Abstract

Morris water maze is one of the most extensively used tasks to investigate spatial learning and memory in rodents. In the probe test of the task, most researchers have measured the time spent navigating in the previous "target quadrant" where the platform had been during training. We compared the target quadrant data with the time swum in a narrow "target area" that was defined as a diameter-40 cm circle round the center of the platform. The target quadrant data were liable to overestimate the memory of poor learners, in which the basal nucleus of Meynert, a key structure of chlonergic system, was destroyed. It was proved by a bivariate regression analysis that the target area data are more valid than the target quadrant data. The results suggest that the target area data should be gathered as a alternative memory index together with the target quadrant data in future studies using Morris water maze.