A novel spatial Delayed Non-Match to Sample (DNMS) task in the Göttingen minipig

The pig (Sus scrofus) is a valuable animal for modeling human brain diseases. When evaluating animal models of many human brain disorders cognitive testing is crucial, but the pig's ability to learn the typical types of tasks used in neuropsychological testing of other species is largely unknown. The present study is the first study to evaluate the pig's ability to learn the Delayed Non-Match to Sample (DNMS) task. The pigs were trained in a maze on a spatial version of the DNMS task. Initially, the pigs were trained with a 60s delay interval between sample and test phases, and we found that the pigs required an average of 144 trials to reach criterion for learning the task, which is similar to macaque monkeys. We also found that pigs, in contrast to rats, do not have a natural tendency to alternate in their choices in the task. To evaluate the sensitivity to reduced memory function longer delay intervals (300 s and 900 s) and a scopolamine challenge were introduced. In our test condition we found a significant effect of longer delay intervals (F(2,21)=34.43, P<0.0001) and of scopolamine (F(1,14)=14.28, P=0.002) on the number of correct choices in the task. We conclude that the Göttingen minipig can solve the spatial DNMS task and that the task is sensitive to both increasing delay intervals and to scopolamine.