Sensitivity is one of the phylogenetically ancient functions of the nervous system. In the process of evolution, it arose as a means of adequate contact of the organism with the environment, as the basis of the feedback mechanism. The sense organs provide the perception of irritations, the conduct and processing of information that comes from the environment, all organs and tissues of the body. Signal processing is carried out using various nerve formations. Part of the information that is perceived by our senses is transformed into sensation, awareness of the really existing external world. Another part of nerve impulses, which for the most part come from normally functioning internal organs, although perceived by the brain, are not recognized by a person by a certain time. All perceptions of the influence of the environment and internal environment in physiology are usually designated by the term "reception".
Sensitivity is part of the broader concept of reception; sensitivity refers only to that part of the reception that is perceived by the receptors and recognized by the cortex.
All nerve elements that provide the perception, conduct and processing of information belong to sensory systems (from Latin sensus - sensation) or to the system of analyzers according to I.P. Pavlov. They perceive and process stimuli of different modality.
An analyzer is a functional system that includes receptors, afferent pathways and the corresponding area of the cerebral cortex.
The cortical end of the analyzer is the primary projection zones of the cortex, for which the somatotopic principle of structure is characteristic. The analyzer provides the perception, conduction and processing of the same type of nerve impulses.
Analyzers are divided into two subgroups: external, or exteroceptive, and internal, or interoceptive.
External analyzers analyze information about the state and changes that occur in the environment. These include visual, auditory, olfactory, gustatory, and an analyzer of superficial types of sensitivity. Internal analyzers process information about changes in the internal environment of the body, for example, the state of the cardiovascular system, alimentary canal and other organs. Internal analyzers include a motor analyzer, thanks to which the brain constantly perceives signals about the state of the musculo-articular apparatus. It plays an important role in the mechanisms of movement regulation.
Receptors are specialized peripheral sensory formations that can perceive any changes inside the body, as well as on the outer surface of the body, and transmit these irritations in the form of nerve impulses. In other words, receptors are capable of converting one form of energy into another without twisting the information content. Stimuli of the environment or internal environment, being transformed into a nervous process, enter the brain in the form of nerve impulses.
According to their location, as well as depending on the functional characteristics, receptors are subdivided into extero-, proprio- and interoreceptors.
Exteroreceptors are divided into contact receptors, which perceive irritations during direct contact with them (pain, temperature, tactile, etc.), and distant receptors, which perceive irritations from sources located at a distance (sound, light).
Proprioceptors perceive irritation that occurs in deep tissues (muscles, periosteum, tendons, ligaments, articular surfaces) and carry information about muscle tone, position of the body and its parts in space, and the volume of voluntary movements. This is what determined the name "muscular-articular feeling", or "sensation of position and movement (kinesthetic sensation)." The labyrinth receptors, which provide the body with information regarding the position and movements of the head, also belong to proprioceptors.
Interoreceptors perceive a variety of irritations from internal organs and blood vessels. Their main role is to ensure the flow of information into the central nervous system about changes in the internal state of the body. Most interoreceptors are polymodal. They respond to chemical (chemoreceptors) and mechanical stimuli (baroreceptors), temperature changes (thermoreceptors), pain (nocireceptors) and are related to the autonomic (autonomic) nervous system.
Each type of receptor reacts only to a specific type of irritation. Due to this specialization of receptors, the primary analysis of external stimuli is carried out at the level of peripheral endings of afferent nerve fibers.
The largest number of receptors are localized in the skin. Distinguish between mechanoreceptors (react to touch, pressure), thermoreceptors (perceive cold, heat) and nocireceptors (perceive pain).
The cutaneous receptors include free nerve endings of sensory nerves and encapsulated terminal formations. The simplest structure is the free nerve endings of the dendrites of sensory neurons. They are located between epidermal cells and perceive painful irritations. The tactile bodies of Merkel and Meissner respond to touch. Pressure and vibration are perceived by the Vater-Pacini lamellar bodies. Krause's flasks are Cold receptors, and Ruffini's bodies are heat receptors.
Receptors are also located in deeper tissues: muscles, tendons, joints. The most important muscle receptor is the neuromuscular spindle. They respond to passive muscle stretching and are responsible for the stretch reflex, or myotatic reflex. The tendons contain Golgi receptors, which also respond to stretching, but their sensitivity threshold is higher. Special receptors in the body that perceive pleasure are beneficial receptors.
The receptors of the visual and auditory analyzers, which are concentrated in the retina of the eye and in the inner ear, have the most complex structure. The complex morphological structure of these receptors affects their function: for example, retinal ganglion cells respond to electromagnetic radiation of a certain frequency spectrum, auditory - to mechanical vibrations of the air environment. However, this specificity is relative. The sensation of light occurs not only when a quantum of electromagnetic radiation enters the eye, but also in the case of mechanical irritation of the eye.
Thus, at the receptor level, primary information processing is carried out, which consists in recognizing the modality of the stimulus. This processing ends with the formation of nerve impulses, which with a certain frequency enter the higher parts of the central nervous system.
The impulses that arise in the receptor apparatus are carried to the nerve centers by sensitive fibers at different speeds. The German anatomist Gasser (J. Gasseri, XVIII century) divided sensitive fibers, depending on the structural and functional features, into three groups: covered with a thick layer of myelin, thin and myelin-free. The speed of the nerve impulse conduction by these three groups of fibers is not the same. Fibers with a thick myelin sheath, or fibers of group A, conduct an impulse at a speed of 40-60 m in 1 s; fibers with a thin myelin sheath, or fibers of group B, at a speed of 10-15 m in 1 s; myelin-free, or C-fibers, at a speed of 0.5-1.5 m per 1 s.
Fibers of group A with a high speed of impulse conduction are conductors of tactile and deep sensitivity.
Fibers of group B with an average speed of impulse conduction are conductors of localized pain and tactile sensitivity.
Fibers of group C, which slowly conduct impulses, are conductors of pain sensitivity, mainly diffuse, non-localized.
Sensitivity classification. Distinguish between general (simple) and complex sensitivity. General sensitivity, taking into account the localization of receptors, is divided into exteroceptive, or superficial (skin and mucous membranes), proprioceptive, or deep (muscles, connections, joints), and interoceptive (internal organs).
Exteroceptive, or superficial, sensitivity includes pain, temperature (heat and cold) and tactile. Proprioceptive sensitivity includes the sensation of passive and active movements (musculo-articular sensation), vibration sensation, a feeling of pressure and mass, kinesthetic sensation - determining the direction of movement of the skin fold. General, or simple, sensitivity is directly related to the function of individual receptors, analyzers.
Complex types of sensitivity are due to the combined activity of different types of receptors and cortical parts of the analyzers: a sense of the localization of the injection, with the help of which the place of the inflicted irritation is determined; stereognosis - the ability to recognize objects by feeling them; two-dimensional spatial sensation - the patient recognizes, provided his eyes are closed, which figure, number or letter is written on the skin; discrimination - the ability to perceive separately two simultaneously applied stimuli at close range. Complex types of sensitivity do not have separate analyzers, they are carried out by general types of sensitivity.
Interoceptive sensitivity is called the sensitivity that occurs in case of irritation of internal organs, walls of blood vessels. As already noted, under normal conditions, impulses from internal organs are practically not recognized. During irritation of interoreceptors, pain of varying intensity and discomfort occur.
In the process of evolution, sensory systems undergo improvement, which predetermines the emergence of a special sensation: sight, hearing, smell, taste, touch.
In the clinic, another classification has become widespread, which is based on biogenetic data. In accordance with these ideas and, distinguish between protopathic and epicritical sensitivity.
Protopathic sensitivity is phylogenetically more ancient. It serves to perceive and conduct strong nociceptive stimuli that can cause tissue destruction or threaten the life of the body. These irritations are mostly non-localized and cause a general generalized reaction. The thalamus is the center of protopathic sensitivity. Therefore, this system also has the name of the vital, nociceptive, thalamic, unresolved feeling.
Epicritical sensitivity is a phylogenetically new species of it. It provides a subtle quantitative and qualitative differentiation of irritations, their localization, which allows the body to accurately navigate in the environment, to adequately respond to irritation. Epicritical sensitivity is due to sensations that arise in the cerebral cortex. It is in it that subjective sensations of pain are formed. Therefore, this system of sensitivity is called epicritic, cortical, gnostic, it is able to alleviate the sensation of pain.
Muscles have nerve endings of two kinds: centrifugal, or motor, along which nerve impulses descend from the brain into the muscles, and centripetal, or sensitive, which send signals to the brain about the movement performed by the muscles. These sensitive nerve endings in muscles and are receptors for muscle sensations... It is believed that from 1/3 to 1/2 of all fibers in the nerve connecting the spinal cord to the muscle are sensitive, or centripetal. Considering the enormous number of all muscles in a person, one can imagine a huge number of muscle receptors. These receptors are found not only in muscle tissue, but also in tendons, capsules of muscles and tendons, etc. Therefore, the receptors of the entire locomotor apparatus are called muscular-articular. These receptors are diverse in their structure. In the muscle tissue there are the so-called Ruffini endings, in the tendons - the Golgi apparatus, in the capsules of the muscles and tendons - the Golgi body - Mazzoni, etc.
Musculo-articular receptors are divided into groups of fusiform and tendon, as well as connective. Fusiform endings are found among striated muscles. Each such "spindle" has its own shell, its own blood and lymphatic vessels. Several nerve fibers branch out within this "spindle", forming complex spirals, rings, and flower-like branches. Human muscles are predominantly characterized by these flowering branchings.
The size of the fusiform endings is different in different muscles.
8 Ibid., Pp. 433-434.
20 B.G. Ananiev
muscles (from 0.05 to 13.0 mm). These endings are most numerous in the limbs, especially in their extreme parts "(fingers, hands and feet). Muscles contain muscle receptors of another structure (naked nerve endings scattered between muscle and tendon fibers, pain receptors in connective tissue formations). -x there are special receptors - spindle-shaped formations (up to 1.5 mm in length), most often located at the junction of muscles and tendons. Muscle-articular receptors arise during excitation and muscle contractions. Their "stimulus is therefore the movement of one or another part of the body. ...
When moving any part of the body, there is movement in the joint: movement of the articular surfaces relative to each other, change in the tension of the ligaments, tendons, passive muscle tension. During movements, the general tone, or muscle tension, changes, "which is a state of incomplete contraction or muscle tension, not accompanied by fatigue. Therefore, a change in the tone of certain muscles and associated tendons is a specific irritant of muscle-articular sensations. Irritation of muscle-articular receptors is tonic. changes are transmitted along sensory (or afferent) pathways to the spinal cord, and the final station for receiving these tonic impulses is the cerebral cortex.
Musculo-articular receptors are stimulated by tonic changes, predominantly by a mechanical method. Their work is closest to the work of skin-mechanical receptors, with the difference that the mechanical properties of muscles and joints (especially the elastic properties of muscle tissue) are the irritant of the latter.
