Brodmann's Localisation in the Cerebral Cortex

Translated by Laurence Garey
Published by Smith-Gordon, London (1994)
Second impression by Imperial College Press (1999)

In 1909 the Johann Ambrosius Barth Verlag in Leipzig printed the first edition of Korbinian Brodmann's famous book Vergleichende Lokalisationslehre der Grosshirnrinde in ihren Prinzipien dargestellt auf Grund des Zellenbaues, one of the major "classics" of the neurological world. To this day it forms the basis for "localisation" of function in the cerebral cortex, with Brodmann's "areas" still widely used by clinical neurologists and neurosurgeons in man, as well as by experimentalists in various animals. Indeed, his famous "maps" of the cerebral cortex of man, monkeys and other mammals must be among the most commonly reproduced figures in neurobiological publishing. In spite of this, few people have ever seen a copy of the book, and even fewer have actually read it!

There had never been an English translation available, and although Barth-Verlag still exists the original book has been almost unavailable for 50 years or more, even the second edition of 1925. The few antiquarian copies still around command high prices.

I had long thought such a translation would be of value, as just about everyone quotes Brodmann without having seen a copy. Even if a copy is available, the language means it is inaccessible to most workers. In addition, it gives an interesting insight into the state of neuroscience at the turn of the century.

So who was Brodmann?

Korbinian Brodmann was born on 17 November 1868 in Liggersdorf, Hohenzollern, the son of a farmer. He studied medicine in Munich, Wrzburg, Berlin and Freiburg, where he received his "Approbation" in 1895. After this Brodmann worked in University Clinics in Munich, with the intention of perhaps establishing himself as a practitioner in the Black Forest.

But he contracted diphtheria and "convalesced" in 1896 by working as an Assistant in the Neurological Clinic in Alexanderbad then directed by Oskar Vogt. Under his influence, Brodmann turned to neurology and psychiatry, and Vogt described him as having "broad scientific interests, a good gift of observation and great diligence in widening his knowledge". Vogt was preoccupied with the idea of founding an Institute for Brain Research, that finally materialised in Berlin in 1898. In order to prepare for a scientific career Brodmann took his Doctorate in Leipzig in 1898 with a thesis on chronic ependymal sclerosis. He worked in the Municipal Mental Asylum in Frankfurt from 1900 to 1901, where meeting Alzheimer inspired an interest in the neuroanatomical problems that occupied his further scientific career.

In Autumn 1901 Brodmann joined Vogt and until 1910 worked with him in the Neurobiological Laboratory in Berlin where he undertook his famous studies on comparative cytoarchitectonics of mammalian cortex. Vogt suggested to Brodmann that he undertake a systematic study of the cells of the cerebral cortex, using sections stained with the new method of Nissl.

Cecile and Oskar Vogt were engaged on a parallel study of myeloarchitectonics, and physiological cortical stimulation. In April 1903, Brodmann and the Vogts gave a beautifully coordinated presentation, each of their own architectonic results, to the annual meeting of the German Psychiatric Society in Jena. Brodmann described the totally different cytoarchitectonic structure of the pre- and postcentral gyri in man and the sharp border between them.

Brodmann's major results were published between 1903 and 1908 as a series of communications in the "Journal fr Psychologie und Neurologie". The best known is his sixth communication, of 1908, on histological localisation in the human cerebral cortex. He edited this renowned journal until his early death in 1918, a journal which lived on as the "Journal fr Hirnforschung", and . recently became the "Journal of Brain Research". His communications served as a basis for his famous monograph, but he did not live to see its second edition in 1925.

Brodmann's career in Berlin was marred by the surprise rejection by the Medical Faculty of his "Habilitation" thesis on the prosimian cortex. So when, as Oskar Vogt admitted, the Neurobiological Laboratory did not seem to be developing as well as he had expected, Brodmann went to work in Tubingen. The attitude of the Berlin Faculty remains incomprehensible. In contrast, he was warmly welcomed to the Faculty of Medicine in Tubingen where he was appointed Professor. The Academy of Heidelberg also honoured his work with the award of a prize. On 1 May 1916 Brodmann took over the Prosectorship at the Nietleben Mental Asylum in Halle. For the first time he was assured of reasonable material security and here he met Margarete Francke, who became his wife on 3 April 1917. In 1918 their daughter Ilse was born.

During his time in Berlin Brodmann had lectured in postgraduate courses in Munich organised by Kraepelin who anticipated an important contribution to neuroanatomical research from architectonics and neurohistology. Nissl joined the Psychiatric Research Institute in Munich, and in 1918 Brodmann also received a prestigious appointment to the Institute and took charge of the Department of Topographical Anatomy. Thus began a harmonious collaboration with Nissl, although Brodmann was only to live for less than a year.

In his biography of Brodmann, Vogt wrote in 1959: "Just at the moment when he had begun to live a very happy family life and when, after years of interruption because of war work, he was able to take up his research activities again 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 snatched him away after a short illness, on 22 August 1918". Kraepelin declared at Brodmann's graveside that science had lost an inspired researcher.

Before Brodmann, the greatest confusion had reigned concerning the laminar structure of the cortex. In 1858, Meynert's pupil, Berlin, gave a first description of the six layers of the human isocortex as distinguished by variations in cell size and type. Brodmann refined and extended these observations, integrating ideas on phylogenetic and ontogenetic influences with his theories of adult cortical structure, function and even pathology. In 1905 Campbell's major work entitled "Histological studies on the localisation of cerebral function" appeared. However, in 1953 von Bonin commented that Campbell's division of the primate brain was not as "fine as those of the German school", referring particularly to the work of Brodmann. Several authors had produced studies on individual human cortical areas. They include Bolton (1900) on the visual cortex and Cajal between 1900 and 1906 on several areas. In particular, Brodmann had little respect for Cajals's "erroneous" views on cortical lamination.

The basis of Brodmann's cortical localisation is its subdivision into "areas" with similar cellular and laminar structure. He compared localisation in the human cortex with that in a number of other mammals, including primates, rodents and marsupials. In man, he distinguished 47 areas, each carrying an individual number, and some being further subdivided. The Vogts described some four times as many areas from their myeloarchitectonic work. Later work was to a great extent elaboration of Brodmann's observations. In the cytoarchitectonic atlas published by von Economo and Koskinas in 1925, Brodmann's numbers were replaced by letters. In 1962 Hassler commented that "von Economo and Koskinas describe almost exclusively Brodmann's cortical areas ... there is therefore no justification for replacing Brodmann's numbers". Bailey and von Bonin (1951) were among the few people to accept von Economo's parcellation; they criticised Brodmann and the Vogts, and only differentiated some 19 areas themselves. Others, including Kleist (1934) and Lashley and Clark (1946), were also against a too vigorous subdivision of the cortex. However, since then a number of atlases have appeared, essentially vindicating Brodmann's view, among which is that of Sarkissov and his colleagues in 1955.

Modern experimental methods have supported cortical localisation, both anatomical and functional. One need only consider the exquisite correspondence found in the visual and somatosensory systems between individual cortical areas and subtle variations in physiological function (Powell and Mountcastle, 1959; Hubel and Wiesel, 1962, 1977). In many cases Brodmann's areas have been further subdivided, but no major objections to his pioneering work have been upheld for long. In reading his "Localisation" one is struck by the many forward-looking references to concepts and techniques that emerged only much later, such as multiple representations of functional areas, the chemical anatomy of the brain, and ultrastructure. What might Brodmann have discovered if he had lived beyond the age of 49?