Effect of memory age on the stability of reactivated memories. A–D, Experimental design used with data presented below. A, Effect of 1 week retention on freezing during test between reexposure (3 min) and test (control, n = 10; ANI, n = 10). B, Effect of 3 week retention on freezing during test between reexposure (3 min) and test (control, n = 10; ANI, n = 10). C, Effect of 8 week retention on freezing during test between reexposure (3 min) and test (control, n = 10; ANI, n = 10). D, Effect of 8 week retention on freezing during test between reexposure (10 min) and test (control, n = 10; ANI, n = 10).