PYD-106 is a stereoselective pyrrolidinone (PYD) positive allosteric modulator for GluN2C-containing NMDA receptors. PYD-106 increases opening frequency and open time of single channel currents activated by maximally effective concentrations of agonist but only has modest effects on glutamate and glycine EC50. PYD-106 selectively enhances the responses of diheteromeric GluN1/GluN2C receptors but not triheteromeric GluN1/GluN2A/GluN2C receptors[1].