Differential roles of dorsal hippocampal subregions in spatial working memory with short versus intermediate delay

In order to determine the role of subregions of the hippocampus in spatial working memory, this study combined selective neurotoxic lesions of the hippocampal subregions with a simple delayed nonmatching-to-place task on a radial maze in rats. Lesions of the dentate gyros or the CA3, but not the CA1, subregion of the hippocampus induced a deficit in the acquisition of the task with short-term delays (i.e., 10 s) and impaired performance of the task in a novel environment. All subregional lesions produced sustained impairment in performing the task with intermediate-term delays (i.e., 5 min) when rats were tested in a familiar environment. The results suggest a dynamic interaction among the dorsal hippocampal subregions in processing spatial working memory, with the time window (i.e., delay) of a task recognized as an essential controlling factor.