The History of Neuroscience 4: What is the Mechanism of the Brain? Localization Theory versus Holistic Theory

Abstract

Luigi Galvani exposed the nerves of the frog leg and demonstrated twitching of the attached muscles by electrical stimulation. He could also elicit twitching of the corresponding muscles by simple me-tallic tapping of the nerve. This Giovanni Aldini performed a theatrical demonstration of reanima-tion of a dead body by electrical stimulation, which also supported this view. At the start of the 19th century, Franz Joseph Gall and Johann Spurzheim proposed that the brain could be divided func-tionally into many parts. They also argued that the functional dominance of each individual human produced different patterns of brain development, resulting in different skull features. The basic idea that the brain was not one functional unit, but a collection of many anatomical units with different functions, was remarkable. A holistic view of brain function was reemphasized by Marie-Jean-Pierre Flourens. Flourens, who deeply believed in laboratory science, found no apparent functional chang-es after ablation or electrical stimulation of parts of the brain, mainly in birds. Through these experiments, Flourens harshly rebuked the idea of phrenology. Beyond this anti-phrenological role, Flourens conducted important experiments revealing the functions of the cerebellum, pons, and semicir-cular canals. The first widely accepted localized human brain function was language. Paul Broca pre-sented his famous case who had developed motor aphasia with a left inferior frontal focal lesion. Eduard Hitzig and Gustav Fritsch performed an important experiment in which they identified the motor cortex of the dog brain. Finally, the excitability of the human cerebral cortex was confirmed by Roberts Bartholow.