22 Gen Unconventional NMDA Receptor Signaling
In the classical view, NMDA receptors (NMDARs) are stably expressed at the postsynaptic membrane, where they act via Ca 2 to signal coincidence detection in Hebbian plasticity. More recently, it has been established that NMDAR-mediated transmission can be dynam- ically regulated by neural activity. In addition, NMDARs have been found presynaptically, where they cannot act as conventional coin- cidence detectors. Unexpectedly, NMDARs have also been shown to signal metabotropically, without the need for Ca2 . This review highlights novel findings concerning these unconventional modes of NMDAR action.