The current study investigates exploration as a possible confound when interpreting increased rearing to be a withdrawal sign in morphine-dependent rats. Conditioned Withdrawal or Exploration Previous experiences and expectations can influence drug effects with repeated administration. Tolerance, defined as a gradual decrease of the drug effect over time, is one phenomenon given much attention by researchers. Related to tolerance is a lesser examined phenomenon, dependence.
Drug dependence is defined by the presence of withdrawal signs upon discontinuation of the drug.
Through associative learning the body compensates for the drug effect in an attempt to maintain homeostasis. Siegel's Compensatory Response Model is most successful in explaining context-specific tolerance and may be extended to explain dependence. When environmental cues elicit the drug opposite response in anticipation of the drug and the drug is not administered, the compensatory response is experienced exclusively. If dependence is defined by the presence of withdrawal symptoms, then tolerance and dependence may be mediated by the same compensatory response process. The withdrawal signs may actually be the compensatory conditioned response.