Types of nervous systems. General characteristics of the nervous system
In most animals, the nervous system consists of two parts - central and peripheral. The central nervous system of vertebrates (particularly humans) consists of the main cord and the spinal cord. The peripheral nervous system consists of sensory neurons, collections of neurons called ganglia, and the nerves that connect them to each other and to the central nervous system.
Depending on the composition of their fibers, nerves are divided into sensory, motor and mixed. Sensory nerves contain centripetal fibers, motor nerves contain centrifugal fibers, and mixed nerves contain both types of nerve fibers. Many nerves and their branches on the periphery, in addition to nerve fibers, have nerve ganglia (ganglia). They consist of neurons, the processes of which are part of the nerves, and their branches (nerve plexuses).
1. Types of nervous systems
In the process of evolution, the following types arose in animals nervous system: diffuse, nodular and tubular.
Diffuse The nervous system is the oldest, characteristic of coelenterates, in which it is formed by a diffuse plexus of nerve cells in the ectodermal layer of the animal’s body. . The primitiveness of such a system lies in the fact that there is no distribution of it into central and peripheral parts and there are no long conducting paths. The network conducts stimulation relatively slowly in all directions from neuron to neuron. Since neurons are connected to epithelial muscle cells, the wave of excitation from any point in the body spreads further and is accompanied by muscle contractions. The body's reactions are inaccurate. But a large number of connections between elements of the diffuse nervous system cause their wide interchangeability, and this ensures reliable functioning.
Stem The nervous system is characteristic of Flatworms and Roundworms and is characterized by the formation of clusters of nerve cells that take the form of cords running along the body. In this case, the paired cerebral ganglion especially develops, i.e. During evolutionary development, a process of cephalization is observed. At the periphery of the nervous system of this type, elements of the diffuse plexus are preserved. The advantages that organisms with a stem nervous system receive compared to a diffuse one are, first of all, the complication of behavior, in particular, the possibility of forming conditioned reflexes and increasing the speed of reaction to a stimulus. At the same time, their nervous system retains a high ability to regenerate due to incomplete specialization of the departments, which is an advantage compared to perfect systems. However, reactions to the stimulus are primitive. In addition, this type of nervous system provides only primitive conditioned reflexes through an insignificant degree of concentration of nerve cells.
Nodal the nervous system is typical of annelids, mollusks, and arthropods. It is characterized by the accumulation of nerve cell bodies with the formation of nodes - ganglia. Neurons, concentrated in ganglia, form the central part of the nervous system. Neurons are differentiated according to different functions. Neurons through which information enters the nerve centers are called centripetal (sensitive) or afferent. Neurons through which information from nerve centers goes to organs are called centrifugal (motor) or effector. Nerve cells that receive excitation from other neurons and transmit them further to nerve cells are called intercalary or intercalary. Thanks to the specialization of neurons, the nerve impulse is carried out in a certain way, which ensures the speed and accuracy of reactions. Also, this type of nervous system, due to its high centralization, allows the formation of complex conditioned reflexes and instincts. Thus, in organisms with this type of nervous system, a significant complication of behavior is observed. Moreover, the most central nervous system is characteristic of cephalopods, which are called “mammals of the sea” due to the complexity of behavioral reactions. They are also characterized by a high level of development of sensory systems.
Tubular the nervous system is characteristic of higher animals - chordates. This system provides the greatest accuracy, speed and locality of the corresponding reactions. It is characterized by a high degree of concentration of nerve cells. The central nervous system consists of the spinal cord in the form of a tube and the main cord. In the process of evolution, the development of the main parts of the brain intensified and its regulatory role grew. This process was called cephalization. In the brain of higher vertebrates, a new section was formed - the cerebral cortex. It collects information from all sensory and propulsion systems, carries out higher analysis and serves as an apparatus for subtle conditioned reflex activity. In humans, the cortex is also an organ of mental activity and conscious thinking.
Cephalization of the nervous system promotes the development of sensory organs and the musculoskeletal system. The more complex the organ, the higher the degree of cephalization. The development of the motor system, its high differentiation and variety of forms of movement are corrected by cephalization of the nervous system.
