Measures
Non-spatial confounds: when it isn't memory
Before you report a memory deficit, rule out the other explanations.
A group that does worse in the water maze hasn't necessarily got a worse memory. The original notes return to this again and again:
- Vision. Hooded rats may do better than albino rats, "possibly because albino rats do not see as well" (rats). A cued, visible-platform phase helps here (cued and hidden).
- Anxiety and swimming. "If the mice are too nervous, or too weak to be at their ease swimming, their performance is compromised independently of spatial learning" (1999 essay).
- Activity. Swim speed is the water maze's built-in activity measure (swim speed).
- Giving up. Floating and wall-hugging can look like forgetting (inactivity, thigmotaxis).
- Strategy. Animals can find the platform without a place memory (search strategies).
: The essay's suggestion: test exploration and anxiety before the water maze, not after.
Swim speed is the usual first check; see swim speed in Morris water maze analysis.
Sources
- Vorhees & Williams (2006). Morris water maze: procedures for assessing spatial and related forms of learning and memory. Nature Protocols 1(2):848-858. doi:10.1038/nprot.2006.116
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