Spatial learning in the guinea pig: cued versus non-cued learning, sex differences, and comparison with rats.

This paper provides the first report of spatial learning in guinea pigs using the Morris water maze (MWM). Male and female guinea pigs were trained for 5 consecutive days (8 trials/day; acquisition phase) in either the visible (cued) or the hidden (non-cued) platform version of the MWM. In both tests, guinea pigs learned to navigate to the escape platform, as indicated by a decrease in escape latency over the 5 training days. There were no sex differences in either test version. A comparison of guinea pigs and male Wistar rats showed that performance during acquisition training was not different for the two species in the visible platform test, but rats performed better during the early training days in the hidden platform test. A retention test (probe trial) was given 5 days after the last acquisition training day. Again, there was no sex difference, and no difference between guinea pigs and rats. Finally, acquisition of a new escape response to a shifted platform location was equivalent for rats and guinea pigs of both sexes. These results demonstrate that guinea pigs show robust cued and non-cued learning in the MWM. Both acquisition and retention performance in guinea pigs is similar to that in rats, even though rats appear to have a slight advantage in the acquisition of non-cued, spatial information in this test. We conclude that the MWM provides a valuable paradigm to assess behavior and learning/memory in the guinea pig.