Neurophysiological mechanisms of perception of attention and memory. Neurophysiological mechanisms and age-related characteristics of emotions. Differences between conditioned reflexes and unconditioned ones

Perception- a cognitive process that forms a subjective picture of the world. This is a reflection in the human brain of a holistic image of an object. A person perceives isolated sensations about an object as a whole. The activity of the information selection system occurs with the help of attention.

Properties of perception

Objectivity - objects are perceived not as an incoherent set of sensations, but constitute images of specific objects.

Structurality - an object is perceived by consciousness as a modeled structure abstracted from sensations.

Apperception - perception is influenced by the general content of the human psyche.

Contact (constancy) - perception is influenced by the circumstances in which it occurs. But despite this, the perception remains relatively unchanged.

Activity - at any given time we perceive only one object. The nature of the activity of perception is determined by the very nature of our consciousness.

Meaningfulness - an object is consciously perceived, mentally named (associated with a certain category), belongs to a certain class

Perception factors

External: size, intensity (physical or emotional), contrast (contradiction with the environment), movement, repetition, novelty and recognition

Internal:

The perceptual setting is the expectation to see what should be seen based on past experience. Needs and motivation - a person sees what he needs or what he considers important. Experience - a person perceives that aspect of a stimulus that is taught by past experience. Self-concept - the perception of the world is grouped around the perception of oneself. Personal characteristics - optimists see the world and events in a positive light, pessimists, on the contrary, in an unfavorable one.

Three mechanisms of perception selectivity: The principle of resonance - what corresponds to the needs and values of the individual is perceived faster than what does not correspond. The principle of protection is that something that opposes a person’s expectations is perceived worse. The principle of vigilance - what threatens a person’s psyche is recognized faster than others.

Attention

Attention- a factor that guides the selection of information for perception. Attention can be stable and unstable. Sustained attention can be strengthened by training and willpower. There is a distinction between conscious and unconscious attention. The biological basis of unconscious attention is the orienting reflex. It occurs when an important or new stimulus occurs. Conscious attention is actively maintained.

The physiological mechanism of attention is complex. Pavlov’s discovery of the optimal focus of excitation, which has an average intensity, but is the most favorable in the given conditions of the body’s vital activity, helps to understand it. According to the law of negative mutual induction, it extinguishes other sources of excitation in the cerebral cortex. The focus of optimal arousal is dynamic. A.A. Ukhtomsky created the doctrine of the dominant. The dominant (the dominant focus of excitation) is more stable. It not only inhibits newly emerging foci of excitation, but is also able to intensify them. However, both types of foci of excitation do not fully explain the mechanism of human attention, because a person is able to control his attention.

The most important property of the nervous system is memory- the ability to accumulate, store and reproduce incoming information. The accumulation of information occurs in several stages.

In accordance with the stages of memorization, it is customary to distinguish short-term and long-term memory. If information stored in short-term memory (for example, a phone number just read or heard) is not transferred to long-term memory, it is quickly erased. In long-term memory, information is stored for a long time in a form accessible for retrieval. Memory traces, or engrams, are strengthened each time they are retrieved. The process of strengthening engrams as they are reproduced is called consolidation of memory traces. It is assumed that the mechanisms of short-term and long-term memory are different. Short-term, or operational, memory is associated with information processing in neural networks; it is assumed that its mechanism may be the circulation of impulse flows along closed neural circuits. Long-term memory is apparently associated with complex processes of protein synthesis in neurons higher departments CNS. Memorizing, storing and retrieving the most relevant information from memory at a given moment is the result of a complex dynamic interaction of various brain structures.

Neurons from various areas of the cortex, limbic system and thalamus take part in the operations of imprinting and retrieving memory traces. Clinical observations have shown that when one of the main parts of the limbic system, the hippocampus, is damaged, memory for recent events is lost, but memory for the long past is preserved.

The activity of neurons in the posterior associative cortex is closely related to the storage and retrieval of memory traces. When the temporal lobe is irritated during surgery, clear pictures of the past appear, accurately reproducing the setting of the recalled event. A qualitative feature of human memory, which distinguishes it from the memory of animals, even higher primates, is that a person is able to remember not so much all the details of information as general provisions. In a text read, an adult remembers not the verbal formulation, but the content. This is a verbal-logical abstract memory characteristic of humans.

Memory mechanisms undergo significant changes with age. Memory based on storing traces of excitation in the system conditioned reflexes, is formed in the early stages of development. The relative simplicity of the memory system in childhood determines the stability and strength of conditioned reflexes developed in early childhood. As the brain matures structurally and functionally, the memory system becomes significantly more complex. This may lead to uneven and ambiguous changes in memory performance with age. Yes, in the younger school age The memory volume significantly increases, and the speed of memorization decreases, then increasing towards adolescence. The maturation of higher cortical formations with age determines the gradual development and improvement of verbal-logical abstract memory.