With certain tonic changes, the skin changes. Consequently, the general condition of the tone of the muscular apparatus of this part of the body is also reflected in the general condition of the skin-mechanical receptors.
Both this fact and the close proximity of the pathways of the tactile and musculo-articular sensory nerves indicate the commonality of tactile and musculo-articular receptors in their sources and nature.
Conductors (musculo-articular sensory nerves)
To the intervertebral nodes, the pathways of the cutaneous and musculo-articular sensory nerves go together without dividing. The fibers of the muscle-articular sensory nerve proper
BOBs originate in the cells of the intervertebral nodes. The central cells of these nodes are directed to the spinal cord into the dorsal roots. At the point of entry into the spinal cord, these fibers are divided into short descending and long ascending branches. The latter pass through the entire spinal cord to the oblong, where they form two bundles, from them there are successive paths to the pons, to the midbrain, to the optic tubercle, and then to a certain area of the cerebral cortex. Part of the pathways are directed to the cerebellum, which is important for the automatic regulation of motor
The conduction of muscular-articular stimuli along these pathways is characterized by certain currents of action, which can be diverted by special electrophysiological devices. These currents of action are vibrations of a two-phase and one-phase nature that occur when a muscle is stretched. Between individual impulses of the action currents, the interval is 0.03 sec. With an increase in the load on the muscle fiber, the pulse frequency increases. Long-term constant loading of the fiber leads to a slow decrease in the vibration frequency. Based on this *, it is believed that muscle-articular receptors adapt less than other receptors, due to constant changes in muscle tone or other muscles associated with it.
The action currents, as well as the entire work of receptors and pathways, are affected by the interaction of muscles, especially their mutual inhibition during the work of antagonist muscles (for example, flexors and extensors). Excitation of the flexor centers is accompanied by inhibition of the extensor centers and vice versa, and this form of interaction occurs with the direct participation of impulses from muscular-articular reflexes. Musculo-articular receptors and pathways determine the creation and maintenance of muscle tone, without which any movement is unthinkable. But these sensitive formations are directly involved in the implementation and coordination of all motor acts. This participation is associated with special reflexes for muscle stretching (myotatic reflex), tendon reflexes (for example, knee reflex), rhythmic reflex movements (chain reflex), etc. The degree of complexity and arbitrariness of movements excited by the work of muscle-articular receptors depends on which nerve centers regulate these movements. Voluntary movements, dismembered and perfect, are the result of higher analysis and synthesis of movements performed by the cerebral cortical end of the motor analyzer.
Cortical ends of the human motor analyzer
The problem of cortical conditioning of muscular-articular sensations was first posed and experimentally solved by Pavlov and his collaborators. Before Pavlov's work, anatomists and physiologists believed that in the cerebral cortex there is a special motor (motor) region in the front of the cerebral hemispheres, which regulates all human movements. At the same time, it was argued that the motor area regulates the movements themselves, but has nothing to do with muscular-articular sensations. So, for example, Brodman divided the cerebral cortex into different fields, in which the localization of movements (in the external and partly the anterior central gyrus) and the localization of muscular-articular sensations (in the posterior central gyrus, together with skin sensations) are sharply separated.
As evidence that the area of the anterior central gyrus is the cortical center of movements, it was usually cited that when this area is affected, a person experiences paralysis or paresis (weakening of strength and range of motion).
Pavlov, by precise experiments, proved the inconsistency of this view. Already forty years ago, Pavlov came to a new understanding of the function of the motor area of the cerebral cortex as an area of analysis and synthesis of movements.
The exact experiments of Krasnogorsky in Pavlov's laboratory proved the discrepancy between the areas of the skin-mechanical and motor analyzers, and it was established that the area of the motor analyzer is what physiologists considered the motor area of the cerebral cortex.
This is the area of analysis of the body's skeletal-motor energy, just as its other areas are analyzers of various types of external energy acting on the body.
Higher analysis and synthesis of movements of body parts is carried out in the process of formation and differentiation of conditioned motor reflexes. Human behavior consists precisely of conditioned motor reflexes, not unconditioned motor reflexes, which exist "in their pure form" only in the first months of a child's life. All human movements, from gait to articulatory movements of the speech-motor apparatus, are movements, individually
3 Neurological studies of Bekhterev and his co-workers were also extremely important for substantiating the cortical nature of kinesthesia.
acquired, educated and learned. After they have been developed, human movements become automated, but they are not automatic * in the sense of the spinal machine-like nature of innate reflexes. Some conditioned motor reflexes are developed on the basis of others (for example, the writing skill based on the child's separate finger operation during play or household operations - holding a spoon, etc.). Only in the very primary basis are these conditioned motor reflexes developed on. the basis of unconditioned motor reflexes (for example, holding an object). The combination of the influence of various external properties of the object with the motor reflex of the child himself forms a complex motor act.
The development of conditioned motor reflexes is carried out by combining any external stimulus (light, sound, etc.) with a motor reflex (orienting, grasping, defensive, etc.). This position was thoroughly proved by Bekhterev and his collaborators. But the very fact of the formation of such complex conditioned motor systems does not yet explain the mechanism of the motor analyzer itself. It was important to prove that a conditioned-secretory reflex to musculo-articular signals can be developed. This directly proves that musculo-articular signals enter the cortex, are analyzed by the cerebral cortex and enter into a temporary connection with any other reaction of the body. Then the musculo-articular impulses, like any impulses from the receptors of sight, hearing, etc., are made by conditioned stimuli. In 1911 Pavlov and Krasnogorskiy first proved and discovered such a pattern. They created a stimulus from flexion of the metatarsophalangeal joint, reinforcing it with a food stimulus. Flexion of the other (ankle) joint was not supported by food. In these experiments, an exact answer was obtained to the question posed, since the conditioned salivary reflex was developed for flexion of the metatarsophalangeal joint, and differentiation was obtained for flexion of the ankle joint, i.e., an inhibitory reaction.
This proved for the first time that, firstly, the cerebral cortex differentiates (performs higher analysis) musculo-articular signals and, secondly, that the musculo-articular signals analyzed by the cortex can enter into any temporal connection with any external reaction (not only motor, but also secretory). In other words, the cerebral cortex analyzes and synthesizes endless signals from
working muscles and tendons, that is, from the skeletal-motor energy of the body.
As for the motor apparatus as such, it is only an executive device that carries out the "orders" of the cerebral cortex, and different impulses of the cortex can be performed by the same device (for example, in the act of breathing, eating or eating, coughing, etc.) part of the same muscles, tendons and bones that are part of the human speech motor apparatus, that is, in the acts of speech movements). And, conversely, the same impulses from the cortex can be performed by different motor devices (for example, a person can write not only with his right, but also with his left hand, in case of damage to the arms - with a foot or mouth, etc.), the same the same movements can be performed by different muscle groups, etc.
The cerebral end of the motor analyzer, like any analyzer, consists of a nucleus and scattered elements that extend far beyond the motor region. This explains the extreme plasticity, substitution of the affected functions by others, developed on the basis of conditioned reflexes. The possibility of restoring the affected complex actions of a person with damage to the motor area of the cerebral hemispheres was proved during the Great Patriotic War in our Soviet evacuation hospitals. Particularly great work in this regard was done by the physiologist Asratyan and the psychologist Luria. The experience of such recovery proves that motor paralysis is indeed a paralysis of the movement analyzer. The restoration of the analysis of movement led to one or another restoration of the lost movements themselves. This experience proves, on the other hand, that when the nucleus of the motor analyzer is damaged in the anterior central gyrus of the cerebral cortex, the analysis functions are taken over by the scattered elements of this analyzer.
The anatomy of the brain and the clinic of cerebral diseases consider the area of the anterior central gyrus, as well as the adjacent zones, as the center of voluntary or conscious movements. In one of the fields of this area there are giant pyramidal Betz cells (named after the Russian anatomist Betz who discovered them), from which the so-called pyramidal path begins. The fact is that axons (axial spinal processes giving rise to a nerve fiber) depart from Betz cells, which reach the spinal cord through the forebrain and brain stem. On the way through the medulla oblongata, they form a cross, that is, they go from the right hemisphere to the left half
body, from the left hemisphere to the right. The intersection of the pyramidal bundles is the border between the medulla oblongata and the spinal cord. But this intersection is not complete, therefore there are two pyramidal bundles in the spinal cord - a straight and a cross. The fibers of the pyramidal path, passing along the spinal cord, end in the anterior horns of the spinal cord, transmitting impulses to the cells located here, and through them
axons - "- muscles.
This pyramidal path from the anterior central gyrus of the cerebral cortex to the spinal cord, and through it to the muscles, is a motor path, or centrifugal. However, the fact that in the nerve connecting the spinal cord and muscles there are from 113 to 112 sensory fibers, as well as the fact that in general the motor region is understood by Pavlov as the region of the motor analyzer, suggests that this path is a pathway for conducting sensory impulses in cerebral cortex. This, obviously, is associated with the extreme dissection of the cortical regulation of the movements of individual parts of the human body. Such dismemberment would not have been possible without a fractional analysis of movements from the side of the human cerebral cortex. This must be emphasized because every elementary voluntary movement of a person is individually acquired, conditioned reflex in its origin. Therefore, the motor center in the cerebral cortex is formed during life, and the division of functions in this area is entirely a product of analysis and synthesis in the work of the cerebral cortex. This must be emphasized in order to understand the dismembered differentiated nature of the human motor region.
It is characteristic that the general arrangement of special centers of various movements is exactly the same as in the area of the posterior central gyrus (the core of the skin-mechanical analyzer and the “muscle sense” itself). "The center of the big toe is located above all, then the center of the foot, lower leg, thigh , abdomen, chest, shoulder blade, shoulder, forearm, hand, little finger, ring finger, middle, index, thumb, then neck, forehead, upper face, lower face, tongue, chewing muscles, pharynx,
The most differentiated is the cortical regulation of finger movements. The motor region (motor) is closely related to the most anterior parts of the frontal lobes (premotor region), which are associated with the regulation of speech-motor functions in general, as well as complex actions of thought processes.
The localization of these dismembered motor functions is relative, the substitution of functions in this area is very diverse, which indicates the role of the scattered elements of each of these parts of the human motor analyzer. Like any analyzer, the motor analyzer is two-pronged. The duality of the human motor analyzer is especially difficult, since the functional inequality of the motor apparatus of both sides of the human body is extremely large.
It is known that right-handedness and left-handedness are the capital "i-th fact of human motor development. This functional separation of the right and left sides is only" in a person, it is associated with upright posture - the vertical position of the body, with the division of functions between both hands (of which one is the right one - performs the main working operation, the other - the left one - auxiliary). This i functional inequality was interpreted by some scientists incorrectly, believing that each of the hands is regulated by only one hemisphere (the right hand - by the left, the left hand - by the right), given the cross nature of the paths of the pyramidal | path. Such a statement seems to be incorrect, since this cross is partial, incomplete, and the work of each hand is a product of the joint activity of both hemispheres. Recording of bioelectric currents in the motor area of the right and left hemispheres during voluntary movements of the right and left hands (Idelson from our laboratory) showed that with simple movements of the right hand active currents of action appear in the left hemisphere, / but with the complication of voluntary movements currents appear actions in the eponymous (right) hemisphere.
