ASPECTS OF BRAIN LOCALIZATION IN LATE XIXTH CENTURY GERMANY1

Michael Hagner

In a historical review of fifty years of neurology, the Swiss neurologist Constantin von Monakow gave a noteworthy interpretation of the development of the localization idea in the last three decades of the 19th century. In a footnote he noted that the revolutionary experiments on producing motion through electrical stimulation of certain parts of the cerebral cortex by Eduard Hitzig and Gustav Fritsch, performed in 1870 in Berlin, had been carried out in a clinical setting. At that time, Hitzig was interested in a physiological explanation of the particular symptoms of one of his patients. Monakow continued: "The discovery of such eminent physiological importance was not made by physiologists but by a clinician. Inititally, mainly physiologists contradicted Hitzig' s results "2 • Several questions of interest to the historian arise from this statement. What was the position of German physiologists before the experiment by Hitzig and Fritsch? Why were physiologists against cerebral localization, and why did it resist such a challenge successfully? Is it really true that physiologists harboured anti-localization views? Does the assumption of a competition or rivalry between physiologists and clinicians illuminate the scenario? Finally, how did professional authority shape the localization debate? Questions such as these lead into historical territory that has already been traversed by other historians of medicine3 • This is not surprising because the localization of brain functions is commonly regarded as one of the most important aspects of the development of modern neurology, neurophysiology and neurosurgery. The historical trek usually starts from the following basic premise: the story of localization is characterized by a long-lasting debate between localizationists and anti-localizationists or holists. This polarity applies to at least four important controversies in the history of brain research from the eighteenth to the twentieth centuries. First of all, it shaped the debate about a localization of the organ of the soul in the 18th century, which was dominated on the one hand by anatomists and physiologists in the Cartesian tradition, who argued for such a circumscribed region in the brain, and on the other hand by the physiologist Albrecht von Haller and his successors, who favored an 74 equipotentiality theory, according to which the complete white substance of the brain was the organ of the soul. Second, during the first half of the 19th century, there was the debate generated by Franz Joseph Gall's assumption that several independent organs or faculties of mind were located in the cerebral cortex. Third, after Paul Broca's postulate of a motor speech area in the left third frontal convolution of the cortex in 1861, and after the aforementioned experimental discovery of the localized electrical excitability of the cerebral hemispheres by Hitzig and Fritsch, the debate ran about circumscribed functional regions in the cortex. Finally, the story of localization continued in the early twentieth century, characterized by a powerful revival of the holistic tradition4 • In this paper I will concentrate mainly on the third controversy. I claim that the traditional dichotomy of localization vs. anti-localization though not absolutely false, is insufficient to understand the significance of brain localization in late nineteenth century Germany. Instead of telling the story of localization in terms of theoretical or philosophical ideas, I want to explain it in terms of scientific practice. In the first section I shall argue that physiologists and physicians rejected localization in the 1860s because the various clinical reports about circumscribed brain lesions and corresponding mental defects did not fit their standard of a valid experimertt. The situation changed dramatically after the Hitzig-Fritsch• experiment on the excitability of the cerebral cortex, evoking not only debates within the medical faculty, but also helping to establish the authority of the medical viewpoint concerning the knowledge of human nature. In the second section, I want to show that the localization of mental qualities became, after 1870, the subject of a controversy between linguistics and medicine. Undoubtedly, this was a manifestation of the more general and fundamental split between Natur- and Geisteswissenschaften, expressing incompatible views of human nature. Philosophies of language played a crucial role. In France, for example, a physiological interpretation of language meant a break with the Cartesian tradition. Descartes' old argument that language signified an ontological difference between man and animals was not given up in France until the middle of the nineteenth century because it served as a key argument against materiallst and reductionist interpretations of man5• In Germany the situation was different, because Cartesianism was irrelevant for the self• perception of the intellectual and scientific elites. Language was thus not made part of an ontological, but only of a methodological, dualism. This dualism became obvious in the competition between philosophical and physiological approaches. The main question was: who was competent to deal with the nature of intellectual qualities? We shall see that those