3.9. Neurophysiological mechanisms of perception,
attention, motivation and emotions

The process of perception plays a vital role in ensuring contacts with the external environment and in the formation of cognitive activity. Perception- a complex active process, including analysis and synthesis of incoming information. Various areas of the cortex take part in the process of perception, each of which is specialized in the operations of receiving, analyzing, processing and evaluating incoming information. In the primary projection cortical zones (the cortical end of the analyzer, according to I.P. Pavlov), the reception and analysis of individual signal features occurs. In secondary projection zones, information coming from certain analyzers is synthesized into complex sensory complexes. In the overlapping areas of analyzers - associative areas of the cortex - excitation coming from different analyzers is integrated and compared with a standard formed on the basis of past experience. In these areas, a comprehensive assessment of incoming information is carried out, a decision is made about its nature, and the stimulus is recognized and its significance is determined.

The gradual and non-simultaneous maturation of cortical areas in the process of ontogenesis determine the essential features of the process of perception in different age periods. A certain degree of maturity of the primary projection cortical zones by the time the child is born creates the conditions for the reception of information at the level of the cerebral cortex and the elementary analysis of qualitative characteristics of the signal already in the newborn period. It has been established that newborns are able to distinguish objects from the surrounding background. They fix their gaze on one of the elements of the presented image. During the first months of life, the analysis of sensory stimuli in the projection cortex becomes more difficult. EEG studies of the formation of visual perception have shown a significant complication of the cortical response to the afferent stimulus of the so-called evoked potential (EP), the presence of which has been noted in newborns. By 2-3 months, the resolution of the visual analyzer sharply increases. Periods of rapid development of visual function are characterized by high plasticity and increased sensitivity to environmental factors. They are considered as sensitive periods of development, sensitive to directed developmental influences. This indicates the need for an early start to sensory education.

According to I.M. Sechenov’s definition, a newborn “sees, but does not know how to see.” Perception and creation of an image of an object is associated with the function of associative areas. As they mature, they begin to be included in the analysis of incoming information. In early childhood up to 3-4 years of age inclusive, association zones duplicate the function of the projection cortex. The responses they evoke in form, timing and reactivity correspond to the responses of the projection zone.

A qualitative leap in the formation of the perceptual system was noted after 5 years. By the age of 5-6 years, the posterior associative zones are specializedly involved in the process of recognizing complex images, and in the projection cortex a simpler analysis is carried out, for example, isolating contour and contrast. At this age, it becomes much easier to recognize complex, previously unfamiliar objects and compare them with a standard. This gives grounds to consider preschool age as a sensitive (especially sensitive) period in the development of visual perception. Clinical observations have shown that cataracts - clouding of the lens of the eye that occurs in a child under 5-6 years of age, leads to irreversible impairment of visual function.

At school age, the visual perception system continues to become more complex and improved due to the inclusion of frontal associative areas. These areas, responsible for making decisions, assessing the significance of incoming information and organizing an adequate response, ensure the formation of voluntary selective perception. Significant changes in selective response, taking into account the significance of the stimulus, were noted by the age of 10-11 years. The insufficiency of this process in the primary grades causes difficulty in highlighting the main significant information and distraction by unimportant details. Structural and functional maturation of the frontal areas continues in adolescence and determines the improvement of the systemic organization of the perception process. The final stage of development of the perceiving system provides optimal conditions for an adequate response to external influences.

Attention is one of the most important psychophysiological functions that ensure optimization of the processes of education and training. Just like perception, attention is a complex systemic act in which various brain structures take part. Attention increases the level of activation of the cerebral cortex. The system of structures involved in this process includes structures that cause generalized activation of the cerebral cortex - the reticular formation of the midbrain, local activation - the limbic system and the higher cortical centers of regulation and control - the frontal areas of the cerebral cortex. Generalized activation mediates involuntary attention processes. The implementation of voluntary attention is associated with the mechanisms of local activation. There is a close two-way connection between the processes of attention and perception. On the one hand, attention, activating certain areas of the cerebral cortex, optimizes perception and creates conditions for the selective inclusion of different areas of the cortex in this process. On the other hand, attention is carried out on the basis of analysis and processing of all incoming information. Therefore, the formation of the attention process with age is associated both with the structural and functional maturation of the activating system of the brain, and with the maturation of cortical structures involved in the analysis and processing of information.

Signs of involuntary attention are detected already in the newborn period in the form of an elementary indicative reaction to the emergency use of a stimulus. This reaction is still devoid of a characteristic research component, but it is already manifested in certain changes in the electrical activity of the brain and autonomic reactions (changes in breathing, heart rate). The critical period in the formation of involuntary attention is 2-3 months of age, when the indicative reaction acquires features of an exploratory nature. In infancy, as well as in preschool age, cortical generalized activation is represented by an increase in the theta rhythm, reflecting increased activity of structures associated with emotions. Features of activation processes determine the specifics of voluntary attention at this age - the attention of a small child is attracted mainly by emotional stimuli. As the speech perception system develops, a social form of attention is formed, mediated by speech instructions. However, up to the age of five, this form of attention is easily pushed aside by involuntary attention that arises to new attractive stimuli.

