Is activation of N-methyl-D-aspartate receptor gated channels sufficient to induce long term potentiation?

Superfusion of hippocampal slices with Mg2+ free medium (20-30 min) produced in CA1 interictal bursts and an enhancement of the Schaffer collateral synaptic response which persisted for over 2 h after return to control media. This long lasting effect, which was blocked by N-methyl-D-aspartate (NMDA) antagonists, was not associated with changes in postsynaptic cell excitability. A cut between CA3 and CA1, which blocked the bursts in CA1 (but not in CA3), also abolished the long lasting effects of Mg2+ free medium. It is concluded that the activation of NMDA receptors gated ionic channels is insufficient per se to induce a long term potentiation of synaptic transmission.