radial arm water maze; Morris water maze

Introduction

Device often used in assessment of spatial memory in rodents. The maze contains a number of arms radiating from a central area. One of the areas generally contains a platform upon which the animal can rest without swimmming. The time required for the animal to find the platform is generally used as an assessment of spatial memory.

Hidden (spatial) & non-hidden (non-spatial) version

Method considerations:

• body weight, physical development
• gender
• species/strain difference
• nutrition
• stress & infection

Disadvantages

• testing requires an animal to flee from an aversive environment seemingly devoid of escape routes
• initial immersion can cause stress; temperature of water & prior handling can reduce this stress
• relative inability to control extra-maze cues that determine the acquistion process

Procedure

Maze setup:

• tank: 110 cm for mice; 180 cm for rats
• circular tank filled with opaque water
• temperature: 25 degrees or higher
• 10 cm plexiglass patform
• tracking/imaging system (HVS)

Basic Protocols

• hidden platform acquisition training
• probe trial
• working memory

Day	Task	Blocks	Time
Mon	visible training	2 blocks, 4 trials each	AM & PM
Tue	visible training	1 block	AM
Wed	acquisition	2 blocks	AM & PM
Thurs	acquisition	2 blocks	AM & PM
Fri	acquisition & probe	2 blocks + probe trial	AM & PM
Mon	working memory 1	2 blocks	AM & PM
Tue	working memory 2	2 blocks	AM & PM

Notes

Pitfalls:

• thigmotaxis & passive floating
• using the same animals for both spatial & non-spatial tasks
  • standard protocol is to run the spatial/hidden test, then a control study using the non-spatial/visible test
  • a normal performance on the non-spatial/visible test & impaired performance on the spatial/hidden test is taken as evidence of hippocampal dysfunction
  • potential FLAWS in this interpretation

More general terms

• water maze