Online

Schepers, Scott Timothy

Psychology

2017

Ph.D.

In the animal laboratory, stressors can produce the relapse of drug-seeking behaviors after the behavior has been inhibited by extinction. This type of relapse has been called stress-induced reinstatement, and it models the relapse that is commonly reported in human populations. Interestingly, in the laboratory, stress does not typically reinstate extinguished behaviors that have been reinforced by food. One account of the discrepancy is that drugs of abuse may induce stress; therefore, when organisms learn to respond for drugs, they might learn to make the response in the ⁰́₋context⁰́₊ of stress. If so, then stress-induced reinstatement may be better described as renewal in a stress context. Renewal is the type of relapse that occurs when a behavior is returned to the original training context (or is shifted to a new context) after it has been inhibited or suppressed by extinction. Although renewal has usually been studied with contexts that differ in their exteroceptive cues, interoceptive cues (e.g., mood, food deprivation, and drug states) may also provide contexts. Accordingly, if an interoceptive stress state is present when food-seeking behavior is learned, then extinguished food seeking, like drug seeking, should also renew when the organism is stressed after extinction. In this dissertation, I discuss six experiments that investigated this hypothesis. Experiment 1 found that stressors renew extinguished food-seeking if they are also present during instrumental training. Experiments 2 and 3 then provided preliminary evidence that this effect is not exclusively due to incentive learning. Experiment 4 then suggested that interoceptive stress, and not the particular stressor that produces it, may indeed serve as a general interoceptive context that controls the effect. Experiment 5 found that stressors present for acquisition but not extinction training render behavior susceptible to stress induced relapse. The final experiment found that food-reinforced behavior learned in a context created by a cocaine injection renews after cocaine administration but not after footshock stress. Overall, the results indicate that the presence of interoceptive stress stimuli may play the role of context in a renewal paradigm and promote behavioral relapse when re-encountered after extinction. The implications for relapse that often occur following successful suppression of drug use and overeating behaviors are both discussed.