Effects of piracetam on the performance of rats in a delayed match-to-position task.

1. The influence of acute and chronic treatment with piracetam on spatial working memory of rats was examined. A new version of an operant chamber "delayed match-to-position task" was used, in which the animals had to visit one randomly baited box out of three boxes ("choice boxes") in a front panel. Hereafter a delay period began, in which the subjects had to visit an alcove in the back panel ("reference box"). At the end of the delay the animals should return to the front panel and choose the same choice box that was baited before the delay, thereby obtaining a reward. 2. Rats were trained to a stable level of performance, measured as per cent correct responses during sessions of 20 trials. Additionally, the time spent between leaving the choice box and entering the reference box was recorded. Results were obtained from a single group of rats tested repeatedly under different experimental conditions. 3. Injections of scopolamine (0.6 mg/kg) significantly reduced the percentage of correct choices and increased the time spent to reach the reference box. The impairment of correct choices was reversed after chronic treatment with piracetam (250 mg/kg). However, the same treatment did not reverse the effect of scopolamine on the time performance. 4. Scopolamine also induced an increase of repetitive errors (a measure of perseverance), and the chronic treatment with piracetam caused full reversal of this increase. These results represent the first observation of a piracetam induced reversal of scopolamine impairments in a working memory test. 5. In normal animals not treated with scopolamine, acute injection of piracetam had no effect compared to saline injected controls, but chronic treatment with the nootropic significantly enhanced working memory performance. The drug did not affect the time used to reach the reference box.