Physiology of the human extrinsic. See what "Physiology of higher nervous activity" is in other dictionaries
Higher nervous activity is understood as the activity of the cerebral cortex and the subcortical structures closest to it, which carry out complex behavioral reactions that ensure individual adaptation to changing environmental conditions. The idea of the reflex nature of the activity of the higher parts of the brain was expressed by I.M. Sechenov. I.P. Pavlov developed a method for objectively assessing the functions of the higher parts of the brain - conditional reflex method.
Conditioned reflex – This is a complex individual response of the body, which is developed on the basis of an unconditioned reflex in response to an initially indifferent stimulus, which acquires a signal character. It signals the upcoming impact of the unconditioned stimulus.
Differences between conditioned reflexes and unconditioned ones. Unconditioned reflexes: congenital, specific, persist throughout life, are carried out at the expense of the lower parts of the central nervous system, have ready-made anatomically formed reflex arcs. Conditioned reflexes: acquired, individual, non-permanent, are predominantly a function of the higher parts of the central nervous system, do not have ready-made reflex arcs, are formed as a result of the formation of temporary connections in the higher parts of the central nervous system, and are developed on the basis of unconditioned reflexes.
Rules for the development of conditioned reflexes: the presence of two stimuli (unconditioned and conditioned), a multiple combination of conditioned and unconditioned stimuli, the conditioned stimulus must precede the action of the unconditioned, the unconditioned stimulus must be stronger than the conditioned stimulus, the need to eliminate extraneous stimuli, the animal in which the conditioned reflex is developed must not be inhibited and not excited .
The physiological basis for the emergence of conditioned reflexes is the formation of functional temporary connections in the cerebral cortex. Temporary connection is a set of neurophysiological, biochemical and ultrastructural changes in the brain that occur in the process of repeated actions of conditioned and unconditioned stimuli.
Classification of conditioned reflexes: intero-, extero- and proprioceptive (according to the receptive field of the conditioned stimulus); somatic and vegetative (on the efferent link); food, defensive, sexual (by biological significance); coinciding, lagging, trace (by coincidence in time of the conditioned signal and reinforcement); conditioned reflexes of I, II, III and higher orders (according to the number of conditioned stimuli).
dynamic stereotype - a stable sequence of conditioned reflexes developed and fixed in the cerebral cortex.
Inhibition of conditioned reflexes. Types of braking: external, or unconditional; beyond; conditional, or internal. Kinds conditional braking: fading, differentiating, conditional brake and retarded.
The biological significance of inhibition lies in the ordering and improvement of conditioned reflexes. Thanks to inhibition, concentration is achieved on the most important activity for the organism at the moment, and everything secondary (unconditional inhibition) is delayed. Conditioned reflexes are continuously improved and refined in relation to changing environmental conditions (conditioned inhibition). Thanks to inhibition, the body is protected from overvoltage (protective inhibition).
Types of braking: external or unconditional(occurs in response to the impact of a new extraneous stimulus that causes an orienting reaction); beyond(occurs with an excessive increase in the strength or duration of the conditioned stimulus and prevents the depletion of nerve cells); conditional or internal(formed in the structural components of the conditioned reflex). Types of conditional braking: fading(the conditioned stimulus ceases to be reinforced by the unconditioned one); differentiation(produced for stimuli close in characteristics to the conditional); Conditional brake(occurs if a positive conditioned stimulus is reinforced by an unconditioned one, and the combination of a conditioned and indifferent stimulus is not reinforced); delayed(with an increase in the interval between the onset of the action of the conditioned stimulus and the moment of reinforcement).
Physiology of sleep. Dream- a physiological state characterized by the loss of active mental connections of the subject with the world around him. Phases of transition from the state of wakefulness to sleep: leveling, paradoxical, narcotic. Stages of sleep: slow (orthodox) and REM (paradoxical) sleep. Sleep theories: cortical theory according to I.P. Pavlov (spilled, spreading inhibition); theory of the sleep center (bottom of the 3rd ventricle of the brain); humoral theory; cortical-subcortical theory (reduction of ascending activating influences of the reticular formation on the cerebral cortex).
Properties of nervous processes: strength of nervous processes, balance of nervous processes, mobility of nervous processes.
Types of GNI according to I.P. Pavlov (based on properties of nervous processes): strong, unbalanced (corresponds to choleric temperament); strong, balanced, mobile (sanguine temperament); strong, balanced, inert (phlegmatic temperament); weak (melancholic temperament). These types are characteristic of both humans and animals.
Types of GNI according to I.P. Pavlov, characteristic only for humans, are distinguished on the basis of the predominance of IorIIsignaling systems.. 1st signaling system - these are sensory signals (visual, auditory, etc.) from which images of the outside world are built . II-th signaling system - these are verbal (verbal) signals, which are signs (symbols) of objects and phenomena of the surrounding world. Based on them, the world is perceived through reasoning, the creation of abstract concepts. Artistic type - the predominance of the I-th signal system, figurative thinking (artists, poets, musicians); mental type - the predominance of the second signal system, the logical type of thinking (scientists, philosophers); mixed type - the properties of both the 1st and 2nd signal systems are evenly expressed; genius type - strong development of both the 1st and 2nd signal systems (people capable of both scientific and artistic creativity).
Higher mental functions. Psyche- this is a specific property of highly organized matter - the brain, which consists in the reflection of objects and phenomena of the material world that exists outside of us and independently of us. Thinking- the process of indirect, generalized reflection of reality with its connections, relationships and patterns. This is the highest form of reflection of the world. Language- a means of expressing thought and a form of existence of thought. Speech- perception of words - audible, spoken (aloud or to oneself) and visible (when reading and writing). Speech functions: communicative, conceptual, regulatory. Attention- concentration and orientation of mental activity on a particular object. With the help of attention, the selection of the necessary information is ensured. Memory- the ability to store information about the events of the external world and the reactions of the body. Stages of memory: memorization, storage of experience, reproduction of experience. Types of memory: genetic and individual; figurative, emotional, verbal-logical; sensory, short-term, long-term. Physiological mechanisms of short-term memory: reverberation theory, electrotonic theory. Physiological mechanisms of long-term memory: anatomical theory, glial theory, biochemical theory (restructuring of DNA and RNA molecules in brain neurons). Emotions- reactions of the organism, which have a pronounced subjective coloring, to the influence of external and internal stimuli. With their help, a person's personal attitude to the world around him and to himself is determined. Emotions are realized in certain behavioral reactions. There are positive and negative emotions, lower (associated with organic needs) and higher (associated with the satisfaction of social and ideal needs: intellectual, moral, aesthetic, etc.), sthenic and asthenic, emotions of mood, passion, affect. Consciousness- subjective experiences of reality, flowing against the background of the individual's experience, and perceived by him as a certain subjective reality. This is the highest form of reflection of reality. Regulates the form of human contact with the outside world.
Scheme of the functional system of a behavioral act according to P.K. Anokhin. The main stages of a functional system: afferent synthesis, decision making, formation of an action program, formation of an acceptor of the results of an action, action and its result, comparison of the parameters of the result with their model in the acceptor of the results of an action, carried out with the help of reverse afferentation.
All forms of human mental activity are determined by a wide variety of biological and social needs. The more perfect the nervous system in the evolutionary series, the more diverse the possibilities of contact with the outside world, the more perfect the form of adaptation of the organism to the environment. A person has an extremely high adaptability and variability of behavior, which is due to the maximum development of the brain, the emergence of the highest form of reflection of reality, including all manifestations of mental activity: sensation and perception, representation and thinking, attention and memory, feelings and will. The doctor must remember that the characteristics of the GNI and the mental properties of the patient's personality form a certain attitude towards his condition.
Lesson 1. Conditioned reflex and its neurophysiological
mechanisms. dynamic stereotype.
Task 1. Determination of mental reaction time. (Demonstration).
Lesson 2. Types of inhibition in the cerebral cortex. Dream.
Research methods of GNI.
Electroencephalography. (Video film).
Lesson 3. Types of higher nervous activity (HNA).
Task 1. Determining the type of GNI in humans on the IBM PC.
Lesson 4. Higher mental functions. memory mechanisms.
Task 1. An Attention Distribution Study (Ex. p. 422).
Task 2. Attention Switching Research (Ex. p. 423).
Task3. The dependence of the amount of memory on the degree of meaningfulness
material (Ex. p. 427).
Task 4. Tests for the study of visual and auditory memory.
(Ex. p. 427).
ANALYZERS (SENSOR SYSTEMS).
Analyzers - a set of formations that ensure the perception of the energy of the stimulus, its transformation into specific excitation processes, the conduction of this excitation in the central nervous system, the analysis and synthesis of this excitation by specific zones of the cortex, followed by the formation of sensation. Each analyzer (according to I.P. Pavlov) consists of three sections: peripheral (receptors), conductive (paths for conducting excitation), central (cerebral cortex).
