The physiological basis of sensations is the work of analyzers. The physiological apparatus by which sensation arises is the analyzer. The analyzer (sense organ) is anatomical and physiological an apparatus located on the periphery of the body or in internal organs, it receives irritation from the external and internal environment. Each such device connects the brain with the outside world and provides a variety of information. In order for a person to have normal sensations, a healthy state of all three sections of the analyzer is necessary: a conductive receptor; neural pathway; cortical part.
1. 3. 2. 4. 1. Neuroconductive pathways 2. Cerebral cortex 3. Analyzer sections in c.g.m. 4. Taste buds
Exteroreceptive Interoreceptive Proprioceptive 1. Visual 2. Olfactory 3. Taste 4. Auditory 5. Temperature 6. Tactile 1. Feeling pain 2. Feeling balance 3. Feeling acceleration
The process of irritation consists in the appearance of an action potential in the nerve tissues and its penetration to the sensitive nerve fiber. Stimuli cause excitation in the nervous tissue. A specialized part of the analyzer, through which a certain type of energy is transformed into a process of nervous excitation, is called a receptor.
physical process stimulus sense organ physiological process excitation Pathways Psychological process Center in the cerebral cortex
The quality of sensation is a property that characterizes the basic information displayed by this sensation, which distinguishes it from other sensations. One can also say this: the quality of sensation is a property that cannot be measured with the help of numbers, compared with some kind of numerical scale. For a visual sensation, the quality can be the color of the perceived object. For taste or smell - chemical characterization subject: sweet or sour, bitter or salty, floral smell, almond smell, hydrogen sulfide smell, etc.
It is important to understand that the intensity of sensation depends on two factors that can be designated as objective and subjective: - the strength of the acting stimulus (its physical characteristics), - the functional state of the receptor, which is affected by this stimulus. The more significant physical parameters stimulus, the more intense the sensation. For example, the higher the amplitude of a sound wave, the louder the sound appears to us. And the higher the sensitivity of the receptor, the more intense the sensation.
A person exists in space, and the stimuli that act on the sense organs are also located at certain points in space. Therefore, it is important not only to perceive the sensation, but also to spatially localize it. The analysis carried out by the receptors gives us information about the localization of the stimulus in space, that is, we can tell where the light comes from, the heat comes from, or which part of the body is affected by the stimulus.
The duration of the sensation - it indicates the time of existence of the sensation that has arisen. The duration of sensation is also influenced by objective and subjective factors. The main factor, of course, objective - the longer the action of the stimulus, the longer the sensation. However, the duration of sensation is also affected by the functional state of the sense organ, and some of its inertness. After the beginning of the impact of the stimulus on the sense organ, the sensation does not occur immediately, but after some time. latent period various kinds feelings are not the same. For tactile sensations - 130 ms, for pain - 370 ms, for taste - only 50 ms. The sensation does not arise simultaneously with the beginning of the action of the stimulus and does not disappear simultaneously with the termination of its action.
General laws of sensations: absolute threshold The absolute threshold of sensation (lower threshold of sensations) is those minimum physical characteristics of the stimulus, starting from which a sensation arises. Stimuli, the strength of which lies below the absolute threshold of sensation, do not give sensations. By the way, this does not mean at all that they do not have any effect on the body.
General patterns of sensations: The upper threshold of sensations is a high stimulus, at which it ceases to be perceived adequately. Another name for the upper absolute threshold is the pain threshold, because when we overcome it, we experience pain: pain in the eyes when the light is too bright, pain in the ears when the sound is too loud, etc.
General laws of sensations: relative threshold Relative threshold (distinction threshold) is the minimum change in the intensity of the stimulus that causes changes in sensations.
Adaptation, or adaptation, is a change in sensitivity under the influence of a constantly acting stimulus, which manifests itself in a decrease or increase in thresholds. Strong stimulus - weak sensitivity Weak stimulus - high sensitivity ADAPTATION RULE: When moving from strong to weak stimuli, sensitivity increases, from weak to strong decreases (stimulus and sensitivity are in inverse proportion)
The interaction of sensations is a change in the sensitivity of one analyzer system under the influence of the activity of another system. General pattern The interaction of sensations is as follows: weak stimuli of one analyzer system increase the sensitivity of another system, strong ones reduce it. For example, weak taste sensations (sour) increase visual sensitivity. Weak sound stimuli increase the color sensitivity of the visual analyzer. At the same time, there is a sharp deterioration in the various sensitivity of the eye due to the strong noise of an aircraft engine. All our analyzer systems are capable of influencing each other to a greater or lesser extent.