The same fact is evidenced by many cases of restoration of movements of the right hand with damage to the motor area of its centers in the left hemisphere: substitution of functions is possible because the scattered elements of the motor analyzer of the left hand are also in the left hemisphere, and the right hand is in the right hemisphere.
The same should be said about the motor center of speech (Broca's center) in the posterior third of the frontal gyrus of the left hemisphere. This "center" is the nucleus of the motor analyzer of speech movements, the scattered elements of which are located in the right hemisphere in right-handers (in left-handers, this center is in the right hemisphere).
As in other analyzers, each hemisphere works relatively independently, being a special center of the opposite side of the motor apparatus of the body. But no less, and more importantly, they work together
locally, in a coordinated manner, and the pairing of work depends on the need for such work, dictated by the nature of human activity. Sechenov showed that this joint activity of the hands (and, consequently, of both hemispheres) is a general condition for the performance of each individual hand. He established in 1902 that the restoration of the working capacity of the right hand (after the expenditure of great muscular energy) occurred not when the whole body of a person was resting, but when the left hand was working during the break. Sechenov emphasized that this position refers to the right-handed person, for whom working with the left hand turned out to be a condition for restoring the working capacity of the right hand, since there was "energization of the nerve centers." It is clear that the muscular-articular impulses of the left hand, which arose during its operation, "were transmitted to the centers of the right hand, that is, there was an irradiation of excitation in both hemispheres of the brain.
Studies by Bychkov, Idelson, Semagin in our laboratory have shown that during muscular work of one of the hands, currents of action take place in both hemispheres. From the experiments of Semagin it follows that currents of action also arise in the deltoid muscle of the left hand when the right hand is working. All this speaks of the spread of excitation in both digital regions of the brain.
But it is important to note that the conjugate currents of the action of the hand that is not currently working or of its cortical center are inhibited (in comparison with the currents of the action of the working hand).
As in all other analyzers, with the interaction of both hemispheres, a mutual induction of nervous processes occurs. The "leading hand" is the result of negative induction, in which excitation of the nucleus of the motor analyzer of the left hemisphere causes inhibition of the nucleus of the right side of the motor analyzer, which regulates the work of the left hand. But as in all analyzers, the leading side is not absolute and unchanging, confined to only one of the hemispheres. The right-hander is actually also left-handed in a number of operations (for example, lifting and holding weights, holding objects, etc.) when negative induction extends from the right hemisphere to the left.
Further, it should be noted that it is the inhibition of one of the hemispheres that is the condition for the creation of a focus of excitation in the other (i.e., positive induction). Therefore, the work of one side of the motor analyzer is impossible without interaction with the opposite side of this analyzer. With hemiplegia (unilateral motor lesions
on the entire side of the body) there is not only a loss of motor functions of the affected side, but also a sharp limitation of the volume, speed and complexity of movements of the intact side of the body.
In cases of hemiplegia, there is a disorder in distinguishing the direction of movements, in the exact coordination of the hand and the object, that is, in spatial relationships. Such patients re-orient themselves in space, and they go a long way to restore complex spatial functions of the hand. It can be assumed that the duality of the motor analyzer, expressed in the paired work of both hemispheres, the mutual induction of the processes arising in them, is of particular importance in the analysis of the spatial components of the movements of a person themselves and his orientation in the space of the external world.
Basic properties and basic forms of muscular-articular sensations of a person
Muscular-articular sensations of a person are infinitely diverse. This diversity reflects the change in all aspects of human activity in all the various forms of this activity. Nevertheless, it is possible to single out the general and basic properties of these sensations, despite the fact that far from each of these properties is realized by a person separately at every moment of his activity. In contrast to the clearly recognized separation of sensations from irritations of the external sense organs, these muscular-articular sensations are often perceived by a person as one, in the form of the so-called "dark feeling (Sechenov). However, during exercise, with special types of activity (physical labor, sports, physical culture) there is a dismembered awareness of these sensations.The general and basic properties of these sensations are, as shown by Kekcheev, the following.
1. Reflection of the position of parts of the body (ie, the position of one part of the body relative to another). These general sensations of the position of body parts are essential for the formation of a body diagram, without which a person cannot correctly and arbitrarily use its various parts in certain actions.
2. Reflection - analysis of passive movements, especially with static muscle tension. These sensations are characterized by certain spatial and temporal moments. The spatial ones include: a) recognition of distances or the length of passive movement, b) distance
cognition of the direction of passive movement (top, bottom, right and left side of movement). Time moments include: a) analysis of movement activity and b) analysis of movement speed. A common property of all passive movements is also the analysis of the total expenditure of neuromuscular energy, that is, the state of fatigue.
3. Analysis and synthesis of active movements (with dynamic human work). These sensations are more complex, characterized by a combination of a number of separate reflections of the spatio-temporal features of human actions. The spatial moments of these sensations are:
a) distance analysis, b) direction analysis. Time components are: a) analysis of duration and b) analysis of movement speeds.
With the active movement of the hand, operating with an object and a tool of labor, the most important properties of muscular-articular sensations arise, which include: a) reflection of the hardness and impenetrability of an external object with which one or another movement of the human hand is performed,
b) reflection of the elasticity of this object, c) reflection of the weight of the object, that is, the feeling of heaviness. Through the assessment of muscular effort, sensations signal the mechanical properties of external bodies, which a person actively operates with in his activities. These sensations arise in the process of reflecting the resistance of external bodies to the influence of a person on them. Thus, muscular-articular sensations reflect not only the state of the internal elements of a person's activity, but also the objective properties of objects and tools of this activity, that is, they are a form of reflection of objective reality.
Due to the spatio-temporal components of musculo-articular sensations, these sensations are, according to Sechenov, a fractional analyzer of the time and space of the external world.
The connection of muscular-articular sensations with all other external sensations provides a sensory basis for a person's reflection of space and time, external, material reality.
These general properties of all muscular-articular sensations appear in a peculiar form and combinations in the following basic forms of muscular-articular sensitivity of a person:
1. General musculo-articular sensitivity of a person (sensation of the position of body parts relative to one another).
2. Muscular-articular sensitivity of the human musculoskeletal system.
3. Muscular-articular sensitivity of the human working apparatus (both hands).
4. Muscular-articular sensitivity of the human speech-motor apparatus.
All these forms of sensitivity are interconnected with each other, but at the same time separate and independent. Some of them interact according to the principles of mutual induction, exciting and inhibiting each other, as will be shown below.
Distinctive muscle-joint sensitivity
human
The minimum change in muscle tone in the process of a particular movement determines the absolute threshold of muscular-articular sensations. At present, science has not yet developed precise methods for determining this type of absolute sensitivity, has not established the values that characterize the absolute thresholds of sensations in various motor apparatus. The reason for this is not only the extreme difficulty of dosing tonic changes, the isolation between the study of the mechanism of the movements themselves and their sensations, which has not yet been overcome in science. Indirect evidence of shifts in the absolute musculo-articular? sensitivity can be obtained from well-studied data on the difference thresholds of muscular-articular sensations.
The most studied is the discriminatory sensitivity in relation to the sensation of heaviness, that is, the discrimination of the weight of an object (one of the types of sensations of active movements). Is it usually used for this purpose to compare human differences? between loads, the weight of which gradually increased with a constant increase to the initial weight of the load lifted by chelovekol. Found to be minimal sense of difference? between the weights is equal to "/ 40 of the initial gravity. This value * is constant only within certain limits, since for large weights the magnitude of the increase increases (up to" / 2o), and the sensitivity decreases due to physical fatigue.
The difference threshold of the sensations of gravity is measured in grams of the weight of the added loads. Difference threshold of sensation? the size of objects and diameters of length, and in connection with this, the direction and length of the felt movements are measured in millimeters (the increase in the size of objects relative to the original size). Kekcheev found that the value of the difference threshold for distinguishing the thickness of the feeling
of the objects being felt is "/ 25, for distinguishing the diameter of the objects being touched -" / g, -, and for feeling the length of objects - "As. be expressed in degrees.
The difference threshold of sensations of the size of the object expressed in a similar way is equal to 0.27-0.48 ° for the part of the hand that is most sensitive in the musculo-articular relation (the articulation between the metacarpal bones and phalanges of the fingers).
Distinctive musculo-articular sensitivity changes in the course of individual development. In young children, it is still very rough and limited to the circle of habitual everyday and play movements. A sharp increase in discriminatory sensitivity takes place at school age, especially under the influence of drawing and writing skills, and especially physical education. From 8 to 18 years old, differential sensitivity increases 1 "/ 2-2 times. Qualified physical labor and sports activity have a sensitizing effect on muscular-articular sensations. The boundaries of differential sensitivity are constantly expanding in the process of accumulating experience of professional labor and sports movements. a role in their development is played by the rationalization of movements by the foremost workers in the conditions of the socialist organization of labor processes.
The relationship between spatial and temporal moments of muscular-articular sensations
Acceleration or deceleration of movement, that is, their duration and speed, are reflected in the accuracy of recognition of spatial signs of movement (its length and direction). Slowly performed movements give the greatest number of errors in recognizing not only the duration of movements (overestimation of duration), but also space. Slow movements are more difficult to analyze their extent and direction. However, at all rates, the spatial errors are less than the temporal ones.
If we ignore the speed of movements and establish the role of the size of hand movements (its range) in the accuracy of recognition of spatial and temporal moments of movements, it turns out, according to Kekcheev, that with an increase in the range of movements, the accuracy of recognition of the length and direction of movements increases, that is, the sensitivity in this respect to increase
swings. On the contrary, with an increase in the range of movements, the accuracy of recognition of temporal moments of movement (its duration and speed) decreases. Consequently, in muscular-articular sensations, we have a fractional and special analysis of the spatio-temporal signs of the objectified movements performed, that is, those operating with certain things of the external world.
The spatial nature of movements is especially hidden when a person reproduces active movements. In a sighted person, these movements are performed under the control of vision, in conditions of a strong connection, and visual-motor coordination. The hand of a sighted person, when acting with his eyes closed, is more tied in relation to the radius of action than that of a person born blind. At a distance of 15 to 35 cm from the midpoint of the body, the hand of a sighted person gives the most accurate signals about the place, direction and range of movements. Outside this zone, increasing difficulties begin, great for distances over 40-50 cm from the body. Movements forward and J to the left (for the right hand) are especially difficult for analysis. These data Kekcheeva was confirmed in our laboratory by Pozdnova, who showed that there are differences between the right and left hands of the same person in this regard.
