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. 2014 Feb 12;39(7):1645–1653. doi: 10.1038/npp.2014.11

Figure 1.

Figure 1

Temporal duration and dopaminergic modulation of the persistence of a short-lasting cocaine-associated memory. (a) Three doses of cocaine were tested. The dose of 20 mg/kg induced a significant retention of the memory for cocaine–place association when tested 24 h after a one-trial training (n=5–21 per group). Therefore, this dose was used in all the remaining approach experiments. (b) A weak (one-trial training) memory for the cocaine–place association was retained for 24 h but not for 7 or 14 days (n=7–11 per group). (c) A strong (three-trial training) memory for the cocaine–place association was retained for at least 21 days (n=8–10 per group). Asterisks indicate significant differences between cocaine-injected animals and its corresponding saline controls (Newman–Keuls, *p<0.05; **p<0.01). (d–g) Effects of D1-type dopamine agonist (SKF 38393) or antagonist (SCH 23390) injections—given 12 h after the training trial—on the persistence of the memory for cocaine–place associations established by one-trial training. (d) The D1-type agonist had no effect on the 24 h memory for cocaine–place associations established by one-trial training (n=8–10 per group). (e) The D1-type agonist had no effect on the persistence of the memory for cocaine–place associations when tested at 7 days after one-trial training (n=10–12 per group). (f) The D1-type antagonist had no effect on the 24 h memory for cocaine–place associations established by one-trial training (n=16–17 per group). (g) The D1-type antagonist prolonged the duration of the memory for cocaine–place associations after one-trial training (n=11–14 per group). Post hoc analyses demonstrated that the group conditioned with cocaine, infused with SCH 23390 12 h later, and tested at 7 days showed a higher score when compared with the other groups (Newman–Keuls, **p<0.01). Asterisks upon bracket indicate a significant difference between saline- and cocaine-injected animals, collapsed across intracerebral infusion treatments (Newman–Keuls, *p<0.05; **p<0.01). Coc, cocaine; Sal, saline; Veh, vehicle.