Drugs as chemical stimuli

Analogies can be drawn at many levels between psychoactive drug effects as discriminative stimuli and stimulus control by traditional exteroceptive stimuli. The most useful analogy may be between drug stimuli and the chemical senses. At the behavioral level, drug discrimination studies have already drawn heavily from behavioral science research on stimulus control. Training of a drug discrimination is operationally identical to training discriminations based on exteroceptive stimuli. Concepts from generalization studies and research with compound stimuli have also been used in drug discrimination research. At the cellular level, a parallel can also be drawn between the study of mechanisms for drug stimulus effects and research on olfactory transduction. One theory of olfactory transduction proposes receptor-mediated actions of odorants, with subsequent biochemical events involving the cyclic nucleotide cascade, that is very similar to theories of receptor-mediated drug action. There is a broad basis for cross-fertilization between the study of drug stimuli and behavioral and cellular studies in classical sensory systems.