Acquisition of responses to a methamphetamine-associated cue in healthy humans: self-report, behavioral, and psychophysiological measures.

Drug-associated cues elicit conditioned responses in human drug users, and are thought to facilitate a drug-seeking behavior. Yet, little is known about how these associations are acquired, or about the specificity of the conditioned response modalities. In this study, healthy, nondependent volunteers (N=90) completed a conditioning paradigm in which they received a moderate dose of methamphetamine paired with one stimulus and placebo with another stimulus, each on two separate occasions. Their responses to these cues were measured with a behavioral preference, self-reported 'liking', emotional reactivity, and attentional bias measures, both before and after the conditioning. Following the conditioning procedure, subjects exhibited a behavioral preference, positive emotional reactivity, and attentional bias toward the methamphetamine-associated cue, compared with the placebo stimulus. In addition, subjects who reported greater positive subjective drug effects during the conditioning displayed a more robust conditioning. This work demonstrates that healthy nondependent volunteers readily acquire conditioned responses to neutral stimuli paired with a drug. The procedure has significant value to study individual variation in acquisition of conditioned responses as a possible risk factor for drug taking, and to study the neural basis of conditioned drug responses.