Exploratory motivation in response-to-change test in rats

Abstract

The tendency to select T-maze arm that has been changed in brightness between two consecutive trials was investigated under different experimental conditions. In trial 1 rat was confined in maze stem for 10 min and allowed to observe black-and-white arms through transparent partitions. In trial 2 the color of one arm was changed, so that both arms were alike (either white or black) and the rat was allowed a free choice. Eight tests separated by 48 h intervals were performed on 4 groups of 20 rats. In the first group rats were removed from the maze immediately after the arm choice. This group showed preponderance of responses to change only in the first test. In successive test repetitions the choices of changed arm dropped to chance level. Rats spent less time on maze arms observation and their choice-latency increased. Two procedural modifications, i.e. providing an exploratory reward for response to change and an opportunity to explore the black and white maze arms independently from test situation, were introduced separately in the second and third group. Each modification resulted in the increase of choice frequency of the changed arm and in the decrease of response latency relative to first group. Application of both modifications in the fourth group led to its superior performance during test repetitions. The effects appeared to result from providing outcome of responses to change and/or attenuation of frustration caused by confinement in trial 1.