Government of
the Autonomous City of Buenos Aires
Neuropsychiatric Hospital "José Tiburcio Borda"
Laboratory of
Electroneurobiological Research
and Journal
Electroneurobiology
ISSN:
0328-0446
Morphogenetic versus morphofunctional theory:
Franz J. Irsigler's intervention
in the Behavioral and Brain
Sciences' discussion
on the
implications of the "initial brain" concept for brain
evolution in Cetacea (1988)
Franz Johann Irsigler
Correspondencia
/ Contact:
vixit
Electroneurobiología
2004; 12 (3), pp. 257-264; URL http://electroneubio.secyt.gov.ar/index2.htm
Introduction, by
Mariela Szirko <Mzirko[at]Sion.com>: When
in 1987 Behavioral and Brain Sciences launched
a debate (11, 75-116, 1988) on one of its target articles, hardly could its
editors have foreseen that it was to provide a first opportunity for their
readers to hear about one of the basic anatomical concepts of the
Argentine-German neurobiological tradition. Harder even could have been for
the Argentinian researchers to foresee that such a silence-breaking, first
international technical mention in a long time, was to be proferred by a
Third-Reich neuroscientist who learned it as a part of a neuroscience later
globally eclipsed, perhaps, by its supposed being redolent of horror deeds. Because
of this – not of that – I find salutary to briefly remind the episode.
One of the open peer commentaries (p. 95-6) to the Behavioral and Brain Sciences' target
article was provided by a Prague
University's graduate, medical doctor and later race-differences intellectual
Professor Franz Johann Irsigler, former senior neurosurgeon at the University
in Berlin, and (1939-1945) member of the (then Kaiser-Wilhelm) Institut für
Hirnforschung in Berlin-Buch (now Max-Planck-Institut für Hirnforschung in
Frankfurt am Main). The institute was directed, 1937-45, by Professor Hugo Spatz
(1888-1969), who was also Irsigler's teacher of brain anatomy. On Spatz and the
institute during the period of Irsigler's association with them, judgment has
been passed: see e.g. Benno
Müller-Hill, Tödliche Wissenschaft: Die
Aussonderung von Juden, Zigeunern und Geisteskranken 1933-1945 (Hamburg,
Rowohlt Verlag, 1984 and many further editions and translations). Commenting on this topic,
Katrin Weigmann ("In the name of science. The role of
biologists in Nazi atrocities: lessons for today's scientists", EMBO reports 2, 10, 871–875, 2001, and
refs. therein, in
http://www.nature.com/embor/journal/v2/n10/full/embor304.html) points out:
"Julius Hallervorden, head of the department of histopathology at the KWI
for Brain Research in Berlin-Buch, took the initiative to co-operate with the
Euthanasia movement. 'You kill them anyway; at least take out the brains so the
material can be used', he said. The brain research community had developed a
close network of collaborations between research institutes and psychiatric
wards so efficient that the scientists were supplied with an excess of brain material."
Prof. Irsigler later (1963) described himself as a student of Spatz also in his
later speculative essays on brain evolution. As an adherent to the fallen
regime, after 1945 Irsigler left
This point of interest is Irsigler's having been
formed in the 1920' and 1930's in such an intellectual sphere and
distinguishing himself in the BBS's debate by pointing out one of Jakob's
results, an important technical concept, in 1988. It finely illustrates the
sectorization of the results taken into account in doing science and, by the
way, it also illustrates the nefarious association of cultures, and the
scientific results attained in them, with their political regimes. It probably
played a role in the neglect of this relevant technical concept developed
decades before in the Argentine-German neurobiological school, of which concept
due notice was taken in German neuroscience independently of the tolerance or
collaboration of some of its researchers as regards the atrocities perpetrated
between 1937 and 1945, and the parallel inattention encountered by this
concept in other countries' neurosciences. One cannot help but mind of the
cerebral circuit that Jakob described and taught in his lessons since 1907 and
he reiterately published since 1909, which another researcher – one, of
irreproachable honesty and professional
integrity – introduced bona fide
also in 1937 and is since known as "the circuit of Papez". It, too,
illustrates aspects of the dementia dichotoma, der Zweikulturenwahn denounced by an earlier collaborator of Electroneurobiología (1995: cf. http://electroneubio.secyt.gov.ar/Tercero.htm) then President of the Berlin-Brandenburg Academy of Sciences,
Prof. Hubert Markl. (Professor Markl was later appointed President of the Max
Planck Gessellschaft and set up an important research program to discriminate
science and misdeeds at the Kaiser Wilhelm Institut). Irsigler introduced, into
the BBS discussion's conceptual landscape, Christfried Jakob's
anatomical-developmental concept of hemispheric rotation around the sylvian
pivot (Vom
Tierhirn zum Menschenhirn, 1911), which is the point of interest of
the present recounting.