Receptor - specialized formations that are designed to perceive the energy of the stimulus and transform it into a specific activity of the nerve cell. Classification of receptors: cold, heat, pain, etc.; mechano-, thermo-, chemo-, baro-, osmoreceptors, etc.; extero-, interoreceptors; mono- and polymodal; contact and distance.
The most important of all analyzers is visual analyzer, since it gives 90% of the information that goes to the brain from all receptors. Optical system of the eye: cornea, lens, vitreous body, anterior and posterior chambers of the eye. Accommodation- adaptation of the eye to a clear vision of objects remote at different distances. Peace of accommodation. Tension of accommodation. Refractive anomalies of the eye. Nearsightedness (myopia) due to a too long longitudinal axis of the eye, as a result of which the main focus is in front of the retina (correction with biconvex lenses). Farsightedness (hypermetropia) happens with a short longitudinal axis of the eye, the focus is located behind the retina (correction with biconcave lenses). Senile farsightedness (presbyopia) is the loss of elasticity of the lens with age. Astigmatism- uneven refraction of rays in different directions, due to the not strictly spherical surface of the cornea. Pupillary reflex- reflex changes in the diameter of the pupil depending on the illumination (in the dark - expansion, in the light - narrowing), is adaptive. Pupil dilation is an important symptom of pain shock, hypoxia. Receptor apparatus visual analyzer is presented sticks and cones. Rods are responsible for twilight vision. Rhodopsin cycle. Cones provide daylight and color vision. Theories of color perception: three-component (G.D. Helmholtz) and contrast (E. Goering). Color vision disorders. Daltonism. Visual acuity- the ability of the eye to distinguish two luminous points separately with a minimum distance between them. line of sight- the space visible to the eye when fixing the gaze at one point. binocular vision. Nerve pathways: optic nerves, their partial decussation (chiasm), optic tracts, anterior tubercles of the quadrigemina, lateral or external geniculate bodies, visual cortex (occipital lobe, 17 field according to Brodmann).
The second most important analyzer is auditory . Functions of the outer, middle and inner ear. The receptor apparatus of the auditory analyzer is the receptor hair cells in the organ of Corti. Nerve pathways: auditory nerve, posterior colliculus, and medial geniculate bodies. Center: cortical region in the upper part of the temporal lobe. Theories of sound perception: resonator (G.D. Helmholtz) and places. A person perceives sounds with a frequency of 16 to 20 thousand Hz. Maximum sensitivity is in the zone from 1000 to 4000 Hz.
Vestibular analyzer responsible for orientation in space. It analyzes and transmits information about the acceleration or deceleration of rectilinear and rotational movements, as well as when changing the position of the head in space. The peripheral section is the bony labyrinth of the pyramid of the temporal bone. Receptors (hair cells) are located in the semicircular canals and vestibule. From the receptors, signals travel along the vestibular nerves to the medulla oblongata to the bulbar vestibular complex, from here to many parts of the central nervous system. The concept of vestibular stability.
Olfactory analyzer responsible for the perception and analysis of odorous substances, chemical irritants of the external environment and food intake. Receptor cells are located in the back of the upper nasal passage. Pathways: olfactory bulb, olfactory tract, olfactory triangle. Central section: anterior part of the pear-shaped lobe in the region of the gyrus of the sea horse (hippocampus). Stereochemical theory of perception of odorous substances.
Taste analyzer. Taste sensations are a complex sum of excitations going to the cortex from taste, olfactory, tactile, temperature and pain receptors. Taste receptors are located in the taste buds. Pathways: fibers of the facial, glossopharyngeal, upper laryngeal cranial nerves, medulla oblongata, ventral nuclei of the thalamus. Central region: lateral part of the postcentral gyrus and hippocampus. 4 types of taste sensations: sweet, sour, salty, bitter. Taste threshold- the smallest concentration of a solution of a flavoring substance that, when applied to the tongue, causes a corresponding taste sensation.
Skin analyzer. Types of skin sensitivity: tactile (sense of pressure and touch), temperature (heat and cold) and pain (nociceptive).
Tactile receptors: Meissner's corpuscles (responsible for the sense of touch), Merkel's discs (sense of pressure), Vater-Pacchini corpuscles (for vibration). Pathways: type A and C nerve fibers, posterior roots of the spinal cord, neurons of the spinal cord, Gaulle and Burdach nuclei of the medulla oblongata, ventrobasal nuclei of the thalamus. Central department: 1st and 2nd somatosensory cortex zones of the opposite hemisphere. The spatial threshold of skin sensitivity (determined by esthesiometry) is the minimum distance between two points at which two simultaneously applied stimuli are perceived as separate.
Cold receptors are Krause flasks, heat receptors are Ruffini bodies. The number of heat and cold receptors is determined by thermoesthesiometry.
Pain receptors (nociceptions) are free nerve endings. Pathways: spinothalamic, spinoreticular, spinomesencephalic and spinocervical tracts. Central department: zones C1 and C2 of the cerebral cortex. Types of pain: visceral and somatic (deep and superficial: epicritical, early and protopathic, late). Reflected pain. Phantom pain. The causes of pain are damage, tissue hypoxia. Algogens - substances that cause pain (histamine, bradykinin, substance P, kallidin, mediators acetylcholine and norepinephrine, serotonin. Antinociceptive system. Opiates: enkephalins, endorphins, etc.
Lesson 1. visual analyzer.
Task 1. Determination of visual acuity (Ex. p. 377).
Task 2. Determining the field of view (Ex. p. 378).
Task 3. Color vision test (Ex. p. 383).
Lesson 2. Physiology of hearing and vestibular apparatus.
Task 1. Determination of hearing thresholds. Audiometry
(Ex. p. 387).
Task 2. Study of the functional stability of the vestibular
Lesson 3. Skin, taste, olfactory analyzers.
Task 1. Examination of tactile sensitivity (Esthesiometry)
(Ex. p. 394).
Task 2. Determination of thresholds of taste sensitivity
1. The main stages in the formation of views on the functions of the nervous system and brain, on behavior (R. Descartes, J. Prochazka, I.M. Sechenov, I.P. Pavlov, P.K. Anokhin). Principles of the reflex theory. The subject of physiology of higher nervous activity. Relationship of GNI physiology with other sciences (ergonomics, psychology, pedagogy).
Reflex principle
The system of scientific knowledge is based on the principle of determinism, which makes it possible to reveal a regular cause-and-effect relationship of phenomena, determined by the interaction of material factors. The modern materialistic science of higher nervous activity is based on four principles: the principle of reflex, the principle of dominant, the principle of reflection, and the principle of systemic activity of the brain.
Mechanical concept of reflex. The concept of reflex arose in the 16th century. in the teachings of R. Descartes (1596-1650) about the mechanical picture of the world. R. Descartes lived in the heyday of mechanics, physics and mathematics. His worldview was influenced by the discovery by W. Harvey of the mechanism of blood circulation and the innovative ideas of A. Vesalius that the carriers of the psyche are "animal spirits" that are produced in the ventricles of the brain and transmitted through the nerves to the corresponding organs. R. Descartes represented nervous processes on the model of the circulatory system, using the principles of optics and mechanics that existed at that time.
Under the reflex R. Descartes understood the movement of "animal spirits" from the brain to the muscles by the type of reflection of a light beam. According to his scheme, external objects act on the peripheral endings of the nerve "threads" located inside the "neural tubes", which, stretching, open the valves of the openings leading from the brain to the nerves. Through the channels of these nerves, "animal spirits" move to the corresponding muscles, which as a result swell, and thus movement occurs. The cause of the motor act is determined by material changes on the skin periphery of the body, and the nervous process is similar to the movement of blood through the vessels. R. Descartes can rightfully be considered the founder of deterministic psychophysiology. Important in the work of R. Descartes is the development of the concept of the stimulus necessary to activate the mechanisms of the human body.
Based on the reflex principle, R. Descartes also tries to explain the learning behavior of behavior: people, even with a weak soul, could acquire unlimited power over all their passions if they made enough effort to discipline and manage them. Descartes' desire to understand holistic behavior was especially clearly manifested in his teaching on passions. Sadness and joy are the factors that form the expedient attitude of the organism to the outside world, make the reaction coordinated and complex. In passions, the connection of the soul with the body is manifested.
The main theoretical provisions of R. Descartes, used by modern physiology, are as follows: the organ of sensations, emotions and thoughts is the brain; the muscular response is generated by processes in the nerve adjacent to the muscle; sensation is due to changes in the nerve that connects the sense organ with the brain; movement in the sensory nerves is reflected in the motor ones, and this is possible without the participation of the will (reflex act); movements caused by the sensory nerve in the substance of the brain create a readiness to again produce the same movement (learning ability).
However, being under the influence of the socio-historical contradictions of his era, R. Descartes made serious concessions to idealism: he considered human consciousness as a substantial principle capable of influencing subordinate reflex laws of bodily processes. Thus, the body and soul are independent substances. The dualism of R. Descartes, his interpretation of consciousness prevented consistent determinism, because he allowed acts of imagination, thinking, will that came from an immaterial substance. Behavior and consciousness were divorced, turned into two independent series of phenomena.
