| Abstract: | Two experiments were conducted to determine the role of the response and of reward in spatial working memory. Rats were initially trained on a four-arm maze to run to the end of each arm for a single pellet of food. On subsequent tests, rats were first placed at the end of one, two, or three arms. In Experiment 1, the arms on which the rat was placed (“placed arms”) had food which the rat was allowed to eat, whereas in Experiment 2 these placed arms did not have food. Following the placements the rat was allowed to choose among the four arms; only unplaced arms contained food. Two measures indicated that the response made a slight but reliable contribution to spatial memory. (a) When a rewarded arm was still available, choice accuracy after placements was less than choice accuracy on tests in which no placements had occurred; this difference diminished over test days. (b) When all four arms had been chosen once, the rats were more likely to go back to a placed arm rather than an unplaced arm. No influence of the presence or absence of food on the placed arms was found. These data demonstrate that the response of running down an arm, but not the reward outcome at the end, had a small influence on the memorability of a visit. Overall, above chance performance in the spatial working memory task was maintained without either running to the arm or obtaining food on it. |
