Figure 3.

GluN2A-NMDARs are required for SDIA extinction memory restabilization. (a) Animals were trained in SDIA (TR; 0.4 mA/2 s) and, beginning 24 h later, they were submitted to one daily extinction training trial for 5 consecutive days. Twenty-four hours after the last extinction training trial, SDIA extinction memory was reactivated (RA) and, 5 min thereafter, the animals received bilateral intra-dorsal CA1 infusions of vehicle (VEH; 0.1% DMSO in saline), the GluN2B-containing NMDAR antagonist RO25-6981 (RO; 2.5 µg/side), or the GluN2A-containing NMDAR antagonist TCN201 (TCN; 0.05 µg/side). Retention was assessed 1 day and 7 days later (Test). (b) Animals were treated as in A except that RA was omitted (No RA). (c) Animals were treated as in A, but a group of them received bilateral intra-CA1 infusions of VEH, RO or TCN 5 min after a pseudo-reactivation extinction session (pRA) carried out in an SDIA training box modified to be non-aversive (NA) for SDIA-trained animals. The non-aversive box was similar in dimensions to the SDIA-training apparatus but was painted gray and the elevated platform was made of transparent plexiglass instead of wood. Data are expressed as median ± IQR. (***) p < 0.001 versus VEH in Dunn's multiple comparisons after Kruskal–Wallis test; n = 10–12 animals per group.