Technical context to
Irsigler's commentary: The Behavioral and Brain Sciences set up a debate on its target
article, "Implications of the 'initial brain' concept for brain evolution
in Cetacea" by Ilya I. Glezer, Myron S. Jacobs and Peter J. Morgane, which
became published in BBS 11, 75-116
(1988). Open peer commentary was provided, besides Prof. F. Irsigler, by other
24 scientists, seven of whom were from
"We review the evidence for
the concept of the 'initial' or prototype brain. We outline four possible modes
of brain evolution suggested by our new findings on the evolutionary status of
the dolphin brain. The four modes involve various forms of deviation from and
conformity to the hypothesized initial brain type. These include examples of
conservative evolution, progressive evolution, and combinations of the two in
which features of one or the other become dominant. The four types of
neocortical organization in extant mammals may be the result of selective
pressures on sensory/motor systems resulting in divergent patterns of brain
phylogenesis. A modular 'modification/multiplication' hypothesis is proposed as
a mechanism of neocortical evolution in eutherians. Representative models of
the initial ancestral group of mammals include not only extant basal Insectivora
but also Chiroptera; we have found that dolphins and large whales have also
retained many features of the archetypal or initial brain. This group evolved
from the initial mammalian stock and returned to the aquatic environment some
50 million years ago. This unique experiment of nature shows the effects of
radical changes in environment on brain-body adaptations and specializations.
Although the dolphin brain has certain quantitative characteristics of the evolutionary
changes seen in the higher terrestrial mammals, it has also retained many of
the conservative structural features of the initial brain. Its neocortical organization
is accordingly different, largely in a quantitative sense, from that of
terrestrial models of the initial brain such as the hedgehog."
In addition, providing an
introduction, the three authors added: "We have been studying the
morphology of the dolphin brain for many years (see Morgane et al. 1986a;
1986b) and, like earlier investigators (Beauregard 1883; Breathnach 1953; 1960;
Kükenthal & Ziehen 1889; Langworthy 1931; 1932), we were struck by the extreme
size and convolutional complexity of cetacean neocortical formations. Our
histological studies, however, revealed a 'relatively simple underlying
neocortical organization in the dolphin that is in many ways similar to that of
hedgehogs and bats' (Morgane et al., 1985; 1988 in press). The studies of
Sanides (Sanides & Sanides 1972; 1974) and Valverde (Valverde 1983;
Valverde & Facal-Valverde 1986; Valverde & López-Mascaraque 1981) on
the cortical neuronal structure of the hedgehog and bat provide further
evidence of neuroarchitectonic similarities with the neocortex of the dolphin.
Our recent studies (Morgane et al. 1985; 1986a; 1986b) have accordingly led us
to interpret the dolphin brain in terms of an initial or prototype brain
concept that we now propose to elaborate in this target article.
The initial brain concept concerns
the evolution of the mammalian nervous system and suggests that the full
spectrum of extant patterns of brain organization in mammals arose from a
common ancestral mammalian brain (Elliot Smith 1910; Filimonoff 1949; Herrick
1921; Wirz 1950). A number of well-established evolutionary concepts
documented by comparative neuromorphology and physiology have been drawn upón
in this account. (Ariens Kappers et al. 1936; Brodmann 1909; Ebbesson 1984;
Ebner 1969; Elliot Smith 1910; Filimonoff 1949; 1965; Herrick 1921; Kaas 1980;
Kesarev 1970; Le Gros Clark 1932; Morgane et al. 1985; 1986a; 1986b; Northcutt
1984; Poliakov 1958; Sanides 1969; 1970; 1971; 1972). The following major
features of brain evolution recognized by comparative neuroanatomists will be
used in discussing the initial brain concept:
1. There is a general trend toward
an allometric increase in the absolute and especially the relative mass of the
brain with respect to body size. This implies an increase in the number of
functional units (neurons), an increase of interneuronal communication due to
the corresponding growth of neuronal processes (dendrites and of the glial
channels), leading to tangential cortical growth; (2) a prolonged period of
neuronal generation (or a reduction in the number of glial channels), leading
to radial increase of the cortex. Both modifications may be caused by the
acceleration or retardation of normal developmental processes secondary to DNA
changes, in agreement with modern evolutionary views (Gould 1977).
