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The Man who Mapped the Brain

Neuroletter, Volume 2 Issue 1

Korbinian Brodmann was born in Liggersdorf, Hohenzollern, on November 17, 1868, the son of a farmer named Joseph Brodmann. He got his medical degree (the "Approbation") on February 21, 1895, after studying medicine at the Universities of Munich, Würzburg, Berlin, and Freiburg-im-Breisgau. Brodmann then worked in Munich's University Paediatric Clinic and Policlinic in order to establish himself as a Black Forest practitioner.

He did, however, acquire diphtheria and, as Oskar Vogt wrote in 1959, "convalesced" in

1896 by working as an Assistant in the Neurological Clinic in Alexanderbad in the

Fichtelgebirge district, which was then run by Vogt himself. Brodmann was influenced by him, and Vogt regarded him as having "vast scientific interests, a good gift of observation, and great devotion in broadening his knowledge." Vogt w

as fascinated with the notion of establishing an Institute for Brain Research, which became the Neurobiological Laboratory in Berlin in 1898. Brodmann studied pathology in Leipzig to prepare for a scientific career, earning his doctorate in 1898 with a thesis titled "A Contribution to the Understanding of Chronic Ependymal Sclerosis." Following that, he worked at Otto Binswanger's University Psychiatric Clinic in Jena before shifting to the Municipal Mental Asylum in Frankfurtam-Main from 1900 to 1901, when he met Alzheimer, who sparked an interest in neuroanatomical difficulties that shaped the remainder of his professional life.

Brodmann joined Vogt in the Neurobiological Laboratory in Berlin in the Autumn of

1901 and remained with him until 1910 when he conducted his famous studies on comparative cytoarchitectonics of the mammalian cortex. Brodmann should "undertake a thorough examination of the cells of the cerebral cortex," according to Vogt, using sections stained with the new Nissl method. Cécile and Oskar Vogt were working on a myeloarchitectonics investigation and physiological cortex stimulation experiments at the same time. Brodmann and the Vogts delivered a superbly synchronised presentation at the annual meeting of the German Psychiatric Society in Jena in April 1903, each of their architectural results. Brodmann described the pre-and postcentral gyri's cytoarchitectonic structures, as well as the strong distinction between them.

Brodmann's primary findings were published in a series of communications in the

"Journal für Psychologie und Neurologie" between 1903 and 1908. His sixth communication, on histological localization in the human cerebral cortex, from 1908 is the most well-known. He was the editor of this famous publication until his death in 1918, when it was renamed "Journal für Hirnforschung" and afterwards "Journal of Brain Research." His conversations served as the foundation for his 1909 monograph on comparative cortical localization, which is the subject of this translation, although he died before the second edition was published in 1925. Brodmann's career in Berlin was derailed when his "Habilitation" thesis on the prosimian cortex was unexpectedly rejected by the Medical Faculty. When the Neurobiological Laboratory did not seem to be developing as well as Oskar Vogt had hoped, Brodmann proceeded to work with Robert Gaupp in Tübingen, where he was appointed Profesor by the Faculty of Medicine on Gaupp's recommendation. The Berlin Faculty's behaviour continues to be perplexing. Faculty members had caused injury not only to Brodmann but also to the Laboratory's development, according to Vogt (1919). In contrast, in a speech of congratulations, the anatomist Froriep warmly welcomed Brodmann to membership in the Faculty of Tübingen, and the Academy of Heidelberg honoured his work with a prize.

Brodmann assumed the Prosectorship at the Nietleben Mental Asylum in Halle a der

Saale, which was headed by Berthold Pfeiffer, on May 1, 1916. He was assured of reasonable

material stability for the first time, and it was here that he met Margarete Francke, whom he

married on April 3, 1917. Ilse, their daughter, was born in 1918. Brodmann had lectured in postgraduate courses in Munich conducted by Kraepelin, who predicted that architectonics and neurohistology would make a significant contribution to the neuroanatomical study. Nissl joined the Munich Psychiatric Research Institute, while Brodmann was appointed to the newly founded Munich Institute in 1918, taking charge of the Department of Topographical Anatomy. Even though Brodmann would barely live for a year, he and Nissl began a fruitful collaboration.

