Spatial working memory and reference memory of Brown Norway and WAG rats in a holeboard discrimination task.

To determine whether working memory (WM) and reference memory (RM) represent different aspects of spatial memory, albino WAG rats and the pigmented Brown Norway rats were tested in the acquisition, retention, and reversal of spatial orientation tasks in the holeboard, which allows the simultaneous assessment of WM and RM. Putative nonmnemonic factors, such as the speed of visiting the holes or the development of a search strategy (preferred sequence of visiting the baited set of holes) were also evaluated because they might influence WM and RM performance. The WM performance of Brown Norway rats was generally worse than that of the WAG rats. The reverse was true for the RM performance. Correlation analysis supported the notion that these two measures are independent. Differences in the speed of visiting the holes and in the development of a preferred sequence of visiting the baited set of holes could not explain the strain differences in WM and RM performance. Because spatial WM and RM appear to be independent measures in the holeboard, this task could be used to investigate whether different neural substrate(s) underlie these two memory components.