An increase in sensitivity as a result of the interaction of analyzers, as well as systematic exercises, is called sensitization. The possibilities for training the sense organs and their improvement are very great.
The phenomenon of sensitization of the sense organs is observed in people who have been engaged in certain types of activities for a long time. professional activity. High level perfection is achieved by olfactory and gustatory sensations in tasters of tea, cheese, wine. Tasters can accurately indicate not only what grape variety the wine is made from, but also the place where the grapes are grown. Painting makes special demands on the perception of form, proportions and color relationships when depicting objects. Experiments show that the artist's eye is extremely sensitive to the assessment of proportions. Our sensations develop under the influence of the conditions of life and the requirements of practical activity.
- compensatory sensitization due to the need to compensate for sensory defects (blindness, deafness); Loss of sight or hearing is compensated by the development of other types of sensitivity. There are cases when people who have lost their sight have developed skin sensitivity, they have well-developed tactile sensations, vibration sensitivity. A person suffering from deafness, holding his hand on the interlocutor's throat, can understand who is talking about what, and also, taking a newspaper in his hands, knows whether he has read it or not. ANDREA BACELLI RAY CHARLES DIANA GURTSKAYA
Desensitization - a decrease in the sensitivity of analyzers in the process of interaction of sensations. The interaction of sensations in some cases leads to sensitization, to an increase in sensitivity, and in other cases to its decrease, i.e., to desensitization. Strong excitation of some analyzers always lowers the sensitivity of other analyzers. So, the increased noise level in "loud shops" lowers visual sensitivity.
The contrast of sensations is a change in the intensity and quality of sensations under the influence of a preliminary or accompanying stimulus. In the case of the simultaneous action of two stimuli, a simultaneous contrast occurs. Such a contrast can be traced in visual sensations. The same figure appears lighter on a black background, darker on a white one. A green object on a red background seems more saturated. The phenomenon of consistent contrast is also well known. After a cold, a weak warm stimulus seems hot. The sensation of sour increases the sensitivity to sweet. If you fix a bright spot with your eye for 20-40 seconds, and then close your eyes or look at a low-light surface, then within a few seconds you can feel a fairly clear dark spot. This will be a consistent visual image.
Synesthesia (joint sensation) is the ability of a stimulus addressed to a particular sense organ to simultaneously cause a sensation in another sense organ (the sight of a yellow lemon causes a sour sensation). Engineer K. L. Leontiev, using the phenomenon of synesthesia, developed an apparatus that transforms sound signals into color ones. Based on this invention, colored music was created.
The complete deprivation of a person of sensory impressions, carried out for experimental purposes (for example, by immersion in water in special equipment). In response to the insufficiency of sensations, the processes of imagination are activated, which in a certain way affect the figurative memory. Bright eidetic representations arise, projected outward, which are evaluated as protective (compensatory) reactions. As the time spent in S.'s conditions increases, at the stage of unstable mental activity people develop emotional lability with a shift towards low mood (lethargy, depression, apathy), which for a short time are replaced by euphoria, irritability. There are memory impairments that are directly dependent on the cyclical nature of emotional states. The rhythm of sleep and wakefulness is disturbed, hypnotic states develop with the appearance of hypnotic representations, which, in contrast to the sleepy states that occur in normal conditions, are delayed for a relatively long time, projected outward and accompanied by the illusion of involuntariness. The more severe the conditions of S. d., the faster the processes of thinking are disrupted, which manifests itself in the inability to concentrate on anything, consistently think over problems, appear
The sensation arises as a reaction of the nervous system to a particular stimulus and has a reflex character. The physiological basis of sensation is a nervous process that occurs when a stimulus acts on an adequate receptor,
The analyzer consists of three sections:
peripheral department (receptor), which is a special transformer of external energy into the nervous process;
afferent (centripetal) and efferent( centrifugal) nerves - pathways connecting the peripheral section of the analyzer with the central one;
subcortical and cortical regions (brain end) of the analyzer, where the processing of nerve impulses coming from the peripheral regions takes place.
For a sensation to arise, the work of the entire analyzer as a whole is necessary.
