Norepinephrine-induced potentiation is not blocked by the local diffusion of the NMDA channel blocker, ketamine, at concentrations that prevent tetanically-induced long-term potentiation in the dentate gyrus in vivo

An enduring increase in the size of the perforant path-evoked dentate gyrus response follows brief tetanic stimulation. This Long-Term Potentiation (LTP) is considered a cellular substrate of memory. A similar phenomenon, Norepinephrine-Induced Potentiation (NEP), results from exogenous application of NE or from endogenous NE release following Locus Coeruleus (LC) stimulation. It has been postulated that NE promotes LTP induction in a manner consistent with a role in arousal and attention. lt has been documented both in vitro and in vivo that LTP induction requires the NMDA receptor and that NEP induction requires activation of the...