Significant changes in cortical activation underlying attention were noted at 6-7 years of age. A mature form of cortical activation is detected in the form of a generalized blockade of the alpha rhythm. The role of speech instructions in the formation of voluntary attention increases significantly. At the same time, at this age the importance of the emotional factor is still great.

Qualitative changes in the formation of neurophysiological mechanisms of attention were noted at 9-10 years of age. Structural and functional maturation of the frontal areas of the cortex ensures the organization of processes of local regulated activation in accordance with decision-making based on analyzed information or verbal instructions. As a result of this, certain brain structures are selectively included in activity, the activity of others is inhibited, and conditions are created for the most economical and adaptive response.

At the beginning of adolescence (12-13 years), neuroendocrine changes associated with the onset of puberty lead to changes in cortical-subcortical interaction, weakening of cortical regulatory influences on activation processes - attention is weakened, mechanisms of voluntary regulation of function are disrupted.
By the end of adolescence, with the completion of puberty, the neurophysiological mechanisms of attention correspond to those of an adult.

Motivation- active states of brain structures that encourage you to perform actions (acts of behavior) aimed at satisfying your needs. Motivations create the necessary prerequisites for behavior. Motivation can be created both by biological needs (for example, food motivation) and by higher cognitive needs. Any information, before behavior is organized, is compared with the currently dominant motivation. A well-fed animal cannot develop a conditioned food reflex, because it has no food motivation. Emotions are inextricably linked with motivation. Achieving a goal and satisfying a need causes positive emotions. Failure to achieve goals leads to negative emotions. One of the most important human needs is the need for information. This source of positive emotions is inexhaustible throughout a person’s life.

In the formation of motivations and emotions, an important role belongs to the limbic system of the brain, which includes structures of different parts of the brain. The functions of the limbic system are diverse.
When the hypothalamus and amygdala are irritated by electric current or the cingulate gyrus is removed, animals exhibit reactions of rage and aggressive behavior (snorting, growling, dilated pupils, changes in heart rate). Bilateral destruction of the amygdala in rats causes a decrease in motor activity; reactions of rage and aggression cannot be observed. When the amygdala is destroyed in a person, for medical reasons, emotional activity such as fear, anger, and rage decreases. The activity of limbic structures is regulated by the frontal parts of the cerebral cortex, the function of which is associated with the formation of higher cognitive needs and the regulation of emotional state based on information analyzed in the cerebral cortex and assessment of its significance.

Emotions change the state of the entire organism. Negative emotions have a bad effect on health and depress a person: he becomes lethargic, absent-minded, and apathetic. A sharp expression of negative emotions - crying. Positive emotions, the expression of which is a smile and laughter, increase the intensity of energy processes. Accordingly, the potential capabilities of the body increase. The intellectual sphere works more subtly, the influences of the external environment are especially clearly perceived, and memory is facilitated. The role of emotions is especially great in childhood, when processes of cortical emotional activation dominate. Children have a very high need for novelty. Satisfying the need for novelty promotes positive emotions, which, in turn, stimulate the activity of the central nervous system. According to P. V. Simonov, emotion, compensating for the lack of information necessary to achieve a goal, ensures the continuation of actions, promotes the search for new information and thereby increases the reliability of a living system. The close connection between emotions and needs determines the need to take into account the age-related characteristics of the child’s emotional sphere in the process of upbringing. Education can significantly influence even biological, innate needs, and change the degree and forms of their manifestation. The role of education is even greater in the formation of socially determined, including cognitive, needs. Expanding the scope of needs with the help of targeted educational activities that are closely related to emotions at the stage of development, which is characterized by increased emotional activation, will help expand the range of external influences that attract attention, and thereby lead to the improvement of cognitive processes and goal-directed activity of the child.

The maturation of the higher parts of the central nervous system at primary school age expands the possibility of developing cognitive needs and contributes to the improvement of emotion regulation. Children's emotions, due to the weakness of control on the part of the higher parts of the central nervous system, are unstable, their external manifestations are unrestrained. The child cries easily and quickly and can move from crying to laughter just as quickly. The child laughs loudly with joy, screams, and waves his arms. With age, restraint of emotional manifestations increases. Educational influences aimed at improving internal inhibition play a significant role in this. A child learns restraint from adults, and it is so important that adults set an example in this regard. When organizing the educational process, it should be taken into account that positive emotions increase general level the functioning of nervous structures in ensuring their mobilization readiness to perceive information from the outside world.

IN textbook presented modern concepts human ontogenesis, taking into account the latest achievements of anthropology, anatomy, physiology, biochemistry, neuro- and psychophysiology, etc. The morphofunctional characteristics of the child at the main stages are considered age development, their connection with the processes of socialization, including training and education. The book is illustrated with a large number of diagrams, tables, drawings that facilitate the assimilation of the material, and questions for self-test are offered.

Book:

Attention is one of the most important psychological functions. It is a prerequisite for the effectiveness of any activity, be it the perception of real objects and phenomena, the development of a motor skill, or operations with numbers, words, images performed in the mind.

