The decay time course of excitatory postsynaptic currents generated by slow glutamatergic synapses is determined by the single-channel kinetics of postsynaptic NMDA receptor channels. In a recent study, examination of these single-channel kinetics has revealed that NMDA receptors can enter into modal gating. Linear free-energy analysis suggests that the various modes arise from a common reaction mechanism, providing further insight into the gating underlying decay of the slow synaptic response.