Architectonics of the brain cortex

Architectonics of the brain cortex - the doctrine of the General plan of the structure of the crust and local peculiarities, expressed by a number of characteristics concerning both the quantity, size, shape and distribution of the cells (cytoarchitectonic)and caliber myelinated fibers and their distribution (Malakhitovka), features nevernogo structure (cinephilia), structures of clay (geoarchaeological), distribution vessels (angioarchitectonics). On the basis of these characteristics and the structure divides the entire surface of a large brain by structural units of different significance: the core area (or areas), region, subregion, fields, subfields. The architecture is significantly different from histology, the study of which is mostly not the architecture of the anatomic structures and thin structure of the individual tissue cells, and topographic ratios of having to architectonics of basic importance, in histological studies or not at all, or play a subordinate role.

                          Cytoarchitectonic
The brain cortex is divided into five main areas (zones)that are different from each other by their tab: ancient crust (paleocortex), the old bark (archicortex), new bark (neocortex), interstitial periarterial zone (periarteritic separates the neocortex from archicortex) and interstitial peripatetically zone (parapalegics separates the neocortex from paleocortex).
Ancient crust, or paleocortex, appears in phylogeny very early (already at selachii) and is characterized by primitive structure cortical plate, slightly separated from the subcortical cell clusters. It includes olfactory tubercle (Fig. 1, T) with cortical plate, weakly separated from the head of the caudate nucleus, diagonal area (Fig. 1, ld) with cortical plate, not separating from unnamed substance, Peremyshlyany area adjacent to the almond kernel (semilunar gyrus, Fig. 1, sl), partition with highly reduced cortical plate and preparatory area comprising mainly lateral olfactory area (Fig. 1, gol).
Old bark, or archicortex, appears in the process of phylogenesis later than the early crust: in amphibians she only planned, but in a reptile are expressed clearly and difficult differentiated on the field and the field. Unlike the ancient crust, old bark, like new, characterized completely separated cortical plate.
At the same time it differs sharply from the new cortex, an adult presents cortical plate single-layer or with only scheduled stratification. Part of old bark are located in the depth of hippocampus grooves (Fig. 1, fh) Amonov horn with very large cells that is divided into a number of fields (subiculum, sectors h1, h2, h3, h4, h5), and gear fascia with very dense and small cell cortical plate. To the old crust and is severely reduced cortical plate taenia tecta, covering the top of corpus callosum and passing on the base of the brain in the medial olfactory area (Fig. 1, gom).


Fig. 1. The base of the brain of the human fetus 5 months:
amb - gyrus ambiens;
THE bulbus olfactorius;
fh - fissura hippocampi;
gh - gyrus hippocampi;
gol - gyrus olfactorius lateralis;
gom - gyrus olfactorius medialis;
in - insula;
ld - ligamentum diagonale;
ra - sulcus rhinalis anterior;
rp - sulcus rhinalis posterior;
sa - sulcus semianularis;
sl - gyrus semilunaris;
T - tuberculum olfactorium;
U - uncus.


Interstitial bark. Peripatetically zone, separating from new crust ancient crust, is a person of very small lower part of the insular areas (Fig. 1, in), mainly represented by formations of new crust. Periorbitalny zone, separating from new crust old bark, is hippocampal gyrus (Fig. 1, gh) and the lower part of the limbic region. On hippocampus gyrus area is divided into presbycusis and enteralnoe region, the latter differentiated especially rich in sub-regions and fields and has a complicated bundle.
New bark (gamogenetically bark of Brummana, isocortex Vogt) dimensions far superior to man the rest of the territory together (heterogeneously bark of Brummana, allocortex Vogt), occupying about 96% of the entire surface of a large brain. In the evolution of new crust is allocated for the first time only in a reptile, but here it is limited in size (the so-called side bark). Typical six-plane structure of the new crust gets only in mammals, where at a certain stage of development (the person on the 5-6th month of fetal life) it splits into six main sections. For the most part six-plane structure of the new bark stores for adult (gomotopicheskii bark of Brodman), but in some fields (heterotypic bark of Brodman) the number of layers is increased or decreased.
1. Layers and sublayers new crust (Fig. 2). Layer I, zone, the so-called boundary layer of the wall of the brain, is not of itself cortical plate. The adult is very poor cells. Layer II, outdoor grainy, by contrast, is characterized by a large number of densely spaced cells. Layer III, pyramid, consists mainly of pyramidal cells, the value of which for the most part increases towards deeper, so the layer III is divided into three sublayers (III1, III2 and III3). Layer IV, internal grainy, consists of dense cell-grains, like layer II. Layer V, ganglion, for the most part are much less dense than the layer IV, and slightly less dense than located below the layer VI, consists mainly of small cells, among which can meet and very large. Layer VI, multiform, is divided into two sublayers - triangular, consisting mainly of cells, and spindle-shaped, consisting of a spindle-shaped cells.


Fig. 2. Cyto - and maloarhangelska layers in the field of new crust. Cytoarchitectonics layers denoted by Roman numerals, and maloarhangelska - Arab. (Sublayers 6b1 and 6b2 allocated Vogt as the seventh layer.)


