The Architectonics of the Human Neocortex
Speaker: Professor Rudolf Nieuwenhuys, The Netherlands Institute for Neuroscience.
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At the beginning of the 20th century, two fundamentally different approaches to the structure of the cerebral cortex became visible; first, the study of neurons and their contacts, aimed at disclosing the microcircuitry of the cortex, and second, the so-called architectonic approach, pursuing the parcellation of the cortex into structural and functional units. The architectonic approach was initiated by Oscar and Cécile Vogt and Korbinian Brodmann. They used the Nissl technique for neuronal cell bodies (cytoarchitectonis), and the Weigert technique for myelinated fibres (myeloarchitectonics). Brodmann would study the cytoarchitectonics of the cortex, whereas the Vogts (and their numerous co-workers) would focus on the myeloarchitectonics. In this lecture, the achievements of the Vogt-Vogt-Brodmann school (1900-1970) will be discussed. The following points will be highlighted:
(1) The investigations of Brodmann resulted, inter alia, in his famous cytoarchitectonic map, in which the human cerebral cortex is subdivided into some 40 fields or areas.
(2) The parallel myeloarchitectonic studies pointed to the presence of a much larger number of areas, but a complete myeloarchitectonic counterpart of Brodmann's map has never been published.
(3) The Vogts gradually developed a general concept, according to which the cortex is composed of about 200 discrete, juxtaposed structural and functional units.
(4) There is converging quantitative cytoarchitectonic, receptor architectonic, myeloarchitectonic, hodological, and functional evidence, indicating that this concept is essentially correct.
(5) Relating particular cortical functions, as determined with neuroimaging techniques, to particular cortical structures is a major problem in current research.
(6) At present, these 'translation'- operations are generally based on adapted, three-dimensional versions of Brodmann's famous map.
(7) It has become increasingly clear that these maps do not provide the neuroanatomical precision to match the considerable degree of functional segregation, suggested by neuroimaging studies.
(8) Recently, Professor Nieuwenhuys scrutinized the total body of myeloarchitectonic studies of the Vogt-Vogt school (Nieuwenhuys, 2013, Brain Struct Funct 218: 303-351). It was concluded that the data available is adequate and sufficient for the composition of a myeloarchitectonic map of the entire human neocortex.
Professor Nieuwenhuys will then present a new myeloarchitectonic map of the human neocortex based on data from the Vogt-Vogt school (Rudolf Nieuwenhuys, Cees A. J. Broere and Leonardo Cerliani).
The new map is based on a meta-analysis of the studies of Batsch (1956), Braitenberg (1956), Brockhaus (1940), Gerhardt (1940), Hopf (1954, 1955, 1956, 1966, 1968a, b, 1969, 1970), Hopf and Vitztum (1957), Lungwitz (1937), Sanides, 1962, 1964), Strasburger (1937,1938), Vogt (1903, 1910, 1911) and Vogt and Vogt (1911, 1919); see Nieuwenhuys (2013). All of these studies are concerned with the myeloarchitecture of the cortex of a single cerebral lobe or part thereof. Because the data and the resultant partial maps produced by the various authors, are derived from many different brains, a standard brain to which all data can be transferred, had to be selected. For this purpose, we selected one of the brain templates provided by the Montreal Neurological institute (ICBM 152). The procedure followed in the preparation of the new map will be discussed in some detail. The new map contains 181 areas, 64 frontal, 30 parietal, 6 insular, 17 occipital and 64 temporal. The numbering system, introduced by Vogt (1910,1911) for the frontal and parietal lobes, has been extended over the entire neocortex. The new map has several important limitations:
-- It is incomplete (no data about the myeloarchitecture of areas 17 and 18 of Brodmann are available. -- It is largely based on qualitative, observer-dependent observations, although the photometric studies of Hopf (1966, 1968a, b, 1969, 1970) have confirmed the presence of most areas. -- Interhemispheric and interindividual variations are left out of consideration.
