Quantitative changes in the fibroarchitectonics of the human cortex from birth to the age of 12 years.

Brains from 74 children aged from birth to 12 years were used to study fibroarchitectonic characteristics in topographically and functional diverse cortical zones (the temporal-parietal-occipital subregion, occipital, precentral, postcentral, and frontal areas) of the cerebral cortex; children aged up to 12 months were studied on the basis of one-month age intervals. Studies were performed by computer analysis of optical images on frontal sections stained with Nissl cresyl violet and silver nitrate impregnation by the modified Peters method. Data on the rate of increase in the thickness of radial bundles of fibers, the distances between bundles, and the age dynamics of the ratios of the specific volumes of neurons and fibers in fields 3, 4p, 6op, 17, 19, 37ac, 44, and 32/10 were obtained. These measurements showed that age-related transformation of fibroarchitectonics in fields of the sensorimotor, somatosensory, occipital, temporal-parietal-occipital, and frontal areas occurred at different times and with different intensities; the most significant changes were seen in the first 2-3 years of life, with changes continuing at a less intense level to age 9-12 years.

[Quantitative changes in fibro-architectonics of the human cerebral cortex from birth to 12 years of age]. / Kolichestvennye izmeneniia fibroarkhitektoniki kory bol'shogo mozga cheloveka ot rozhdeniia do 12 let.

The peculiarities of fibroarchitectonics in topographically and functionally distinct cortical zones (including temporo-parieto-occipital subarea, occipital, pre-, postcentral, and frontal areas) were studied in the brain specimens of 74 children of different ages (from birth to 12 years) taken with yearly intervals, while those in the first year of life--with monthly intervals. Frontal sections stained with Nissl, Peters and Golgi methods were studied using computer analysis of optical images. The data were obtained on the increment rates of radial fiber fascicles' thickness, distances between fascicles and age dynamics of ratios of volume densities of neurons and fibers in areas 3, 4p, 6op, 17, 19, 37ac, 44 and 32/10. It was shown that age-related transformations of fibroarchitectonics in the areas of sensomotor, somatosensory, occipital, temporo-parieto-occipital and frontal cortex were heterochronic and took place with different intensity; most pronounced changes were found to occur during the first 2-3 years, while less intensive ones were observed up to the age of 9-12 years.

[The individual characteristics of the cytoarchitectonics of the human motor cortex (based on computer analysis data)]. / Individual'nye osobennosti tsitoarkhitektoniki dvigatel'noi kory bol'shogo mozga cheloveka (po dannym komp'iuternogo analiza).

Age and individual peculiarities of cytoarchitecture of layer III field 4p, periods of intensive and slow growth of the area of profile fields (APF) of pyramid neurons were established by method of computer analysis of histological preparations of human motor cortex from birth up to 20 yrs. It was shown that the greatest changes of APF of pyramid neurons including their individual parameters occur in field 4 of motor cortex during first three years.

[Characteristics of the functional organization of neuronal groups in functionally diverse zones of the human cerebral cortex from birth to 20 years of age]. / Osobennosti strukturnoi organizatsii neironnykh gruppirovok funktsional'no razlichnykh zon kory bol'shogo mozga cheloveka v period ot rozhdeniia do 20 let.

Using computer analysis of histological specimens of motor and posterior associative cortex of the man aged from birth up to 20 yrs age and individual peculiarities of focal groups sublayer III3 of areas 4p, 6op and 37ac, periods of intensive and slow growth of the area of profile fields (PF) of cell groups and total area (TA) of neurons in the group were established. It was shown that greater changes of cell groups PF area and neuron TA occurred in the area 4p during first 3 yrs, while in areas 6op and 37ac from birth up to 7 yrs and 8-9 yrs appropriately. Specific features of the group development in functionally different areas of human brain cortex was demonstrated.

Age-related changes in the cytoarchitectonics of the human sensorimotor cortex.

