Figure 2.

Dopaminergic modulation of the persistence of a long-lasting cocaine-associated memory. 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 3-trial training. (a) The D1-type agonist (SKF 38393) had no effect on the 24 h memory for cocaine–place associations established by three-trial training (n=9–10 per group). (b) Treatment with the D1-type agonist (SKF 38393) attenuated the 7-day persistence of the memory for cocaine–place associations established by three-trial training (n=7–10 per group). (c) The D1-type antagonist (SCH 23390) had no effect on the 24 h memory for cocaine–place associations established by three-trial training (n=8–10 per group). (d) The D1-type antagonist (SCH 23390) had no effect on the persistence of the memory for cocaine–place associations when tested at 7 days after three-trial training (n=13–15 per group). Post hoc analyses demonstrated that the group conditioned with cocaine, infused with SKF 38393 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<0.01; ***p<0.001). Coc, cocaine; Sal, saline; Veh, vehicle.