Morris swim tank

Further modifications are the size of the swimming tank and the position of the escape platform. Both parameters differ widely between different laboratories. In general, larger tanks increase the difficulty for the animal to find the escape platform with a consequently flatter learning curve. Indeed age- or drug-related changes in Morris maze performance depend critically on such factors (van der Staay 2000). 

The Morris (1984) water maze is a large circular glass tank (1.5m diameter) filled with opaque (e.g. dye-treated) water to a depth of some 50 cm. A small platform, large enough to take the rat, is placed in the water with its top about 1.5 cm below the surface, so it cannot be seen. When placed in the water the rat finds and escapes to the platform, the position of which is apparently learnt by reference to peripheral visual markers. Memory is demonstrated by the rat s ability to swim to the platform when put back into the water at various points and measured by the time or the length of path taken to do so (Fig. 18.3). 

Named after Richard Morris of Edinburgh who invented this experimental process in which rodents (rats or mice) are required to remember where an invisible platform is in the tank in which they are obliged to swim. 

Morris water maze. Intracerebroventricular (ICV) NaCN has been observed to disrupt normal spatial navigation in rats using the Morris water maze (MWM) swim task. In this task, rats were placed in a round water tank and trained to use spatial cues to locate an escape platform submerged just below the waterline. 

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