A comparison of the effects of diazepam and scopolamine in two positively reinforced learning tasks

Abstract

In a helical maze scopolamine (0.5 and 1 mg/kg) significantly impaired the ability of rats to acquire a spatial learning task using reference memory. In contrast, diazepam (0.5-2 mg/kg) did not impair acquisition of this task and the only effect of diazepam (4 mg/kg) was likely to be secondary to sedative effects. Diazepam (0.5-4 mg/kg) did not impair 8-day retention of the helical maze. In a test of working and reference memory in which spatial processing was minimised, scopolamine (0.5 and 1 mg/kg) significantly impaired acquisition and increased the number of reference memory errors. Diazepam (1 and 4 mg/kg) did not impair acquisition of this task, but when a delay was interposed in the middle of a trial the diazepam-treated rats were slower to complete the task than the controls and made more errors of both working and reference memory. In contrast, when the rats were tested with a change of context, the diazepam-treated rats completed the task more quickly than the controls and made fewer errors of both working and reference memory.