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. 2006 Sep 27;26(39):10051–10056. doi: 10.1523/JNEUROSCI.2466-06.2006

Figure 1.

Figure 1.

Effects of systemically applied MK-801 and DCS on conditioned freezing. a, When administered before brief memory reactivation (LTM; 1 CS re-exposure), MK-801 had no effect on freezing 3 h later (PR-STM) but reduced subsequent freezing relative to saline controls both 24 h (PR-LTM) and 7 d (PR-LTM2) later. In contrast, DCS attenuated the normal decrement in freezing observed in saline controls in tests PR-LTM and PR-LTM2, although having no effect either acutely or on PR-STM. b, When administered before longer extinction training (extinction; 10 CS re-exposures), MK-801 preserved subsequent freezing, whereas DCS enhanced the partial reduction of freezing observed in saline controls. MK-801 also acutely impaired the expression of conditioned freezing in both conditions (n = 8 per group). c, When fear conditioning was weaker, DCS administration before brief memory reactivation elevated freezing 24 h and 7 d later (n = 8 per group). d, When MK-801 and DCS were administered without memory reactivation or extinction training, there was no effect on freezing 24 h later (n = 8 per group). Error bars indicate SE.