In assessing the general scientific significance of the ideas of R. Descartes, however, it is important to emphasize not so much the mechanism as the materialistic essence of the doctrine of behavior, not so much dualism in the understanding of mental activity, but the first attempt at its deterministic understanding.
The biological concept of the reflex. At the end of the XVIII century. the philosophy of the French materialists won wide recognition and influenced many scientists in Europe. The teaching of the Czech anatomist and physiologist Jiří Prochazka (1749-1820) is an important stage in the formation of deterministic ideas about neuropsychic activity.
J. Prochaska expressed the essence of his views on the reflex as follows: external impressions that arise in sensory nerves spread very quickly along their entire length to the very beginning. There they are reflected according to a certain law, pass to the motor nerves corresponding to them and are very quickly sent along them to the muscles, through which they produce precise and strictly limited movements.
For the first time the term "reflex" was introduced into the scientific language by J. Prochazka. He took another step forward in the physiological assertion of the stimulus, for he postulated that the response reflex reaction always manifests itself in sizes corresponding to the strength of the applied stimulus.
Developing the concept of the reflex nature of behavior, J. Prochazka tries to overcome first the mechanistic and then the dualism of Cartesianism. The general law by which sensory stimuli switch to motor stimuli is the inherent sense of self-preservation in man. J. Prochazka asserts a monistic idea of the nervous system, which as a whole refers to the composition of the “general sensible”, the bodily part of which is localized in the spinal cord, and the mental part - in the brain. Moreover, for all neuropsychic functions, one general pattern is characteristic: both parts of the "sensorium" operate according to the law of self-preservation. The abilities necessary for the preservation of the animal and its offspring are mental functions, and the organ serving for this is the brain, the volume and complexity of which corresponds to the degree of perfection of mental functions.
The teachings of J. Prochazka enriched R. Descartes' idea of the reflex nature of behavior with the concept of the biological (rather than mechanical) purpose of the reflex structure itself, of the dependence of its complication on changes in the nature of the relationship of living beings with the environment, of its suitability for analyzing all levels of conscious activity, of determining influence of feeling.
Anatomical concept of the reflex. A thorough anatomical study of the nervous system was a strong impetus to the development and strengthening of the reflex concept in the 19th century. The English anatomist and physician Charles Bell (1774-1842) wrote in 1811 in his treatise “On the New Anatomy of the Brain” that it was possible to cut the posterior bundle of nerves emanating from the back of the spinal cord without convulsive contractions of the back muscles. However, this became impossible even with one touch of the tip of the knife to the front spine.
Thus, the concept of a reflex as a regular motor response to stimulation of sensory nerves was turned into a natural scientific fact.
Regardless of C. Bell, the French physiologist F. Magendie (1783-1855) came to similar conclusions. The transition of nervous excitation along the afferent nerves through the spinal cord to the efferent nerves is called the Bell-Magendie law.
But C. Bell himself went further: he created the theory of "muscle sensitivity" and formulated the physiological justification for the cyclic function of the nervous system. There is a closed nerve circle between the brain and the muscle: one nerve transmits influence from the brain to the muscle, the other transmits the feeling of the state of the muscle to the brain. If the circle is opened by transection of the motor nerve, then the movement will disappear. If it is opened by transection of the sensory nerve, the sensation of the muscle itself disappears, and with it the regulation of its activity disappears. So, for example, a woman lost sensitivity on one arm, and the ability to move on the other. This woman could hold the child on her hand, which had lost only sensation, as long as she looked at him. As soon as she took her eyes off the child, there was immediately a danger of him falling to the floor.
Thus, if earlier only external stimuli were considered determinants of the reflex act, then C. Bell shows the importance of the internal sensitivity of the muscles themselves, which ensures the most accurate and subtle execution of the movement.
Spinal cord reflexes were widely used by clinicians, among whom the most significant figures were the English physician Marshall Hall and the German physiologist Johannes Müller. It is M. Hall who owns the term "reflex arc". The reflex arc consists of the afferent nerve, the spinal cord, and the efferent nerve.
M. Hall and I. Muller insisted on the fundamental difference between the work of the spinal cord and the brain. In their opinion, the reflex mechanism is peculiar only to the spinal cord, only such acts, the nature of which is apsychic, can be called reflexes. The patterns of the course of any reflex act were determined by the connections of nerve substrates originally laid in the body, while the external stimulus was assigned the role of only a trigger. Internal factors were opposed to external ones. The brain found itself further and further away from the sphere of influence of physiology. The distance between physiology and psychology became more and more palpable.
At the same time, it is impossible not to see the progressive tendencies of the ideas of C. Bell, F. Magendie, M. Hall, I. Muller. These scientists undertook attempts to reveal the intraorganic conditions for the flow of the simplest reflex response, strove for its analytical knowledge as an elementary unit of nervous activity, and fought against subjective-psychological explanations of the structure of the reflex. The rigid anatomical nature of these theories already in the middle of the 19th century. met with serious contradictions that arose in connection with the ever-widening spread of evolutionary ideas, most consistently embodied by Charles Darwin.
Psychophysiological concept of reflex. Evolutionary ideas found the most favorable ground in Russia, prepared by the philosophical teachings of Russian revolutionary democrats, who had a significant influence on the formation of the worldview of I. M. Sechenov (1829-1905). The very concept of the reflex nature of nervous activity in I. M. Sechenov has undergone significant changes.
Let us consider the following main features of Sechenov's theory of the reflex (Yaroshevsky, 1961).
1. He understood the reflex as a universal and peculiar form of interaction between the organism and the environment, based on evolutionary biology. IM Sechenov raised the question of the existence of two kinds of reflexes. Firstly, permanent, congenital, carried out by the lower parts of the nervous system. He called them "pure" reflexes. Secondly, the reflexes of the brain are changeable, acquired in individual life. I. M. Sechenov imagined these reflexes to be both a physiological and a mental phenomenon.
Thus, the inseparability of mental processes from the brain and, at the same time, the conditionality of the psyche by the external world was shown for the first time. The most important for I. M. Sechenov was the position on the unity of the organism and the conditions of the external environment. Evolution factors:
define life as the adaptation of organisms to the conditions of existence;
prove that the introduction of influence is capable of modifying the material organization and nature of vital functions.
I. M. Sechenov was an outstanding propagandist of the Darwinian doctrine in Russia, he introduced the evolutionary-biological approach to the physiology of the brain and introduced the concept of variability and transformation of reflexes in order to successfully adapt, complicate and develop. Thus, a materialistic platform was created for linking nervous acts with psychic ones.
2. The physiological substratum of reflex acts is characterized as neurodynamics, different from the dynamics of other systems. The discovery of central inhibition by I. M. Sechenov in 1862 was the first step towards the creation of a new physiology of the brain. The activity of the nerve centers is now conceived as a continuous dynamics of the processes of excitation and inhibition.
3. Intercentral coordinating relations come to the fore. The higher brain centers begin to undergo physiological analysis. If before I. M. Sechenov, the strengthening or suppression of reflex reactions was interpreted only as an effort of will, consciousness, reason, then I. M. Sechenov translates all this into a strict physiological language and shows how the centers of the brain can delay or increase spinal reflexes.
4. The function of brain centers is interpreted in a broad sense of biological adaptation. The centers influence the movements in an intensifying or inhibitory way, not because the "psychic force" inherent in them is released, and not because the path of passage of the nerve impulse is shortened or lengthened. I. M. Sechenov introduces the concept of the “physiological state of the center”, which is directly related to biological needs. The very state of the center, reflecting the nature of the relationship with the environment, is the nervous substratum of need.
An essential addition is made to the doctrine of reflexes. The reaction becomes directly dependent not only on the present stimuli, but also on the total amount of previous influences that have left long-lasting traces in the nerve centers.
5. Muscle sensitivity opens up new perspectives for deterministic analysis of behavior. I. M. Sechenov believes that the muscular feeling during the performance of one movement becomes, in the order of association of reflexes, a signal for another movement. The principle of the association of reflexes underlies the teaching of a person in complex forms of labor activity. A common character is established for movements and for mental activity - this is the presence of muscle sensitivity.
On the question of the relationship between the physiological and the mental, I. M. Sechenov took a completely definite position, which he expressed in the following words: “For us, as for physiologists, it is enough that the brain is an organ of the soul, that is, such a living mechanism that, when no matter what the reasons for the movement, gives in the final result the same series of external phenomena that characterize mental activity.
For all the persuasiveness of the arguments of I. M. Sechenov, which he used to assert his views on behavior and the psyche, he lacked the most important argument - the laboratory objective method of research.
Rising to the extension of the reflex principle to mental activity and considering the reflex as a psychophysiological phenomenon, I. M. Sechenov could not study the specific mechanisms of behavior due to the lack of an appropriate method. Therefore, a number of his statements remained only brilliant conjectures, a wave of his mighty thought.
