The Effect of Electrical Stimulation of the Brain on the Perception of Pain

The fact that electrical stimulation of the brain can produce unconsciousness in man and animals has been known since the eighteenth century, and from time to time this knowledge has been used in the production of anaesthesia for surgical purposes; Hobday, in 1932, performed castrations and herniotomies in small animals under electrical general anaesthesia, and in 1935 Hertz used electrical anaesthesia for laparotomies in dogs. To-day electrical stunning is used in bacon factories with the object of rendering pigs unconscious before slaughter. Electroconvulsant therapy (E.C.T.) is widely used in mental hospitals for the treatment of certain conditions, and recently Freeman (1948) has modified this technique to produce surgical anaesthesia for prefrontal leucotomy.In some instances electrical anaesthesia has proved satisfactory, but there have been reports of “distorted consciousness” after E.C.T. in human subjects (Morgan, 1950), and of electrical curarization after industrial accidents (Hume, 1935); in these conditions the subject is conscious of sensation but unable to make voluntary movements. Such a condition is only appreciated when the subject is questioned after regaining full consciousness, and hence, if it occurred in animals, it would not be readily recognized.The object of the work described in this paper was to determine the effect of the many variables of electric stimulation, and to investigate the state of consciousness of human subjects and animals after electric stunning. It was hoped thus to provide a basis for future work on electrical anacsthesia and to acquire a better understanding of the action of E.C.T.