A different look at measurement and interpretation of drug-induced stereotyped behavior

Stereotyped behavior is a term used widely to describe behavior induced by psychostimulant drugs. However, a historical examination of what is meant by this term shows that different researchers use it to label different behavioral manifestations of the drug-induced syndrome. Moreover, the drug-induced syndrome has not been described adequately. We suggest that to do so requires a morphogenetic approach that will reveal the structure of the behavior as it unfolds during the course of the drug’s action. This can be accomplished by decomposing the observed motor activity into independent kinematic variables. Using this approach, we have identified three kinematic variables (snout contact, progression, and turning) whose coupling explains much of the structure of behavior under apomorphine. Moreover, these variables can help us to understand the topography of drug-induced behavior in different environments and enhance the use of behavior to measure drug action.