Abstract: Separate groups of rats with lesions in the septum or parietal cortex were tested for acquisition and retention of the Morris water maze spatial cognitive task. Some of them in each lesion group received preoperative training in the task. Others in each group received no preoparative training. The results in- dicated that although both lesions lead to a spatial cognitive impairment in both the acquisition and retention of the task, the animals with septum lesions were more severely impaired than were the animals with parietal cortex lesions, as indicated by quantitative measures. Searching strategies were used as an index to eximine the qualitative difference of the animal's swimming beha- vior. The septum damaged animals tended to use "nonmapping" strategies to solve the task, and the strategies emerged a dynamic change. All of these su- ggested that the qualitative nature of the impairment differed from that of the parietal cortex damaged animals. The results of this study support the hypo- thesis that septum plays an important role in the processing of spatial mapping cognition.

Key words: septum, parietal cortex, cognitive mapping, searching strategies, Morris maze