The concept of a conditioned reflex. An extremely responsible mission fell to the share of I.P. Pavlov - he reinforced the brilliant guesses, foresights and thoughts of I.M. Sechenov with the scientific concept of a conditioned reflex. IP Pavlov mobilized all his skill as a talented experimenter so that his concept was introduced into the strict framework of laboratory experiment.
IP Pavlov understood that he, following Sechenov, was invading the realm of phenomena usually referred to as psychic. “All complex nervous activity,” writes I. P. Pavlov already in 1913, “which was previously interpreted as mental activity, appears to us in the form of two main mechanisms: the mechanism for the formation of a temporary connection between agents of the external world and the activities of the body, or the mechanism of conditional reflex, as we usually say, and the mechanism of analyzers, that is, such devices that have as their goal to analyze the complexity of the external world: to decompose it into separate elements and moments. At least until now, all the material we have obtained fits into this framework. But this, of course, does not exclude the possibility of expanding our current understanding of the matter.
IP Pavlov showed himself as a consistent materialist and determinist. No wonder he proclaimed that the study of conditioned reflexes is based on three principles of reflex theory: determinism, analysis and synthesis, and structure. IP Pavlov fully adhered to the reflex scheme of R. Descartes and understood the significance of the reflex as one of the examples of the universal principle of determination. Already at the dawn of the development of the Pavlovian teaching, it became clear that the conditioned reflex is a pattern of a higher and more complex order than simple reflexes. The conditioned reflex ensures the variability of the animal's adaptive behavior in relation to the outside world. The conditioned reflex is the most important factor in biological evolution.
However, I. P. Pavlov, captured by polemics with psychologists and sharing Cartesian determinism, began to study in depth the physiological laws of conditioned reflex activity, leaving the biological side of the phenomenon for the future. Hence the inevitable contradictions in the idea of a conditioned reflex: on the one hand, the adaptive act of the whole organism, on the other, the elementary process of the nervous system. All scientific work of IP Pavlov was devoted to resolving this contradiction and creating the least controversial ideology in his theory of higher nervous activity.
Further, we will repeatedly consider individual provisions of the Pavlovian theory, and here we will restrict ourselves to only its most important elements in relation to the theory of reflex, which were noted by P. K. Anokhin (1979).
1. First of all, a laboratory method was created for an objective study of the adaptive activity of humans and animals - the method of conditioned reflexes.
2. Studying conditioned reflexes on a whole organism, IP Pavlov emphasized their adaptive-evolutionary meaning for the animal world.
3. IP Pavlov made an attempt to localize the nervous process itself of the closure of nerve connections in the cerebral cortex in higher animals and humans. At the same time, he was not categorical and did not exclude the specific participation of other parts of the brain in this process. He wrote that all our laws are always more or less conditional and have meaning only for a given time, under the conditions of a given methodology, within the limits of the available material.
4. IP Pavlov stated the presence of the process of inhibition in the cerebral cortex, which reinforced Sechenov's ideas about the inhibitory effect of the brain.
5. The doctrine of the physiology of analyzers was clearly formulated, under which I. P. Pavlov, following I. M. Sechenov, thought of a triune structure: peripheral receptors, pathways and brain centers up to the cerebral cortex.
6. The phenomena of the dynamics of the processes of excitation and inhibition during conditioned reflex activity were described. As a result, the concept of the cerebral cortex as a mosaic of excitations and inhibitions was formed.
7. At the end of his creative life, I.P. Pavlov put forward the principle of systematicity in the work of the cerebral cortex, capable of forming a dynamic stereotype of activity, already to some extent independent of the quality of external stimuli.
The ideas of I. P. Pavlov conquered the whole world and continue to serve as the basis for the development of new scientific research in the most diverse areas of the science of the behavior of living organisms.
Dialectical concept of reflex. A. A. Ukhtomsky (1875-1942) deserves the merit of the theoretical and physiological plan, which consists in the in-depth further development of the principle of determinism in the reflex theory.
The dialectical thinking of A. A. Ukhtomsky found a vivid manifestation in his understanding of the essence of the reflex. Seeing the mechanism of activity in the reflex, he saw in the reflex act the unity of internal and external determinants, and the internal determinants are ultimately also given and determined by external conditions.
A. A. Ukhtomsky emphasized that “... a reflex is such a reaction that is motivated quite clearly by the current situation or environment. This, however, does not destroy the spontaneous action of the substrate, it only puts it within certain limits in its opposition to environmental factors, and from this it becomes more definite in content and meaning. The reflex is drawn not by a purely passive movement of the bone ball under the influence of an external blow received by it; in this way the reflex could be depicted as long as it was necessary to emphasize in particular its motivation from the environment. But in its fullness, it appears as a meeting in time of two conditions: on the one hand, the activity prepared or formed in the substrate (cell) itself during its previous history, and, on the other hand, the external impulses of the current moment.
Consequently, internal determinants are the accumulated history of the interaction of the reacting substrate with the environmental factor (principle of historicism).
Both by origin and by the conditions of manifestation, internal determinants are ultimately determined by environmental factors, that is, they have only relative independence. The external acts as a complex of conditions for the existence of the internal. This means that the environment of an organism is not the entire physical world surrounding it, but only that small part of it, the elements of which are biologically significant for the organism. But for the organism, only such external is of biological interest, which can become part of life experience, that is, part of the internal, or contribute to the transformation of certain external factors into internal ones.
The modern theory of behavior has gone far from simple Cartesian schemes. The introduction of the principle of historicism makes it possible to understand the biological adequacy, that is, the expediency of the organism's reactions to the influence of the environment. The Cartesian worldview is based on rigid, unambiguous causality (Laplace's rigid determinism); it is alien to the recognition of real contradictions. A. A. Ukhtomsky, on the other hand, shows that real behavior requires the recognition of the existence of contradictions as a continuous attribute of the development process, as driving forces for constructing behavior.
The main provisions of the theory of the functional system were formulated by P.K. Anokhin as early as 1935. Despite the fact that Anokhin was a physiologist and most of the provisions of his theory are based on data from physiological rather than psychological studies, his theory has a general systemic character, and therefore can be successfully used and used in the analysis of mental phenomena.
A functional system is a system of various processes that are formed in relation to a given situation and lead to a result that is useful for the individual (Anokhin P.K., 1979). A beneficial outcome can be interpreted as meeting a variety of needs and goals of an individual: it can be the normalization of blood pressure and a successful purchase, saturation of the lungs with oxygen and victory in political elections.
The most fundamental position of the theory is that systems can be very diverse in terms of the type of tasks they solve and the complexity of these tasks, but the architecture of the systems remains the same. This means that various functional systems - from the system of thermoregulation to the system of political control - have a similar structure. The main components of any functional systems are the following:
- afferent synthesis;
· - decision-making;
- model of action results (acceptor of action) and program of action;
- action and its result;
· - Feedback.
Consider the functions of the system components. Afferent synthesis is a generalization of information flows coming both from outside and from outside. The subcomponents of afferent synthesis are dominant motivation, situational afferentation, triggering afferentation, and memory. The function of the dominant motivation is to provide general motivational activation. The “root cause” of any action is a need, a motivation. An overeaten animal will not frantically search for food, a person devoid of ambition has little concern for the desire to advance through the ranks. The function of situational afferentation is to ensure a general readiness for action. As soon as something appears in the environment that is able to satisfy our need, the triggering afferentation mechanism is activated. Triggering afferentation initiates behavior. However, in order to successfully perform even the simplest action, external information is not enough. Appropriate knowledge and skills are required. The orientation of a functional system to an adaptive, useful result forms a selective search and retrieval of information from memory.
Another component of the system - decision making - is responsible for choosing a variant of a future action, reduces the number of degrees of freedom, introduces certainty into what and how to do.
Based on the chosen direction of action, a model of the results of the action and an action program are formed - ideas about what should be achieved as a result and how this should be achieved. The system receives feedback - information about the progress of the program and the result of the action. By receiving feedback, the system acquires the ability to assess the degree of achievement of the desired and correct its behavior.
Definition of the subject of physiology of higher nervous activity. The physiology of higher nervous activity studies the nervous mechanisms of the complex behavior of animals and the mental activity of humans, related to their mental activity. How does mental activity differ in its manifestations from other, simpler functions of the nervous system?
The mentality of an infant is very simple. However, we will not hesitate to designate as a mental function the ability of a child to recognize his mother and to express a cry of protest at the sight of a spoon from which he was somehow given bitter medicine, but we will not call the automatic act of sucking mental.
The mental world of animals is also peculiar. The dog learns to subtly distinguish the intonations of the owner's voice, runs up to the call for a "reward". But chewing food in the mouth is not a mental activity.
The above examples clearly show the difference between mental and other, simpler functions of the nervous system. The mental functions of the nervous system are based on evolutionary complex conditioned reflexes, of which the higher nervous activity is composed, and its simple functions are performed unconditioned reflexes.
