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Walter Rudolph HessNobel Prize in Physiology or Medicine, 1949, jointly with Egas Moniz
Date of Birth: 17.03.1881
Country:  Switzerland |
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Biography of Walter Rudolf Hess
Walter Rudolf Hess, a Swiss physiologist, was born in Frauenfeld, a small town in the German-speaking region of eastern Switzerland, to parents Clemens and Gertrude (Fischer Saxon) Hess. From a young age, Hess was introduced to experimental scientific work by his father, who was a physics professor at the university. Combining a deep interest in biological processes with a practical inclination, Hess enrolled at the University of Lausanne in 1900 to study medicine. He continued his education at the universities of Bern, Zurich, Berlin, and Kiel, earning his medical degree from the University of Zurich in 1906. His dissertation focused on the relationship between blood viscosity and heart function. The study of hemodynamics, the physical forces that determine and regulate blood flow through the vessels, remained his primary area of interest for many years. Due to a lack of financial resources to complete his medical research, Hess pursued internships in surgery and ophthalmology at his local hospital, allowing him to familiarize himself with the functioning of the vascular system in vivo. In 1908, he opened his own ophthalmology practice, which soon became profitable and took up much of his time. Leaving this practice in 1917, he obtained a poorly paid position as an assistant at the physiological institute of the University of Zurich to continue his research on hemodynamics. For ten years, Hess studied the regulation of heart rate and blood pressure and their relation to other physiological processes, particularly respiration. His research was temporarily interrupted by his service in the Swiss army during World War I, but in 1917, he was appointed as a professor and head of the department of physiology, positions he held until the end of his career.
Research on the Intermediate Brain
By 1925, Hess expanded his research to include the isolated activity of the respiratory and cardiovascular systems to better understand what he called "neuronal mechanisms of adaptation of internal organ activity to constantly changing conditions and to each other." The internal organs are not under the control of consciousness in normal conditions; their functions are coordinated by the so-called autonomic or vegetative nervous system. Previous clinical observations of patients with brain injuries and experiments on animals had indicated that the midbrain, a group of structures located directly below the thalamus and midbrain peduncles, contains centers of the autonomic nervous system. "Something still in darkness when my own research began," Hess later said, "was the localization of specific functions in specific morphological structures... in other words, the organic structure of the control of the autonomic nervous system in the midbrain. How best to study this problem was the goal I set for myself." The standard method for studying the functioning of a specific area of the brain is to observe the animal's response to electrical stimulation of that area. However, it was difficult to use this technique to study the midbrain, which is located deep enough to avoid damaging the surrounding tissue of the cerebral cortex.
Using a stereotaxic instrument (which can be directed along three planes to target a specific brain region), Hess inserted electrodes through a small hole in the skull into specific areas of the brain without directly seeing the internal structures. The use of delicate electrodes and gentle surgical techniques allowed him to observe experimental animals during manipulation without the use of anesthesia. Initially, Hess hoped that within a relatively short time during the experiments, he would be able to determine the basic functions of the midbrain (particularly the hypothalamus, located below the thalamus). The hypothalamus centers, located close to each other, control various functions, and it is impossible to predict what effect stimulation in a particular area will have. Thus, Hess embarked on a long and painstaking journey. He supplemented initial experiments with anatomical and histological studies, films of animal behavior after stimulation, and compared how their behavior corresponded to minor damage in certain brain areas. The results of this work showed that electrical stimulation of different areas of the hypothalamus can cause changes in blood pressure, respiration, body temperature, and other functions of the internal organs. Hess concluded that the hypothalamus controls emotional responses, and stimulation of certain areas can evoke anger, fear, sexual arousal, relaxation, or sleep.
Hess conducted research from 1925 to 1940. Since Switzerland was a neutral country and did not participate in World War II, he had the opportunity to continue his experiments, but the publication of results became possible only after the end of the war. In 1948, his book "The Functional Organization of the Diencephalon" was published, summarizing the research results he obtained over 25 years. In this work, he substantiated the functioning of the midbrain as a connecting link between the internal and external regions of the brain. Hess believed that situational identification, such as identifying a situation of fear, is associated with the activity of the cerebral cortex. However, the animal's response (in this case, fear) such as growling, raised fur, and increased heart rate, is elicited by the midbrain. Conversely, the midbrain, by controlling blood sugar concentration and gastric distension, stimulates the cortex and impels the animal to search for food when hungry. The upper part of the midbrain controls motor functions, while the lower part, especially the hypothalamus, regulates autonomic responses of internal organs. Hess's book became a classic scientific work not only for its description of the midbrain but also because the research results served as a model of accuracy and thoroughness. Hess was awarded the Nobel Prize in Physiology or Medicine in 1949 for the "discovery of the functional organization of the midbrain as a coordinator of the activity of the internal organs." He shared this prize with neurosurgeon Egas Moniz. In his congratulatory speech on the occasion of the award ceremony, Herbert Olivecrona of the Karolinska Institute noted that Hess's research showed "that the midbrain contains higher centers of autonomic functions, coordinating these functions with the reactions of skeletal musculature adapted to specific functions." Olivecrona further stated that "Hess's investigations brilliantly answered several difficult questions regarding the interrelation of individual areas of the brain and the vital functions of the organism under their control."
In 1951, after leaving the Institute of Physiology, Hess continued his research on the functions of the midbrain and the integrative function of the nervous system. In 1908, Hess married Louise Zandmayer, and they had a son and a daughter. In his summer home in the southern Alps, he enjoyed gardening, cultivating vineyards, and learning traditional crafts from local farmers.
Hess passed away in 1973, at the age of 92, in Ascona, near Locarno, Switzerland. Among the numerous awards and honors Hess received were honorary degrees from McGill University, the Universities of Bern, Geneva, and Fribourg. He was a member of many professional societies and the Pontifical Academy of Sciences.