There are two types of attention: voluntary (active), aimed at a consciously chosen goal, and involuntary (passive), which occurs during unexpected changes in the external environment - novelty, uncertainty.

Structural and functional organization of attention. Involuntary attention the mechanism is close to the orienting reaction; it occurs in response to a new or unexpected presentation of a stimulus. The initial situation of uncertainty requires mobilization readiness of the cerebral cortex, and the main mechanism that triggers involuntary attention is the involvement of the reticular modulating system of the brain in this process (see Fig. 55). The reticular formation, through ascending connections, causes generalized activation of the cerebral cortex, and the structures of the limbic complex, which evaluate the novelty of incoming information, as the signal is repeated, mediate either the extinction of the reaction or its transition to attention aimed at perception or organization of activity.

Voluntary attention depending on the specific tasks, needs, motivation facilitates, “optimizes” all stages of cognitive activity: initial - input of information, main central - its analysis and assessment of significance and the final result - fixation of new knowledge in individual experience, behavioral reaction, necessary motor actions.

At the stage of input and primary analysis of the stimulus, its allocation in space, an important role belongs to the motor components of attention - eye movements. Processes occurring at the level of the midbrain (quadrigeminal region) provide saccadic eye movements that place the object in the area of best vision on the retina. The implementation of this mechanism occurs with the participation of the posterior associative parietal cortex, which receives multimodal information from sensory zones (information component) and from the cortical part of the limbic system (motivational component). The descending influences of the cortex formed on this basis control the structures of the midbrain and optimize First stage perception.

Processing information about a stimulus that has a certain significance for the body requires maintaining attention and regulating activation influences. The control effect (local activation) is achieved by the regulatory influences of the frontal cortex. The implementation of local activating influences is carried out through the associative nuclei of the thalamus. This is the so-called frontothalamic attention system. In the mechanisms of local activation, a significant role also belongs to the structures of the limbic system (hippocampus, hypothalamus, amygdala, limbic cortex) and their connections with the frontal neocortex (see Fig. 56).

Activation of executive mechanisms, including motor programs and programs of innate and acquired behavior, is carried out with the participation of the frontal regions and basal ganglia, which are under dual control - the cortex and limbic brain.

Thus, voluntary selective attention is provided by entire complexes of hierarchically organized structures. As a result, activating influences become mediated by the results of situation analysis and significance assessment, which contributes to the formation of a system of activated brain centers that is adequate to the conditions of the task being performed.

EEG analysis of the brain organization of attention . In the EEG, with generalized tonic activation in response to the presentation of a new stimulus that caused involuntary attention, desynchronization of the main rhythm occurs (Fig. 62) - blockade of the mid-frequency alpha component, dominant at rest, and an increase in the representation of high-frequency oscillations in the alpha range, beta and gamma activity.

Rice. 62. Alpha rhythm blockade is a desynchronization reaction in the cerebral cortex upon the first presentation of a new stimulus - a tone (marked on the top line). The leads are indicated to the left of the curves (here and in subsequent figures, odd numbers are the left, even numbers are the right hemisphere). GSR - galvanic skin response

The significance of functional associations of structures during selective attention was demonstrated by studying the brain organization of directed modally specific attention in a situation of anticipation of a specific perceptual task. Information about the modality of the stimulus subject to binary classification, which the subject received in advance, led to the formation in the cortex of the left hemisphere of functional associations at the frequency of the alpha rhythm in the period immediately preceding perceptual activity, with the center of integration in the area of the cortical projection zone of the corresponding modality - in the temporal zone when expecting an auditory task, in the sensorimotor cortical zone during tactile, in the occipital during visual. It is significant that it was precisely this organization of pre-stimulus attention that contributed to the correct solution of the problem (Fig. 63). The activity of the right hemisphere in this situation is not associated with providing the correct answer when anticipating a task.

Age-related features of the structural and functional organization of attention . Signs of involuntary attention are detected already in the neonatal period in the form of an elementary indicative reaction to the emergency use of a stimulus. This reaction is still devoid of a characteristic research component, but it is already manifested in certain changes in the electrical activity of the brain and autonomic reactions (changes in breathing, heart rate).

At 2-3 months of age, the indicative reaction acquires features of an exploratory nature. In the chest, the same as at the beginning preschool age, cortical generalized activation is represented not by blockade of the alpha rhythm, but by an increase in the theta rhythm, reflecting increased activity of limbic structures associated with emotions. The features of activation processes determine the specifics of voluntary attention at this age: the attention of a small child is attracted mainly by emotional stimuli. As the speech perception system matures, a social form of attention is formed, mediated by speech instructions. However, up to the age of 5, this form of attention is easily overshadowed by involuntary attention that arises in response to new attractive stimuli.

Rice. 63. Specifics of the functional organization of the structures of the left and right hemispheres in the situation of pre-stimulus selective attention. The diagrams indicate leads. The lines connect the cortical areas in whose activity there is a significant increase in the Cog values of the alpha rhythm before a correct answer compared to an incorrect one. LP - left, PP - right hemisphere

Qualitative changes in the formation of neurophysiological mechanisms of voluntary attention are associated with the structural and functional maturation of the frontal cortex, ensuring the organization of processes of local regulated activation in accordance with decision-making based on analyzed information, motivation or verbal instructions. As a result of this, certain brain structures are selectively included in activity, the activity of others is inhibited, and conditions are created for the most economical and adaptive response.

