Roles of NR2B and NR2A subunits in depotentiation and repotentiation after LTP. (A) LTP is induced by three successive tetani (100 Hz, 100 impulses each) leading to a near doubling of the EPSP. Subsequent application of NMDA (30 μM, 4 min) leads to persistent depression of the control pathway (gray symbols) and depotentiation of the test pathway (black symbols). Secondary tetanization of the test pathway causes a repotentiation, lifting the test responses back to a potentiated level (n = 12). (B) and (C) show similar experiments but treated with Ro25-6981 (0.5 μM; n = 4)/Ifenprodil (3 μM; n = 2) (total n = 6) or NVP-AAM077 (0.4 μM; n = 5) shortly after LTP induction. Both depotentiation and repotentiation are preferentially attenuated by NVP-AAM077 as compared to Ro25-6981/Ifenprodil. Arrows indicate the tetani. Black bars indicate the duration of drug application.