The disadvantage of the tubular nervous system is its low regeneration potential, which is associated both with the irreplaceability of many structures and with the slow recovery of the neurons themselves. In addition, different parts of the brain perform different functions. Such a narrow specialization of individual structures of one of the most important organs excludes the regeneration of the brain, because if it is damaged, one department cannot replace another, so damage to the centers leads to disruption of the functions of the body as a whole.
2. Nervous system of various animals
2.1. Coelenterata
2.3. Arthropods
2.5. Vertebrates
| Peripheral | Somatic | |
| Autonomous | pretty | |
| Parasympathetic | ||
| Enterichna | ||
| Central | Brain | |
| Spinal cord | ||
And it processes incoming information, stores traces of past activity (memory traces) and accordingly regulates and coordinates the functions of the body.
At the core activity of the nervous system lies a reflex associated with the spread of excitation along reflex arcs and the braking process. Nervous system educated mainly nerve tissue, the basic structural and functional unit of which is the neuron. During the evolution of animals, there was a gradual increase in complexity nervous systems and at the same time their behavior became more complicated.
In development nervous system several stages are noted.
In protozoa there is no nervous system, but some ciliates have an intracellular fibrillary excitable apparatus. As multicellular organisms develop, specialized tissue is formed that is capable of reproducing active reactions, that is, excitation. Reticulate, or diffuse, nervous system first appears in coelenterates (hydroid polyps). It is formed by processes of neurons diffusely distributed throughout the body in the form of a network. Diffuse nervous system quickly conducts excitation from the point of irritation in all directions, which gives it integrative properties.
Diffuse nervous system There are also minor signs of centralization (in Hydra there is densification of the nerve elements in the area of the sole and oral pole). The complication of the nervous system went in parallel with the development of the organs of movement and was expressed primarily in the isolation of neurons from the diffuse network, their immersion deep into the body and the formation of clusters there. Thus, in free-living coelenterates (jellyfish), neurons accumulate in the ganglion, forming diffuse nodular nervous system. The formation of this type of nervous system is associated, first of all, with the development of special receptors on the surface of the body, capable of selectively responding to mechanical, chemical and light influences. Along with this, the number of neurons and the diversity of their types are progressively increasing, and neuroglia. Appear bipolar neurons having dendrites And axons. The conduction of excitation becomes directed. Nerve structures also differentiate, in which the corresponding signals are transmitted to other cells that control the body’s responses. Thus, some cells specialize in reception, others in conduction, and others in contraction. Further evolutionary complexity of the nervous system is associated with centralization and the development of a nodal type of organization (arthropods, annelids, mollusks). Neurons are concentrated in nerve nodes (ganglia), connected by nerve fibers to each other, as well as to receptors and executive organs (muscles, glands).
The differentiation of the digestive, reproductive, circulatory and other organ systems was accompanied by the improvement of the interaction between them with the help nervous system. There is a significant complication and the emergence of many central nervous formations that are dependent on each other. The parathyroid ganglia and nerves that control feeding and burrowing movements develop phylogenetically in higher forms V receptors, perceiving light, sound, smell; appear sense organs. Since the main receptor organs are located at the head end of the body, the corresponding ganglia in the head part of the body develop more strongly, subordinate the activities of the others and form the brain. In arthropods and annelids it is well developed nerve cord. The formation of adaptive behavior of the organism manifests itself most clearly in top level evolution - in vertebrates - and is associated with the complication of the structure of the nervous system and the improvement of the interaction of the body with external environment. Some parts of the nervous system show a tendency to increased growth in phylogeny, while others remain underdeveloped. Fish have a forebrain poorly differentiated, but well developed hindbrain and midbrain, cerebellum. In amphibians And reptiles from the anterior cerebral bladder are separated diencephalon And two hemispheres with primary cortex.
In birds highly developed cerebellum , average And intermediate brain. Bark expressed weak, but instead of it special structures were formed ( hyperstriatum), performing the same as bark at mammals, functions.
