Learning set spatial navigation performance in three mouse strains

Swiss Webster (SW), Dilute Brown Agouti (DBA), and Deer Mice (DM) were tested for acquisition and retention of a learning set place task in the Morris water maze. The learning set consisted of daily placing the hidden platform sequentially at 1 of 4 separate locations in the pool. All animals swam for 63 days in this version of the water task. SW animals were unable to find the platform reliably. The time taken by DBA and DM animals in escaping the pool declined rapidly, reaching asymptote within 21 days. The DM animals reached the platform significantly faster than either SW or DBA mice. Analyses of swim path selection used by the 3 strains indicated clearly that DM mice were the most systematic in the selecting and sequencing from a variety of potential strategies the appropriate methods necessary for the most efficient solution of the problem. The present results suggest that in light of the differences between strains observed in swimming behaviors, investigation of strain differences in the neuroanatomic structures believed to be related to the solving of spatial problems might be useful.