Figure 2.

MgN protein synthesis is necessary for the shift from low to high generalization. (A) Rats were infused with vehicle (ACSF) 30-min before the first training session using a 0.5 mA footshock followed by a test 24-h after training. Rats received a second infusion of either vehicle or anisomycin 30-min prior to the second training session using a 1.0 mA footshock followed by a long-term retention test 24-h later (n = 8–9). (B) There were no differences between groups during the 30-sec tone presentations at the discrimination test. (C) Animals that received anisomycin infusions prior to the second training session showed significantly less freezing during the CS+ and CS− presentations when tested 24-h later. (D) Animals that received vehicle infusions showed increased freezing during the CS− between the discrimination and generalization test in comparison to anisomycin infused animals. (E) Procedures were identical to A–D with the exception that the first test and second training session are separated by 12 d. (F) Groups were not significantly different during the 30-sec tone presentations at the discrimination test. (G) Animals that received vehicle infusions showed increased freezing during the CS− presentations in comparison to animals that received anisomycin infusions. (H) Animals that received vehicle infusions showed increased freezing during the CS− between the discrimination and generalization test in comparison to anisomycin infused groups. (*) P < 0.05.