This fact indicates that there is a dependence of the analysis of movements on the general muscular-articular sensations of the position of body parts. The connection between muscle-and joint sensations and vision is even greater. At the beginning of learning new movements in humans, they are performed under the control of vision | but with the formation of motor skills, control over movement is transferred to muscular-articular sensations, on the accuracy of which the accuracy of habitual movements depends. Therefore, the education of muscular-articular sensations is a general and most important condition for increasing the speed and accuracy of any human movements, that is, a condition for increasing the productivity of human movements.
Musculo-articular sensitivity of the human musculoskeletal system
From observations of the development of a child in the period of 8 months - 1 year 2 months of life, it is known what a complex and difficult process is the formation or formation of walking. This is preceded by the child's transitions from a recumbent position to a sitting position (with the formation of a constant tone of the muscles of the head, neck, back, arms), to standing when
Support of an adult or support, crawling, then uncoordinated walking (simultaneously with two legs tilted forward, which causes the body to fall), etc. For several months adults specially train the child on the act of walking, forming the necessary act cortical mechanisms. But even after the child began to walk independently, his movements are unstable, weak, uncoordinated for a long time; because of this, the child is extremely tired as a result of the high expenditure of muscle energy. Mastering the act of walking is a complex and lengthy process of formation of an integral system of activity of the human musculoskeletal system. With the formation of this system, the entire behavior of the child changes: earlier only the outlined functional inequality of the right and left hands is sharply enhanced, the objective activity of the hands develops at a rapid pace. Thanks to the practical movement in space, the child comes into contact with an infinitely large range of things and their properties than it was in the immobile, recumbent position of the baby, etc. Touch and vision receive a sharp impetus in development together with the child's independent walking. auditory orientation in space, etc.
Under the influence of walking, the process of maturation of the speech motor apparatus is also accelerated, the prerequisites of which are the gradual development of the voice and articulation of the child (voice modulation, crying and screaming, humming and babbling). Obviously, a sharp increase in impulses from the movement of the whole body when walking is a condition that contributes to the formation of the most subtle and differentiated system of speech movements.
Initially, each element of walking is trained, and this training is carried out due to the dismemberment of a separate movement into all its component parts. In the process of formation and strengthening of motor skills, a complex of separate movements is synthesized, generalized. This is how, for example, a "single step" arises, which is called the distance between any phase of movement of the right leg, or, conversely, a single step is the result of the existing coordination of movements of both legs, that is, the synthesis of these movements. But the creation of such a synthesis was preceded by a higher cortical
analysis of the separate movements of the ankle and hip joints and all other parts of the body involved in walking.
A "single step" is a sensual measure of space through which a person moves at a certain speed. The moment of step acceleration changes the ratio of the phases of movement of both legs, the difference between them, causes an urgent reaction by means of muscular-articular sensations, from the side of the cerebral cortex ensuring the balance of the body and maintaining the center of gravity as a necessary condition for the normal position of the body during movement in space. It is wrong to think that only the legs carry out the act of walking. The whole body takes part in this act, and the coordination of movements of individual parts of the body is conditioned reflex from beginning to end.
During walking, interconnected vertical movements of the head, center of gravity of the body, shoulder and hip joints take place. These changes are associated with the moments of inertia, the rotating moment of the carrying leg relative to the hip and knee joints of the supporting leg. The movements of the ankle joint of the portable (at the moment) and supporting (also at the moment) legs are, as it were, the resulting value relative to the entire set of body movements.
This generalized nature of the movements in walking determines the position that in walking there is no such sharp permanent functional inequality between both limbs that exists between the hands. However, in the process of walking, there is a variable functional inequality in the "double step", which is called the combination of periods of support and leg transfer. The duration of leg support and leg transfer (per 1 m of path) is 0.37 seconds for support and 0.20-0.22 seconds for leg transfer during normal walking. The alternation for each leg of the periods of support and transfer eliminates the constancy of functional inequality, but creates at each separate moment a difference in signals from the moving legs, of which at a particular moment one is in static (support), the other in dynamic tension.
When walking, there are conjugate movements of the hands. The hand of one side moves to the opposite one ;! the direction of movement of the leg on the same side (for example, the right arm moves backward when the right leg moves forward). The elbow angle develops more and bends less during normal walking due to the change in successive positions of the shoulder and forearm. When walking elbow
the angle is closer to a straight line. During normal walking, the angle of the knee joint does not exceed 80 °. Vertical movements of the shoulder and hip joints occur simultaneously and in the same direction.
The result of all these changes is the formation of angles of the moving ankle joint.
The ankle angle has the largest value before the start of the leg transfer, and the smallest value at the end of a single support. For normal walking, the maximum value of the ankle joint is 128-132 °. and the minimum is 90-103 °. Each act of walking, thus, is carried out by a system of movements coordinated in time and space of all parts of the body, which determine the ratio of dynamic and static stress in the human musculoskeletal system. The basis of such coordination is the urgent systemic response of the cortex to a multitude of signals from all parts of the motor apparatus. Differentiation of these signals forms the basis of the discriminatory sensitivity of the musculoskeletal system.
The exceptional sensitization of this form of sensitivity is evidenced by the facts of the high development of the technique of sports and military walking, running, football games, swimming, skiing. Puni's study of the culture of muscular-articular sensations in skiers showed an increase in this sensitivity in masters of skiing by 1 "/ 2-2 times compared with ordinary skiers. The same was noted in relation to masters of running, jumping, etc.
Working posture of the human body
Walking is not the only general act of the locomotor apparatus in which the entire motor analyzer of a person takes part. Another such general and most time-consuming motor act is the working posture of the human body. , i
The natural state of the human body is the state of vigorous activity. This natural state finds its fullest expression in human labor and productive activity. The working person implements the children normally inherent in the human body.
pregnancy.
The general working posture of the human body is a condition for each labor act (production operation, design on drawings or writing, etc.), which is performed with the hands. Such a working posture is the position of the whole body (when working at the machine for workers, when
B. G. Ananiev
writing and reading, drawing, working with devices, etc.), necessary for the normal and active work of the hands and senses (especially the eyes). It is known that the working posture, like the working movements of the hands, is brought up and trained by a whole system of exercises. So, for example, a child is taught not only rational finger movements when learning to write, play or play the piano, but also how to hold the body, in what position the shoulder and elbow joints should be, how the child should keep his feet under the desk, etc. e. For "writing or listening in a lesson, a working posture should be developed in which long-term work of the brain and hands could be provided without fatigue. It has been established that maintaining a long working posture is a large neuromuscular work in which work plays a leading role. Compared to a hand moving during labor, the general position of the body seems at first glance motionless, resting, but this is only an appearance. Ukhtomsky called the working position operational rest or stationary supported work of the human body. When working, musculo-articular impulses continuously enter the brain both from those parts of the locomotor system that provide a working posture, and from those that carry out the process of labor itself. As Ukhtomsky pointed out, “behind such a work or posture one has to assume the excitation of not a single point, but a whole group of centers,” 4 which he called “a constellation or constellation of nerve centers”. He showed that the basis of stationary supported work is a certain interaction of nerve centers, namely, persistent excitation of one of them when the others are inhibited (the case of negative induction of nervous processes). But at the same time, there is not a simple suppression of impulses from the inhibitory motor apparatus, but their use by the currently dominant center in the form of an increase in excitation in it due to the accumulated excitations from the inhibited points. During labor action, such a dominant nerve center is that part of the motor analyzer that regulates the work of the hands. The rest of the motor analyzer increases the excitation of this "manual" part of the motor analyzer, being themselves inhibited. At the same time, motor inhibition of other parts of the body does not at all mean the cessation of sensory
4A. A. Ukhtomsky. Collected cit., vol. I, p. 200.
(muscular-articular sensations) impulses from motor-inhibited parts of the body. On the contrary, the impulses coming from them excite the entire motor analyzer and especially that part of it that acts in accordance with the objective requirements of the external environment.
Ukhtomsky formulated his well-known principle of dominant in the following general form: “A sufficiently persistent excitation proceeding in the centers, at the moment acquires the importance of a dominant factor in the work of other centers: the accumulation of excitation from distant sources in oneself, but inhibits the ability of other receptors to respond to impulses that they have a direct relationship. ”5 To understand the mechanism of the working posture, it is especially important to take into account the nature of the most important feature of the dominant, namely its inertia. Et: 1 "inertia is reflected in the fact that" once caused by domi 1 "anta is able to hold firmly in the centers for some time and be reinforced both in its elements of excitement and in its elements of inhibition by various and distant stimuli." the inertia of the working posture is conditioned reflexively due to the action of signals from the usual working environment of labor actions (workshop, office, classroom, etc.). In other words, together with the working movements of the hands, the working posture forms an integral dynamic stereotype of the temporal connections of the activity process.
Muscular-articular sensations of a person in the process of work are of a double nature: sensations of active movements of the hands and sensations of passive movements of the rest of the body. STOM reflects the tilt of the head and body, the length of movement of individual joints, their duration, the range of motion of the hand relative to the center of gravity of the body and the midpoint of the body, etc. Accurate recording of body movements while sitting at work shows continuous vibrations of the whole body f with a slight displacement of the center the severity of the body.
The cerebral cortex, receiving impulses from all parts of the motor analyzer, continuously redistributes muscle energy between parts of the motor apparatus. ensuring the preservation of a person's working capacity, especially actively working hands.
Musculo-articular sensations of working movements
The most diverse, accurate, clearly perceived muscular-articular sensations are sensations of
5 Ibid., P. 198.
6 Ibid., P. 202.
sideways movements carried out by the joint work of both hands. It is no coincidence that the general ideas about muscular feeling were formed precisely during the study of sensations obtained during labor movements of the hands and the process of active touch and touch. In fact, we have already said about them earlier, with a general characteristic of muscular-articular sensations. Here we will touch on some special and additional materials.
Studies have shown high exercise capacity, therefore, sensitization of the sensation of heaviness and effort, i.e., overcoming the resistance of the external body when working with it, as well as a reflection of its elastic properties. Such sensitization especially takes place when working with weighing, with the determination of gravity, elastic properties, and body dimensions during work.
An experienced seller accurately calculates the preparation of products when weighing, making very little mistakes; workers of procurement shops achieve great savings in materials not only due to the eye, but also by the developed discriminatory muscular-articular sensitivity. In this case, it is especially characteristic to overcome the differences that arise when feeling heaviness by weighing with both hands at the same time. Without special training, in this case, an illusion or a perception error usually occurs, which (especially when operating with open eyes) in the fact that each of the hands gives different readings. At the same time, as Khachapuridze from Uznadze's laboratory showed, the left hand of right-handers often overestimates the actual severity of an even figure. During training, this illusion is removed, both hands give identical or close readings. Differences in the muscular-articular sensations of both hands are especially evident with active touch or palpation with both hands at the same time. Initially, from one object, two separate images of the right and left sides arise according to the work of the hands. Such double vision of the image does not occur with simultaneous, alternating actions of the hands, but only with simultaneous actions, which indicates the difficulty of developing a general, rhythm of movement and simultaneous equal excitation of both hands.
