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Formation of functional systems
Having considered the ontogenesis of sensorimotor structures, we turn to the formation of functional systems described by academician P.K. Anokhin 1. The theory of functional systems considers the body as a complex integrative structure consisting of many functional systems, each of which, with its dynamic activity, provides a result that is useful to the body.
Systemogenesis is part of the general doctrine of functional systems, closely related to indicators of the internal environment of the body, the satisfaction of biological needs, and the effects of the social environment. Any purposeful activity of animals and humans, from the point of view of functional systems, represents the final stage of activity. PC. Anokhin evaluates systemogenesis as the selective maturation of functional systems and their individual components in ontogenesis. Along with the leading genetic and embryological aspects of the maturation of functional systems in the pre- and postnatal periods of development, systemogenesis includes regularities in the formation of behavioral functions. The whole process of reflection of the external world by living organisms, fixed in the phylogenesis by hereditary factors, finds its expression in the development of the embryo in mammals. In the embryonic period
1 Anokhin P.K. Nodal questions of the theory of functional systems. - M., Science, 1980.
During the development of precisely those functional systems that are necessary for the implementation of the vital functions of the newborn, adapting it
to the external environment.
The main process that selects functional systems for existence in a new (external) environment is accelerated (heterochronous) and selective maturation of central and peripheral structures. These adaptive reactions of the body are hereditarily fixed in phylogeny and embryogenesis.
Such simultaneous maturation of various structures of the embryo is necessary for the concentration of nutrients and energy in certain systems at specified age periods. A person has his own early maturing set of functional systems, i.e. own systemogenesis. In this case, the system may begin to function, not yet fully developed. For its formation, signals (irritations) coming from the external environment are necessary. The sequence of maturation of the departments of the central nervous system is determined genetically. The spinal cord begins to differentiate before the brain and independently of it. The readiness of the nerve cell and the entire neuron for activity is due to the accumulation of nutrients and the presence of the myelin sheath, the formation of synapses.
In the first half of fetal development, the spinal cord ripens in the fetus. His readiness for activity is signaled by the first movements of the fetus, which appear by the 20th week of pregnancy. Gradually, fetal movements become more active, which indicates the inclusion of the entire length of the spinal cord. In the brain, according to B.N. Klosovsky, the earliest ontogenetic receptor is the vestibular apparatus, providing a certain position of the fetus. The vestibular apparatus develops at an accelerated pace and reaches a certain maturity by 6-7 months of fetal development. In the second half of pregnancy, the brain is actively formed in the fetus, especially its posterior sections: the brain stem and cerebellum, which is functionally closely related to the vestibular system. In the brain stem, which is an extension of the spinal cord, the nuclei of the cranial nerves, the reticular formation, and the pathways are laid. The second half of pregnancy ends
the formation of the fetal brain, it takes on a full shape.
The act of birth is a transition from intrauterine to extrauterine conditions and is designated as a critical period. For the onset of the birth act itself, it is necessary for the fetus to accumulate sufficient energy to move along the birth canal of the mother, as well as the inclusion of the vagus nerve function, which ensures the activity of the respiratory and cardiovascular systems, since a number of changes must occur in the child's body due to the termination of placental circulation and the transition to pulmonary respiration, self-circulation, digestion, etc.
The nucleus of the vagus nerve and the nuclei of other cranial nerves are located in the brain stem and are combined by the reticular formation - a nonspecific accumulation of nerve cells - activating and amplifying impulses from the periphery to the center and from the center to the periphery. Thanks to the unifying and activating function of the reticular formation, special blocks are formed - functional systems for performing certain activities.
In the first days of life, a sucking reflex is formed in the child. Any irritation of the lips of the child causes a response. The nuclei of the cranial nerves (trigeminal, facial, vestibular, lingual-pharyngeal, vagus and sublingual) located in the trunk of the brain participate in the implementation of the sucking reflex. Combining into one functional system is carried out by the reticular formation, which is also located in the stem part of the brain. When performing a sucking action, heterochrony also occurs, which manifests itself in the fact that the simplest movements of the tongue back and forth, the bow of the lips (grip of the nipple), the inflation of the cheeks, the tension of the soft palate, and swallowing are necessary for sucking.