In contrast, changes in the size
and shape of cortical neurons may, to some extent, exploit the normal
developmental modifiability of neuronal shape, although for more drastic
structural and chemical changes in cortical neurons some genetic innovations
may be necessary. Normal developmental mechanisms can also allow changes in the
number of at least one type of cortical 'module' (Van der Loos & Welker
1985).
Finally, cortical connectivity
develops through a phase of initial exuberancy (Innocenti, in press; Innocenti
et al. 1977) characterized by the fact that an area or part of an area projects
to and receives from a broader and more diverse territory than in the adult,
followed by focussing or rededication of these projections. As discussed elsewhere
(Innocenti, in press), this developmental strategy might have appeared by
fortuitous mutation and then been maintained through phylogenesis because of
its adaptive ontogenetic value. Since this strategy may also have allowed the
incorporation of genetic caprices such as addition or loss of neurons, the
invasion of new territories by a projection, and the segregation of projections
into separate territories (Ebbesson 1984; Katz et al. 1983), structures that
have adopted this strategy, such as cortex, have enjoyed and still may enjoy
explosive evolution." Irsigler's contribution is as follows:
Morphogenetic
versus morphofunctional theory
F. J. Irsigler
The target article by Glezer et al. about the
"initial brain" concept offers a phylogeny of the cetacean neocortex
in terms of its laminar and modular cytoarchitectonics. On that account the
Cetacea appear as a unique feature of evolution in the direction of
"conservative/progressive" corticalisation. The authors start from an
hypothesized archetypal brain model, represented by extant basal Insectivora
and Chiroptera. They reconstruct four evolutionary modes by postulating a
modification/multiplication model wherein the modular components of the
cortical areas are considered to be the elementary functional units and
"some of the main targets of evolutionary forces."
In contrast to this, morphogenetic theory starts from
extant allocortical (phylogenetically early) formations - that is, reptilian
and paleomammalian - preserved throughout vertebrate evolution and considered
to be the foundation of species-typical behaviour in man and animal, from the
mammal-like reptiles upwards.
Morphogenesis (a well-ordered sequence of transformations)
rests on:
1.
Allo-isocortical contiguity, that is, "interpenetration" (Edinger
1909) or "interfaces";
2. Hemispheric
rotation around the sylvian pivot (Jakob 1911); it involves the sagittal and
coronal planes and starts from the peri-insular segment resulting in a
maturation gradient (Kahle 1969) which means heterochrony in cortical
differentiation;
3. Folding in of
the allocortex at the base; there, the allocortex loses contact with the bone
(Spatz 1937). These processes are autonomous (Monod 1970) and emerge early in
phylogeny and ontogeny (Gegenbaur 1898; Hyman 1962; Kahle 1969; Rose 1935).
4. Different and
independent rates and modes of these processes result in lateralisation
(dominance) of the two brain halves; that is, in a heterochronic shift of encephalisation.
5. Morphogenesis
is closely related to metamorphosis: (a) In both, an orderly sequence of events
is involved that cannot be imposed on the evolving system by outside forces;
(b) in both, information is transmitted by chemical means, analogous to the
mRNA in the Monod-Jacob lactose system. The concept of morphogenetic induction
(Spemann 1936) is fundamental in metamorphosis and morphogenesis, uniting both
under one heading (Monastra 1986).
6. Chemoaffinity
(Sperry 1963) is the essential feature of the reptilian type of brain, which
forms the core of the "paracrine" neuraxis and constitutes the
"chemoarchitecture" of the brain (Nieuwenhuys 1985); it includes the
"R-complex" of MacLean (1978) and the allocortices at the base of the
frontal and temporal lobes ("basale Rinde" in the human: Spatz 1937;
Jakob 1979).