The most important stage in the organization of voluntary attention is primary school age. At 7–8 years of age, the insufficient maturity of the frontal-thalamic system for regulating activation processes determines a greater degree of their generalization and a less pronounced selectivity of combining cortical zones into working functional constellations in a situation of pre-stimulus attention that precedes a specifically implemented activity. By the age of 9-10, the mechanisms of voluntary regulation are improved: activation processes become more manageable, determining the improvement in indicators of the organization of activity.

Description of the presentation Feeling and. perception Neurophysiological mechanisms on slides

Neurophysiology of sensations Individual properties of objects and phenomena that affect our sense organs are called stimuli, the process of exposure is called irritation, and the nervous process that arises as a result of irritation is called excitation. A complex system of nervous formations that carry out the finest analysis of individual irritations affecting the body was called analyzers by I. P. Pavlov.

Each sense organ (eye, ear, sensitive skin cells, taste buds of the tongue) is specialized in receiving and processing various specific external influences. The main part of each sense organ - the endings of the sensory nerve - are receptors that convert the energy of an external stimulus into a nerve impulse. An influence that can excite a receptor is called a stimulus.

The nerve impulse generated in the receptor travels along centripetal, afferent nerve pathways to the corresponding parts of the brain. Receptors, ascending (afferent) nerve pathways and corresponding areas in the cerebral cortex - these are the three components of the analyzer Functional diagram of the analyzer Stimuli - external influences Receptor Brain. Afferent nerve connections

For sensation to arise, the analyzer as a whole needs to work. It cannot be said that visual sensations arise in the eye. Only analysis of the nerve impulse coming from the eye to the corresponding parts of the cerebral cortex (occipital part) leads to the appearance of a visual sensation. On the way from the receptors to the cerebral cortex, impulses pass through various brain structures, where they receive primary processing.

Analyzer structure diagram: 1–7 receptors (visual, auditory, skin, olfactory, gustatory, motor apparatus, internal organs). I – region of the spinal cord and medulla oblongata. A – centripetal (afferent) fibers. II – visual hillocks (thalamus), where nerve impulses pass to a neuron going to the cerebral cortex. III – cerebral cortex.

The activity of analyzers is conditioned reflex: the brain, receiving a feedback signal about the activity of the receptor, continuously regulates its operation. Formed in the cerebral cortex, a nerve impulse, spreading along centrifugal, efferent nerve pathways, affects the motor mechanisms of the sensory organ and causes a corresponding adjustment of the sensitivity of the receptor.

Thus, sensation is not a one-act passive reflection of this or that property, but an active process, the most complex activity of analyzers, which has a certain structure. Each type of sensation has its own neurophysiological mechanism – its own analyzer.

The sense organs are connected with the organs of movement. Thus, in the process of visual sensations, the eye makes continuous movements, as if feeling an object. (The fixed eye is practically blind.) The activities of various analyzers are interconnected. The combined activity of all analyzers is called the sensory sphere of the human psyche. Interesting!

Sensations not only carry information about the individual properties of phenomena and objects, but also perform an activating brain function. (There is a known case when the patient had only one sense organ remaining active - the eye; closing this only channel that connected him with outside world, the patient immediately fell asleep.)

Neurophysiological bases of perception The physiological mechanism of perception is the complex activity of analyzers. In the process of perception, relationships are established between the parts and properties of an object, therefore one of the physiol. mechanisms of perception is the formation of conditioned reflexes to relationships. That is, if the analyzer is constantly exposed to a system of stimuli, then the response begins to depend not on an individual stimulus, but on the connection between the stimuli and their relationships.

One of the main physiological mechanisms of perception is the formation of a dynamic stereotype, as well as the establishment of conditioned reflex connections between analyzers. Human perception is always associated with the activity of the second signaling system (speech). A person does not just look at objects and react passively to them. Isolating and combining the most significant of them, he always designates perceived objects with words, thereby gaining a deeper knowledge of their properties. Thanks to the word, perceived objects acquire meaning.

Perception is based on two types of neural connections: connections that are formed within the same analyzer; inter-analyzer connections. In the first case, the process of influencing the body by a complex stimulus of one modality (for example, a melody, which is a unique combination of individual sounds) occurs. They affect the auditory analyzer. IN in this case a complex of stimuli acts as 1 single complex stimulus. And at the same time, nerve connections are formed not only to the particular stimuli themselves that are included in the complex, but also to their relationship (temporal and spatial).

Thus, a process of integration and complex synthesis occurs in the cerebral cortex. Another type of neural connections that are formed when exposed to a complex stimulus are connections within different analyzers.

