Amphetamine as a model for hyperactivity in the rat.

Abstract Exploratory behavior of saline and amphetamine-injected rats has been analyzed using time-lapse photography. Three models are proposed for the expected effects of drugs causing hyperactivity in rats. The conclusions which are reached from the analysis are that control behavior of rats under the condition employed shows a high degree of patterning and stability and that at moderately low doses amphetamine causes dose-related changes in frequency of certain behavioral acts and a shortening of the duration of an act, once it is initiated. These two actions can be assumed to encompass the effect of amphetamine described as behavioral stimulation or hyperactivity. In addition, amphetamine causes increased randomization of initiation of behavior acts. This disruption of normal behavior sequences is not detected by most methods of analysis of hyperactive behavior but has been shown here to be a dose-related phenomenon accompanying the other drug-induced changes.