Mental and behavioral effects of brain stem and hypothalamic stimulation in man.

Electrical stimulation of deep brain regions in man yields specific and reproducible physiological and behavioral effects. Stimulation of the rostral midbrain in the dorsal and periaqueductal regions results in a variety of effects such as somatosensory, ocular, emotional, and vasomotor responses. These responses are somatotopically organized in the dorsal midbrain suggesting this region is of great importance to humans' experience of pain and suffering.