Rats with fimbria-fornix section or complete hippocampal aspiration lesions were postoperatively compared to unoperated controls in a nonspatial working memory task using an enclosed plus maze. Initial training (stage 1) was on a continuous two-choice nonmatching to sample task, using pseudo-trial-unique stimuli. Subsequent testing (stages 2-4) always had four boxes available at each choice opportunity, with each goal arm containing a distinctive goalbox. The positions of these boxes were int...