The analyzer (sensory system) is named after the type of sensory information for which it is specially adapted to perceive - visual, auditory, tactile, gustatory and olfactory stimuli, as well as the force of gravity. The sensory system consists of: 1) stimulus detectors (sensory cells) - specialized receptor neurons; 2) the primary perceptive center, where information from a group of receptor neurons converges; 3) one or more secondary perceiving and integrating centers that receive information from primary perceiving centers. In more complex nervous systems, integrating centers are also connected with each other. The interaction of these centers creates “perception”.

The sensory system begins to act when a stimulus or irritant is perceived by sensory neurons - primary sensory receptors. In each receptor, the influencing physical factor (light, sound, heat, pressure) is converted into a nerve impulse. Nerve impulses display sensory stimuli as cellular signals that can be further processed by the nervous system.

Nerve impulses produced by receptors are transmitted along the sensory fiber to the perceptive center responsible for this type sensations. Once the impulses reach the primary processing area, information is extracted from the details of the sensory impulses. The very arrival of impulses means that an event related to this sensory channel has occurred. Subsequent integrative centers of the sensory system may add information from other sensory sources, as well as memory information from similar past experiences. When perceiving a flower, for example, its color, shape, size and distance to it are highlighted.

Thus, perception is a series of transitions: Stimulus stimulus detectors primary perceiving center (integrating) perceiving center

At some point, the nature and meaning of what we experience is determined by a conscious identification (Latin indentifico - to identify), which we call perception. After this, it is time for a conscious response, if required.

General scheme of operation of the sensory system 1. Each receptor, when excited (perceived signal about an Event-Fact), sends sensory information along a chain of synaptic switchings. In this case, signals are transmitted to higher “floors” of the brain. At each level, the signal undergoes additional processing. After physical stimuli have been converted into nerve impulses by the receptor, they exist as a code of nerve impulses in specific sensory channels of the nervous system. Subsequently, the brain reconstructs the Image of the Event-Fact, adding together all the information currently received from each of the activated receptors. It is this totality of information that is interpreted by the brain to create the construction called “perception” of an Event-Fact.

Thus, the sensory system is the result of a series of transitions: Event Outgoing signal Perceived signal Code of nerve impulses Reconstruction of an image, event, fact Construction of an event, fact

2. Each link of the sensory system represents a subsystem. The first external receptor that perceives incoming from environment irritation - exteroceptor - usually, like in an electric machine, has an input device, a converter and an output mechanism. Input device - perceives stimuli from the outside. Transducer - amplifies the incoming signal and translates it into the language of intracellular signaling. The output mechanism, through a synaptic contact, transmits the encoded signal to the second link of the sensory system - the afferent interneuron, to the central nervous system.

Perceptions are classified according to. : receptor modalities There are 1. visual, 2. auditory, 3. olfactory, 4. gustatory, 5. tactile receptors, 6. thermo-, proprio- and vestibuloreceptors (receptors for the position of the body and its parts in space), 7. pain receptors. Depending on the location, all receptors are divided into: 1. external (exteroceptors) and 2. internal (interoreceptors). Exteroceptors include auditory, visual, olfactory, gustatory, and tactile. Interoceptors include vestibulo- and proprioceptors (receptors of the musculoskeletal system), as well as visceroreceptors (signaling about the state of internal organs).

Perception (like sensation) is determined by the activity of not one, but several analyzers, i.e., the activity of the perceptual system. But their meaning is not always equivalent; a certain analyzer is the leading one, while others only complement the perception of an object or phenomenon. According to the form of existence of matter reflected in perception, the perception of time, movement and space is distinguished.

In the perception of space, a distinction is made between the perception of size, shape, volume and depth (or distance) of objects. The perception of the size and shape of objects is ensured by the simultaneous activity of visual, muscle and tactile sensations. The basis for this perception is the size and shape of objectively existing objects; it is their images that are obtained on the retina. But vision cannot provide the correct perception of the shape of objects; a good result is achieved by combining visual sensations with muscle-motor and tactile sensations, as well as with ideas that remain from past experience.

Properties of perception Objectivity - objects are perceived not as an incoherent set of sensations, but constitute its images of specific objects. Structurality - the object is perceived by consciousness as a modeled structure abstracted from sensations. Apperception - perception is influenced by the general content of the human psyche. Contact (constancy) - perception is influenced by the circumstances in which it occurs. But despite this, the perception remains relatively unchanged. Activity - at any given time we perceive only one object. The nature of the activity of perception is determined by the very nature of our consciousness. Meaningfulness - an object is consciously perceived, mentally named (associated with a certain category), belongs to a certain class

How does the sensation differ from? perception 1. Sensation – component perception, while perception is always a complex of sensations. Perception - more difficult process than sensation. 2. The ability to feel is given from birth to all living beings who have a developed nervous system. The ability to perceive is inherent only in humans and higher animals, and it is transformed in the process of life experience. 3. Sensation provokes the emergence of a feeling, perception forms an image. Sensation is an exclusively internal process; perception is closely related to the process of objectification, when we project personal experiences onto an object. 4. Sensation is the process of reflecting a separate property of an object. Perception is based on a complex of sensations and is formed.

