receptor, is the predominant molecular device for controlling synaptic plasticity and memory function (1). The NMDA receptor forms a heterotetramer between two NR1 and two NR2 subunits (the subunits are also called glutamate-binding NMDA receptor subunits or GluN for short); two obligatory NR1 subunits and two regionally localized NR2 subunits. A related gene family of NR3 A and B subunits have an inhibitory effect on receptor activity. Multiple receptor isoforms with distinct brain distributions and functional properties arise by selective splicing of the NR1 transcripts and differential expression of the NR2 subunits.