The leading role of muscular-articular sensations in active touch is evidenced by the fact that even with shutdowns, so; With strong sensitivity, it is quite possible to accurately recognize the shape and elasticity of the objects being touched. -,
Zaporozhets showed / that with closed eyes and by means of a "tool" (stick, pencil, etc.), that is, without the participation of skin sensitivity, a person can accurately recognize
size, shape, elastic properties of external objects. From the data of Yarmolenko and Pantsyrnaya, it follows that under such conditions, drawing a pointer around the contour of an object with the right hand gives an accurate reflection of the contour. A special adaptation is required on the left-hand side in order for it to give similar results in right-handers.
The right, dominant hand in right-handers is characterized by a higher discriminative sensitivity in recognizing the objective and spatio-temporal properties of the objects being touched. But at the same time, the static tension of the left hand or its partial dynamic tension enhances the discriminatory work of the right hand.
Sensitization of the severity of the muscular-articular sensations of the right hand was established when Puni studied various types of sports techniques. This is especially true for fencing. Puni's experiments give an accurate idea of the increase in the severity of these sensations and the aiming ability of the right hand. They showed that the severity of muscular-articular sensations increases unevenly. After 3 / d months of training in fencing, this acuity increased with movements in the wrist joint by 25%, and when moving in the elbow joint - by 40%.
If at the beginning of training in fencing technique deviation from the target (fencing strike) in millimeters was 35, then after 3 "/ 2 months of exercise only 8.6 mm. The number of accurate hits on the target increased by 81.3%. At the same time, as shown by Puni , the sensitization of the acuity of the muscular-articular feeling is influenced by such factors as the density of the fencing fight, interaction with a strong or weak opponent, etc.
Science has similar data regarding sensitization in other sports and shooting.
The leading role of the cerebral cortex in sensitizing active movements is especially evident in the restoration of disturbed motor systems. So, Leontiev and Zaporozhets showed that the restructuring of the cerebral cortex after amputation of one or both hands gradually leads to sensitization of the remaining stumps of the hands or a two-fingered hand artificially created from the stump (the so-called Krukenberg hand). Industrial training (occupational therapy) and remedial gymnastics, correctly physiologically and psychologically grounded, provide a high recovery rate of movements. In this case, the formation of the difference in muscular-articular sensations of both hands plays an important role. Schenck summarized the valuable experience of such a functional education of handicapped disabled people, showing the
versatile substitutions of motor functions of the hands, etc.
It has been established that between the muscular-articular sensations from the process of walking or working posture, on the one hand, and the sensations of working movements, on the other hand, there is a relationship of mutual induction, especially negative induction. Operational rest and cessation of walking, in which the distinctive work of both hands is enhanced, is most conducive to precise hand movements.
In turn, similar inductive relationships are formed between working movements and speech movements (articulate speech) of a person.
The considered forms of musculo-articular sensitivity in the state of walking, working posture and working movements are carried out by the first signal system, although the second signal system plays a very important role in sensitization and development of the entire human motor apparatus.
Even Lesgaft, in his teaching on physical education, emphasized the meaning of the word and verbal explanation of the nature of movements in physical education. The experience of physical education fully confirmed this thesis of Lesgaft, and at the same time the position of Pavlov about the influence of the second signal system on the work of all human analyzers, including the motor one, accelerating and rationalizing the development of musculo-articular sensitivity.
Feelings of speech movements
The sensations of speech movements are a condition for the formation of motor differentiation in the pronunciation of consonants and vowels. This differentiation is formed by. gradually, and in conditions of closed connections between the auditory analysis of audible foreign speech and the movements of all separate parts of the speech motor apparatus (from the respiratory apparatus to the teeth and lips). A particularly important role is played by the differentiation of the position of the tongue in relation to the palate and teeth. At first, the child has a physiological inarticulateness, in which the child still incorrectly performs: -these movements (they do not separate from each other, similar positions of the language are mixed, etc.), which is removed in the process of educating the child's speech. An exceptional role in this process is played by the differentiation of muscle sensations during movements necessary for the pronunciation of similar vowels and similar consonants. After the formation of such a differentiation, it becomes possible to synthesize speech movements, it is with him and coherent, continuous verbal speech, and then communication
new construction of words in a sentence based on mastering grammatical rules.
This exceptional role of muscle sensations can be easily and clearly detected when eliminating defects in oral speech by means of special speech therapy exercises, in which the movements of the tongue are quiet, smooth and are provided by the education of a subtle distinction of muscle sensations when the teacher sets various sounds of the articulatory apparatus. Speech movements, together with verbal hearing, initially determine the movements of the writing hand.
As Blinkov, Luria and others have shown, articulatory movements accompany and enhance the differentiated movements of the squeaky hand. The most complex muscle sensations in the act of writing should also be attributed to speech movements. "Speech movements in the act of reading also include muscular sensations from moving the gaze, ie, the visual axes of the eyes. Thus, speech movements also capture a large area of interrelated movements of the speech motor apparatus, arms and eyes, with a particularly increasing value of the general working posture of the human body. this complex of movements and sensations of movements is formed at the level of the second signal system and is determined by the social nature of the sound structure of the given language.
Speech kinesthesia is the “basal component” (Pavlov) of the second signaling system. However, a systematic study of this component is only just beginning. In recent years, valuable data have been obtained on the mechanisms of speech, especially in a series of works by Zhinkin.7
7N. I. Zhinkin. Mechanisms of speech. M., Ed. APN RSFSR, 1958.
FEELING OF BALANCE AND ACCELERATION (STATIC-DYNAMIC SENSES)
The position of the human body in space as a source
sensations
The historical, social and labor transformation of human nature has put the human body in a new relationship to the surrounding space of the external world. Direct walking and vertical position of the body in relation to the horizontal plane of the Earth, labor actions of hands, articulate speech and new functions of all analyzers - all these are products of social and labor changes in the human body, developed in the process of social and labor influence of a person on the outside world. In each act of such an impact, the human body itself experiences many irritations from the outside world and the changing internal environment of the body. In any of his actions, a person moves in space, and maintains the balance of his body, and thereby his constant vertical position in relation to the horizontal plane of the Earth. This movement occurs in different forms - translational, rotational, oscillatory, etc. Signals about various changes in body position are continuously received in the human brain, the brain ensures the restoration of the body in any form of movement. Each of the integral movements of the human body occurs at a different speed, and the acceleration of movement occurs with variable values of time.
Thanks to the production of means of production, society receives more and more new means of transportation and acceleration.
the movement of a person in space. Even in ancient times, people used horse traction as a means of transportation and acceleration of movement. From horse-drawn traction to the most advanced technology of rail and trackless, water and air transport, the technology of movement and acceleration has passed a difficult historical path. Modern transport-barking technology changes the nature of the signaling about the balance of the body in the process of movement. A person in the conditions of modern transport technology moves with ever greater accelerations, and these accelerations are experienced by a person with a relatively stationary position of the body. Thus, a pilot or passenger of an airplane, a driver or a passenger of a car, etc., experience not only a change in the balance of the body in the narrow sense of the word (for example, when the body of the car moves vertically when climbing to a height or when the airplane lands), but also the acceleration of the car in the same plane of horizontal movement. If in the first case there is also a change in the general muscle tone and intense muscular-articular signaling, in the second case, special sensations of acceleration that cannot be reduced to muscular-articular sensations arise. These sensations are static sensations or sensations of the general position of the body in the process
movement.
It can be said that the progress of transport technology has given rise to a special development of these sensations, closely related to muscular-articular feeling and visual orientation in space. As we will see further, a person is aware of the balance of the body insofar as it is disturbed, changes when the position of the body changes. A person feels acceleration insofar as it is not continuously constant, but variable, that is, he feels a change in speeds (from high to low and vice versa), and the most important role in these sensations is played by contrasting ratios of positions and accelerations. So, a person experiences static sensations with a sharp change from a horizontal position to a vertical one (for example, quickly jumping out of bed) or with a sharp change
acceleration.
The constant position of the body and constant speed is usually not felt by a person, since the cerebral regulation of these states is carried out automatically by unconditional reflexively by the lower parts of the central nervous system. Signals about the position of the body and accelerations reach the koza of the brain in a generalized form and in those cases when an urgent reaction of the human body is required to a change in the position of the body in accordance with the requirement of its activity.
Receptors for static-dynamic sensations (vestibular,
In the inner ear, not only is the hearing receptor located, but also there are receptors for the acceleration of body movement and its positioning in space. The inner ear consists of three main sections: the vestibule, the semicircular canals, and the cochlea. The latter, that is, the cochlea, is, as is already known, a slave receptor. The vestibule and semicircular canals form the vestibular apparatus, which is a statically receptor for sensations. It is the window of the vestibular nerve of one of the main parts of the VIII auricular nerve. The vestibular apparatus itself. Consists of two groups of red
tori. The first is the set of hair cells, ___ „.,
styling the surface of the semicircular canals in the inner ear. In these channels there is a liquid endolymph, which moves when the position of a person in space changes (when changing the vertical position to horizontal, when the body is tilted, etc.). These movements of the endolymph irritate the hair cells of the semicircular canals, and it is believed that this irritation is not only mechanical in nature, but is also characterized by a certain electrical phenomenon (current of action). The Bjropoft group of receptors are otoliths, or auditory stones, located in the vestibule of the inner ear.
The activity of both groups of vestibular receptors is interrelated. It is assumed, however, that the receptor function of the semicircular canals is specifically to signal the acceleration of body movements. To study the excitability of the semicircular canals, the clinic uses the methods of mechanical and caloric (thermal) irritation. The method of mechanical stimulation consists in a rotational test. This test is performed on a special swivel chair. The person is slowly rotated (one full revolution in 2 seconds) on this chair, and after 10 revolutions outside. abruptly interrupt. In this case, two kinds of phenomena / with opposite spatial signs arise: 1) ni- \ stagmus, or involuntary convulsive trembling movements of the eyeballs, and it takes place in the direction opposite to the former movement, and 2) reflex inclination of the head and body in the same direction as the former movement.
Rotation excites both vestibular apparatus (right and left ears), but the apparatus that was opposite to the side of the movement is more excited. Therefore, left-sided nystagmus occurs when rotating to the right
th is due to the left vestibular apparatus. Right-sided nystagmus occurs when rotating to the left and is caused by the right vestibular apparatus. By the size of the intensity and duration of nystagmus when rotating in one direction or the other, it is judged which side is affected. With a caloric test, the semicircular canals of each of the ears can be examined separately. For this purpose, water is slowly poured into the external auditory canal without pressure (temperature 15-20 or 40-45 ° C). Cooling of the semicircular canals causes the movement of endolymph in them, irritating the hair cells. As a result, nystagmus occurs in the opposite direction and deviation of the head and outstretched arms, as well as a fall towards the ear irritated by cooling. With the defeat of one vestibular apparatus from the irritated side, neither nystagmus nor other reactions are obtained. With an increase in its excitability, nystagmus and other reactions are intensified and more prolonged.