The main difference between perception and sensation is the objectivity of awareness of everything that affects us, that is, the display of an object in the real world in the totality of all its properties, a holistic display of the object. Compared to sensations, perception is highest form analytical-synthetic activity of the brain. Without analysis, meaningful perception is impossible. It is the analysis that ensures the selection of the object of perception, on the basis of which all the properties of the object are synthesized into a holistic image.

Neurophysiological mechanisms of attention

Structural-functional organization of attention. Involuntary attention is close in mechanism to the orienting reaction; it occurs in response to a new or unexpected stimulus. The initial situation of uncertainty requires mobilization readiness of the cerebral cortex, and the main mechanism that triggers involuntary attention is the involvement of the reticular modulating system of the brain in this process (see Fig. 55). The reticular formation, through ascending connections, causes generalized activation of the cerebral cortex, and the structures of the limbic complex, which evaluate the novelty of incoming information, as the signal is repeated, mediate either the extinction of the reaction or its transition to attention directed toward perception or organization of activity.

Voluntary attention, depending on specific tasks, needs, motivation, facilitates, “optimizes” all stages of cognitive activity: initial - input of information, main central - its analysis and assessment of significance and the final result - fixation of new knowledge in individual experience, behavioral reaction, necessary motor actions.

At the stage of input and primary analysis of the stimulus, its allocation in space, an important role belongs to the motor components of attention - eye movements. Processes occurring at the level of the midbrain (quadrigeminal) provide saccadic eye movements that place the object in the area of best vision on the retina. The implementation of this mechanism occurs with the participation of the salonassociative parietal cortex, which receives multimodal information from sensory zones (information component) and from the cortical part of the limbic system (motivation component). The descending influences of the cortex formed on this basis control the structures of the midbrain and optimize the initial stage of perception.

In this activation, a significant role also belongs to the structures of the limbic system (hippocampus, hypothalamus, amygdala, limbic cortex) and their connections with the rich neocortex (see Fig. 56).

EEG analysis of the brain organization of attention. In the EEG, with generalized tonic activation in response to the presentation of a new stimulus that caused involuntary attention, desynchronization of the basic rhythm occurs (Fig. 62) - blockade of the mid-frequency alpha component, dominant at rest, and an increase in the representation of high-frequency oscillations of the alpha range, beta - and gamma activity.

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The significance of functional associations of structures during selective attention was demonstrated by studying the brain organization of directed modally specific attention in a situation of anticipation of a specific perceptual task. Information about the modality of the stimulus subject to binary classification, which the subject received in advance, led to the formation in the cortex of the left hemisphere of functional associations at the frequency of the alpha rhythm in the period immediately preceding perceptual activity, with the center of integration in the area of the cortical projection zone of the corresponding modality - in in the temporal zone when anticipating an auditory task, in the sensorimotor cortical zone during tactile, in the occipital during visual. It is significant that it was precisely this organization of pre-stimulus attention that contributed to the correct solution of the problem (Fig. 63). The activity of the right hemisphere in this situation is not associated with providing the correct answer when anticipating a task.

Age-related features of the structural and functional organization of attention. Signs of involuntary attention are detected already in the neonatal period in the form of an elementary indicative reaction to the emergency use of a stimulus. This reaction is still devoid of a characteristic research component, but it is already manifested in certain changes in the electrical activity of the brain and autonomic reactions (changes in breathing, heart rate).

At 2-3 months of age, the indicative reaction acquires features of an exploratory nature. In infancy, as well as at the beginning of preschool age, cortical generalized activity

POCT COHERENCE OF ALPHA OSCILLATIONS IN A SITUATION OF PRESTIMULUS ATTENTION

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tion is represented not by blockade of the alpha rhythm, but by an increase in the theta rhythm, reflecting increased activity of limbic structures associated with emotions. The features of activation processes determine the specifics of voluntary attention at this age: the attention of a small child is attracted mainly by emotional stimuli. As the speech perception system matures, a social form of attention is formed, mediated by speech instructions. However, up to the age of 5, this form of attention is easily overshadowed by involuntary attention that arises in response to new attractive stimuli.

Significant changes in cortical activation underlying attention were noted at 6-7 years of age. A mature form of cortical activation is detected in the form of a generalized blockade of the alpha rhythm. The role of speech instructions in the formation of voluntary attention increases significantly. Along with heme, the emotional factor is still of great importance at this age.

The most important stage in the organization of voluntary attention is primary school age. At 7-8 years of age, the insufficient maturity of the frontal-thalamic system for regulating activation processes determines a greater degree of their generalization and a less pronounced selectivity of combining cortical zones into working functional constellations in a situation of pre-stimulus attention that precedes a specifically implemented activity. By the age of 9-10, the mechanisms of voluntary regulation are improved: activation processes become more manageable, determining the improvement in indicators of the organization of activity.

The role of various brain structures in the need-emotional sphere

Needs and motivations. Needs are an internal source of active interaction of the organism with the external environment and are considered as the main determinant of behavior aimed at achieving a specific goal. I.P. Pavlov introduced the concept of “goal reflex” as an expression of the desire of a living organism to possess something - food, various objects. The scope of human needs is very wide. It includes both biological and social and spiritual needs.