Hopefully, the new map represents, for the time being (i. e. as long as a probabilistic, observer-independent multiarchitectonic map of the entire neocortex is not available), a useful frame of reference for:
(a) the morphological interpretation of the results of functional neuroimaging studies; (b) the selection of starting points (‘nodes’, ‘seeds’) in diffusion tractography studies; (a) the interpretation of putative myeloarchitectonc features, visualized in vivo mappings of the cerebral cortex.
Professor Rudolf Nieuwenhuys graduated from the Faculty of Medicine of the University of Amsterdam in 1954. Despite his education as a physician, he was never anthropocentric in his focus. On the contrary, he was inspired by the amazing morphological diversity in vertebrate brains in such a way that the field of comparative neuroanatomy became a natural choice for him. In becoming a comparative neuroanatomist, he followed the footsteps of C.U. Ariëns Kappers, the illustrious first director of the Central Institute for Brain Research in Amsterdam, i.e., the predecessor of the NIN. At that same institute, where he already worked as a student, he started his research on the development and structure of the telencephalon of anamniote vertebrates, about which he published a large number of papers, including his Ph.D. thesis: ‘Het Telencephalon der Actinopterygii’. In 1955, after having fulfilled his military service, he became a staff member of the Institute.
In 1968, Professor Nieuwenhuys moved to the University of Nymegen, where he held the chair of Human Neuroanatomy in the Medical Faculty, and that of Comparative Neuroanatomy in the Faculty of Natural Sciences. He retired from both chairs in 1992. The 24 years in Nymegen have been extremely productive. With his numerous collaborators and graduate students, he worked and published on the following themes: (1) the histology of the cerebellum, in particular the gigantocerebellum of Mormyrid fishes; (2) the structural and functional organization of the brainstem; (3) the organization of the limbic system; (4) the phenomenon non-synaptic or volume transmission, and (5) structural changes in the human brain in Alzheimer’s disease. In addition, he published the following three books: (1) The Human Central Nervous System (with Jan Voogd and Chris van Huyzen) This book went through three editions (1978, 1981, 1988), and was translated into German, Italian, Spanish, Greek, Chinese and Japanese. The German Edition was in 1982 awarded with the “Silbermedaille der Internationalen Buchkunst-Ausstellung” in Leipzig. (2) The Central Nervous System of Cartilaginous Fishes (1983), with Wil Smeets and Barry Roberts. (3) The Chemoarchitecture of the Brain (1985). A Japanese translation of this book appeared in 1991.
During his ‘Nijmegen-period’, Professor Nieuwenhuys has directed the thesis work of 31 graduate students. During the same period, he developed the concept that the central nervous contains a built-in, natural coordinate system, and that this coordinate system plays a crucial role during development. Moreover, he introduced the principles of the branch of mathematics, known as topology, into the analysis of the structure of the central nervous system, providing a new basis to the concept of homology in neuromorphology.
After his retirement in 1992, Professor Nieuwenhuys returned to the Central Institute for Brain Research, renamed in the mean time: Netherlands Institute for Brain Research. He published several papers on the neocortex and on the central nervous system of invertebrates, but most of his time was taken by the completion of his opus magnum: “The Central Nervous System of Vertebrates”, (with Hans ten Donkelaar, Charles Nicholson, Jan Voogd, Jaap Dubbeldam, and several others as co-authors). This work, which appeared in 1998, is published in three volumes, comprising over 2000 pages. After its appearance, he and his co-authors Jan Voogd and Chris van Huijzen started working on a new (4th) edition of “The Human Central Nervous System”. This, totally rewritten, and much extended standard work, appeared in 2008, and now runs to 1000 pages.
Professor Rudolf Nieuwenhuys has received several honours. The Royal Netherlands Academy of Sciences awarded the Academy Medal 1998 to him, and in 2000 he received the C. U. Ariëns Kappers Medal. In 2001 he received the Dutch Royal Honour of Knight in the order of the Netherlands Lion.