2. Scope and field new crust (Fig. 3 and 4). Occipital region (field 17, 18, 19) is characterized in General by the density of a location and the small size of cells, very light layer V, columnar layer VI, small width of the bark, dominated by the width of the top floor of the crust (layers II, III and IV) above the lower layers V and VI). The Central Department of the region forms a box 17 (area striata), occupying sporno furrow and the adjacent part of the sphenoid and reed brains. Small - and customlocale expressed in box 17 especially sharply (the so-called koniarek, or powdered bark); very typical splitting layer IV four sublayer; very pronounced columnar arrangement of the cells layer VI. Surrounding heterotypic box 17 fields 18 and 19 refer to gomotopicheskii cortex and in its structure represents the transition from the field to 17 are located next to the front fields parietal and temporal areas.
The top and bottom of the parietal region belong to gomotopicheskii cortex and are characterized by a clear division of bark on six layers with separate external and internal granular layers. Box 5 top parietal region is characterized by the presence in layer V very large cells resembling giant cells Betz. Box 7, no such cells, its field 5 from fields 39-40 lower parietal less customlocale and the large size of the cells.
Potentially area (fields 3/4, 3,1,2 and 43). The bottom of the Central sulcus is a field 3/4 representing in its structure the transition from typical postcentral region (the presence of a layer IV) to field 4 precentral.net region (Betz cells). On the back wall of the Central sulcus is zero 3, characterized by thick and melcockletocny and very light layer V. Fields 1 and 2, located on the back Central gyrus, sharply differ from field 3 significantly greater magnitude of cell layers III, V and VI.
Precentral.net region (field 4 and 6) is characterized especially by the lack of granular layers (II and IV), the weakest isolation layers from each other and large width cortical plate, mainly to its lower floor (layers V and VI). The 4th field (area gigantopyramidalis) is characterized also by the presence in layer V giant cells Betz, in box 6 missing.
Frontal area includes fields 8, 9, 46, 10, 11, 12, 44, 45, 47 and 32, of which the most rear box 8 is similar in structure agranular precentral region, as the layer IV expressed in it poorly, although, unlike in field 6, is still there. In the rest of the field frontal region presents gomotopicheskii bark with a very clear division into six layers.
The temporal area (upper temporal subregion with fields 41, 41/42, 42, 22, 22/38 and 52, middle temporal subregion with fields 21 and 21/38, the lower temporal subregion with fields 20tc, 20l, 20b and 20/38 and temporo-parietal-occipital subregion with fields 37A, 37b, s, 37d, AV and 37 ░ C). Field temporal area have homotopy structure-goniocorella in the back part of the upper surface of the temporal lobe, hidden in silvavoc furrow (fields 41 and 42).
The limbic regionacross the top of the limbic area, are presented in the depth of furrows of the corpus callosum interstitial bark (perfectly region), mostly occupied by fields of a new bark (23, 23/24, 24, 25, 31, 31/32 and 24/32), in the posterior part has a typical six-plane, and in the front - agranular (no layers II and IV) building.
Islet area, occupying an island, in a very small lower his Department is busy interstitial bark separating new bark from ancient. Basically, it presents new fields crust (field 13 and 14), with the back of her Department refers to gomotopicheskii bark, and the front is like a field precentral.net region and the anterior limbic area, agranular structure.


Fig. 3. Cytoarchitectonics map of the brain cortex. The outer surface of the hemisphere.

Fig. 4. Cytoarchitectonics map of the brain cortex. The inner surface of the hemisphere.

                          Malakhitovka
Malakhitovka studies the structure and distribution of myelinated fibers. Maloarhangelsky as cytoarchitectonics, new crust is divided into six layers (maloarhangelska layers, unlike cytoarchitectonics, by Arabic numerals, Fig. 2). For division by formation is set to the character of structure as the transverse and especially radial fiber, as the peculiarities of the distribution of the latter there are three main, on the classification of Vogt, type crust: 1) eurodaily type, in which rays reach the middle layer 3 (isocortex, corresponding mainly gamogenetically the bark of Brodman), 2) interracially type, in which rays reach only layer 4 (the front part of the limbic area), and 3) separately type, in which they reach the layer 1 allocortex).

Architectonics of a bark of a large brain and issues of topical diagnosis
In addition to a large value for solving specific issues of topical diagnosis, architectonics gives a great material for solution of the most General and fundamental issues of localization features. Showing that the brain cortex differentiated on very different in its structure formation, architectural research find complete failure ideas about the functions of the crust in the spirit of equipotentiality, i.e. about the homogeneity of its functions in all areas. But the data of architecture (especially evolutionary) testify as definite and about incorrectness views narrow localizationism, showing that all areas of the cortex, including the most primitive, are entities functionally multivalued that there is no such area of the cortex, which would constitute "centres"providing fully and exclusively to any one function, and that, therefore, the functions in the brain cortex localized in a very complex way. Cm. also Furrow and gyrus of a bark of a large brain, brain (anatomy, physiology).