The impact of the stimulus on the receptor causes the appearance of irritation. The beginning of this irritation is expressed in the transformation of external energy into a nervous process, which is produced by the receptor. From the receptor, this process along the centripetal nerve reaches the central part of the analyzer. When excitation reaches the cortical cells of the analyzer, the body responds to irritation and we feel light, sound, taste, or other qualities of the stimulus.
1-receptor; 2-central link; 3 effector; 4- afferent nerve pathway; 5- efferent nerve pathway; 6-7 - feedback channel: 1-4-2 - analyzer circuit; 1-4-2-5-3 - scheme of the reflex arc; 1-4-2-5-3-6-7 - diagram of the reflex ring.
Classification of sensations
According to the nature of the reflection and the location of the receptors, it is customary to divide sensations into three groups:
exteroceptive, reflective properties of objects or phenomena external environment and having receptors on the surface bodies:
interoceptive, having receptors located in internal organs and tissues of the body and reflecting the state internal organs.
proprioceptive- receptors are located in muscles and ligaments: they give information about movement and position our body in space.
Exteroceptive sensations are divided into contact and remote:
Contact receptors transmit stimuli immediate contact with objects affecting them ( tactile and gustatory receptors).
distant receptors respond to stimuli from distant objects
(visual, auditory. olfactory receptors).
Part touch are included, along with tactile sensations (sensation of touch) temperature, regulating the process of thermoregulation and heat exchange between the body and the environment. play an important role in human life vibrating sensations, sensations balance and acceleration, pain, muscular-articular, static-dynamic.
General properties sensations
Quality- this is the main feature of a daily sensation, which distinguishes it from other types of sensations and varies within the limits of a given type of sensation.
Intensity- the quantitative characteristic of sensation is determined by the strength of the acting stimulus and the functional state of the receptor.
Duration- temporal characteristic, determined by the time of action of the stimulus and its intensity.
When a stimulus is exposed to the sense organs, sensation does not occur immediately, but after some time - the so-called latent (hidden) period of sensation. The latent period of various types of sensations is not the same: for tactile sensations it is 130 ms. for pain - 370 ms, and for taste - only 50 ms.
Spatial localization stimulus - a property of sensation that gives a person information about the localization of the stimulus in space. Contact sensations are related to the part of the body that is affected by the stimulus.
Patterns of sensations
Thresholds of sensations.
The minimum value of the stimulus at which a sensation first occurs is called absolute threshold of sensation.
So, we do not feel individual dust particles falling on the surface of our body.
The value of the absolute threshold characterizes absolute sensitivity sense organs.
The weaker the stimuli that cause sensations (small value of the absolute threshold), the higher the ability of the sense organs to respond to these influences.
The average values of the absolute thresholds for the occurrence of sensations for different human senses
There is a concept relative or differential sensitivity- sensitivity to a change in the stimulus.
The smallest difference between two stimuli that causes a barely perceptible difference in sensations is called differential threshold or discrimination threshold,
This means that the ratio of the additional stimulus to the main stimulus is a constant value. The greater the magnitude of the initial stimulus, the greater must be the addition to it in order to cause the sensation of a change in the magnitude of the stimulus. For the visual analyzer, this ratio is 0.001; for auditory - 0.1; for tactile - 0.3.
Adaptation.
The change in the sensitivity of the analyzer, depending on the environmental conditions is called adaptation sense organs to the environment.
So. The sensitivity of the eye during the transition from bright to dark illumination increases 200,000 times. Also known as auditory. temperature, taste and other types of adaptation.
There are 3 varieties of the phenomenon of adaptation.
adaptation as the complete disappearance of sensation during prolonged action of the stimulus.
Adaptation as a dulling of sensation under the influence of a strong stimulus.
Adaptation as an increase in sensitivity under the influence of a weak stimulus.
9.4.3 The interaction of sensations.
The intensity of sensations depends not only on the strength of the stimulus and the level of adaptation of the receptor, but also on the stimuli currently affecting other sense organs.
Increased sensitivity as a result of the interaction of analyzers and exercises called sensitization.
The appearance under the influence of irritation of one analyzer of a sensation characteristic of other analyzers is called synesthesia.
There are people with "colored" hearing. It is widely known that we consider high sounds as "light" and low sounds as "dark"
Topic 10 Perception.
