Spatial memory and instrumental conditioning.

Abstract

Short-term spatial memory of rats was studied in a 12-arm radial tubular maze. Correct performance does not depend on maze structure which affects, however, the rat’s trajectory through the maze. Rats overtrained in the 12-arm radial maze show considerable transfer of the habit to a maze consisting of 12 parallel alleys entered from a common choice area. When isolated maze channels equipped with one way doors on both ends are randomly scattered over an enclosed area of 2 square meters the rats are capable of visiting them sequentially, even when they encounter this particular configuration for the first time. Rats which were allowed 6 choices in the 12-arm radial maze and were then transferred to linear configuration of the same maze channels do not show significant preference for the yet unvisited channels. This indicates that in absence of spatial cues other sensory properties of the different channels cannot guide the choice behavior of the animal. An essential prerequisite of spatial memory tests is elimination of cues which would allow direct sensory location of the baited alleys. Smelling the food hidden in the food-cups may significantly improve the rats performance unless the maze channels are saturated with food odor. It is concluded that a prerequisite for the striking performance of rats in the tasks of the above type is their thorough familiarization with the list of choices. The spatial location of an item is an important cue for the recognition of the choices already made.