抄録
Food-reinforced barpressing behavior of rats was suppressed when a sound previously had been paired with posterior hypothalamic stimulation was activated by each barpress. This suppression was not observed in groups in which septal stimulation was used, or in which 200 “free” posterior hypothalamic stimulations were given before pairing. However, the suppression did appear if animals were anesthetized during the “free” posterior hypothalamic stimulations. In later self-stimulation tests, intracranial stimuli at both sites were revealed as positively reinforcing. It is hypothesized that posterior hypothalamic stimulation initially has aversive components but that these diminish with additional stimulations. This shift in the characteristics of the stimulation does not seem attributable to tissue changes in the brain.