Deepened extinction of cocaine cues

Abstract

Background: A method for reducing the power of drug cues could help in treating drug abuse and addiction. Extinction has been used, with mixed success, in such an effort. Research with non-drug cues has shown that simultaneously presenting (compounding) those cues during extinction can enhance the effectiveness of extinction. The present study investigated whether this procedure could be used to similarly deepen the extinction of cocaine cues.

Methods: Rats were first trained to self-administer cocaine during tone, click, and light stimuli. Then, these stimuli were subjected to extinction in an initial phase where they were presented individually. In a second extinction phase, one of the auditory stimuli (counterbalanced) was compounded with the light. The other auditory stimulus continued to be presented alone. Rats were then given a week of rest in their homecages prior to testing for spontaneous recovery of cocaine seeking.

Results: The cue that was compounded with the light during the second phase of extinction training occasioned less spontaneous recovery of cocaine seeking than the cue that was always presented individually during extinction. Increasing the number of compound cue extinction sessions did not produce a greater deepened extinction effect.

Conclusions: The present study showed that simultaneously presenting already-extinguished cocaine cues during additional extinction training enhanced extinction. This extends the deepened extinction effect from non-drug cues to drug cues and further confirms predictions of error-correction learning theory. Incorporating deepened extinction into extinction-based drug abuse treatments could help to reduce the power of drug cues.

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Experiment 1 results. Data presented are the mean (±SEM) response rates (responses per min) in Stimuli X (black bars) and Y (white bars) during the first and final sessions of Extinction Phase 1, the Extinction Phase 2 session, the whole spontaneous recovery test, and only the first 4 X and Y presentations of the test. * indicates p < 0.05.

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Experiment 2 results. Data presented are the mean (±SEM) response rates (responses per min) in Stimuli X (black bars) and Y (white bars) during the first and final sessions of Extinction Phase 1, the 3 sessions Extinction Phase 2, the whole spontaneous recovery test, and only the first 4 X and Y presentations of the test. * indicates p < 0.05. Note that the Y-axis range is smaller than in Figure 1.