Higher development of the nervous system reaches at mammals, especially in humans, mainly due to the increase and complexity cortical structure large hemispheres. The development and differentiation of the structures of the nervous system in higher animals led to its division into central And peripheral.
Origin of the brain Savelyev Sergey Vyacheslavovich
§ 20. Nervous system with radial symmetry
We find the simplest version of the structure of the nervous system in cnidarians (coelenterates). As mentioned above, their nervous system is built according to the diffuse type. The cells form a spatial network, which is located in the mesoglea (Fig. II-4, a). A small accumulation of nerve cells in the peripharyngeal region forms a kind of distributed nerve center. It integrates all the simple reactions of the body of coelenterates and is the evolutionary predecessor of the ganglion nervous system. In the peripharyngeal nerve ring, the parallel ganglia described in the chapter form (see Fig. I-16). Apparently, this type of structure of the nervous network was the initial one for all groups of animals.
Despite its apparent simplicity, the diffuse type of nervous system ensures the rather complex behavior of coelenterates. It is well known that hermit crabs use sea anemones for protection from predators. They select the most suitable individuals and transplant them onto their shell. A classic example is the symbiosis of sea anemones and hermit crabs. However, little is known that sea anemones themselves can also choose the most suitable shell surface and move to it. In other words, sea anemones are just as active, albeit unconscious, participants in the symbiosis as hermit crabs (Kholodkovsky, 1914; Meglitsch and Schram, 1991).
Within the modest framework of the diffuse nervous system, an unusually large number of structural variants are known. They are all united by radial or isomorphic symmetry and a general tendency to unite nerve cells into certain clusters. Since the appearance of the proneural network in sponge-like organisms, a differential concentration of neural elements began. At the beginning of the evolution of multicellular animals, an endless variety of variants of the structure of the nervous system appeared, which were realized in the coelenterates and were partially preserved to this day (see Fig. II-4).
Nerve cells were concentrated in various ways. The most in a simple way integration of nerve networks became the peripharyngeal nerve ring. Its appearance is fully justified by the fact that it was located on the border of food entry into the body of coelenterates. Food was the leading stimulus that determined and assessed the success of morphological changes in the nervous system. Those who could more effectively control their food intake increased their metabolism and reproductive capabilities. The simplest movement to illustrate the action of the diffuse nervous system is the reaction to mechanical stimulation. Freshwater hydra (Pelmatohydra oligactis) at the slightest irritation it shrinks into a microscopic lump. This occurs due to contractile proteins located longitudinally in the ectoderm and transversely in the endoderm. In addition to a generalized reaction, coelenterates can differentially use individual tentacles or their groups. Hydras are able to move, alternating between support on the sole and the mouth when turning over.
However, the diffuse network with the peripharyngeal nerve ring was a relatively slow-acting device. The measured conductivity along the nervous network of coelenterates is no more than 5-20 cm/s. This is clearly not enough for animals larger than 5 cm in size, therefore, already in sea anemones, sections of the nervous network with a high conduction speed have emerged (see Fig. II-4, c). In some cases it reaches
cm/s, which makes sea anemones sophisticated hunters of much more evolutionarily advanced vertebrates. The peripharyngeal nerve ring was a clear advance, but it could not differentially control the entire body or provide control of free swimming.
Among the ancestors of modern solitary anemones there were clearly free-swimming creatures. This is indicated by the double nerve network in their body (see Fig. II-4, b). One diffuse network is located under the ectoderm in the mesoglea and is no different from that of other coelenterates (see Fig. II-4, a). Another nerve network lies in the same mesoglea, but already near the endoderm. They are connected to each other only in the area of the peripharyngeal nerve ring, which begins to play both an integrating and separating role. Apparently, such double networks arose at the dawn of the evolution of the nervous system and were needed for active free swimming. An animal with an autonomous “ectodermal” network could actively move in the water column. The contraction of ectodermal cells allowed the animal to move without involving the digestive system in this process.