Perception- this is a cognitive mental process of reflection of those acting in this moment on the sense organs of objects and phenomena of reality in the aggregate of their various properties and parts.
The physiological basis of sensations
Introduction
2. The concept of sensation
3. Physiology of sensations
3.1 Analyzers
3.2 Properties of sensations
3.3 Classification of sensations
4. Types of sensations
4.1 Vision
4.3 Vibratory sensations
4.4 Smell
4.7 Proprioceptive sensitivity
Bibliography
Introduction
It is known that a personality is realized in activities that are possible due to cognition. environment. In ensuring the interaction of a person with the outside world, the leading role is played by the properties of the personality, its motives, attitudes. However, any mental phenomenon is both a reflection of reality and a link in the regulation of activity. The regulation of activity begins already at the level of sensations and perceptions - from mental cognitive processes. Sensations, perceptions, representations, memory belong to sensory forms of knowledge. Sensual reflection in a person is always associated with logical knowledge, thinking. The individual in human sensory cognition is reflected as a manifestation of the general. In sensory cognition, an essential role is played by language, the word, which always performs the function of generalization. In turn, logical cognition (thinking) is based on the data of sensory experience, on sensations, perception and memory representations. In a single process of cognition, a continuous interaction of all cognitive processes is carried out. More complex cognitive processes are based on sensations: perceptions, ideas, memory, thinking, imagination. Otherwise, except through sensations, we cannot learn anything about any forms of movement. Sensation is the simplest, further indecomposable mental process. The sensations reflect the objective qualities of the object (smell, color, taste, temperature, etc.) and the intensity of the stimuli affecting us (for example, a higher or lower temperature).
1. Sensory organization of personality
The sensory organization of the personality is the level of development of individual systems of sensitivity and the possibility of their association. The sensory systems of a person are his sense organs, as if receivers of his sensations, in which sensation is transformed into perception. Every receiver has a certain sensitivity. If we turn to the animal world, we will see that the predominant level of sensitivity of any species is a generic trait. For example, bats have developed sensitivity to the perception of short ultrasonic pulses, dogs have olfactory sensitivity. The main feature of the sensory organization of a person is that it develops as a result of all his life path. The sensitivity of a person is given to him at birth, but its development depends on the circumstances, desire and efforts of the person himself.
2. The concept of sensation
Sensation is a manifestation of the general biological property of living matter - sensitivity. Through sensation there is a psychic connection with the external and inner world. Thanks to sensations, information about all the phenomena of the external world is delivered to the brain. In the same way, a loop is closed through sensations to receive feedback about the current physical and partly mental state organism. Through sensations, we learn about taste, smell, color, sound, movement, the state of our internal organs, etc. From these sensations, holistic perceptions of objects and the whole world are formed. It is obvious that in human sensory systems there is a primary cognitive process and already on its basis, cognitive processes that are more complex in their structure arise: perceptions, ideas, memory, thinking. No matter how simple the primary cognitive process may be, but it is precisely this that is the basis of mental activity, it penetrates into our consciousness only through the “entrances” of sensory systems. the world.
2.1 Processing sensations
After the information is received by the brain, the result of its processing is the development of a response or strategy aimed, for example, at improving physical tone, focusing more on current activities, or setting up for accelerated inclusion in mental activity. Generally speaking, the response or strategy worked out at any given time is the best choice of the options available to the person at the time of making the decision. However, it is clear that the number of options available and the quality of choice are different for different people and depend, for example, on: - mental properties of the personality; - Strategies for relationships with others; - partly physical condition; - experience, the availability of the necessary information in memory and the possibility of retrieving it; - degree of development and organization of higher nervous processes etc.
3. Physiology of sensations
3.1 Analyzers
Physiological mechanism sensations is the activity of the nervous apparatus - analyzers, consisting of 3 parts: - receptor - the perceiving part of the analyzer (carries out the transformation of external energy into a nervous process); - the central section of the analyzer - afferent or sensory nerves; - cortical sections of the analyzer, in which the processing of nerve impulses takes place. Certain receptors correspond to their sections of cortical cells. The specialization of each sense organ is based not only on the structural features of the receptor analyzers, but also on the specialization of the neurons that make up the central nervous apparatus, which receive signals perceived by the peripheral senses. The analyzer is not a passive receiver of energy; it is reflexively rebuilt under the influence of stimuli.