So, subject of physiology of higher nervous activity- this is an objective study of the material substrate of the mental activity of the brain and the use of this knowledge to solve practical problems of maintaining human health and high performance, controlling behavior and increasing the productivity of animals.
Higher nervous activity- the basis of behavioral reactions. The foundations of the doctrine of higher nervous activity are laid down in the works of I. M. Sechenov and I. P. Pavlov. The greatest merit of IP Pavlov is the creation of an experimental foundation for studying the neurophysiological mechanisms of the individual adaptive activity of an animal. With the help of the method of conditioned reflexes, IP Pavlov managed to reveal the most important patterns of higher nervous activity.
Higher nervous activity is a physiological function of the central nervous system that ensures the interaction of the organism and the environment. In higher animals and humans, this interaction is under the control of the cerebral cortex. In lower animals, this role is played by nervous structures of various levels of complexity.
Unlike higher nervous activity, the physiological function of the lower parts of the brain and spinal cord is aimed at integrating the internal systems of the body. This, according to IP Pavlov, is the lowest nervous activity. It provides reflex self-regulation of the work of internal organs. If the basis of the integration of the functions of the internal organs are only unconditioned reflexes, then the basis of higher nervous activity is both unconditioned and conditioned.
The final act of the higher nervous activity of man and animals are behavioral responses aimed at obtaining a useful adaptive result. In behavioral acts, conditioned and unconditioned reflexes represent a kind of fusion, the unity of the innate and acquired. However, even this unity does not allow revealing with exhaustive completeness the essence of complex behavioral reactions, where elementary forms of thinking, ingenuity, and intuitive forms of animal behavior are manifested.
Unconditioned and conditioned reflexes have a single material basis - the nervous process. Therefore, unconditioned reflexes extremely quickly enter into the composition of newly acquired reflexes. In the process of individual development, not only the acquisition of new reflexes occurs, but also the “ripening” of innate ones.
The relationship of conditioned and unconditioned reflexes- complex processes of mutual reinforcement or inhibition - are improved in the process of individual experience. Conditioned reflexes can inhibit unconditioned and, conversely, unconditioned reflexes can remove the action of conditioned ones. For example, severe hunger can slow down a dog's reaction to the owner's prohibitions.
"Human Physiology", N.A. Fomin
The most general features that make it possible to classify conditioned reflexes are: the qualitative composition of reflex stimuli (natural and artificial); the nature of the conditioned response (inherited or acquired); level (order) of the reflex. Natural conditioned stimuli are qualities or properties inherent in an unconditioned agent. For example, the smell of meat is a natural conditioned stimulus of food reflexes. A food conditioned reflex to the smell of meat is developed when its ...
In conditioned reflexes of the second kind, the response is not innate, in other words, both the afferent and executive links are formed anew. An example of such reflexes are operant (instrumental) reflexes. Self-stimulation reflexes known in physiology, especially demonstrative ones in rats, are a typical example of operant reflexes. The initial, primary form of the conditioned reflex is the reflex of the first order. A reinforcing agent in these conditioned reflexes...
One of the main conditions for the formation of a temporary conditioned connection in natural conditions is the coincidence in time of action of the conditioned and unconditioned stimuli. In a laboratory experiment, the conditioned stimulus precedes the action of the unconditioned one. But even in this case, part of the time they act together. Other conditions include repeatability, sufficient intensity of stimuli, and the level of excitability of the nervous system. Repeat combinations...
Under the action of an indifferent stimulus, excitation occurs in the corresponding sensory area of the cortex. The unconditioned reinforcement following the signal stimulus causes a powerful focus of excitation in the subcortical centers and their cortical projections. A strong focus, according to the principle of dominance, “attracts” excitation from a weaker one. There is a "closure" of the nerve connections between the subcortical and cortical foci of excitation caused by conditioned and unconditioned agents ....
According to modern concepts, afferent influences of different sensory content and biological significance converge to the same cortical neurons and cause specific chemical reactions in them. A special role is played by the convergence of ascending excitations from the unconditioned stimulus. Covering vast areas of the cerebral cortex, they have a chemically stabilizing effect on all neurons that receive information from ...
NOVOSIBIRSK STATE MEDICAL ACADEMY
DEPARTMENT OF NORMAL PHYSIOLOGY
EDUCATIONAL AND METHODOLOGICAL AID FOR THE COURSE OF NORMAL PHYSIOLOGY
PHYSIOLOGY OF HIGHER NERVOUS ACTIVITY
Professor of the Department of Normal Physiology of the Novosibirsk State Medical Academy, Doctor of Biological Sciences N.B. Pikovskaya
NOVOSIBIRSK 2004
Methodological guide for the course of normal physiology to the section "Physiology of higher nervous activity": Novosibirsk State Medical Academy, 2002. 81 p.
The manual is intended for use in the course of practical exercises in normal physiology by second-year students of all faculties as a supplement to the textbook material.
Approved by the Central Commission of methodological
Professor of the Department of Normal Physiology of the Novosibirsk State Medical Academy, Ph.D. n. N.B. Pikovskaya
Reviewers:
Head Department of Pedagogy and Medical Psychology, NSMA, Associate Professor G. V. Bezrodnaya
Novosibirsk State Medical Academy
General ideas about higher nervous activity
While studying particular physiology, we examined many regulatory systems, and made sure that these regulatory systems cope with many changes in the external and internal environment, maintaining the main parameters of the internal environment of the body at a constant level. However, changes in the external environment may be such that the highest form of regulation, behavior change, is required to maintain the constancy of the internal environment. In addition, both animals and humans use purposeful behavior to search for food, social partners, and avoid danger. The activity of the nervous system in the process of organizing various forms of behavior is called higher nervous activity, in contrast to the lower, reflex.
The term higher nervous activity (HNA) was introduced into science by I.P. Pavlov, who considered it equal to the concept of mental activity. Indeed, the object of study of both psychology and physiology of higher nervous activity is the work of the brain. At the same time, these sciences study different aspects of brain activity. Psychology studies the results of the activity of the central nervous system, manifested in the form of images, ideas, ideas and other mental manifestations. The physiology of GNI studies the mechanisms of activity of the whole brain, its individual structures, neurons, the connections between structures, their influence on each other, and the mechanisms of behavior. The works of psychologists and physiologists who study GNI have always been closely intertwined, even a new science has arisen - psychophysiology. However, our interests will still be focused on getting to know the nervous mechanisms by which the central nervous system organizes the behavior and mental activity of a person.
The idea that mental activity is carried out with the participation of the nervous system arose even before our era, but how this happens remained unclear. And even now, we cannot say that the mechanisms of the brain are fully disclosed, especially when it comes to the human brain. The first scientist The Roman physician Galen (2nd century AD) proved the role of the nervous system in behavior. He discovered that a rupture of the nerve connecting the brain and muscle leads to paralysis.
The origin of the physiology of the brain as a science is associated with the work of the French mathematician and philosopher Rene Descartes (XVII century). It was he who created the idea of the reflex principle of the nervous system, however, the term “reflex” itself was proposed in the 18th century by the Czech scientist J. Prochazka.
The ideas of Descartes formed the basis of the theories developed by physiologists over the next two centuries, including the basis of the works of I.M. Sechenov. The most famous book by Ivan Mikhailovich Sechenov "Reflexes of the Brain" was published in 1863. In it, the scientist proved that a reflex is a universal form of interaction between the body and the environment, that is, not only involuntary, but also arbitrary, conscious movements have a reflex character.
At the beginning of the 20th century, several scientific directions were formed that considered the reflex principle as the basis of human behavior. The most famous of them is the school of classical physiology of the VND I.P. Pavlova and the American school of behaviorism (behavior - behavior) (B. Thorndike and J.
Watson). The creators of these directions believed that behavior is built on the principle: stimulus brain reaction. Scientists realized and tried to take into account that behavior depends not only on the sensory signal, but also on the internal processes occurring in the central nervous system.
To date, it is believed that the most perfect model of the structure of behavior is set out in the concept functional system P. K. Anokhin's brain work.
Stages of a behavioral act
Figure 1. Scheme of the central structure of a purposeful behavioral act (according to P.K. Anokhin).
Let's try to achieve two results using the example of this functional system: both to get acquainted with the scheme, and to list the main differences between the GNI and the lower (simple reflex).
The first difference is that a behavioral act of any degree of complexity begins not simply with stimulation of the receptors, but with the combination and interaction of a rather complex set of stimuli, which P.K. Anokhin called afferent synthesis. What is included in this complex?
First, motivation. GNI is most often motivated. Motivation is an impulse to act, which is formed in the structures of the central nervous system and is associated with the satisfaction of certain needs.
