Conventional theories of diencephalic amnesia have focused on a single thalamic region as a critical factor in the origins of anterograde amnesia. A more contemporary view is that different thalamic regions might contribute in unique ways to normal diencephalic functioning and therefore provide distinct contributions to the learning and memory. This study directly compared the effects of AT and MT lesions on a spatial pattern separation task, a spatial working memory task and a conditioned place preference task. AT lesions but not MT lesions produces deficits on the spatial working memory task on a cheeseboard. No group AT, MT or control rats acquired a conditioned place preference on the AT/MT lesion conditioned place preference task. Furthermore, this study determined the effect of systematic procedural variations on control rats in a conditioned place preference control task. The only variation that acquired a condition place preference was a separate arms conditioned place preference with one pre-exposure and three training trials. The results of this study provide new information regarding the role of thalamic lesions in spatial memory and suggests a revision of the current theories regarding learning and memory to incorporate the thalamic involvement that has been highlighted