According to certain principles and containing the observer himself as one of the elements under study. Unlike sensation, in perception the image of a holistic object is formed by reflecting the totality of its properties. The process of perception includes such complex mechanisms as memory and thinking. Therefore, perception is called the human perceptual system. Perception is the result...
The human body, the integrity of the sensory reflection of the objective world. An increase in sensitivity as a result of the interaction of analyzers and exercise is called sensitization. The physiological mechanism of the interaction of sensations is the processes of irradiation and concentration of excitation in the cerebral cortex, where the central sections of the analyzers are represented. According to I.P. Pavlova, weak...
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PHYSIOLOGICAL BASES OF SENSATIONS. THE CONCEPT OF THE ANALYZER.
All living beings have the ability to feel. nervous system. As for conscious sensations (about the source and quality of which an account is given), only a person has them. In the evolution of living beings, sensations arose on the basis of primary irritability, which is a property of living matter to respond to biologically significant impacts environment by changing your internal state and outward behavior.
In their origin, from the very beginning, sensations were associated with the activity of the organism, with the need to satisfy its biological needs. The vital role of sensations is to timely bring to the central nervous system (as the main organ for managing human activity and behavior) information about the state of the external and internal environment, the presence of biologically significant factors in it. Sensation, in contrast to irritability, carries information about certain qualities of external influence.
A person's sensations in their quality and diversity reflect the diversity of the properties of the environment that are significant for him. The sense organs, or human analyzers, from the moment of birth are adapted for the perception and processing of various types of energy in the form of stimuli-stimuli (physical, mechanical, chemical, and others). Stimulus- any factor that affects the body and can cause any reaction in it.
It is necessary to distinguish between stimuli that are adequate for a given sense organ and those that are not adequate for it. This fact indicates a fine specialization of the sense organs to reflect one or another type of energy, certain properties objects and phenomena of reality. The specialization of the sense organs is a product of a long evolution, and the sense organs themselves are products of adaptation to the influences of the external environment, therefore, in their structure and properties, they are adequate to these influences.
In humans, subtle differentiation in the field of sensations is associated with historical development human society and social work practices. “Serving” the processes of adaptation of the organism to the environment, the sense organs can successfully perform their function only if they correctly reflect its objective properties. Thus, the non-specificity of the sense organs gives rise to the specificity of sensations, and the specific qualities of the external world gave rise to the specificity of the sense organs. Sensations are not symbols, hieroglyphs, but reflect the actual properties of objects and phenomena of the material world that act on the senses of the subject, but exist independently of him.
Sensation arises as a reaction of the nervous system to a particular stimulus and, like any mental phenomenon, has a reflex character. Reaction The body's response to a specific stimulus.
The physiological basis of sensation is a nervous process that occurs when a stimulus acts on an analyzer adequate to it. Analyzer- a concept (according to Pavlov), denoting a set of afferent and efferent nervous structures involved in the perception, processing and response to stimuli.
efferent is a process directed from the inside out, from the central nervous system to the periphery of the body.
Afferent- a concept that characterizes the course of the process of nervous excitation through the nervous system in the direction from the periphery of the body to the brain.
The analyzer consists of three parts:
1. Peripheral department ( or receptor), which is a special transformer of external energy into the nervous process. There are two types of receptors: contact receptors- receptors that transmit irritation by direct contact with objects that act on them, and distant receptors- receptors that respond to stimuli emanating from a distant object.
2. Afferent (centripetal) and efferent (centrifugal) nerves, conducting paths connecting the peripheral section of the analyzer with the central one.
3. Subcortical and cortical sections (brain end) of the analyzer, where the processing of nerve impulses coming from the peripheral sections takes place (see Fig. 1).
In the cortical region of each analyzer is analyzer core, i.e. the central part, where the main mass of receptor cells is concentrated, and the periphery, consisting of scattered cellular elements, which are located in one quantity or another in various areas of the cortex.
The nuclear part of the analyzer consists of a large mass of cells that are located in the area of the cerebral cortex where the centripetal nerves from the receptor enter. Scattered (peripheral) elements of this analyzer enter the regions adjacent to the nuclei of other analyzers. This ensures participation in a separate act of sensation of a large part of the entire cerebral cortex. The analyzer core performs the function of fine analysis and synthesis, for example, it differentiates sounds by pitch. Scattered elements are associated with rough analysis functions, such as distinguishing between musical sounds and noises.
