Recently developed ethoexperimental tests aimed at description and analysis of defensive reactions to the presence of unconditioned, nonpainful threat stimuli, or to situations associated with such stimuli, indicate substantial differences between the two. Present threat stimuli (in the FEAR/DEFENSE TEST BATTERY) elicit reactions such as flight, freezing, and defensive threat and attack, while situations associated with threat (in the ANXIETY/DEFENSE TEST BATTERY) produce a pattern of time-based changes from avoidance/movement inhibition, through risk assessment and interference with nondefensive behaviors. These two patterns, fitting the traditional psychological division between fear and anxiety, provide a full range of defensive behaviors for analysis of bidirectional changes in behavior associated with administration of pharmacological compounds. Since these tests do not use painful stimuli or involve learning of reactions to stimuli associated with pain, they are analytically less complex than traditional anxiety models, while providing a wider range of behavioral measures. Work completed with benzodiazepine and 5-HT1A agonists suggests a close correspondence between effects on these models and the clinical efficacy of pharmacological agents. The proposed program will examine the usefulness of these test batteries, plus a more inclusive VISIBLE BURROW SYSTEM test, as models for investigating the effects of pharmacological compounds previously shown to alter fear or anxiety reactions. These compounds include Benzodiazepine, GABA, 5-HT, Dopamine, Noradrenalin and Colinergic agonists and antagonists, plus Anti- Panic Agents. The effects of these drugs on wild and laboratory rats in these test batteries will provide an extremely detailed behavioral profile form each compound, and will permit in-depth comparisons within and between the different classes of compounds. This data base should thus enable much finer analysis of the effects of pharmacological manipulations on fear/anxiety reactions, resulting in increased understanding of the neurobiology of this system.