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Learning and memory in the Morris water maze. (from the archives)

We found this in Rich Baker's old archives and thought that it might be of interest

We can examine reference learning and memory in the Morris water
maze. Initially the mice are trained to locate a cued, flagged
platform.During this phase of the study both the cued platform
position and the starting position of the mouse are randomly varied
to avoid habituating the mouse to a particular area of the pool.

Following this sensory motor test the cued platform is switched
with a submerged platform the position of which is fixed for each
mouse. As the mouse learns its position the path-lengths &
latencies to locate the platform are reduced.

Following the final placed session, the platform is removed and
the swim-pattern of the mice is tracked for one minute. We then
compare the time the mouse spends swimming in the former platform
quadrant with the time in the other three.

This gives a measure of memory and also allows us to see if the mice
are using different strategies to find the platform. For example,
instead of using the distal cues, some mice learn to swim at a
fixed distance from the edge of the pool until they find the platform.

An additional HVS measure one can take includes the number of
platform position crossings. Again if the mouse shows good evidence
of spatial memory the mouse will exhibit a significantly increased
number of former platform position crossings in comparison with
the other three.

A further advantage of this model is that by reversing the submerged
platform position, it allows us to examine flexibility of learning,
ie how easy is it for the mouse to let go of one learned behaviour
and acquire the new task. Inflexibility of learning is an early
feature of AD dementia.

Statistical Analysis... When looking for statistical differences
in latencies, pathlengths and swim speeds one uses repeated-
measures analysis of variance (ANOVA).

Assuming a significant overall main effect of treatment, genotype
etc. one can employ post hoc comparisons e.g. Dunnett's test. For
probe data one way ANOVA is sufficient.

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