Post-training infusion of APV into the striatum impaired long-term fear memory. (A) Examination of dye spread in the striatum. Bright field photomicrograph of colonal brain sections showing the spread of the dye solution (0.5 μl) in the striatum. An angled line indicates a track of guide cannula. (Left) Dye solution spreads largely in the NAc and along the cannula track in the overlying CP. (Middle) Dye solution in the NAc usually spreads vertically as well (n = 6). (Right) Dye solution did not reach the BLA or CeA. Scale bar: 1 mm. (B) Experimental design. Mice were injected with 0.5 μl of ACSF or APV into the striatum immediately after auditory fear conditioning with a lower-intensity footshock, and tested 24 h later. (C) Freezing responses of ACSF (n = 10) and APV (n = 10) groups on the conditioning (left) and test (right) days. A solid line and a thin arrow represent tone and footshock (0.3 mA), respectively. (D) Freezing responses of ACSF (n = 15) and APV (n = 12) groups on the conditioning (left) and test (right) days. A solid line and a thick arrow represent tone and footshock (1.0 mA), respectively.