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. 2001 Feb 13;98(4):1976–1981. doi: 10.1073/pnas.98.4.1976

Figure 1.

Figure 1

Lever-press responses during the self-administration training, extinction, and cue exposure test phases at the active (a and b) and inactive (c, d) lever. Self-administration (SA): cocaine-reinforced (●) and saline/nonreinforced (○) responses in the presence of discriminative stimuli respectively associated with cocaine (S+) vs. saline (S−) availability across the final 3 days of the self-administration phase in rats assigned to the immediate (a and c) and 4-month delayed (b and d) cue exposure tests. Extinction (EXT): mean (±SEM) number of responses during the last 3 days of the extinction phase. Reinstatement: responses during exposure to the cocaine S+, the S−, and the S+ preceded by administration of SCH 39166 (S+SCH) during the immediate (a and c) and 4-month delayed (b and d) tests. In both test conditions, presentation of the S+ increased the number of responses over extinction performance, whereas the S− had no effect. SCH 39166 significantly attenuated the effect of the S+, and responding in this condition was not statistically different from extinction levels. **, P < 0.01 (different from the extinction and S− conditions); ++, P < 0.01) (different from the S+ condition).