PERFORMANCE OF 4 DIFFERENT RAT STRAINS IN THE AUTOSHAPING, 2-OBJECT DISCRIMINATION, AND SWIM MAZE TESTS OF LEARNING AND MEMORY

The performance of four strains of rats commonly used in behavioural r esearch was assessed in three different tests of learning and memory. The four strains included three outbred lines (Long-Evans, Sprague-Daw ley, Wistar) and one inbred strain (S3). Learning and memory were test ed using three different paradigms: autoshaping of a lever press, a tw o-object discrimination test, and performance in a two-island swim maz e task. The pigmented strains showed better performance in the autosha ping procedure: the majority of the Long-Evans and the S3 rats acquire d the response, and the majority of the Wistar and Sprague-Dawley fail ed to acquire the response in the set time. The albino strains were sl ightly better in the swim maze than the pigmented strains. There appea red to be a speed/accuracy trade-off in the strategy used to solve the task. This was also evident following treatment with the cholinergic- depleting agent hemicholinium-3. The performance of the Long-Evans rat s was most affected by the treatment in terms of accuracy and the Wist ars and Sprague-Dawleys in terms of speed. In the two-object discrimin ation test only the Long-Evans showed satisfactory performance and wer e able to discriminate a novel from a known object a short interval af ter initial exposure. These results show large task- and strain-depend ent differences in performance in tests of learning and memory. Some o f the performance variation may be due to emotional differences betwee n the strains and may be alleviated by extra training. However, the re sponse to pharmacological manipulation may require more careful evalua tion. These results suggest some advantage for the Long-Evans strain i n speed of learning, if not in actual final level of performance, in m any tests.