Radial arm maze performance of mice: acquisition and atropine effects.
CD-1 mice were successfully trained in a six-arm radial maze in which half of the arms were baited, a procedure which had been used to differentiate between reference and working memory. Stable performance was achieved following eight daily training sessions, as measured by decreasing running time and number of errors. This finding strengthens the foraging hypothesis as a basis for the performance of rodents in the radial maze. Acute subcutaneous administration of the cholinergic antagonist atropine sulfate (1-6 mg/kg) to trained mice produced dose-related increases in running time and working memory errors, with a slight decrease in reference memory errors. This is in agreement with other studies on the role of the cholinergic system in memory processes. The peripheral cholinergic blocker, atropine methyl nitrate (4 mg/kg), somewhat increased running time without decreasing performance accuracy. In contrast to the prolonged pharmacological and physiological effects of atropine, behavioral decrements disappeared within 3 hr. It is concluded that mice trained in the radial arm maze may be used for screening of the effects of drugs on cognitive function.