Figure 4. Pten deletion in pyramidal neurons during postnatal development causes a deficit in spatial memory.

A, spatial learning is not impaired in Pten^−/− mice, as indicated by the lack of difference in the mean path lengths of WT (black) or Pten^−/− (red) mice swimming in the Morris water maze to find a hidden platform as a function of training days. B and C, long-term memory retention is, however, impaired in Pten^−/− mice. The mean number of counter passes across the platform location measured during the first 10 s (B) and during the entire 60 s probe trial (C) in WT and Pten^−/− mice differed significantly (*P < 0.05). D, non-spatial memory is normal in Pten^−/− mice. Mean path lengths to swim to a visible platform, as a function of training days, was comparable in WT and Pten^−/− mice.