Similarly, in another MWM study it was found that 11-
month-old Fischer-344 rats are impaired in the platform
crossings measure but not in other less challenging PT
(Frick et al., 1995). Note that the platform crossings measure
is a highly challenging measure because it requires
precise localization of the platform. The two above reports
indicate the presence of a mild spatial reference memory
deficit in rats as young as 11–12 months which becomes
detectable only in difficult measures of performance.