José Manuel Rodriguez Delgado (1915–2011), a Spanish physiologist, was among the first scientist to perform electric brain stimulation in both animals and humans. His work on brain-stimulation research during the 1960s and 1970s was innovative but also controversial.

To present the scientific papers of Jose Delgado on psychosurgery.

To review available literature and to show evidence that Jose Delgado made a significant contribution to the development of psychosurgery.

A biography and private papers are presented and discussed followed by a literature review.

Delgado showed that with electrical brain stimulation one could evoke well-organized complex behavior in primates. A rhesus monkey was stimulated with an electrode implanted inside the red nucleus, followed by a complex sequence of events. After stimulation of an area three millimeters from the red nucleus, the rhesus monkey just yawned. Delgado also investigated the mechanisms of aggressive behavior in other animals. Stimulation of the caudate nucleus by remote control in a fighting bully resulted in sudden paralysis. In some human patients suffering from depression, euphoria was induced after stimulation of the septum.

Delgado pioneered the brain electrode implantation in order to electrically stimulate specific brain areas for treatment epilepsy and of different types of mental illness. He was severely criticized. His studies, however, paved the way for new modulation techniques such as the development of deep brain stimulation.

The authors have not supplied their declaration of competing interest.