Brain stimulation as the reinforcer in alcohol-saline discrimination

Male Wistar rats were trained to discriminate intraperitoneal injections of 1 g/kg alcohol from saline injections. The reward that reinforced correct choices was an electrical brain stimulation which the animals self-administered according to a FR10 schedule of bar pressing; the stimulation was given in the postero-lateral hypothalamus. Quantitative generalization experiments revealed a mean ED 50 of 0.39 g/kg. The main advantages of this method using direct intracranial stimulation as the reward would seem to be: (1) quantitative and qualitative generalization experiments can be carried out in non-deprived rats having a normal body weight and (2) the possibility of estimating, in addition to the analysis of their discriminative properties, the effects of drugs on self-stimulation rate.