Secondly - situational afferentation- the sum of afferent excitations that occur in specific conditions and signal the situation in which the body is located. Any activity to a certain extent depends on the conditions in which it takes place. Let's try to understand what "to a certain extent" means? The fact is that there are stimuli that serve as an impetus for the deployment of a certain behavior. Such stimuli are the third component of afferent synthesis and are called trigger stimuli. Such stimuli are, for example, signals
danger. The fourth component of afferent synthesis is the memory apparatus. The value of memory lies in the fact that for a certain type of behavior associated with the satisfaction of some need, memory provides a ready-made set of programs. This set consists of genetically determined forms of behavior - instincts and acquired - conditioned reflexes. If there is no such ready-made behavior in memory, then this behavioral act will proceed in parallel with the learning process. The use of the memory apparatus - the extraction of existing information and the possibility of memorizing new ones - fundamentally distinguishes GNI from simple reflex activity.
The main condition for the formation of afferent synthesis is the meeting of all four types of afferentations, which are processed simultaneously due to the convergence of all types of excitation. Completion of the stage of afferent synthesis leads to the transition to the next stage - decision-making. Thanks to the decision, a form of behavior is adopted that corresponds to the satisfaction of a certain need, previous experience and the environment, which allows you to carry out exactly the action that should lead to the programmed result.
The third stage is the formation action programs. At this stage, ways of realizing a specific goal are provided, efferent commands are formed to various executive bodies. At the same time, a special apparatus is created in the neural structures - an acceptor of the result of an action, which predicts all the parameters of the future result. Pay attention to these two fundamental differences between GNI and reflex activity: the reflex response always proceeds stereotypically, on a constantly morphological basis, which is the reflex arc. When forming a program of behavior, it is provided, firstly, the possibility of choosing several options for the program, and secondly, the memory apparatus is used and the result of the action is predicted. The end result may not coincide at all with the predicted one, or it may coincide in some parameters, and differ in some (the feeling of hunger is satisfied, but the taste of the food did not correspond to the expected). The acceptor of the result of an action must provide mechanisms that allow not only to predict the parameters of the required result, but also to compare them with the parameters of the actually obtained result. It is assumed that the acceptor of the result of the action is represented by a network of intercalary neurons covered by a ring interaction (impulse reverberation). Excitation, once in this network, continues to circulate in it for a long time. Thanks to this mechanism, the goal of the activity is retained for a long time and regulates behavior. Regulation consists in the fact that when comparing the predicted and actually achieved results, the program of action is adjusted. If the results do not match the forecast, then a mismatch reaction occurs, activating the orienting-exploratory reaction, which increases the associative capabilities of the brain, providing an active search for additional information.
On its basis, a new, more complete afferent synthesis is formed, a more adequate decision is made, which, in turn, leads to the formation
ing a more perfect program of action that allows you to get the desired result. The neurons involved in the formation of a functional system are located in all structures of the CNS, at all its levels. When the desired useful result is achieved in the acceptor of the results of the action, an agreement reaction is formed, an afferentation arrives, signaling the satisfaction of motivation. At this point, the functional system that was formed in the structures of the central nervous system to achieve a specific goal ceases to exist.
As you can see, the functional system of behavior is formed according to the reflex principle: there is an irritant - afferent synthesis, there is a central link that forms a program that includes an acceptor of the result of an action, a method for its implementation, there is an effector link - those specific movements that are used to achieve the goal. The main difference is that the behavior can change, adjust to the desired result based on a comparison of the obtained and the desired result.
The processes of agreement or disagreement that occur when comparing the parameters of the actually obtained result with the action programmed in the acceptor of the results of the action are accompanied by either a feeling of satisfaction or dissatisfaction, i.e. positive and negative emotions. This means that at all stages of planning and implementation of a behavioral act, a special form of reaction occurs, which is characteristic only of higher nervous activity. This reaction occurs as a subjective reflection of the probability of achieving the goal, when comparing the desired and the results obtained - emotional
Having examined the structure of a behavioral act, we found several fundamental differences between GNI and a simple reflex. GNI is motivated, requires activation of memory, accompanied by emotions, but these are far from all the differences. Behavior is highly dependent on functional state central nervous system, that is, on the level of its activity. One of the characteristics of CNS activity is attention. Both the formation of a program of behavior and the specific methods of its implementation depend on type of higher nervous activity animal and human, as well as on which hemisphere of the cerebral cortex is dominant in receiving sensory information and in performing movements, in other words, on the profile of the function
rational interhemispheric asymmetry . All these features of GNI are
are similar to both animals and humans, but humans have one more feature. When raising a child develops second signal system, which is unique to humans. This transfers the higher nervous activity of a person to a higher level. It acquires new qualities, which determine the expansion of opportunities for communication with the outside world and the versatility of its manifestations. IP Pavlov called the second signaling system an "extraordinary addition" to the mechanisms of higher nervous activity of a person. The second signaling system is speech, the word, visible, audible, pronounced mentally. This is the highest signaling system of the surrounding world. It consists of
verbal designation of all its signals and in speech communication.
And now look at the table of contents - in this manual we will consider in more detail all of the listed features that distinguish goal-directed behavior, or higher nervous activity, from a simple reflex response.
Neural Mechanisms of Behavior
A behavioral act is always an integration of innate and acquired forms of behavior. Innate forms of behavior are organized in a simpler way; at the neural level, they can be represented as an integration of sensory and command neurons. Command neurons realize their effects through the motor neurons of the spinal cord.
Behavior, which is the result of learning and is formed during life, has a more complex organization. The study of the function of individual neurons during the execution of complex behavior made it possible to identify a large number of neuron groups that differ in their functions.
First of all, a large group of sensory neurons has been isolated. Among these neurons are neurons - detectors. These neurons respond to the simplest qualities and properties of the outside world: angles or line segments, the color of objects. Among the sensory neurons, gnostic units, neurons that respond to more complex, complex stimuli: a face or a photograph, displaying emotions on a face. Such neurons are found in the superior temporal cortex and amygdala.
A special group of neurons are environmental neurons, which are selectively excited in a certain environment. They received the name selective, and found in the motor, somatosensory and visual cortex. The excitation of these neurons does not depend on the position of the body. A similar group of neurons are place neurons, which are excited at a certain position of the animal in space.
Neurons have been found in many brain structures, the activation of which is associated with the selection of the goal of a behavioral act, but only in the presence of motivation. Such neurons are found in the hypothalamus, caudate nucleus, frontal and temporal cortex of monkeys. Among these neurons, the most studied waiting neurons found in the hypothalamus. The activity of these neurons increases during motivational arousal and drops sharply when the goal is achieved.
A group of neurons is identified that are excited before the execution of a behavioral act, and immediately fall as soon as the motor execution of the program begins. These neurons are named neurons of motor programs. These neurons are followed by activation command neurons and motor neurons that determine the contraction of a single muscle.
A special class of neurons is called search behavior neurons. The excitation of these neurons is observed in cases where the result of the action does not match the parameters of the result. In this case, even such calm animals as rabbits, not finding a pedal on a new feeder (and they had already learned how to press the pedal and receive food), tore out the feeders with their teeth and scattered them around the cage. Orienting-search behavior, which can be replaced by aggressive, has an adaptive value.
A characteristic feature of orienting-search behavior is the increased activity of a special class of neurons - novelty neurons. Novelty neurons have been described for the hippocampus, nonspecific nuclei of the thalamus, and the reticular formation of the midbrain.
Needs
Needs are the source of animal and human activity. All human and animal needs can be divided into three groups: vital
nye (biological), social and ideal the need for knowledge and creativity. Biological needs are those needs, the non-satisfaction of which can lead to the death of an individual. These are the needs for food, water, a certain temperature, rest, a certain level of security.
Social needs are those needs, the dissatisfaction of which threatens the death of the population. These are the needs associated with the implementation of such types of behavior as sexual, parental, territorial. For a person, in addition to gender and parental, it is also the need to belong to some social group and occupy a certain position in it. The need for education can also be attributed to social needs. In animals, this need is realized with the help of the instinct of imitation, in play behavior, where there is a "rehearsal" of all forms of search, food-procuring, protective and defensive behavior and, at the same time, methods of social contact are being worked out. Both children and young animals learn to take, maintain and defend their place in the peer group. For a person, this is the need to follow the behavioral, moral, aesthetic standards adopted in a given social environment.
Of particular importance for the social life of a person is the need for competence, or equipment. Only on the basis of this need a high level of professionalism is formed. Satisfaction of this need generates positive emotions, due to which even the most routine work becomes attractive. A high level of human competence makes him confident, self-reliant and independent.
Ideal needs include the need to know the world around us and our place in it. The biological basis of ideal needs is orienting-search behavior, which also manifests itself in the satisfaction of biological needs - both food and a place to rest must be found, and in the satisfaction of social needs. It is accepted that the main component of ideal needs is the search for new information. There are two reasons for such a search: the first is a lack of incentives, an information-poor environment, the second is the uncertainty of the information received and the need for clarification. Special attention should be paid to the fact that the failure to satisfy ideal needs does not threaten the death of either an individual or a population. Failure to meet these needs threatens to stop the development of the population and the species as a whole. It should be noted that all people and animals have some average level of creative needs, however, both among people and among animals, a small group stands out, no more than 3–5% of the population, which has the most pronounced needs in finding something new. These are a kind of scouts of the future, which the population can even sacrifice.
to acquire information about new territories, new types of food, new living conditions, etc.