7. Flechsig's
original concept (1920; 1927) of "primary" receptive areas having
connections only with adjacent "parasensorv"areas known as
"associative areas" was later developed into a "connectivity"
(Pribram 1971) hypothesis of neocortical "crossmodal associations"
(Geschwind 1965) supposedly underlying the "higher cortical functions in
man" (Luria 1980). Contrary to this, it is found that the association
cortices belonging to the late-myelinized areas on the Flechsig scale
represent the more generalized architectonic pattern (compared to the sensorimotor
cortices) and come closest to the general cyto- and myeloarchitectonic scheme
of Brodmann (1909) and the Vogts (1919) (Sanides 1970; 1975).
Thus, in the ontogenesis of higher placentals there is
a spacetime dislocation between cortices having different rates and modes of
differentiation; this results in contiguity of the "primary" areas
with paleomammalian and mesocortical (insular) boundary zones (Sanides 1975 and
coworkers). According to morphogenetic theory, the crucial feature of this kind
of interrelationship is that it is species-typical (innate) and, in the words
of Sperry (1983) "largely preorganized independently of sensory
input" (p. 95).
Critique of Glezer et al.
First,
the cortical subdivisions offered in the target article (Figure 5) are
artifacts construed to fit a preconceived neocorticalisation scheme. They do
not coincide with definite extant mammalian species. Consequently, there is considerable
overlap, even with "deviant" Cetacea. Thus, cortical subdivisions
based on purely cytoarchitectonic descriptions seem inadequate for speciation
and taxonomy. Generally speaking, in the whole cortex there is a definite trend
toward progressive differentiation from the paleo- to the eulaminate neocortex
(Braak 1980; Brockhaus 1940). Nevertheless, during early development there is a
great deal of variability in stratification and myelinization (Humphrey 1966;
Kahle 1969; Sanides 170; Stephan 1975), contradicting Glezer's et al.'s
emphasis on the uniformity of the vertical modules in different functional
types of cortex "extending beyond taxonomic boundaries."
Second, Glezer et al.'s hypothetical mechanism of columnar
modification (Figure 7) rests on specific afferent inputs and main efferent
layers with intercalated association zones between the primary projection areas
(Figure 6). This strongly reminds one of Pavlov's "reflex principle,"
recently called by Luria (1980) "the modern materialistic psychology"
(p. 30). Likewise, Kotchetkova (1960), in studying the specifically human
regions in the hominid neocortex, concludes that certain neocortical regions
concerned with tool making and praxis ("labour" in the sense of
Friedrich Engels), have been the driving forces in anthropogenesis - a view as
morphofunctional as that of Glezer at al. (See abstract on Sinanthropus in
Edinger 1975, p. 233.)
Glezer et al.'s cytoarchitectonics make the module - a
single, variable functional element - the causal determinant, outclassing and
superceding all lower levels of neuronal activity; this is not likely to be one
of the "main targets of evolutionary forces."
Glezer,
Jacobs and Morgane's reply (p. 108) was as follows: "We
could hardly agree more with Irsigler's
comments about the use of cytoarchitectonic subdivisions for evolutionary
generalizations about the neocortex. However, in our case, we are using not
only cytoarchitectonic subdivisions of the dolphin neocortex, but also
correlations with electrophysiological mappings by Russian authors along with
our own Golgi and electron microscopic studies (Glezer et al., in press;
Morgane et al., in press). The second point made by Irsigler is evidently based
on a misunderstanding. Although vertical cortical modules are accepted as basic
components of the morphofunctional organization in the neocortex, there is
great variability in the dimensions of the columns as well as in their inner
structure. We believe that the quantitative and qualitative variability of
columnar organization may reflect functional specializations of different
cortical areas. In our view the cortical module is likely to be one of the main
targets of evoolutionary forces through the influence of subcortical and peripheral
neural mechanisms subjected to selective pressures in specific ecological
niches"
(For
the complete discussion, details and references, cf. the original Behavioral
and Brain Sciences 11:1, 75-116, 1988).
_____
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