A 3D SPATIAL NAVIGATION TASK FOR ASSESSING MEMORY IN RODENTS

In the present report we describe a 3-D maze spatial navigation task for rats based on a modification of an eight-arm radial maze. The arms radiating from a central platform can be presented in a horizontal plane either raised 10 cm above the level of a central platform or lowered 10 cm below. Memory of visited and non-visited arms can be guided by distinct internal cues (patterns) that are presented on panels set at the end of each arm. Rats are trained in three different maze configurations (eight session each) with arms set lowered, flattened or raised relative to a central platform. A food pellet is placed at the end of each arm and rats are allowed to make eight arm choices only, in each testing session. In this task rats perform better when moving uphill to raised arms than when moving on flattened arms or when moving downhill to lowered arms. It is likely that spatial navigation on raised arms is based on visual cues that were highly visible from the central platform. This result can be accounted for by the position of the rats' eyes that are placed laterally on the sides of their heads