Stimulation of dorsal midbrain during septal and hypothalamic self-stimulation.

Abstract

Three experiments were performed to study the effects of aversive dorsal midbrain (DM) stimulation on posterior hypothalamic or septal self-stimulation. In Experiment 1, both posterior hypothalamic and septal self-stimulation rates were reduced by crystalline carbachol stimulation of DM, but posterior hypothalamic self-stimulation was reduced significantly more. In Experiment 2, injection of liquid carbachol into DM suggested that .75-2.25 [mu]g. of chemical is necessary for suppression of hypothalamic self-stimulation. In Experiment 3, which repeated Experiment 1 using electrical stimulation of DM, DM electrical stimulation reduced self-stimulation behavior, and hypothalamic self-stimulation was reduced significantly more. Septal and hypothalamic self-stimulation were compared in terms of their relation to DM.