Biological needs are associated with the activity of the nerve centers of the hypothalamus. In experiments on animals with electrodes implanted into various nuclei of the hypothalamus, it was noted that in a hungry animal the electrical activity of certain areas of the hypothalamus sharply increased. Upon saturation, the increase in electrical activity of these structures stopped. Their irritation was caused by food seeking behavior. When other nuclei were irritated, refusal to eat, sexual arousal, and aggressive-defensive behavior were observed.

The biological needs of humans are different from those of animals. Their implementation is not direct and is largely determined by social and cultural factors. This indicates that even biological needs in humans are under the control of the regulatory structures of the cerebral cortex. The actualized, most significant need at the moment, acquiring all the properties of a dominant, is called motivation. According to the theory of dominance by A.A. Ukhtomsky, it subjugates the activity of the body, ensuring the priority of a given behavioral act and suppressing other types of activity.

Experiments with the creation of an artificial dominant have shown that against its background, the sensitivity of neural systems in structures covered by the dominant state, the speed of processes occurring in them and convergent abilities increase. Motivation acts as a trigger for the formation of a functional system, activating structures included in afferent synthesis, decision making, program development and all correction based on the results of action.

Motivation is realized with the direct participation of the hypothalamus and other parts of the limbic system, where, along with the main centers associated with biological needs, there are structures involved in the assessment and regulation of the stages of command aimed at satisfying the need. The cerebral cortex, which organizes active search behavior, is also involved in the general multi-level system for the implementation of motivation.

Emotions, their physiological basis. Emotions are closely related to the motivational-need sphere. Emotions are considered as a mental process that is actively involved in the modulation of the functional state of the brain and the organization of behavior aimed at satisfying current needs. At the same time, emotions reflect a subjective attitude towards the outside world, surrounding people, oneself, one’s own activities and its results.

The cerebral organization of emotions was studied in experiments on animals with the destruction and irritation of various subcortical structures, as well as in the clinic of local brain lesions in humans. The most striking effects were obtained by irritating certain nuclei of the hypothalamus, which caused emotional reactions of different signs. Stimulation of the zones of the lateral hypothalamus led to the desire of animals (rats) to prolong this state through self-irritation. Irritation of other centers of the hypothalamus caused an avoidance reaction. The areas of the brain whose stimulation led to reinforcement and avoidance were called centers of pleasure and displeasure, respectively, with positive and negative emotional connotations. Emotional reactions of different signs were also obtained when other parts of the limbic system were irritated.

As mentioned above, limbic structures are part of the modulatory system of the brain, and this determines the important role of emotions in the regulation of activation processes - generalized and local activation, and, consequently, in the organization of behavioral reactions.

The brain organization of emotions, like other mental functions, is multi-level. The limbic system has connections with the associative areas of the neocortex.

Clinical studies have revealed the specific role of the frontal and temporal cortex in the expression of emotions. With different types of damage to the frontal lobes, profound disturbances in the emotional sphere were noted, affecting mainly higher emotions associated with social relationships, voluntary activities, and creativity. Disinhibition of drives and instability of the emotional background from depression to euphoria were observed.

With temporal lesions, especially on the right, recognition of the emotional intonation of speech is impaired.

The unequal role of associative departments in emotional regulation has been revealed. Thus, it has been shown that with right-sided lesions a state of euphoria and carelessness occurs. Left-sided lesions lead to a predominance of concern and anxiety: patients are restless and often cry.

Based on these data, the idea arose about the predominant connection of the right hemisphere with a negative emotional background, and the left hemisphere with a positive one.

Age-related characteristics of the child’s need-emotional sphere. From the first months of life, children have a very high need for novelty. Satisfying the need for novelty evokes positive emotions, which, in turn, stimulate the activity of the central nervous system. According to P.V. Simonov, emotion, compensating for the lack of information necessary to achieve a goal, ensures the continuation of actions, promotes the search for new information and thereby increases the reliability of a living system.

Children's emotions, due to the weakness of control on the part of the higher parts of the central nervous system, are unstable, their external manifestations are unrestrained. The child cries easily and quickly and can move from crying to laughter just as quickly. The child laughs loudly with joy, screams, and waves his arms. With age, as the cerebral cortex matures and its influence on the underlying subcortical structures increases, the restraint of emotional manifestations increases. The close connection between emotions and needs determines the need to take into account the age-related characteristics of the child’s emotional sphere in the process of upbringing. Education can significantly influence even biological, innate needs, and change the degree and forms of their manifestation. An even greater role of education is in the formation of socially conditioned, including cognitive, needs. Expanding the scope of needs with the help of targeted educational activities that are closely related to emotions at the stage of development, which is characterized by increased emotional activation, will help expand the range of external influences that attract attention, and thereby lead to the improvement of cognitive processes and goal-directed activity of the child.

The maturation of the higher parts of the central nervous system at primary school age expands the possibility of developing cognitive needs and contributes to the improvement of emotion regulation.