The tLTP requires a rise in postsynaptic intracellular Ca2+ but not the activation of NMDA receptors. A, Buffering postsynaptic intracellular Ca2+, but not blockade of NMDA receptors, abolishes the tLTP. Lower panel is a summary graph of tLTP obtained in control condition (O, n = 11), in the presence of D-AP 5 (•, 50 µM, n = 10), and with intracellular solution containing BAPTA (□, 20 mM, n = 10). Upper panel illustrates superimposed averaged AMPAR-EPSC traces taken at time points indicated in lower graph. Scale bars: 20 pA, 5 ms. B, Blockade of voltage-dependent Ca2+ channels abolishes tLTP. Lower panel is a summary graph of the time course and magnitude of tLTP obtained in control (O, n = 10) and in the presence of nifidepine (Δ, 20 µM, n = 11). Upper panel illustrates superimposed AMPAR-EPSC traces taken before and during the tLTP in control (left traces) and in the presence of nifidepine (right traces). Scale bars: 25 pA, 10 ms.