Figure 1.

Conditioned Place Preference (CPP) Cue Configurations. Abbreviations for each configuration are based on the number of CPP compartments (one-,1 or two-compartments, 2) and the type of spatial cue (consistent, c or alternating, a) during CPP acquisition (A) and extinction (E). CPP preparations consisted of tactile cues (grid, G or hole, H floors) for all animals. Two-compartment chambers were identical to one-compartment chambers except that a clear divider bisected the chamber area, leaving the opposite conditioned stimulus (CS) flooring/position visible. During acquisition (A), mice were injected IP with 20 mg/kg cocaine (+) or saline (−) and placed on their assigned CS+ or CS− paired floor in a one- or two-compartment apparatus. Cocaine was paired with the grid floor (G+/H−) for half of the animals and with the hole floor (G−/H+) for the other half (not shown). During extinction (E), CPP was extinguished by placing mice on the previously paired CS+ floor without a cocaine injection (mice did not receive tactile exposure to the previous CS− floor during extinction). Preference for the CS+ paired floor was determined by a Choice Test before and after acquisition or extinction.