Certain cells of the peripheral parts of the analyzer correspond to certain parts of the cortical cells. So, spatially different points in the cortex are, for example, different points of the retina; spatially different arrangement of cells is presented in the cortex and the organ of hearing. The same applies to other sense organs.
Numerous experiments carried out by methods of artificial stimulation now make it possible to quite definitely establish the localization in the cortex of certain types of sensitivity. Thus, the representation of visual sensitivity is concentrated mainly in the occipital lobes of the cerebral cortex. Auditory sensitivity is localized in the middle part of the superior temporal gyrus. Tactile-motor sensitivity is represented in the posterior central gyrus, etc.
For the sensation to arise, the work of the entire analyzer as a whole is necessary. The impact of the stimulus on the receptor causes the appearance of irritation. The beginning of this irritation lies in the transformation of external energy into a nervous process, which is produced by the receptor. From the receptor, this process along the centripetal nerve reaches the nuclear part of the analyzer located in the spinal cord or brain. When the excitation reaches the cortical cells of the analyzer, we feel the qualities of the stimuli, and after this, the body's response to the irritation occurs.
If the signal is due to a stimulus that threatens to cause damage to the body, or is addressed to the autonomic nervous system, then it is very likely that it will immediately cause a reflex reaction emanating from the spinal cord or other lower center, and this will happen before we are aware of this effect ( reflex- an automatic response of the body to the action of any internal or external stimulus).
Our hand pulls back when burned by a cigarette, the pupil constricts in bright light, salivary glands start to salivate if you put a lollipop in your mouth, and all this happens before our brain decodes the signal and gives the appropriate order. The survival of an organism often depends on the short neural circuits that make up the reflex arc.
If the signal continues down the spinal cord, then it takes two different paths: one leads to the cerebral cortex via thalamus, and the other, more diffuse, passes through filter reticular formation , which keeps the cortex awake and decides whether the signal transmitted directly is important enough for the cortex to “engage” in deciphering it. If the signal is considered important, a complex process will begin, which will lead to a sensation in the truest sense of the word. This process involves changing the activity of many thousands of cortical neurons, which will have to structure and organize the sensory signal in order to give it meaning. ( Sensory- associated with the work of the senses).
First of all, the attention of the cerebral cortex to the stimulus will now entail a series of movements of the eyes, head or torso. This will allow you to get acquainted with the information coming from sensory organ- the primary source of this signal, and also, possibly, connect other senses. As new information becomes available, it will be associated with traces of similar events stored in memory.
Between the receptor and the brain there is not only a direct (centripetal), but also a reverse (centrifugal) connection. The feedback principle discovered by I.M. Sechenov, requires the recognition that the sense organ is alternately both a receptor and an effector.
Thus, sensation is not only the result of a centripetal process; it is based on a complete and complex reflex act, which in its formation and course obeys the general laws of reflex activity. In this case, the analyzer constitutes the initial and most important part of the entire path of nervous processes, or the reflex arc.
reflex arc- a concept denoting a set of nervous structures that conduct nerve impulses from stimuli located on the periphery of the body to the center , processing them in the central nervous system and causing a reaction to the corresponding stimuli.
The reflex arc consists of a receptor, pathways, a central part, and an effector. The relationship of the elements of the reflex arc provides the basis for the orientation of a complex organism in the surrounding world, the activity of the organism, depending on the conditions of its existence.
Figure 2 shows a variant of the action of a human reflex arc in the event of a mosquito bite (according to J. Godefroy).
The signal from the receptor (1) is sent to the spinal cord (2) and the reflex arc turned on can cause hand withdrawal (3). The signal, meanwhile, goes further to the brain (4), heading along straight path to the thalamus and cortex (5) and indirectly to the reticular formation (6). The latter activates the cortex (7) and prompts it to pay attention to the signal it has just become aware of. Attention to the signal is manifested in the movements of the head and eyes (8), which leads to the recognition of the stimulus (9), and then to the programming of the reaction of the other hand in order to “drive away the unwanted guest” (10).
