Daily Posttraining Exposure to Pulsed Magnetic Fields that Evoke Morphine-Like Analgesia Affects Consequent Motivation But Not Proficiency in Maze Learning in Rats

Abstract

Male rats were exposed to sham field conditions or to pulsed (burst firing pattern for 1 s every 3 s) magnetic fields (14 µT) for either 5 min or 30 min either immediately or after a 30 min delay following 8 daily training sessions in a maze. The maze was automated to record the proficiency of spatial learning and memory as well as response (lever press)/reward ratios. The strongest effect (approximately 40% of the variance) over the sessions occurred when the rats were exposed for 30 min to the field immediately after the training. Analyses of the data suggested that the reduced rate of acquisition was due primarily to the enhanced value of the reward rather than to interference with the consolidation of the spatial pattern.