Facilitated induction of plasticity overrides the blockade by NVP-AAM077. (A) Blocking effect of NVP-AAM077 on NMDA-induced LTD (see Fig. 1C) is overcome by lowering Mg2+ concentration (0.1 instead of 1.3 mM; n = 6). (B) Bar diagram shows NMDA-induced LTD in different Mg2+ solutions. Dashed bar is control data from Fig. 1D. (C) In a "slow LTD" experiment, similar to that in Fig. 3C, lowering the concentration of Mg2+ in the perfusion solution (0.01 instead of 0.1 mM) helps with the induction of "slow LTD" in presence of NVP-AAM077 (0.4 μM; n = 7). (D) Bar diagram reveals the "slow LTD" induced in different Mg2+ solutions. Dashed bar is control data from Fig. 3D. (E) Similarly, using low Mg2+ solution (0.1 instead of 1.3 mM) in LTP experiments (compare Fig. 4C) enables a small potentiation of EPSPs under inhibition of NR2A subunits by NVP-AAM077 (n = 7). (F) Bar diagram shows LTP induced in different Mg2+ solutions. Dashed bar is control data from Fig. 4D. Data are shown as mean ± SEM. Inserts show the EPSP-traces taken at the indicated time points (a-d). Calibrations: 0.5 mV (A, E), 0.2 mV (C), 20 ms.