"Just at the moment when he had begun to live a very happy family life and when, after

years of interruption due to war work, he was able to resume his research activities in

independent and distinguished circumstances, just at the moment when his friends were looking forward to a new era of successful research from him, a devastating infection struck him," wrote Oskar Vogt in Brodmann's obituary in their beloved Journal für Psychologie und Neurologie in 1919. In 1959, Vogt published a biography of Brodmann in which he expresses his admiration for the man and scientist.

"If we look at his career, we are painfully aware that little provision was made in German

universities for a researcher of Brodmann's stature," Kraepelin said at Brodmann's graveside, and Spielmeyer said in 1924 about the contemporary German academic world: "If we look at his career, we are painfully aware that little provision was made in German universities for a researcher of Brodmann's stature... Brodmann had to make do with subordinate positions that had nothing to do with his importance until he was 48 years old, and he watched with bitterness as officious mediocrity led to the most prestigious positions while he, the successful and well-known researcher, could never get even the most modest permanent university position despite his lack of pretension."

Prior to Brodmann, there was some ambiguity about the cortex's laminar organization. In

1858, Meynert's student Berlin published the first description of the human isocortex's six layers, which are defined by differences in cell size and type, such as pyramidal and granule cells. Beginning in 1867, Meynert identified the segmentation of the human cortex into multiple functional areas. Betz's 1874 study, in which he pointed out "nests" of unusually large cells, his so-called "giant pyramids," in the human motor cortex of the precentral gyrus, an area separated by the central sulcus from the sensory cortex of the postcentral gyrus, which contained no such giant cells, was a significant early cortical localization study. Ferrier's Croonian Lecture in 1878 was devoted to brain localization. Kaes (1893), Bechterew (1896), and Flechsig (1897) reported human cerebral maps based on fiber architecture (myeloarchitectonics).

Several publications on the laminar pattern of the cerebral cortex in several animals,

including man, appeared before the end of the nineteenth century, the most well-known of which are those of Lewis (1878, 1881), Lewis and Clarke (1878), and Hammarberg (1878). (1895).

Brodmann examines them in depth, pointing out the numerous contradictions. Cajal's research on the human cortex, as well as Bolton's book on the human visual cortex, began to be published in the year 1900. Brodmann was particularly dismissive of Cajal's "erroneous" beliefs on cortical lamination. In 1907, Elliot Smith published a thorough atlas of human cerebral localization, citing Flechsig, Campbell, and Brodmann's previous work.

Campbell's major work, "Histological studies on the localization of cerebral function,"

was published in 1905. He was an Australian who had studied with Krafft-Ebbing in Vienna and in Edinburgh. He looked at the brains of chimps, orangutans, cats, dogs, and pigs, as well as eight human cerebral hemispheres. Campbell's division of the primate brain was not as "fine as those of the German school," according to von Bonin in 1953, referring specifically to Brodmann's work.

In the first half of the twentieth century, myeloarchitectonics advanced as well. Cécile

and Oskar Vogt, and their colleagues from the Berlin Neurobiological Laboratory, such as Mauss (1908) and Zunino (1909), made significant contributions between 1900 and 1906, which were especially important to Brodmann because of his professional relationships with them (1909). Brodmann built on these findings, incorporating phylogenetic and ontogenetic influences into his theories of adult cortical structure, function, and even pathology. Brodmann's cortical localization is based on the division of the cortical structure into "areas" with similar cellular and laminar structure. He compared human cortical localization to that of primates, rodents, and marsupials, among other mammals. He identified 47 areas in man, each with its own number and some of which were further subdivided. From their myeloarchitectonic work, the Vogts described four times as many areas. Foerster's electrical stimulations of the human cortex, published in 1926 and based on Brodmann's structural studies, provided important support for Brodmann's concepts of functional localization.

Brodmann has been chastised for drawing broad conclusions from a small sample of

brains. He is said to have only studied one human brain. He doesn't say how many brains he

used, but he does say he "thanks Professor Benda for kindly providing human brains." He

certainly used many brains later, when he turned to more "anthropological" aspects of the human cortex (1913).

