Centralization (biology)

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In developmental psychology, centralization is a theory by Heinz Werner (1890–1964), among others, gestalt psychologists such as Kurt Lewin , Kurt Koffka and Felix Krueger , with the help of which developmental processes can be described and understood in more detail. The theory is based on the basic assumptions of Gestalt psychology . When setting up and developing functional structures, centralization is, so to speak, the counterpart of peripheralization .

On the origin and justification of the theory

Originally it was an attempt to clarify both the differentiation of perception and the self-organizing development of superordinate centers of stimulus processing. The concepts of differentiation and centralization can, however, also be applied comprehensively to all development processes. - The egg cell can be understood holistically as a functionally totipotent prototype of a cell, cf. also the pluripotent function of stem cells . Such cells may be located in different tissues differentiate . The concept of differentiation therefore appeared suitable - insofar as it includes the separation of special partial functions from diffuse wholes - to be viewed as a shaping factor for the development of organs . As a separate functional unit in the service of an entire organism , organs are always to be understood as centers. Organogenesis is therefore always also centralization, insofar as it is understood as the unifying combination of partial functions in the service of common concerns. Centralization can therefore not only be illustrated using the example of the nervous system. Other organs, such as the pancreas, also consist of a complex of particularly highly specialized cells. Taking the pancreas as an example, these are the actual exocrine gland cells and the endocrine-disrupting islets of Langerhans . - The terms of differentiation and centralization have established themselves in biology . This pair of terms is often used when comparing different blueprints of animals and when assessing the higher development of the organization that may result from this.

perception

Recognition is seen as insight into a new gestalt context. In this respect, perception is subject to a certain individual development ( actual genesis ). It leads from diffuse, strongly emotional and dynamic initial states ( preliminary design, shape germination ) under suitable conditions to concise and clearly structured final forms . As Friedrich Sander showed, this applies not only to perception, but also to the development of living beings. These shapes are not necessarily only to be seen as submicroscopic changes in nerve cells, but are also able to shape the organization of the cells in the visible area ( self-organization ). Cases of brain pathology provide examples of incomplete actual genesis .

Centralization as an expression of the self-organization of brain centers

Fig. 1. The coat of arms can be understood as Albrecht Dürer's illustration of the principle of “die and become!”.

While the concept of differentiation is linked to the simultaneous construction and dismantling of functions in the sense of a change in biological units of nerve cells, the concept of centralization is understood to mean the “wrapping” (integration) of partial functions, which is achieved by cells of different differentiation Form working groups that not only encompass a large number of functions and thus of skills, for example in the organization of brain centers , but can also lead to the development of new sensory qualities . This results in a unifying combination of partial functions in the service of common concerns. Even Johannes Nikolaus Tetens (1736-1807) pointed under the concept of "wrapping" on the opposing aspect of "assembly and dismantling" out can be observed at each "development" and can sometimes even experienced as a loss of older skills, cf. . Goethe “Die and Become!” In West-Eastern Divan , cf. a. Fig. 1. Immanuel Kant (1724–1804) also used the term “wrapping” to treat the concepts of cosmological ideas in the sense of a relationship (a regressus ) between the whole and the parts. This build-up and breakdown is understood today under the term of steady state , i.e. H. as forms (e.g. cell types ) whose contents (functions associated with them) are constantly changing.

Centralization using the example of the retina

Humans and vertebrates

Fig. 2. Development of the vertebrate eye - phase 1: bulge of the brain and formation of the optical vesicles (humans: 4th week) as well as the beginning of the formation of two eye cups
Fig. 3. Cell types in the three layers of a mammalian retina -, light enters from the left, the layers rich in cell nuclei are highlighted in white. v. l. Right: white: ganglion cells and their axons, gray: inner layer, white: bipolar cells, yellow: outer layer, white: photoreceptors, light brown: photoreceptors outer segments. - The developmental process of centralization takes place v. r. n. l. Finally, the axons of the ganglion cells grow out.

The example of the retina is the eye development noted in vertebrates and in humans, the neural tube in the area of the midbrain runs out (Fig. 2). Centralization progresses from peripheral to central (Fig. 3.). The style of the eye cup serves as a guiding structure. The axons of the ganglion cells must be connected to the corresponding centers of the diencephalon, midbrain and cerebral cortex. The layered structure of the retina is similar to the layers of the cerebral cortex ( allocortex ). The bipolar retinal ganglion and the optic nerve ganglion correspond to the gray matter of the brain. They are grouped together to form the brain layer of the retina. The inverted eye of the vertebrate compared to the pit eye of the invertebrate offers advantages in terms of vascular supply. In vertebrates, the retina does not face the light, but the pars optica retinae has contact with the vascular layer of the choroid , which leads to an overall increase in visual performance.

Cephalopods

Among the cephalopods , the Mollusca tribe reaches its highest level of organization. This is shown in the rich development of the sense organs. It goes hand in hand with an increase in performance and a centralization of the nervous system. The eyes of the cephalopods are similar in structure and performance to the vertebrate eye. However, the development of cephalopods has taken a different course. It is a classic example of convergence . The evolutionary differences compared to the vertebrate eye lie in different types of tissue from which the development of the retina starts. While the retina of the vertebrate eye is of neurectodermal origin (see above), the retina of the cephalopod is formed from purely ectodermal tissue. The consequence of this is that the centralization and corticalization of the cephalopods takes place from the inside of the ocular vesicle outwards, while in vertebrates the centralization runs initially from the outside to the inside of the ocular vesicle. Therefore the centripetal nerve fibers in vertebrates have to be led out of the inside of the eye through the optic nerve papilla. This is not necessary with the cephalopods. Although the nerve fibers lying on the outside of the eye also combine to form an optic nerve in the cephalopods, there is no optic nerve papilla inside the eye and therefore no blind spot .

literature

  • Heinz Werner : Introduction to Developmental Psychology . 1926

Individual evidence

  1. ↑ a b c d Peter R. Hofstätter (Ed.): Psychology . The Fischer Lexicon, Fischer-Taschenbuch, Frankfurt a. M. 1972, ISBN 3-436-01159-2 ; (a + b) to district “Centralization, Differentiation, Development” pp. 102, 164 f .; (c) on tax unit “Gestalt psychology, basic assumptions” p. 164 f .; (d) to district “Centralization” p. 102 f.
  2. ↑ a b Markus Antonius Wirtz. (Ed.): Dorsch - Lexicon of Psychology . Verlag Hans Huber, Bern, 16 2013, ISBN 978-3-456-85234-8 ; Lexicon lemma: "Development": online
  3. ^ A b c Alfred Kühn : Outline of general zoology . Georg Thieme, Stuttgart 15 1964; on "Centralization": pp. 7, 55 f., (151 ff.)
  4. ↑ Kant, Immanuel: Critic of pure reason. Riga, 1781, (KrV A 527 , B 555)
  5. ↑ Helmut Ferner : Human development history. Reinhardt, Munich 7 1965; to Stw. “Retina = retinal sheet of the eye cup, neuroblasts ”: p. 137
  6. ^ A b c Alfred Benninghoff and Kurt Goerttler : Textbook of Human Anatomy. Shown with preference given to functional relationships. 3rd volume nervous system, skin and sensory organs. Urban & Schwarzenberg, Munich, 7 1964; (a) Re. “Building functional structures”: p. 106 f .; (b) Re. “Retina”: p. 428; (c) on district “Chorioidea, inversion of the retina”: p. 438.