The dynamics of the processes occurring in the reflex arc is a kind of likening to the properties of an external influence. For example, touch is just such a process in which hand movements repeat the outlines of a given object, as if becoming like its structure. The eye operates on the same principle due to the combination of the activity of its optical “device” with oculomotor reactions. The movements of the vocal cords also reproduce the objective pitch nature. When the vocal-motor link was turned off in the experiments, the phenomenon of a kind of pitch deafness inevitably arose. Thus, due to the combination of sensory and motor components, the sensory (analyzing) apparatus reproduces the objective properties of the stimuli acting on the receptor and is likened to their nature.
Numerous and versatile studies on the participation of effector processes in the occurrence of sensation have led to the conclusion that sensation as a mental phenomenon is impossible in the absence of an organism's response or its inadequacy. In this sense, the fixed eye is as blind as the fixed hand ceases to be an instrument of knowledge. The sense organs are closely connected with the organs of movement, which perform not only adaptive, executive functions, but also directly participate in the processes of obtaining information.
Thus, the connection between touch and movement is obvious. Both functions are merged in one organ - the hand. At the same time, the difference between the executive and groping movements of the hand is also obvious (Russian physiologist, author of the doctrine of higher nervous activity) I.P. Pavlov called the latter orienting-exploratory reactions related to a special type of behavior - perceptual rather than executive behavior. Such perceptual regulation is aimed at enhancing the input of information, optimizing the process of sensation. All this suggests that for the emergence of a sensation it is not enough that the organism is subjected to the corresponding action of a material stimulus, but some work of the organism itself is also necessary. This work can be expressed as internal processes, as well as in external movements.
In addition to the fact that the sense organs are a kind of “window” for a person into the world around them, they are, in fact, energy filters through which the corresponding changes in the environment pass. By what principle is the selection of useful information in sensations carried out? In part, we have already touched on this issue. To date, several hypotheses have been formulated.
According to the first hypothesis, there are mechanisms for detecting and passing restricted signal classes, with messages not matching those classes being rejected. The task of such selection is performed by comparison mechanisms. For example, in insects, these mechanisms are involved in solving the difficult task of finding a partner of their own species. "Winks" of fireflies, "ritual dances" of butterflies, etc. - all these are genetically fixed chains of reflexes that follow one after another. Each stage of such a chain is sequentially solved by insects in a binary system: “yes” - “no”. Not the movement of the female, not the spot of color, not the pattern on the wings, not the way she “answered” in the dance - it means that the female is alien, of a different species. The stages form a hierarchical sequence: the beginning of a new stage is possible only after the previous question is answered “yes”.
Second hypothesis suggests that the acceptance or non-acceptance of messages can be regulated on the basis of special criteria, which, in particular, represent the needs of a living being. All animals are usually surrounded by a "sea" of stimuli to which they are sensitive. However, most living organisms respond only to those stimuli that are directly related to the needs of the organism. Hunger, thirst, readiness for mating, or some other internal attraction can be the regulators, the criteria by which the selection of stimulus energy is carried out.
According to the third hypothesis, the selection of information in sensations occurs on the basis of the criterion of novelty. Under the action of a constant stimulus, the sensitivity seems to be dulled and the signals from the receptors cease to flow to the central nervous apparatus ( sensitivity- the ability of the body to respond to environmental influences that do not have a direct biological significance, but causing a psychological reaction in the form of sensations). Thus, the sensation of touch tends to fade away. It can completely disappear if the irritant suddenly stops moving across the skin. Sensitive nerve endings signal the brain that irritation is present only when the strength of the stimulation changes, even if the time during which it presses harder or weaker on the skin is very short.
The same is true with hearing. It has been found that the singer needs vibrato, a slight fluctuation in pitch, to control his own voice and to keep it at the right pitch. Without stimulation of these deliberate variations, the singer's brain does not notice the gradual changes in pitch.
The visual analyzer is also characterized by the extinction of the orienting reaction to a constant stimulus. The visual sensory field, it would seem, is free from the obligatory connection with the reflection of movement. Meanwhile, the data of the genetic psychophysiology of vision show that the initial stage of visual sensations was precisely the display of the movement of objects. The compound eyes of insects work effectively only when exposed to moving stimuli.
This is the case not only in invertebrates, but also in vertebrates. It is known, for example, that the retina of a frog, described as a “detector of insects,” reacts precisely to the movement of the latter. If there is no moving object in the frog's field of vision, its eyes do not send essential information to the brain. Therefore, even being surrounded by many motionless insects, the frog can die of hunger.