The second function of the semicircular canals manifests itself in signaling the general movement of the body and its acceleration. Volumetric signs of this function are nystagmus and reflex movements of the head, neck, trunk and arms.
The reflex function of the otoliths, apparently, consists in the primary analysis of changes in the position of the body in relation to the plane of support. In order to study the receptor functions of otoliths, a movable table is used, the slope of which can change (according to a certain measuring scale in degrees). A person is placed on such a table (in a sitting, standing, lying position), his reactions to a sudden movement of the support plane, a change in the position of his body are studied. As you can see, the functions of vestibular receptors bt step especially in such conditions when the human body itself is relatively motionless, but either the direction of the plane of the external support of the human body or the speed of movement of this support changes. With this apparent immobility of the human body under conditions of a moving support, there is a movement of endolymph in the semicircular canals and a movement of otoliths. It has been established that this movement occurs aperiodically. From both vestibular apparatuses, several "identical signals about a change in balance come to the brain. This difference in signals is an important condition for the formation of static sensations. Although the vestibular receptors themselves are located in the internal environment of the body, the signaling of these receptors, which occurs when the inner ear changes under the influence of external stimuli," has the character of signaling about external changes in the human body ~] G ~ bktyar ~ * His space.
Therefore, as Bekhterev first established, the vestibular function is an integral part of a person's orientation in the space of the external world and plays an important role in the "lysatory function" of the human cerebral cortex.
Vestibular nerves
In the depths of the internal auditory meatus there is a special ganglion (accumulation of nerve cells), consisting of cells of the peripheral nerve of the otoliths and semicircular canals. \ From here, from the inner ear canal, fibers from this :! the ganglion and the auditory nerve go together, forming the VIII pair of auricular nerves. At the entrance to the hindbrain, they divide] into two branches: vestibular and auditory. The vestibular branch branches out in three directions, ending respectively in each of them. The first fork has an ending; inward from the so-called rope body in the auditory region of the cerebral hemispheres, the second - in the nucleus! Ankylosing spondylitis, located between the bottom of the IV cerebral ventricle and the posterior cerebellar peduncle, the third - in the nucleus of Day-Children. From the Deidets nucleus, the cell axons are sent to the spin- | noah brain, ending at the peripheral motor 1 nerve. From the first two branches (in the auditory tubercle and the nucleus of ankylosing spondylitis), the fibers of the vestibular nerve go through the posterior 1 cerebellar pedicle into the so-called cerebellar worm and to | to the nuclei of the oculomotor nerve located in the middle |
Feel - the simplest mental process, consisting in the reflection of individual properties of objects and phenomena with their direct impact on the corresponding receptors
Receptors - these are sensitive nerve formations that perceive the impact of the external or internal environment and encode it in the form of a set of electrical signals. These signals are then sent to the brain, which decodes them. This process is accompanied by the emergence of the simplest mental phenomena - sensations.
Some of the human receptors are combined into more complex formations - sense organs. A person has an organ of vision - an eye, an organ of hearing - an ear, an organ of balance - a vestibular apparatus, an organ of smell - a nose, an organ of taste - a tongue. At the same time, some receptors do not combine into one organ, but are scattered over the surface of the entire body. These are receptors for temperature, pain and tactile sensitivity. A large number of receptors are found inside the body: receptors for pressure, chemical feeling, etc. For example, receptors that are sensitive to the content of glucose in the blood, provide the emergence of a feeling of hunger. Receptors and senses are the only channels through which the brain can receive information for further processing.
All receptors can be divided into distant who can perceive irritation at a distance (visual, auditory, olfactory) and contact (gustatory, tactile, painful).
Analyzer - the material basis of sensations
Feelings are a product of activity analyzers person. An analyzer is an interconnected complex of nerve formations that receives signals, transforms them, tunes the receptor apparatus, transfers information to nerve centers, processes and decrypts them. I.P. Pavlov believed that the analyzer consists of three elements: sense organs , pathway and cortical ... According to modern concepts, the analyzer includes at least five sections: receptor, conductor, tuning unit, filtration unit and analysis unit. Since the conductor section is essentially just an electrical cable carrying electrical impulses, the four sections of the analyzer play the most important role. The feedback system allows you to make adjustments to the work of the receptor department when the external conditions change (for example, fine-tuning the analyzer with different impact forces).
Sensation thresholds
In psychology, there are several concepts of the threshold of sensitivity
Lower absolute sensitivity threshold defined as the smallest stimulus force that can produce a sensation.
Human receptors are very sensitive to an adequate stimulus. So, for example, the lower visual threshold is only 2-4 quanta of light, and the olfactory one is equal to 6 molecules of an odorous substance.
Irritants with a strength less than the threshold do not cause sensations. They're called subthreshold and are not realized, however, they can penetrate into the subconscious, determining the behavior of a person, and also forming the basis of it dreams, intuition, unconscious drives. Research by psychologists shows that a person's subconscious can react to very weak or very short stimuli that are not perceived by consciousness.
Upper absolute sensitivity threshold changes the very nature of sensations (most often - to painful). For example, with a gradual increase in water temperature, a person begins to perceive not heat, but already pain. The same thing happens with strong sound and or pressure on the skin.
Relative threshold (threshold of discrimination) is called the minimum change in the intensity of the stimulus, causing changes in sensations. According to the Bouguer-Weber law, the relative threshold of sensations is constant when measured as a percentage of the initial value of stimulation.
Bouguer-Weber law: “The discrimination threshold for each analyzer has
constant relative value ":
DI / I = const, where I is the strength of the stimulus
Classificationsensations
1. Exteroreceptive sensations reflect the properties of objects and phenomena of the external environment ("five senses"). These include visual, auditory, gustatory, temperature and tactile sensations. In fact, there are more than five receptors that provide these sensations, and the so-called "sixth sense" has nothing to do with it. For example, visual sensations occur with arousal. chopsticks("Twilight, black and white vision") and cones("Daylight, color vision"). Temperature sensations in a person arise with separate arousal. cold and heat receptors... Tactile sensations reflect the impact on the surface of the body, and they occur when aroused or sensitive touch receptors in the upper layer of the skin, or with a stronger effect on pressure receptors in the deep layers of the skin.
2. Interoreceptive sensations reflect the state of internal organs. These include the feeling of pain, hunger, thirst, nausea, suffocation, etc. Pain sensations signal damage and irritation of human organs, are a kind of manifestation of the protective functions of the body. The intensity of pain is different, reaching in some cases great strength, which can even lead to the emergence of a state of shock.
3. Proprioceptive sensations (muscular-motor). These are sensations that reflect the position and movement of our body. With the help of musculoskeletal sensations, a person receives information about the position of the body in space, about the relative position of all its parts, about the movement of the body and its parts, about contraction, stretching and relaxation of muscles, the state of joints and ligaments, etc. Musculoskeletal sensations are complex. Simultaneous stimulation of receptors of different quality gives sensations of a peculiar quality: stimulation of receptor endings in muscles creates a feeling of muscle tone when performing a movement; sensations of muscle tension and effort are associated with irritation of the nerve endings of the tendons; irritation of the receptors of the articular surfaces gives a sense of direction, shape and speed of movement. Many authors refer to the same group of sensations the sensations of equilibrium and acceleration, which arise as a result of excitation of the receptors of the vestibular analyzer.
Properties of sensations
Sensations have certain properties:
·adaptation,
·contrast,
Thresholds of sensations,
Sensitization,
· Sequential images.
A brief excursion into the development of the concept of sensations
Feel- “the law of the specific energy of the sense organ”, that is, the sensation does not depend on the nature of the stimulus, but on the organ or nerve in which the process of stimulation takes place. The eye sees, the ear hears. The eye cannot see, but the ear cannot see. 1827 g.
The objective world is fundamentally unknowable. The result of the sensing process is a partial, that is, a partial image of the world. All that we perceive is the process of specificity of the impact on the senses. "Mental processes" Vekker L.M.
Power-law dependence of changes in sensations with changes in the intensity of stimuli (Stevens law)
The lower and upper absolute thresholds of sensations (absolute sensitivity) and thresholds of discrimination (relative sensitivity) characterize the limits of human sensitivity. Along with this, distinguish operational thresholds of sensations- the magnitude of the difference between the signals at which the accuracy and speed of their discrimination reach a maximum. (This value is an order of magnitude greater than the discrimination threshold.)
2. Adaptation... The analyzer sensitivity is not stable, it changes depending on different conditions.
So, entering a poorly lit room, at first we do not distinguish objects, but gradually the analyzer's sensitivity increases; being in a room with any odors, after a while we stop noticing these odors (the analyzer's sensitivity decreases); when we get from a poorly lit space into a brightly lit space, the sensitivity of the visual analyzer gradually decreases.
The change in the sensitivity of the analyzer as a result of its adaptation to the strength and duration of the acting stimulus is called adaptation(from lat. adaptatio- device).
Different analyzers have different speed and adaptation range. Adaptation occurs quickly to some stimuli, and slower to others. The olfactory and tactile ones adapt faster (from the Greek. taktilos- touch) analyzers. The auditory, gustatory and visual analyzers adapt more slowly.
Full adaptation to the smell of iodine occurs in a minute. After three seconds, the sensation of pressure reflects only 1/5 of the strength of the stimulus. (The search for glasses shifted to the forehead is one example of tactile adaptation.) For a complete dark adaptation of the visual analyzer, 45 minutes are required. However, visual sensitivity has the largest adaptation range - it changes 200,000 times.
The phenomenon of adaptation has an expedient biological significance. It helps to repel weak stimuli and protects the analyzers from excessive exposure to strong ones. Adaptation, like getting used to constant conditions, provides an increased orientation to all new influences. Sensitivity depends not only on the strength of external stimuli, but also on internal states.
3. Sensitization... An increase in the sensitivity of analyzers under the influence of internal (mental) factors is called sensitization(from lat. sensibilis- sensitive). It can be caused by: 1) the interaction of sensations (for example, weak taste sensations increase visual sensitivity. This is explained by the interconnection of analyzers, their systemic work); 2) physiological factors (the state of the body, the introduction of certain substances into the body; for example, vitamin "A" is essential to increase visual sensitivity); 3) the expectation of this or that influence, its significance, a special attitude to distinguish stimuli; 4) exercise, experience (for example, tasters, specially exercising gustatory and olfactory sensitivity, distinguish between various varieties of wines, teas, and can even determine when and where a product is made).
In people who are deprived of any kind of sensitivity, this deficiency is compensated (compensated for) by increasing the sensitivity of other organs (for example, an increase in auditory and olfactory sensitivity in the blind). This is the so-called compensatory sensitization.
Strong excitation of some analyzers always desensitizes others. This phenomenon is called desensitization... Thus, an increased noise level in "loud workshops" lowers visual sensitivity; desensitization of visual sensitivity occurs.
Rice. 4. . The inner squares produce sensations of varying intensity of gray. In reality, they are the same. Sensitivity to the properties of phenomena depends on adjacent and successive contrast effects.
