ABSTRACT
Walter Rudolf Hess was a Swiss physiologist who pioneered the use of electrical brain stimulation in unanaesthetised freely moving animals – work that showed the importance of the diencephalon in the regulation of the sympathetic and parasympathetic nervous systems. After the World War I Hess turned his attention to the higher reflex control of arteries and heart, which inevitably led him to become interested in the autonomic nervous system – the array of nerves that control the vital organs of the body. His paper on the subject appeared in 1925 entitled On the interrelations between psychic and vegetative functions, and it was apparent he had recognised the importance of a brain area with direct links to the spinal cord, which lay directly under the cerebrum called diencephalon. With higher levels of stimulation, Hess observed signs of hunger and thirst, cleaning behaviours, urination and defecation.
