(Sutherland &Hoesing, 1993):

The Morris water maze consists of a submerged platform placed somewhere within a pool of water made opaque with milk or chalk (Morris, Garrud, Rawlins, & O’Keefe, 1982). When placed in this pool, rats try to find a way out; they initially swim randomly until they find the platform and climb out. Normal rats quickly learn the location of the platform: if the platform is removed, the rats search at the place where the platform had been (Morris et al., 1982). Rats with hippocampal lesions cannot learn this task (Morris et al., 1982; Morris, Schenk, Tweedie, & Jarrard, 1990; McDonald & White, 1994). If the rats are trained on the task first and then given a hippocampal lesion 1 week later, they showprofound deficits; however, the same lesion 12 weeks after training produces much smaller deficits (Sutherland & Hoesing, 1993). Here, then, is a specific amnesia result that can be modeled in detail.