Rice. II-4. The supposed first stages (shown by arrows) of the complication of the structure of the nervous system of coelenterates with radial symmetry.
a - single-layer network of primitive hydroids; b - double nerve network of sea anemones; c - nervous network of sea anemones with high-speed conducting chains of cells; d - neural network of an eight-rayed polyp; d - nervous apparatus of the radial-commissural type.
It is possible that the mesoglea of these creatures was much thicker and looser. The digestive nervous network with endodermal contractile cells functioned relatively autonomously, moving food particles without ectodermal contractions. Such a self-propelled vacuum cleaner could be extremely effective when there is an excess of small food particles. The evolutionary advantages of mobile filter feeders are well known, since baleen whales are the largest animals on the planet.
Free-swimming scyphoid jellyfish have a completely different nervous system. They are predominantly carnivores with a diffuse nervous system that is integrated by a perioral circular cluster of neurons and several nerve rings in the umbel. These creatures have interesting highly specialized areas of the nervous system - rhopalia. These are small clusters of neurons along the edges of the umbrella. Rhopalia may contain statocysts, or light-sensitive ocelli. In statocysts, nodules of various natures form a “pebble” pressing on neurons. It allows you to determine the direction to the gravitational center of the Earth and orient the body in the water. The eyes measure the light, and the moving waves mechanically influence the nervous network, which allows the jellyfish to choose the direction of movement. Such nerve formations could not become significant centers to integrate the behavior of coelenterates, but were the first specialized sense organs. Such primitive receptor systems have repeatedly arisen in evolution, which is confirmed by the diversity of their structural organization with the general wretchedness of receptor capabilities.
It can be assumed that the potential ancestral variant of the structure of the nervous system of invertebrates looked like some kind of coelenterate with high-speed cords of nerve cells (see Fig. II-4, c). If we assume the evolutionary continuation of the concentration of nerve cells, then from such a morphological organization, with equal probability, a nervous system of two types of structure could emerge (see Fig. II-4, G, d). These types differ only in the trunk commissures, which connect the longitudinal nerve trunks.
The peripharyngeal nerve ring has approximately the same structure and integrates the activity of the entire nervous network of the animal. In the well-known structural plan of the radially symmetrical nervous system of many modern coelenterates, there are no transverse commissures connecting the nerve trunks. This type could have evolved along the path of reducing the number of nerve trunks. At the same time, apparently, the most original options symmetry of the nervous system. An example is the nervous system of nematodes (Fig. II-5, b). It is represented by 4 parallel trunks, which are connected only by the peripharyngeal nerve ring. There are no other commissures in the pharyngeal zone and body of roundworms. It is important to emphasize that the 4 nerve trunks of nematodes are located symmetrically, but contrary to expectations in the dorsal, ventral and lateral positions (see Fig. 11-5, b), the 4 nerve trunks innervate the triangular mouth and do not have processes penetrating into the muscle cells. On the contrary, muscle cells form processes that end on the dorsal and ventral nerve trunks running along the body. Each muscle cell has several such processes, and contractile proteins are localized in the distal part of the cytoplasm. A nerve signal passes through these processes, which causes groups of muscle cells to contract.
It is likely that nematodes have preserved the ancient mechanism of “informing” the body’s cells from the nervous system. Muscle cells themselves take care of the source of information suitable for increasing metabolism. This type of neuromuscular connections is extremely primitive and claims evolutionary primacy, which indirectly confirms the previously stated hypothesis of the origin of nerve cells. Nematodes are numerous, but not diverse in the structure of their sensory organs. These are mainly external and internal mechanoreceptors, chemoreceptors (sensitive pits, papillae) and simple eyes. Mechanoreceptors are specialized for male sensory organs and spicules, cephalic and somatic setae. However, this is an example of extreme specialization, which shows that the most evolutionarily promising was the “commissural” path (see Fig. II-5, c).