The projection zones of the movement analyzer show a level of maturity which is required for maintaining the self-regulatory processes in children from the first days of life [4, 8]. The cytoarchitectonics of the motor zone of the cerebral cortex have been studied in a small number of people and at limited ages [1, 2, 4, 10]. One of the leading age-related changes consists of changes in neuronal and interneuronal connections, which have significant influences on the systems organization of the brain and its function as an integral organ. Pyramidal neurons are regarded as the main universal type of cortical neuron, in which the structure of the receptive surface supports transmission of a wide range of polymodal signals [1]. Large pyramidal neurons in layers III and IV can establish connections with all the neurons in a column of cells, which apparently leads to complete and reliable functional interactions between neurons [1, 6]. The aim of the present work was to study the quantitative changes in pyramidal neurons in layers III and IV in various fields of the human sensorimotor cortex from birth to the age of 20 years.

[Age-related changes in the cytoarchitectonics of the human sensorimotor cortex]. / Vozrastnye izmeneniia tsitoarkhitektoniki sensomotornoi kory cheloveka.

The study of human brain sensomotor cortex architectonics within the period since birth up to 20 years with a year long intervals demonstrated that pyramidal neurons differentiation is most intensive in area 4p throughout the period since birth up to 6 months, in area 6p--up to one year and in area 6op--up to 2 years. Pyramidal neurons proportion in sublayer 3 increases significantly in all sensomotor cortex areas within the first postnatal year and its growth continues up to 15-16 years. In area 5 proportion of pyramidal neurons in areas studied undergoes the period of intensive growth up to one year, than it starts to increase by 6-7 years, and finishes its growth in areas 6 and 6op by 14 years and in area 4p--by 16 years.

[The ensemble organization of the sensorimotor cortex in ontogeny]. / Ansamblevaia organizatsiia sensomotornoi kory v ontogeneze.

Examination of sensomotor zone of the human brain cortex in human subjects (from newborns up to 20 year-olds) with yearly intervals revealed the presence of all neuroglia-vascular ensembles components without any relationship in composition by the moment of birth. Significant increase of the cortical layers and sublayers thickness, connected with growth of the volume of all type neurons and development of dendritic-axonic networks, vessels and glia were noted. Stair-like groups of neurons are present by the moment of birth, and so called racemose groups, the composition of which is diverse in different fields form by the age of three when vertical and horizontal contacts system grows more complicate and the astrocyte glia differentiates. The size of pyramidal neurons (Betz cells included), fusiform and stellate neurons increases by the age of six. By 10-12 years intraensemble, interensemble and transcortical contacts attain the high level of development. By 16-18 years ensemble organization of the cortex reaches the level, characteristic to adults in main parameters of its architectonics.

[Characteristics of the ensemble organization of the human cerebral cortex from birth to 20 years of age]. / Osobennosti ansamblevoi organizatsii kory bol'shovogo mozga cheloveka ot rozhdeniia do 20 let.

When studying frontal, somatosensory and visual areas of the human cerebral cortex from birth up to 20 years of age in year-to-year intervals, it has been stated that by birth in neocortex all components of the neuron-glio-vascular ensembles are presented. They are not connected in their composition. During the first year of life the size of all types of neurons increases, long-axonal basket neurons differentiate, fasciculi of radial fibers become thick. By 3 years of life in the ensembles the neurons are definitely grouped as clusters. Sizes of spindle-like and satellite neurons increase; they distribute their axonal collaterals vertically, horizontally and in frontal-posterior direction. By 5-6 years of age the horizontal connection system becomes more complex at the expense of longitudinal growth and ramification of lateral and basal dendrites of the pyramidal neurons. In the section transversal areas occupied with cell groups increase. By 9-10 years of age the pyramidal neurons reach their greatest size. By 12-14 years of age the fibrillar component of the cortex increases considerably, inter- and intraensemble horizontal connections become more complex, the system of local connections becomes more plastic owing to development of short-axonal basket-like neurons. By 16-18 years of age the ensemble cortical organization in its main parameters of architectonics reaches the level specific for mature persons.