Drugs of Abuse as Memory Modulators: the Cocaine Puzzle

It has been proposed that drugs of abuse reinforce behavior partly, or wholly, because they enhance memory consolidation. Cocaine can clearly serve as a reinforcer, but its effect on memory consolidation has not been fully characterized. The objective of this research is to explore the effects of different regimens of pre- and post-training cocaine administration on learning of a win-stay task and object recognition. Cocaine naïve and cocaine pre-exposed male Sprague-Dawley rats received cocaine (0, 1, 2.5, 7.5 or 20 mg/kg, IP) immediately following training on a win-stay task in a radial maze. In other experiments, cocaine was combined with diazepam (1 mg/kg), or was administered following the sample phase of an object recognition task. Post-training cocaine did not improve acquisition of win-stay because of performance deficits. An improvement was found only in object recognition. It is concluded that cocaine can enhance learning, but this effect is highly dependent on the dose and the task employed.