Multivariate and Nonlinear Approaches to Characterizing Drug Effects on the Locomotor and Investigatory Behavior of Rats

Abstract

The measurement of motor activity in rodents is one of the most fundamental behavioral tests used in the study of drugs of abuse. In many cases, the behavior is referred to as unconditioned or spontaneous motor activity because it has not been explicitly conditioned by the experimenter. The related term genera/ motor activity is commonly used when monitoring systems are employed that do not distinguish between different aspects of locomotor behavior; while the term locomotor activity is typically applied when ambulatory movements are monitored more specifically. Various instrumentally and operationally defined measures of motor activity have been used to assess the behavioral effects of drugs or other manipulations, either as strict measures of locomotor activity or as measures of more global and context-dependent constructs such as arousal, curiosity, emotionality, and exploration. In psychopharmacology, activity measures are often used as bioassays of drug effects or to establish macroscopic characteristics for drug classes. For example, psychoactive drugs are defined as stimulants or depressants largely on the basis of their effects on gross measures of the motor activity of rodents.