When the matching-to-sample (MTS) procedure is used, different training structures imply differences in the successive discriminations required in training and test conditions. When the go/no-go procedure with compound stimuli is used, however, differences in training structures do not imply such differences. This study assessed whether the go/no-go procedure with compound stimuli with different training structures would produce significant variations in emergent performances. Fourteen undergraduate students were divided into two training groups: OTM and MTO (one-to-many and many-to-one). During training, responses emitted in the presence of compounds defined as related were reinforced. Responses emitted in the presence of compounds defined as not-related were not. During tests, new compounds structurally emulated MTS equivalence tests. All participants finished training with comparable number of sessions and 13 of 14 showed emergent performances. These results suggest that differences in equivalence-test outcomes with OTM and MTO training structures in MTS procedures may be due to their different successive discrimination requirements.

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A large body of evidence has shown that the Corticotropin Releasing Factor (CRF) system, which plays a key role in stress modulation, is deeply involved in relapse to alcohol seeking induced by exposure to stressful events such as foot shock or yohimbine injections. Exposure to environmental cues is also known to be a trigger for alcohol relapse, nevertheless, the relationship between the relapse evoked by the cue-induced model and the CRF stress systems remains unclear. The purpose of this study was to evaluate, in male Wistar rats, the involvement of the CRF system and Hypothalamic-Pituitary-Adrenal (HPA) axis in relapse induced by environmental cues. Antalarmin, a selective CRF1 receptor antagonist, Metyrapone, a corticosterone (CORT) synthesis inhibitor and CORT were evaluated for their effects on the reinstatement test in a cue-induced relapse model. Antalarmin (20 mg/kg) blocked relapse to alcohol seeking induced by environmental cues. Metyrapone (50 and 100 mg/kg) also blocked relapse in Wistar rats but only at the highest dose (100 mg/kg). Corticosterone had no effect on relapse at the doses tested. The results obtained from this study suggest that the CRF stress system and the HPA axis are involved in cue-induced alcohol relapse.

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