4. ... One of the manifestations of the interaction of sensations is their contrast(from lat. contraste- a sharp opposite) - an increase in sensitivity to some properties under the influence of other, opposite, properties of reality. Thus, the same gray figure appears dark on a white background, and white on a black background (Fig. 4).
5. Synesthesia... An associative (phantom) other-modal sensation accompanying the real one (the sight of a lemon causes a sour sensation) is called synesthesia(from the Greek. synaisthesis- joint feeling).
Rice. 5.
Features of certain types of sensations.
Visual sensations... The colors felt by a person are divided into chromatic (from the Greek. chroma- color) and achromatic - colorless (black, white and intermediate shades of gray).
For the appearance of visual sensations, it is necessary to influence the electromagnetic waves on the visual receptor - the retina of the eye (an accumulation of photosensitive nerve cells located at the bottom of the eyeball). The central part of the retina is dominated by nerve cells - cones that provide a sense of color. On the edges of the retina, rods that are sensitive to changes in brightness predominate (Fig. 5, 6).
Rice. 6.. Light penetrates to light-sensitive receptors - rods (reacting to changes in brightness) and cones (reacting to different lengths of electromagnetic waves, i.e., to chromatic (color) influences), bypassing ganglion and bipolar cells, which carry out the primary elementary analysis of nerve impulses already from the retina. For the appearance of visual arousal, it is necessary that the electromagnetic energy entering the retina be absorbed by its visual pigment: rod pigment - rhodopsin and cone pigment - iodopsin. Photochemical transformations in these pigments give rise to the visual process. At all levels of the visual system, this process: manifests itself in the form of electrical potentials, which are recorded by special devices - an electroretinograph,.
Light (electromagnetic) rays of different lengths cause different color sensations. Color is a mental phenomenon - human sensations caused by different frequencies of electromagnetic radiation (Fig. 7). The eye is sensitive to the region of the electromagnetic spectrum from 380 to 780 nm (Fig. 8). The 680 nm wavelength gives a red feel; 580 - yellow; 520 - green; 430 - blue; 390 - purple colors.
Electromagnetic radiation.
Rice. 7. Electromagnetic spectrum and its visible part (NM - nanometer - one billionth part of a meter)
Rice. eight. .
Rice. 9. . Opposite colors are called complementary - when mixed, they form a white color. Any color can be obtained by mixing two bordering colors with it. For example: red - mixing orange and purple).
The mixing of all perceived electromagnetic waves gives the sensation of white.
There is a three-component theory of color vision, according to which the whole variety of color sensations arises as a result of the work of only three color-perceived receptors - red, green and blue. The cones are divided into groups of these three colors. Depending on the degree of excitation of these color receptors, different color sensations arise. If all three receptors are equally excited, then a sensation of white appears.
Rice. 10. .
To different parts of the electromagnetic spectrum, our eye has unequal sensitivity... It is most sensitive to light rays with a wavelength of 555 - 565 nm (light green color tone). The sensitivity of the visual analyzer at dusk shifts towards shorter wavelengths - 500 nm (blue). These rays begin to appear lighter (Purkinje phenomenon). The rod apparatus is more sensitive to ultraviolet light.
In conditions of sufficiently bright lighting, the cones are switched on, the apparatus of the rods is turned off. In low light, only sticks are included in the work. Therefore, in twilight lighting, we do not distinguish between chromatic colors, the color of objects.
Rice. eleven. . Information about events in the right half of the visual field enters the left occipital lobe from the left side of each retina; information about the right half of the visual field is sent to the left occipital lobe from the right parts of both retinas. The redistribution of information from each eye occurs as a result of the crossing of part of the optic nerve fibers in the chiasm.
Visual arousal is characterized by some inertia... This is the reason for the preservation of a trace of light irritation after the cessation of exposure to the stimulus. (Therefore, we do not notice the gaps between frames in the film, which are filled with traces of the previous frame.)
People with weakened cone apparatus poorly distinguish chromatic colors. (This flaw, described by the English physicist D. Dalton, is called color blind). The weakening of the stick apparatus makes it difficult to see objects in twilight lighting (this drawback is called "night blindness".)
For the visual analyzer, the difference in brightness is essential - contrast... The visual analyzer is able to distinguish contrast within certain limits (optimum 1:30). Strengthening and weakening contrasts is possible through the use of various means. (To reveal a subtle relief, shadow contrast is enhanced by side lighting, using light filters.)
The color of each object is characterized by the rays of the light spectrum that the object reflects. (A red object, for example, absorbs all rays of the light spectrum except red, which are reflected by it.) The color of transparent objects is characterized by the rays that they transmit. In this way, the color of any object depends on what rays it reflects, absorbs and transmits.
Rice. 12.: 1 - chiasm; 2 - optic hillock; 3 - occipital lobe of the cerebral cortex.
In most cases, objects reflect electromagnetic waves of various lengths. But the visual analyzer perceives them not separately, but in total. For example, exposure to red and yellow is perceived as orange, color mixing occurs.
Signals from photoreceptors - light-sensitive formations (130 million cones and rods) go to 1 million larger (ganglion) neurons in the retina. Each ganglion cell sends its process (axon) to the optic nerve. The impulses going to the brain along the optic nerve receive primary processing in the diencephalon. The contrast characteristics of the signals and their temporal sequence are enhanced here. And already from here, nerve impulses enter the primary visual cortex, localized in the occipital region of the cerebral hemispheres (17 - 19 fields according to Brodmann) (Fig. 11, 12). Separate elements of the visual image are highlighted here - points, corners, lines, directions of these lines. (Established by Boston 1981 Nobel laureates Hubel and Wiesel.)
Rice. thirteen. Optogram taken from the retina of a dog's eye after its death. This testifies to the screen principle of the functioning of the retina of the eye.
The visual image is formed in the secondary visual cortex, where the sensory material is compared (associated) with the previously formed visual standards - the image of the object is recognized. (0.2 sec elapses from the beginning of the stimulus action to the appearance of the visual image.) However, already at the level of the retina, a screen display of the perceived object occurs (Fig. 13).
Auditory sensations... There is an opinion that 90% of information about the world around us we get through sight. This can hardly be calculated. After all, what we see with the eye must be covered by our conceptual system, which is formed integratively, as a synthesis of all sensory activity.
Rice. 14. Deviations from normal vision - myopia and hyperopia... These deviations can usually be compensated for with glasses with specially selected lenses.
The work of the auditory analyzer is no less complex and important than the work of the visual analyzer. This channel carries the main stream of speech information. A person senses sound 35 - 175 msec after he reaches the auricle. Another 200 - 500 msec is required for maximum sensitivity to this sound. It also takes time for the head to turn and the appropriate orientation of the auricle in relation to the faint sound source.
From the tragus of the auricle, the oval ear canal deepens into the temporal bone (its length is 2.7 cm). Already in the oval passage, the sound is significantly amplified (due to the resonant properties). The oval passage is closed by the tympanic membrane (its thickness is 0.1 mm, and its length is 1 cm), which constantly vibrates under the influence of sound effects. The eardrum separates the outer ear from the middle - a small chamber with a volume of 1 cm³ (Fig. 15).
The middle ear cavity is connected to the inner ear and to the nasopharynx. (Air from the nasopharynx balances the external and internal pressure on the eardrum.) In the middle ear, sound is amplified many times over by the ossicular system (malleus, incus, and stapes). These bones are supported by two muscles, which stretch when sounds are too loud and weaken the bones, protecting the hearing aid from injury. With faint sounds, the muscles strengthen the work of the bones. The sound intensity in the middle ear is increased by a factor of 30 due to the difference between the area of the tympanic membrane (90 mm 2), to which the malleus is attached, and the area of the base of the stapes (3 mm 2).
Rice. 15. . Sound vibrations of the external environment pass through the ear canal to the tympanic membrane located between the outer and middle ear. The eardrum transmits vibrations and the bony mechanism of the middle ear, which, acting on a lever principle, amplifies the sound by about 30 times. As a result, small changes in pressure at the eardrum are transmitted in a piston-like motion to the oval window of the inner ear, which causes fluid to move in the cochlea. Acting on the elastic walls of the cochlear canal, the movement of the fluid causes an oscillatory movement of the auditory membrane, more precisely, of a certain part of it, resonating at the appropriate frequencies. In this case, thousands of hairy neurons transform vibrational motion into electrical impulses of a certain frequency. The round window and the Eustachian tube extending from it serve to equalize the pressure with the external environment; leaving the nasopharynx, the Eustachian tube opens slightly during swallowing movements.
The purpose of the auditory analyzer is to receive and analyze signals transmitted by vibrations of an elastic medium in the range of 16-20,000 Hz (sound range).
The receptor section of the auditory system - the inner ear - is the so-called cochlea. It has 2.5 turns and is transversely divided by a membrane into two isolated channels filled with liquid (peralmph). Along the membrane, which tapers from the lower curl of the cochlea to its upper curl, there are 30 thousand sensitive formations-cilia - they are sound receptors, forming the so-called organ of Corti. In the cochlea, the primary dismemberment of sound vibrations occurs. Low sounds affect long cilia, high sounds affect short ones. Oscillations of the corresponding sound cilia create nerve impulses that enter the temporal part of the brain, where complex analytical and synthetic activity is carried out. The most important verbal signals for humans are encoded in neural ensembles.
The intensity of the auditory sensation - loudness - depends on the intensity of the sound, that is, on the amplitude of the vibration of the sound source and on the pitch. The pitch is determined by the frequency of vibration of the sound wave, the timbre of the sound - by overtones (additional vibrations in each main phase) (Fig. 16).
The pitch is determined by the number of vibrations of the sound source in 1 second (1 vibration per second is called hertz). The organ of hearing is sensitive to sounds in the range from 20 to 20,000 Hz, but the greatest sensitivity lies in the range of 2000 to 3000 Hz (this is the pitch corresponding to the scream of a frightened woman). A person does not feel the sounds of the lowest frequencies (infrasounds). The sound sensitivity of the ear starts at 16 Hz.
Rice. sixteen. . The intensity of a sound is determined by the amplitude of the oscillation of its source. Height - vibration frequency. Timbre - additional vibrations (overtones) in each "time" (middle figure).
However, subthreshold low-frequency sounds affect the mental state of a person. So, sounds with a frequency of 6 Hz cause dizziness, a feeling of fatigue, depression in a person, and sounds with a frequency of 7 Hz can even cause cardiac arrest. Getting into the natural resonance of the work of internal organs, infrasounds can disrupt their activity. Other infrasounds also selectively affect the human psyche, increasing its suggestibility, learning, etc.
Human sensitivity to high frequency sounds is limited to 20,000 Hz. Sounds that lie beyond the upper threshold of sound sensitivity (those above 20,000 Hz) are called ultrasounds. (Animals have access to ultrasonic frequencies of 60 and even 100,000 Hz.) However, since sounds up to 140,000 Hz are found in our speech, it can be assumed that they are perceived by us on a subconscious level and carry emotionally significant information.
