The term emotion is commonly used as being synonymous with feeling. In psychology, however, emotion is considered as a response (to stimuli) that involves characteristic physiological changes. They might consist of an increase in pulse rate, a rise in temperature, a greater or less activity of certain glands, or a change in rate of breathing. These in turn then tend to stimulate the individual to further activity. Fear, love, and anger are usually considered the three primary responses of this kind. They are aroused either directly by some external environmental stimulus or indirectly by some internal one through memory. As individuals mature, specific stimuli no longer provoke the same emotion in every person, nor is there any universal manner of expressing a given emotion. In varying cultures, emotional expression must at least be partly learned. The development of Psychosomatic Medicine has emphasized the physiological role of emotions, demonstrating that tension from unrelieved emotions may be the underlying cause of physical disorders. The term psychosomatic, emphasized essential unity of the psyche and the soma, a combination rooted in ancient Greek medicine. The treatment ordinarily involves a medical regime as well as some form of psychotherapy for the patient. In recent years the term has taken on the broader meaning of psychotherapeutic medicine, referring to a point of view on the discipline of medicine that utilizes knowledge achieved by dynamic psychiatry in treating patients. Sigmund Freud, at the end of the 19th century, laid the scientific groundwork for the psychosomatic study with his theoretical formulations based upon new methods of treating hysteria. His methods were reinforced by the psychobiology of Adolf Meyer and the research of W. B. Cannon on the physiological effects of acute emotion.