Stimulation of dorsal midbrain during septal and hypothalamic self-stimulation

3 experiments were performed to study the effects of aversive dorsal midbrain (DM) stimulation on posterior hypothalamic or septal self-stimulation. In Exp. I, 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 Exp. II, injection of liquid carbachol into DM suggested that .75-2.25 micrograms of chemical are necessary for suppression of hypothalamic self-stimulation. In Exp. III, which repeated Exp. I 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 are compared in terms of their relation to DM. (PsycINFO Database Record (c) 2006 APA, all rights reserved).