The thresholds for distinguishing sounds according to their pitch are 1/20 of a semitone (that is, they differ up to 20 intermediate steps between the sounds emitted by two adjacent keys of the grand piano).
In addition to high-frequency and low-frequency sensitivity, there are lower and upper thresholds for sensitivity to sound strength. Sound sensitivity decreases with age. So, for the perception of speech at the age of 30, a sound volume of 40 dB is required, and for the perception of speech at the age of 70, its loudness must be at least 65 dB. The upper threshold of auditory sensitivity (in terms of volume) is 130 dB. Noise over 90 dB is harmful to humans. Sudden loud sounds are also dangerous, beating on the autonomic nervous system and leading to a sharp narrowing of the lumen of blood vessels, an increase in heart rate and an increase in the level of adrenaline in the blood. The optimal level is 40 - 50 dB.
Tactile sensation(from the Greek. taktilos- touch) - the sensation of touch. Tactile receptors (Fig. 17) are most numerous on the tips of the fingers and tongue. If on the back two points of contact are perceived separately only at a distance of 67 mm, then at the tip of the fingers and tongue - at a distance of 1 mm (see table).
Spatial thresholds of tactile sensitivity.
Rice. 17..
| High sensitivity zone | Low sensitivity zone |
| Tongue tip - 1 mm | Sacrum - 40.4 mm |
| Terminal phalanges of the fingers - 2.2 mm | Buttock - 40.5 mm |
| The red part of the lips - 4.5 mm | Forearm and lower leg - 40.5 mm |
| Palmar side of the hand - 6.7 mm | Sternum - 45.5 mm |
| Terminal phalanx of the big toe - 11.2 mm | Neck below the occiput - 54.1 mm |
| The back of the second phalanges of the toes - 11.2 mm | Loin - 54.1 mm |
| The back of the first phalanx of the big toe - 15.7 mm | Back and mid-neck - 67.6 mm |
| Shoulder and Thigh - 67.7mm |
Spatial tactile sensitivity threshold is the minimum distance between two point touches at which these influences are perceived separately. The range of tactile distinctive sensitivity is from 1 to 68 mm. High sensitivity zone - from 1 to 20 mm. Low sensitivity zone - from 41 to 68 mm.
Tactile sensations in combination with motor sensations form tactile sensitivity underlying objective actions. Tactile sensations are a kind of skin sensations, which also include temperature and pain sensations.
Kinesthetic (motor) sensations.
Rice. 18. (according to Penfield)
Actions are associated with kinesthetic sensations (from the Greek. kineo- movement and aesthesia- sensitivity) - a sense of the position and movement of parts of your own body. Labor movements of the hand were of decisive importance in the formation of the brain, the human psyche.
Based on muscular-articular sensations, a person determines compliance or non-compliance
their movements to external circumstances. Kinesthetic sensations perform an integrating function in the entire human sensory system. Well-differentiated voluntary movements are the result of the analytic-synthetic activity of an extensive cortical zone located in the parietal region of the brain. The motor, motor area of the cerebral cortex is especially closely connected with the frontal lobes of the brain, which carry out intellectual and speech functions, and with the visual areas of the brain.
Rice. nineteen. .
Muscle spindle receptors are especially abundant in the fingers and toes. When various parts of the body, hands, fingers move, the brain constantly receives information about their current spatial position (Fig. 18), compares this information with the image of the final result of the action and carries out the corresponding movement correction. As a result of training, images of intermediate positions of various parts of the body are generalized in a single general model of a specific action - the action is stereotyped. All movements are regulated on the basis of motor sensations, based on feedback.
The physical physical activity of the body is essential for optimizing the functioning of the brain: the proprioceptors of the skeletal muscles send stimulating impulses to the brain, increasing the tone of the cerebral cortex.
Rice. 20.: 1. The limits of permissible vibrations for individual parts of the body. 2. The limits of permissible vibrations affecting the entire human body. 3. The boundaries of weakly felt vibrations.
Static sensations- sensation of body position in space relative to the direction of gravity, a sense of balance. The receptors for these sensations (gravitoreceptors) are located in the inner ear.
Receptor rotational of body movements are cells with hair endings located in semicircular canals the inner ear, located in three mutually perpendicular planes. When the rotational movement is accelerated or slowed down, the fluid filling the semicircular canals exerts pressure (according to the law of inertia) on the sensitive hairs, in which the corresponding excitation is caused.
Moving into space in a straight line reflected in otolith apparatus... It consists of sensitive cells with hairs over which otoliths (pads with crystalline inclusions) are located. The change in the position of the crystals signals the brain the direction of the rectilinear movement of the body. The semicircular canals and the otolithic apparatus are called vestibular apparatus... It is connected with the temporal region of the cortex and with the cerebellum through the vestibular branch of the auditory nerve (Fig. 19). (Strong overexcitation of the vestibular apparatus causes nausea, since this apparatus is also associated with internal organs.)
Vibration sensation arise as a result of the reflection of vibrations from 15 to 1500 Hz in an elastic medium. These vibrations are reflected by all parts of the body. Vibrations are exhausting and even painful for a person. Many of them are unacceptable (fig. 20).
Rice. 21.. The olfactory bulb is the brain center of the sense of smell.
Olfactory sensations arise as a result of irritation by particles of odorous substances in the air, the mucous membrane of the nasal cavity, where the olfactory cells are located.
Substances that irritate the olfactory receptors enter the nasopharynx cavity from the side of the nose and nasopharynx (Fig. 21). This allows you to detect the smell of a substance both at a distance and if it is in the mouth.
Rice. 22.. The relative concentration of taste receptors on the surface of the tongue.
Taste sensations... The whole variety of taste sensations consists of a combination of four tastes: bitter, salty, sour and sweet. Taste is caused by chemicals dissolved in saliva or water. Taste receptors are nerve endings located on the surface of the tongue - taste buds... They are unevenly located on the surface of the tongue. Individual parts of the surface of the tongue are most sensitive to individual tastes: the tip of the tongue is more sensitive to sweet, the back to bitter, and the edges to sour (Fig. 22).
The surface of the tongue is sensitive to touch, that is, it participates in the formation of tactile sensations (the consistency of food affects taste).
Temperature sensations arise from irritation of the skin's thermoreceptors. There are separate receptors for the sensation of warmth and cold. On the surface of the body, they are located in some places more, in others - less. For example, the skin of the back and neck is most sensitive to cold, and the tips of fingers and tongue are most sensitive to hot. Different areas of the skin themselves have different temperatures (Fig. 23).
Painful sensations caused by mechanical, thermal and chemical influences that have reached a suprathreshold intensity. Pain sensation is largely associated with the subcortical centers, which are regulated by the cerebral cortex. Therefore, they are susceptible to some degree of inhibition through the second signaling system.
Rice. 23. (after A.L. Slonim)
Expectations and fears, fatigue and insomnia increase a person's sensitivity to pain; with deep fatigue, the pain dulls. Cold intensifies and heat reduces pain. Pain, temperature, tactile sensations and sensations of pressure refer to skin sensations.
Organic sensations- sensations associated with interoreceptors located in internal organs. These include feelings of satiety, hunger, suffocation, nausea, etc.
This classification of sensations was introduced by the famous English physiologist C.S. Sherrington (1906);
There are three types of visual sensations: 1) photopic - daytime, 2) scotopic - nighttime, and 3) mesopic - twilight. The greatest visual acuity is located in the central field of view; it corresponds to the central, foveal region of the retina. In scotopic vision, the maximum light sensitivity is provided by the paramolecular regions of the retina, which are characterized by the greatest accumulation of rods. They provide the greatest light sensitivity.
For a specialist in the field of physical culture and sports, it is useful to know not only about the above types of sensations, but also about sensations that largely determine the human motor culture - static-dynamic and kinesthetic.
Stato-dynamic sensations determine the maintenance of balance, which is necessary for normal human activity (labor, sports and other types). They are caused by a change in the parameters of the action of gravitational forces on the static-dynamic analyzer as a result of a change in body position or acceleration. Stato-dynamic sensations also determine a person's orientation in the surrounding reality.
The stato-dynamic analyzer is presented from the position of the peripheral section by the vestibular apparatus, consisting of the vestibule and semicircular canals located in the inner ear. They contain two groups of receptors: hair cells (in the semicircular canals) - form information about acceleration and general movement and the otolith complex (on the eve of the inner ear) - forms information about the position of the body in space and performs a primary analysis of this position in relation to the plane of support.
The conduction section is represented by the vestibular nerve, which runs from the vestibular receptors to the subcortical sections of the analyzer in the brain (to the hindbrain).
The central section is represented by the nuclei of the cerebellum, the oculomotor center and formations in the reticular formation. The cerebral cortex regulates the vestibular function conditioned reflex. Therefore, the static-dynamic analyzer is functionally connected with the work of other analyzers (auditory, visual, kinesthetic and others).
Kinesthetic sensations are caused by mechanical action on the receptor apparatus of the analyzer when the tension of the muscle tissue and the interposition of the joints change. The value of kinesthetic sensations can hardly be overestimated. They allow you to control the movements and actions of a person, form information about the health of the organ and its fatigue (about the state of muscle tissue), make a partial analysis of time and space, form the processes of active touch and have other capabilities.
In special types of activity (for example, sports activity), selective (fractional) analysis of information in kinesthetic sensations allows:
To dismember a holistic activity into its constituent parts and reflect the position of individual parts of the body relative to each other (draw up a "body diagram");
Reflect the analysis of individual passive movements relative to active ones;
Analyze and synthesize the scheme of active movements in the scheme of a holistic motor act, reflected in sensation.
In the process of individual development of a person, the specificity of the functioning of kinesthetic sensations also changes. From 8 to 18 years old, their information capacity doubles, and the resolution reaches its peak by the period of 11-15 years. Therefore, it is this age that is the most productive for mastering complexly coordinated sports. In various sports, different requirements are imposed on a person's motor culture, expressed in the characteristics of the nature of movements, their form, amplitude, direction and in other parameters. Kinesthetic sensations are part of the motor (and sports including) abilities that allow you to quickly and efficiently master various forms of motor culture.
The kinesthetic analyzer is represented by the peripheral part of the centripetal nerve endings or muscle-articular receptors. There are three groups of such receptors: fusiform (Ruffini endings); tendon (Golgi apparatus) and connective (Golgi-Mazzoni bodies). These are specialized nerve cells that convert the energy of mechanical pressure into a nerve impulse that carries relevant information. These receptors are located on the surface of the joint capsules and tendon joints.
The conduction section is represented by nerve pathways running from receptors through the spinal nodes to the subcortical zones of the brain.
The central part of the analyzer consists of scattered elements and a core. The nucleus is located in the motor area of the medulla oblongata (pons Varolievy), in the midbrain and visual hillocks, and the scattered elements are contained in the cerebral cortex. When the nucleus is damaged, the analysis functions are activated in the scattered elements of the analyzer. Such a complex structure of the analyzers increases their functional reliability and makes it possible to compensate for a certain range of violations.
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