Motivations
When a need is not satisfied, for example, the biological need for food, water, deviations from the norm of the parameters of the internal environment of the body (glucose level, osmotic concentration) occur. These changes are perceived by numerous receptors that trigger reflex and humoral regulatory mechanisms that restore the normal value of the parameters. If deviations in the composition of the internal environment are so significant that they cannot be restored with the help of the regulatory systems of the body, the highest level of regulation is activated - behavior change. The incentive to change behavior is motivation. So, for example, with a decrease in blood glucose levels, chemoreceptors are excited in the lateral nuclei of the hypothalamus (hunger center). Excitation from them is transmitted to the cerebral cortex - there is a feeling of hunger. Excitation gradually captures more and more areas of the cortex, which ensures the formation of eating behavior.
Motivation literally means "what causes movement". There are many definitions of motivation, let's focus on two. K.V. Sudakov believes that motivation is a state that develops in the structures of the central nervous system during behavior. Objectively, it is expressed in a change in the electrical activity of the brain, subjectively, in the appearance of certain experiences. According to P.V. Simonov, motivation is an initial impetus (inducement), which always turns into behavior that has a clearly defined goal.
Motivations, like needs, can classify into biological, social and ideal, but these concepts are not identical. Needs
is what the body needs, and motivation is the mechanism by which behavior changes. The need is not always transformed into motivational excitation.
Motivation is divided into two stages, or phases. motivation: 1) the phase of detection of a specific state - this phase reflects the recognition of a change in some something parameter of the internal environment - and 2) the phase of launching and implementing specialized goal-directed behavior - during this phase, a decision is made, an action program is formed, i.e. The central nervous system builds a temporary functional system of a behavioral act. The implementation of behavior, the actual procedure for performing movements, is the result of the emergence of motivation.
During any motivation, the following events occur:
1. Activation of the motor system (the exception is passive fear).
2. Increased tone of the sympathetic nervous system (increase in heart rate, blood pressure, MOD, vasodilation of skeletal muscles). An increase in sympathetic tone is carried out through descending pathways from the limbic system and the hypothalamus.
The subject and tasks of the physiology of higher nervous activity. Connection with other sciences.
Basic concepts: "unconditioned reflex", "conditioned reflex", "higher and lower nervous activity", "mental activity", "sensory systems".
The history of the development of the doctrine of higher nervous activity.
Modern achievements in the physiology of higher nervous activity.
Methods for studying higher nervous activity (within the framework of a practical lesson).
1. Physiology of higher nervous activity is the science of the neurophysiological mechanisms of the psyche and behavior, based on the principle of reflex reflection of the external world. This is a materialistic doctrine that reveals the laws of the brain, allows you to know the nature and internal mechanisms of learning, memory, emotions, thinking and consciousness.
As part of the discipline of physiology of higher nervous activity and sensory systems, we will study the nature of conditioned and unconditioned reflexes, as well as study the patterns of sensory systems and their role in the formation of mental activity.
The purpose of the discipline "Physiology of GNI and sensory systems" is to reveal the patterns of conditioned reflex activity of the nervous system, as well as to study the features of receiving and processing information in sensory systems.
Discipline tasks:
Find out the neurophysiological mechanisms of conditioned reflex activity in the body;
To reveal the principles of interaction between the processes of excitation and inhibition in the nervous system;
Reveal the features of the functioning and interaction of sensory systems;
Determine the value of sensory information in the implementation of human mental activity.
The discipline "Physiology of Higher Nervous Activity and Sensory Systems" is closely related to the Physiology of the CNS, Psychophysiology and other sciences.
2. The founder of the science of Physiology of higher nervous activity is IP Pavlov. He was the first to discover the principle of conditioned reflex connection. IP Pavlov believed that unconditioned and conditioned reflexes lie at the basis of higher nervous and mental activity.
An unconditioned reflex is an innate species-specific reaction of the body that reflexively occurs in response to a specific effect of a stimulus, to the effect of a biologically significant (pain, food, tactile irritation, etc.) stimulus that is adequate for this type of activity. Unconditioned reflexes are associated with vital biological needs and are carried out within a stable reflex pathway. They form the basis of the mechanism for balancing the influences of the external environment on the body. Unconditioned reflexes arise to direct sensory signs of an stimulus adequate for them and can be caused by a relatively limited number of environmental stimuli.
A conditioned reflex is an individually acquired reaction of the body to a previously indifferent stimulus, reproducing an unconditioned reflex. The basis of the conditioned reflex is the formation of new or modification of existing nerve connections that occur under the influence of changes in the external and internal environment. These are temporary connections that are slowed down when reinforcements are canceled, the situation changes. Studying the features of the development of brain structures in various animals, I.P. Pavlov came to the conclusion that in the process of animal evolution, the ratio of innate and acquired reactions changes naturally: in the behavior of invertebrates and lower animals, innate forms of activity prevail over acquired ones, and in more developed animals they begin to dominate individually acquired forms of behavior that are continuously developing, becoming more complex and improving. Proceeding from this, I.P. Pavlov introduces a division of the concepts of higher nervous activity and lower nervous activity. Higher nervous activity was defined by him as a conditioned reflex activity of the leading parts of the brain (in humans and animals - the large hemispheres), which provide adequate and most perfect relations of the whole organism to the outside world, i.e. behavior. Lower nervous activity is defined by him as the activity of the lower parts of the brain and spinal cord, which control the activity of the body systems among themselves.
In addition, Pavlov also introduced the concept of "mental activity" - this is a qualitatively new, higher than conditioned reflex behavior, level of higher nervous activity inherent in man. Mental activity of a person consists not only in the construction of more complex neural models of the surrounding world, but also in the production of new information, various forms of creativity. Despite the fact that many manifestations of the human mental world turn out to be divorced from the direct stimuli of the external world and seem to have no real objective reasons, there is no doubt that the initial, triggering factors are quite deterministic phenomena and objects. This idea was first expressed by I.M. Sechenov in the form of the thesis “all acts of conscious and unconscious human activity by way of origin are reflexes.”
The subjectivity of mental processes lies in the fact that they are a property of an individual organism and cannot exist outside a specific individual brain with its peripheral nerve endings and nerve centers and are not an absolutely exact mirror copy of the real world around us.
The simplest mental element in the functioning of the brain is sensation. It arises as a result of the spatio-temporal distribution of the excitation pattern and serves as an elementary act that, on the one hand, connects our psyche with external influences, and on the other hand, is an element of complex mental processes. Sensation is a conscious reception, which means that it contains a certain element of consciousness and self-consciousness.
At present, the physiology of higher nervous activity has been defined as the science of the brain mechanisms of behavior and the psyche.
The leading role in the perception of the reality surrounding humans and animals belongs to sensory systems. According to the definition proposed by I.P. Pavlov, the sensory system is a part of the nervous system, consisting of perceiving elements - sensory receptors that receive stimuli from the external or internal environment, nerve pathways that transmit information from receptors to the brain, and those parts of the brain that process and analyze this information. The transmission of sensory signals is accompanied by their multiple transformation and ends with a higher analysis and synthesis (image recognition), after which the body's response is formed.
3. The first references to the essence of the psyche are found among ancient Greek and Roman scientists. The very word psychios - spiritual has Greek roots.
In world science, a whole area of research has now been formed, called neuroscience. It is a nourishing source for understanding the higher functions of the brain. By the way, the term "higher nervous activity" in our literature most closely corresponds to the term "cognitive neuroscience" in the English literature.
However, let's go back to today. What discoveries had the greatest influence on the development of the physiology of higher nervous activity?
In the first place, one can put a complete understanding of the physicochemical processes that form the basis of excitation and its conduction along nerve fibers, as well as the process of inhibition in neurons. Nobel Prize for British physiologists A. Hodgkin, A. Huxley and J. Eccles (1963) to develop research in this area.
Another important discovery was the study of synaptic conduction processes, i.e. transmission of signals from a neuron to neurons or other cells in the body. Now there is a complete conviction that the basis of learning (closing a temporary connection, according to I.P. Pavlov), memory, mental illness and many other processes associated with higher nervous activity are synaptic processes. Advances have been made in research on biological models of learning - simple nervous systems of mollusks, insects and other invertebrates, as well as on vital sections of the brain (newborn mice, rats, guinea pigs), potentiation (mono- and heterosynaptic), and a number of others. The ideology of such research is based on the fundamental idea of I.P. Pavlova - the repeated combination of two stimuli leads to the blazing of a path in the nervous system that connects them. This idea in the 50s was reformulated by the American theorist D. Hebb for the neuron and was called the Hebb synapse.
