CHAPTER 6 
Pharmacological Studies 
The administration of a drug or toxicant to animals being observed for behavioral effects can 
be justified by the need to understand the chemical's role in causing health problems for 
humans or animals (e.g., drug dependence, neurotoxicity), or the need to understand whether 
the drug can alleviate health problems (e.g., pharmacotherapy for behavioral and neurological 
disorders). Some research is designed to characterize the behavioral effects of an unknown 
chemical (e.g., the assessment of the abuse liability of new pharmaceuticals). It also is 
important to determine whether an organism's response to a drug changes because of chronic 
exposure to it and whether such exposure may lead to abuse or physical dependence. 
Another category of research examines chemicals that are known or are hypothesized to have 
specific behavioral effects that the investigator wishes to understand in more detail. For 
example, research with a drug commonly abused by humans is aimed at delineating the 
mechanisms underlying the drug's reinforcing or rewarding effects. Other research in this 
category examines how experiential and environmental variables influence the behavioral 
response to a drug. 
Drugs can be used to illuminate physiological and/or neurochemical mechanisms of behavior. 
A drug that blocks a neurotransmitter receptor system can help to determine the 
neurotransmitter's role in producing a specific behavior. A drug may be administered because 
it can produce anxiety reactions so that the research may understand the biological and 
behavioral consequences of chronic stress and possibilities for therapy. More detailed 
information is provided in the several chapters and books on behavioral pharmacology and 
toxicology (Branch, 1993; Ellenberger, 1993; Goldberg and Stolerman, 1986; Meisch and 
Lemaire, 1993; Seiden and Dykstra, 1977; van Haaren, 1993; Weiss and O’Donoghue, 1994). 
BEHAVIORAL BASELINES 
In many behavioral experiments that include drug administration, the animals are trained to 
perform some response that can be objectively measured. The motivation for the response 
often is delivery of an appetitive or a drug reward (as in self-administration studies) or, less 
often, the avoidance or escape from some aversive condition (see Chapter 7. Aversive Stimuli). 
Trained responses usually involve operating a lever or switch. Other dependent variables are 
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