A comparison of visual- and response-generated cues in a spatial DMTS task for rats

In an attempt to clarify the nature of the memory cues used in a spatial, working memory task, rats were tested in a two-choice water maze. Each trial consisted of an information run, which forced the rat to the correct choice compartment, a retention period, and a test run. A response-associated cue condition, in which the relevant cue was the direction of the turn in the information run, was compared to a visual cue condition in which the animal had to remember whether the escape platform had been in the light or dark compartment. Of the subjects supplied with either visual or response-associated cues, the subjects allowed to employ response-associated cues did better, but the best performance occurred when both cues were available. When rats trained with both cues present were forced to choose between cues, they stopped using either and reverted to making a preferred right or left turn. The results support the idea that rats can form integrated, relational-cue memories which, in some circumstances, prove a hindrance to performance.