Exploration and latent learning: Differential effects of dexamphetamine on components of exploratory behaviour in rats

Summary Exploratory behaviour of undrugged rats in a modified Y-maze was recorded during repeated daily trials. Two types of exploration entries into the arms of the maze and a non-locomotor measure, investigation of troughs at the ends of the arms were scored. Latent learning about the location of food-mash in particular troughs was found to be a function of the number of training trials; also there was evidence that learning was greatest in rats which had the highest scores on entries and trough investigation, which validated these as measures of exploration.Dexamphetamine 0.25, 0.50, 1.0 mg/kg had differential effects on activity. Entries were increased while trough investigation was reduced. It is suggested that dexamphetamine reduces true exploration while increasing locomotor activity in a non-specific manner.I thank Mr. J. R. H. Bryant for technical assistance and Mr. B. Hutchings for acting as the co-observer in Experiment II. I am extremely grateful to Dr. I. P. Stolerman and Dr. H. Steinberg for help and discussion and to Smith Kline & French for gifts of rats. This work was supported by research grant No. MH-03313 from the National Institute of Mental Health, U. S. Public Health Service.Beit Memorial Research Fellow