The facts testifying to the extinction of the orienting reaction to a constant stimulus were obtained in the experiments of E.N. Sokolov. The nervous system finely models the properties external objects acting on the sense organs, creating their neural models. These models perform the function of a selectively acting filter. If the stimulus acting on the receptor at the moment does not coincide with the previously established nervous model, impulses of mismatch appear, causing an orienting reaction. Conversely, the orienting reaction fades to the stimulus that was previously used in the experiments.
Thus, the process of sensation is carried out as a system of sensory actions aimed at the selection and transformation of the specific energy of external influence and providing an adequate reflection of the surrounding world.
Sensation is a reflection of the properties of objects of the objective world, arising from their direct impact on the sense organs, this is, firstly, the initial moment of the sensorimotor reaction; secondly, the result of conscious activity.
The emergence of sensation is directly related to the work of human receptors. A receptor is an organ specially adapted for the reception of stimuli; it is more easily irritated than other organs or nerve fibers; its sensitivity is especially high. In addition, each receptor is specialized in relation to a particular stimulus.
In the process of biological evolution, the sense organs themselves were formed in the real relationship of the organism with the environment, under the influence of the outside world. The impact of the outside world forms the receptors themselves. Receptors are, as it were, anatomically fixed in the structure of the nervous system, imprints of the effects of irritation processes.
In sensation, absolute and differential thresholds are distinguished. Not every stimulus causes a sensation, but only one whose intensity has overcome the threshold of sensation. This minimum stimulus intensity at which a sensation occurs is called the lower absolute threshold. Along with the lower, there is also an upper absolute threshold, i.e. the maximum intensity possible to experience a given quality.
The thresholds of sensitivity are significantly shifted depending on the attitude of a person to the task that he solves.
For the sensitivity of an organ, its physiological state is also important. The significance of physiological moments is manifested primarily in the phenomena of adaptation, in the adaptation of an organ to a long-acting stimulus. The phenomenon of contrast is also associated with adaptation, which is associated with a change in sensitivity under the influence of a previous (or accompanying) stimulus.
Differentiation and specialization of receptors does not exclude their interaction, which is expressed in the effect that stimulation of one receptor has on the thresholds of another.
Classification of sensations
organic sensations. Organic sensations include sensations of hunger, thirst, sensations coming from the cardiovascular, respiratory and reproductive systems of the body, and all sensations associated with the state of the human body.
All organic sensations have a number of common features:
They are usually associated with organic needs, which are usually first reflected in consciousness through organic sensations.
All organic sensations are more or less brightly colored.
Organic sensations, reflecting needs, are usually associated with motor impulses and are interconnected in a psychomotor unity.
Static sensations. These are sensations associated with indications of the position of our body in space, its posture, passive and active movements of the body. The central organ that regulates the balance of the body in space is the vestibular apparatus.
kinesthetic sensations. Sensations of movement of various parts of the body are caused by excitations coming from proprioreceptors located in the joints, ligaments and muscles. Through kinesthetic sensations, a person can determine the position and movement of their body parts. Impulses entering the central nervous system from proprioceptors due to changes that occur during movement in the muscles cause reflex reactions and play a significant role in muscle tone and coordination of movements.
Skin sensitivity. Skin sensitivity is subdivided by the classical physiology of the sense organs into 4 types. These are the receptions of pain, heat, cold and touch (pressure). It is assumed that each of these types of sensitivity also has specific receptors.
Touch. Touch includes sensations of touch and pressure in unity with kinesthetic, muscular-articular sensations. The proprioceptive components of touch come from receptors located in muscles, ligaments, and articular bags. When moving, they are irritated by a change in voltage.
Olfactory sensations. Olfactory sensations arise when molecules of various substances enter the nasal cavity together with the inhaled air and are transmitted to the central nervous system through the olfactory receptor.
Taste sensations. Taste sensations, like olfactory sensations, are chemical properties substances. Taste sensations are important role in setup emotional state human, their role is determined by the state of the body's need for food. Arise through the taste receptor, the peripheral part of which is located in the oral cavity.
Auditory sensations. Auditory sensations are a reflection of sound waves affecting the auditory receptor, which are generated by the sounding body and represent a variable condensation and rarefaction of air.
visual sensations. Visual sensations are caused by exposure to the visual analyzer of a light wave, which differ in length and frequency of oscillations.