The response to a nociceptive stimulus normally includes at least four components: "the sensation of pain"; discomfort; withdrawal movements; and some measurable physiological alteration, e.g., a transient or prolonged increase or decrease in blood pressure (Nafe & Wagoner, 1938;Goetzl, Bien, & Lu, 1951). This paper is concerned with the neurological correlates of this total response-hereafter termed the pain response-and how this total response or some components of this response can be mitigated or eliminated by prefrontal leucotomy, opiates, placebos, and hypnosis.
THE NEUROPHYSIOLOGICAL COR-RELATES OF THE PAIN RESPONSE Free Nerve Endings: The So-Called "Pain Receptors"It has generally been assumed that the free nerve endings, which are found widely scattered near the cutaneous and visceral surfaces, are the specific receptors for noxious stimuli. However, Sinclair, Weddell, and Zander (1952) have shown that 5s can discriminate cold, heat, touch,