Brodmann's observations were largely expanded upon in later work. Brodmann's numbers

were replaced by letters in the cytoarchitectonic atlas published by von Economo and Koskinas in 1925. "Von Economo and Koskinas almost exclusively describe Brodmann's cortical areas... there is, therefore, no justification for replacing Brodmann's numbers," Hassler wrote in 1962. Only a few people, including Bailey and von Bonin (1951), accepted von Economo's parcellation; they criticized Brodmann and the Vogts and only differentiated 19 areas themselves. Others, such as Karl Kleist (1934) and Lashley and Clark (1946), were against a cortical subdivision that was too vigorous. Since then, several atlases have appeared, essentially confirming Brodmann's position, the most recent of which was published in 1955 by Sarkissov and his colleagues.

Cortical localization, both anatomical and functional, has also been supported by modern

experimental methods. In the 1950s and 1960s, there was a growing trend to focus much of the experimental effort on the cerebral cortex, which had previously been overlooked. The findings of cortical cytoarchitectonic studies piqued the interest of physiologists. This method was widely used because physiological studies revealed that the cortex could be divided into functionally distinct and localised areas. Consider the exquisite correspondence between individual cortical areas and subtle variations in physiological function found in the visual and somatosensory systems (Hubel and Wiesel, 1962, 1977; Powell and Mountcastle, 1959). Brodmann's areas have been subdivided in many cases, but no major objections to his pioneering work have been upheld for a long time. Sharply circumscribed cortical areas corresponding to those seen with classic cell stains have been confirmed by histochemistry and "chemical neuroanatomy" (the study of specific chemicals, particularly neurotransmitters, in neurons). The series of volumes on the "Cerebral Cortex," edited by Peters and Jones in 1984, provides an in-depth treatment of the various aspects of cerebral cortical structure and function.

Furthermore, clinical observations in cases of localized pathology, as well as descriptions

of wound-related deficits in two World Wars and even more local conflicts, all pointed to the

same conclusion. Massive advancements in medical imaging, such as functional studies using positron emission tomography and magnetic resonance imaging, have paved the way for direct in vivo visualization of the human brain in recent years. The findings are unequivocally in favor of an exquisite cortical localization, though not always in complete agreement with Brodmann's viewpoints.

Brodmann's localisation theories have grown in popularity in tandem with modern

enthusiasm for discovering the neuroanatomical basis for human consciousness and intelligence (eg Semendeferi et al. 2002; Schoenemann et al. 2005). Such work necessitates a solid foundation for brain localization, knowledge of variability, and the ability to identify the same brain areas in different people. The recent discovery of some later, forgotten works by Brodmann, including his work on anthropological aspects of localization (1913, translated by Elston and Garey, 2004), has provided a wealth of new information on the human cortical organization. By 1913, Brodmann's focus had shifted to a systematic study of human brains of various races, with the goal of gathering as much data about a given species as possible, rather than elucidating any differences in "quality" between races. Brodmann presented not only large amounts of new, quantitative data on the human cortex in his 1913 paper but also previously unpublished results on the cortex from a variety of primates and non-primates. The information presented is as relevant today as it was when it was first published. The variation in cortical topography that he discovered in human brains is critical for understanding modern functional imaging studies, especially those involving the visual or prefrontal cortex. The latter has gotten a lot of attention as a potential "site" for differentiating man's brain from that of other primates in terms of intelligence and consciousness. Brodmann's comparative data are still unrivaled today.

Brodmann's famous book "Vergleichende Lokalisierungslehre der Grosshirnrinde in ihren

Prinzipien dargestellt auf Basis des Zellenbaues" was reprinted in 1985 by the Johann Ambrosius Barth Verlag in Leipzig. This book is considered a "classic" in the field of neuroscience. It still serves as the foundation for "function localization" in the cerebral cortex. Brodmann's "areas," such as area 4 for the motor cortex, area 17 for the visual cortex, and so on, are still used to designate cortical functional regions. Clinical neurologists and neurosurgeons in humans, as well as experimentalists in various animals, use this nomenclature. Brodmann's famous "maps" of the cerebral cortex of humans, monkeys, and other mammals must be among the most widely reproduced figures in the field of neurobiology (see, for example, Zilles, 1990). Brodmann's concepts are found in most research publications on systematic neurobiology, and he is cited in many textbooks of neurology, neurophysiology, and neuroanatomy.

Author: Rohan Nath

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