The simplest motor acts that perform the function of sucking are not carried out by the activity of the whole nucleus of the cranial nerve, but by a separate group of cells in this nucleus. As the motor act becomes more complicated (for example, when switching from sucking to eating food from a cup or using a spoon), new groups of cells of the same nuclei are included that determine the formation of a more complex functional system, while the previously formed system (in this case, the sucking reflex) weakens, slows down.
The motor development of the child is due to the inclusion of black substance, red nuclei, quadruple, pallidum (the older core of the subcortex). Thus, the whole extrapyramidal system is turned on and a new signaling system is formed, which ensures the perception of environmental stimuli, information processing and response. The inclusion of the pallidum is manifested by the activation of the emotional sphere: at first the child smiles at the pleasant voice or smile of an adult, and then laughs. At the subcortical level, visual, auditory, sensory and motor connections are formed.
At the age of 4 months, when the child becomes more active (turns over from side to side, moves his arms and legs, looks at and touches toys hanging in front of him, shows interest in them), movements are made under the control of vision and hearing, with the participation of cerebellar structures providing their correction. At first, mimicking is noted, then the movements become more coordinated (the child grabs the toy). A new signaling system is being formed (cerebellum, arm, eye), due to which metricity and coordination of movements, action at a distance, which is very important for the subsequent activity of the child, develops. During this period, the perception of a complex stimulus of the sensory component has a simultaneous effect on various analyzers, forming links between them.
By the 5th month, another core of the subcortex is turned on - the striatum, as a result of which the movements become smoother and more focused. The movements are gradually improved (the child willingly captures the toy, holds it), a grasping reflex is formed and a new functional system is fixed. During this period, the child very actively pronounces sounds, mainly vowels, and listens to them. If an adult supports speech activity and makes sounds or words after the child, he emotionally reacts and enters into communication.
When pronouncing sounds, the motor system is activated (proprioception of all respiratory and vocal muscles, hearing and vision), which provides a comprehensive perception of sounds and the formation of its functional system.
By the age of 6 months, the anatomical maturation (myelination) of the trunk, superbarrow, subcortical formations, as well as the formation of the extrapyramidal system, providing a certain level of physical and psychomotor development, ends. One of the most noticeable changes in physical development is the ability to sit on your own. At the same time, the possibility of reviewing the environment (finding toys and playing with them) changes dramatically, a grasping reflex is improved.
The primary parts of the cerebral cortex begin to turn on, stimuli reach the cortex, and primary gnosis (recognition) appears. Gradually, the connections of primary and secondary fields in their area of the brain and the connections of secondary fields from different parts of the brain are formed. So, the first paths arise between the visual and motor region, forming its own functional system. Connections are formed between the auditory and motor areas and, accordingly, their own functional system is formed to perform a specific action. Soon there are connections between the visual and auditory areas of the cerebral cortex. In these cases, the inclusion of sensory systems (hearing, vision, proprioception) is of great importance, due to which acoustic-motor and optical-motor connections are formed, learned movements are strengthened (praxis).
Speech development also rises to a new level. If up to 6 months the child pronounced individual vowel sounds, emotionally coloring them, then after this critical period the child begins to pronounce syllabic elements (babble). The peculiarity of the formation of babble is that the child begins to use the sounds of his native language. Babble is poor at first. Gradually, the number of repetitions increases, the time of active speech production lengthens. The child has two ways of tracking the speech: the first is the perception of auditory irritations, the second - along the paths of deep sensitivity (kinesthetic). Arriving in the cerebral cortex, in its temporal and parietal regions, they provide a close connection, forming a functional system, due to which phonemic hearing and speech perception are subsequently formed. During this period, speech contact with adults who repeat or actively pronounce syllables and words that are available for repetition by the child is of great importance. There is a perception of not only their own sounds, but also the sounds of speech of others, which are important for the further development of speech.
