Spatial matching and nonmatching in male and female Wistar rats: Effects of delay-interval duration

Abstract

Male and female Wistar rats were trained in a delayed matching-to-position procedure in which one of the two levers (sample) was presented. Pressing this lever resulted in its retraction and began a delay interval of random variable duration, which terminated with the occurrence of the first nose poke in the pellet retrieval unit after the delay interval had expired. Both levers were then inserted into the chamber, and food became available when the subject pressed the lever that had previously been pressed (matching response). When the subject failed to make a matching response, time out (5 sec) was presented. In the next experimental condition, nonmatching was reinforced. Males and females required an equal number of trials to attain 80% accuracy during three consecutive sessions under matching and nonmatching conditions. Response accuracy decreased as the delay interval increased, during both conditions. Differences between the sexes were not observed, suggesting that memory functions in male and female rats may only differ when other behavioral differences between the sexes are allowed to interfere with the assessment of memory functioning.