Works in the field of neurogenetics. Understanding that in certain cell types during synaptic activation, the expression of early genes occurs, which, through the appropriate promoters, turn on the work of late genes, protein synthesis occurs, which is built into the postsynaptic membrane. From the postsynaptic neuron, an information signal (for example, molecules of nitric oxide or arachidonic acid) can pass to the presynaptic neuron. Today's discoveries are, apparently, only the beginning of understanding the processes of synaptic plasticity. This is an unconditional point of growth of modern scientific knowledge in the field of physiology of higher nervous activity.
Important achievements of recent decades include the identification of genome loci responsible for the synthesis of a number of biologically active substances (hormones, neuropeptides, mediators) involved in the activity of the nervous system. It is extremely important to study the genetic aspects of the differentiation of individual elements of the nervous tissue (various types of glia and neurons with different chemical specificity) from cells of the primary epithelium of the neural tube. Now it is quite obvious that neurons in genetic terms are very active cells: for example, polyploidy of neurons is known in the nervous system of both invertebrates and higher mammals.
The next problem, which has a huge impact on the accumulation of knowledge in the field of the physiology of higher nervous activity, is the ontogeny of the processes of higher nervous activity. From the work of ethologists on brood and nestlings, it became obvious that the formation of species-specific behavior (for example, singing, following the mother, choosing a sexual partner, and some others) occurs only in the so-called sensitive periods of development. K. Lorentz called this phenomenon imprinting (imprinting). Now it is obvious that this is the biological principle of the formation of neural structures - in certain periods of ontogeny (prenatal and postnatal), they are formed under the influence of
external (and possibly internal) signals. This is true for higher mammals, including humans. For example, a newborn is born with about 1/4 the weight of an adult brain, but with a full set of neurons. Then begins a long journey, about two decades, until puberty, during which the knowledge necessary for later life is acquired. At the heart of this process is learning, or it is often called early education. For example, object vision in a person is formed up to 15 years of his life. It turned out that if during this period a person's vision was impaired due to cataracts, then after the restoration of vision at a later age, object vision is no longer formed. Speech is formed in the period up to 4 years. The lack of speech practice, for example, in deaf children, leads to the "Mowgli effect".
There are many such examples. This is an extremely important area of the physiology of higher nervous activity, which has practical projections not only into medicine, but also pedagogy, and even sociology. It is now well known that social forms of behavior, for example, in monkeys, are also formed in the early period of development of the cub. We can cite the well-known works of X. Harlow on raising cubs on stuffed animals, which led to irreversible violations of maternal behavior in females who became adults: they treated their cubs as inanimate objects, which often led to the death of the cub.
Enormous progress has been made in the study of the functions of individual structures and systems of the brain. This is primarily due to the development of research methods. During this time, behavioral methods have been improved, a huge arsenal of instrumental methods has appeared (numerous modifications of electrophysiological methods - from microelectrode to clinical ones, as well as a whole set of tomographic ones). In the field of experimental morphology, a huge variety of intravital dyes for neurons, methods using monoclonal antibodies to identify neurotransmitter receptors, and many others have appeared.
Significant progress has been made in the field of sleep physiology. The classical studies of G. Magun, D. Moruzzi (1949) and others finally solved the problem of sleep physiology in favor of the reticular structures of the brain stem.
The study of the limbic system underlies the main problems of the physiology of higher nervous activity, such as, for example, motivation, emotions, reinforcement. All this is directly related to the formation of both instinctive (unconditioned reflex) and conditioned reflex behavior of both animals and humans. It is now clear that all the mechanisms of neuroendocrine regulation underlying seasonal behaviors, reproductive behavior, and many other types of behavior are inextricably linked with the physiology of limbic system structures.
Among the global problems of the physiology of higher nervous activity, which were formulated by I.P. Pavlov, refers to the physiology of the second signaling system. Now it is quite obvious that the basis of this function is the asymmetry of the cerebral hemispheres. This is directly indicated by the discoveries in the last century of the motor and sensory centers of speech in the left hemisphere in right-handers (P. Broca, K. Wernicke). Hymenoptera, cetaceans and other animals have highly developed tongues. Chimpanzees can be taught the language of the deaf and dumb or other ways of signaling. But all these languages cannot be compared with human language. Perhaps this is due to the fact that only humans have "innate grammars" according to N. Chomsky, i.e. innate ability to acquire language.
The most important properties of the language should be listed. First of all, this is the possibility of doubling the surrounding world - the left hemisphere makes a logical copy, and the right - figurative. The second property of the language is the mastery of memory, not only current, but also historical. It is thanks to this that our civilization has appeared, which continues to rapidly accumulate knowledge. It should be noted that the emergence of language is a unique phenomenon in the natural history of the Earth.
Neuroscience has now reached the point where it becomes possible to solve the problem of consciousness among other scientific problems. At the same time, it is currently impossible to state whether there are biological precursors of this function. For example, P.V. Simonov believes that "... consciousness is defined as knowledge that can be transmitted with the help of words, mathematical symbols and generalizing images of works of art, can become the property of other members of society. Consciousness is knowledge together with someone (compare with sympathy, empathy, cooperation, etc.) To realize means to acquire the potential opportunity to communicate, to pass on one's knowledge to another, including to other generations in the form of cultural monuments...". In other words, only humans are conscious. However, a rather complex semantic analysis can take place without the participation of consciousness. For example, the phenomenon of "blind-sighted" patients. These are people who have received extensive brain injuries in the area of the cortical projection of vision. They themselves characterize themselves as "blind", but they are able to copy the drawing, but are not able to understand "what is drawn?". According to the concept of A.M. Ivanitsky, for the act of sensation as a mental phenomenon, a synthesis of sensory information with traces of memory is necessary. Activation of traces of memory occurs by the mechanism of a conditioned reflex. The comparison of sensory and non-sensory information is provided by the mechanism of return of excitation from the subcortical centers of emotions and motivations, as well as other parts of the cortex, including associative zones, to the region of the primary projection of this analyzer. In the case of "blind-sighted", due to the lack of a primary projection zone, such an overlay is impossible and awareness of the visual
the image does not occur. Consciousness and other mental phenomena are the highest level of brain activity, but biologists should have no doubt that they are the result of brain neurobiological processes. The problem is to explain in detail how the brain works in these cases. It can be assumed that the solution of the problem of consciousness will constitute the most important discoveries of the present time.
At the beginning of the XX century. I.P. Pavlov defined the study of higher (mental) forms of brain activity as the subject of physiology of higher nervous activity. A conditioned reflex was singled out as a cell of this activity - it reflects the whole complex world of processes of higher nervous activity. Reflecting on this topic, L.G. Voronin proposed to distinguish phylogenetic levels of higher nervous activity: preconditioned reflex (summation reflex and other forms of changes in the excitability of the nervous system), unstable conditioned reflex (starting with roundworms), persistent conditioned reflex (starting with annelids), complex forms of conditioned reflex activity - such, for example , as chain conditioned reflexes, transfer, reflexes of the nth order and many others; finally, abstract-logical conditional connections that determine the abstract-logical functions of the brain of higher mammals, primarily humans. Thus, psychogenesis originates even in animals with a very simple nervous system. L.V. Krushinsky singled out another type of higher nervous activity, not conditioned reflex - rational activity, which, according to the author, was the biological forerunner of intelligence. This form of higher nervous activity exists only in higher mammals and in some families of birds. If we talk about man, then his brain, as a product of biological evolution, has features that sharply distinguish him from a number of other mammals. Let's list the main ones.
An increase in the size (according to the cephalization index) of the brain. The area of the cerebral cortex increases especially significantly due to the gigantic growth of associative areas. Pronounced asymmetry of the hemispheres. Each hemisphere creates its own world, and perhaps has its own consciousness. This is especially evident in the brain injury clinic. Emotions have become a system of motivations, replacing biological reinforcement in this sense. All this is due to the development of the limbic system of brain structures. A very long childhood. Recall that a child is born with a full set of neurons, but the weight of his brain is only about 1/4 of the weight of the brain of an adult. An increase in the weight of the brain occurs due to the formation of connections between neurons. It is during this period that a civilized person is formed. Extracortical localization of mental functions. This means that we have entered the age of the noosphere (knowledge), about which V.I. Vernadsky. The basis of this is the extracortical (according to Vygotsky) structure of the language function, which forms the basis of the second signaling system. It is thanks to this property that our civilization accumulates knowledge. Thanks to the unique properties of the second signaling system, a person continuously invents more and more new information technologies - starting with the invention of writing and ending in our time with the creation of the World Wide Web (Internet). All this may indicate that the natural evolution of the Earth, starting with geochemical evolution, went through a long biological evolution, as a result of which higher nervous activity (the psyche) appeared, but with the advent of man, the evolution of the Earth entered a new phase - the phase of noogenesis. And all this is the subject of study of the physiology of higher nervous activity!
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