In the second half of life, showing and naming objects, the surrounding form a child’s connection between the visual and auditory areas, and then the motor (when the child begins to manipulate objects). Feeling objects, playing with them creates a new form of communication - tactile-kinesthetic and motor. Thus, all sections of the cerebral cortex are gradually included, creating their own functional systems.
Speech development is associated with the inclusion of tertiary fields, which begin to become more active in the second half of the year. Initially, a passive dictionary is formed (understanding of individual words associated with a subject). By the end of the first year of life, the child speaks the first words. Speech function is closely related to the development of the entire motor region, as indicated by the formation of locomotion (crawling). Crawling, uprightness and walking with support, and by one year and independent walking are due to the myelination of the pyramidal pathway and the inclusion of all parts of the cerebral cortex participating in a complex motor act. Gradually, from the first steps under the control of the spatial-vestibular system, walking becomes an automated process in which the frontal (efferent), parietal (afferent), occipital and temporal areas of the cerebral cortex take part. The relations of these departments form their multi-level functional system, which gradually becomes more complicated with age. Articulatory motility is formed more slowly and is included in the activity as the development of speech communication and the nervous system. Thus ends a certain stage in the formation of functional systems that combine into larger blocks that perform complex sensorimotor functions that ensure the further development of the child.
During the second year of a child’s life, general motor activity becomes more active and differentiated. Articulatory motility is gradually improving, determining the features of pronunciation of speech sounds. The passive and active vocabulary is increasing, phrases and short speech chains appear. With the formation of a certain activity, its own functional system is formed, in which various levels of the nervous system are involved. During this period, cognitive activity, gameplay, interest in communication, colored by an emotional reaction, are activated. By the end of the second year of life, the child pronounces 200-300 words, the structure of which has not yet been strengthened (there may be reductions in syllable elements, simplifications, etc.).
In the third year of life, general motility is significantly activated, articulation that ensures clarity of sound pronunciation is improved, a sense of language appears, interest in listening to tales, memorizing and transferring them to game activity, the ability to imitate, intonational repetition unfolds. Sensory activity (visual, auditory, tactile-kinesthetic) provides a new level of formation of cognitive activity. Speech becomes more coherent, the phrase is expanded, the number of words reaches 1000 (by the end of the third year of life). Three years of age in physiology, anatomy, neuropathology is a critical period, since complex tertiary fields of the frontal region of the cortex are included, providing connections with all parts of the brain. At the same time, the prefrontal region ensures the transition of all human activities to a new mental level, when thinking becomes verbal, and speech becomes meaningful. The lexical and grammatical structures are strengthened, a program of expression, behavior, and emotional-volitional sphere is being formed.
The system of the prefrontal and parieto-occipital region of the cortex is the youngest in phylogenesis and ontogenesis. It ripens later than others and creates a new level of cognitive, motor and speech activity.
After three years, the appearance and physical condition of the child changes dramatically. Children become stronger, independent, motor-agile, there is a need for communication in the game process, the stock of general concepts increases. A prepared child moves from a nursery to a kindergarten, in which the requirements for his psychomotor functions are much higher. In the process of game activity, the circle of knowledge expands, the process of cognition is formed (listening and memorizing tales, poems and other literature). The emotional attitude to the environment is determined. Of great importance are the attention and perseverance with which the child performs certain tasks.
By this time, fine motor skills are significantly activated in children: they sculpt well, assemble mosaics, draw, and hold a pencil and pen correctly. They are quite well oriented in space and in the body diagram, which is reflected in the drawings and game processes.
By this age, a functional speech system should be formed (sound pronunciation, phonemic hearing, vocabulary and grammar, voluntary speech activity) in the form of oral speech and preparation for writing (reading and writing) should begin. A new difficult stage in the development of the child is preparation for studying at school.
Thus, as a result of a series of successive inclusions, accumulation, and jumps with the leading participation of higher frontal structures, a multilevel functional system is formed.
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