Commissures that segment-by-segment connect the longitudinal nerve trunks provide significant advantages in the differential activity of individual parts of the body. It is quite possible that commissural nerve trunks formed at the level of hypothetical coelenterates with radial symmetry. Multiple nerve trunks of such animals could have commissures, which created a developed spatial nervous network. For immobile individuals, the non-commissure option is sufficient (see Fig. II-5, a), therefore the commissures rather indicate an active lifestyle. The segmented network was quite practical in nature and was used for peristaltic movement. The animal moved as a result of the propagation of annular peristaltic waves through the body backward relative to the movement. Differential control of such cavities and the muscles surrounding them is only possible in the presence of repeating neural segments. In such a segment there should be an autonomous center that controls the muscles - the ganglion. A radially symmetrical animal may have several of them, while a bilaterally symmetrical animal may have 2 or 4. Such ganglia are located at the intersection of nerve trunks and transverse commissures.
The intersections gradually transform into contact nodes, and then into full-fledged ganglia. The appearance of additional peripheral centers allows them to take on part of the concerns about controlling the animal’s body. Segmental commissures with ganglia are the main condition for the emergence of specialized cavities and coelom inside the body. Without developed segmental innervation, septal-coelomic structures would have no biological meaning. Their use for peristaltic movements would be impossible. Developed innervation allows them to be deformed over a wide range and to develop great forces with various methods of peristaltic movement. Consequently, the commissures and nodular ganglia created in a radially symmetrical animal all the prerequisites for the emergence of segmentation and bilateral symmetry.
The radially symmetrical animal, which looks like a pipe with waves running through it, is not the best swimmer. This type of movement is very effective in soil, but in water animals with fewer axes of symmetry have an advantage. Flat-bodied animals with wave-like body movements move faster and their energy costs are lower. This applies to both the bottom zone and the water column. Replacing radial symmetry with bilateral symmetry was a matter of very little time. Apparently, the decrease in the number of longitudinal nerve trunks occurred through their fusion. The trunks came closer together and merged, as happens during the metamorphosis of insects. We do not know which radial system made up the bilateral nervous system, but it is unlikely that it had an odd number of nerve trunks. Ultimately, the fusion of the longitudinal trunks led to the emergence of a bilaterally organized nervous system. Most likely, bilaterality developed in the bottom layer. An ancient free-swimming creature switched to a benthic lifestyle. A radially symmetrical tube could also move successfully inside the bottom layer. However, a bilaterally symmetrical creature can swim or crawl on a surface more efficiently. This type of nervous system organization is also widespread among modern free-living animals. flatworms- turbellarian. There are structural options with 4 and 2 parallel nerve trunks (see Fig. II-5, G, e).
Rice. II-5. General view and sections of the main variants of the structure of the nervous system of coelenterates and worms.
a - neural network of an eight-rayed polyp; b - neural network of nematodes; c - nervous apparatus of the radial-commissural type; d, e - nervous system of tubellaria; d - nervous system of the liver fluke. Nerve trunks are indicated in blue in the sections.
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There are three main types of structural organization of the nervous system: diffuse, nodular (ganglionic) and tubular.
The diffuse nervous system is the most ancient, characteristic of coelenterates. It is a network-like connection of nerve cells relatively evenly scattered throughout the body. The primitiveness of such a system lies in the absence of its division into central and peripheral parts, the absence of long conducting paths. The network conducts stimulation relatively slowly from neuron to neuron. The body's reactions to irritation are imprecise and vague. However, the many connections between the elements of the diffuse nervous system ensure their wide interchangeability and thereby greater reliability of functioning.
The nodal nervous system is typical for worms of mollusks and arthropods. It is characterized by the concentration of nerve cell bodies with the formation of ganglia (nodes). The cell bodies of neurons, concentrated in the ganglia, form the central part of the nervous system. The role of the nerve ganglia of the brain increases sharply. Differentiation of neurons occurs in accordance with the various functions performed. Neurons through whose processes the impulse enters the nerve centers are called centripetal (sensitive) or afferent, and neurons through whose processes the impulse from the nerve centers is directed to executive bodies(muscles, gland), - centrifugal (motor) or efferent. Nerve cells that perceive excitation from some neurons and transmit it to other nerve cells are called interneurons or interneurons. Thanks to the specialization of neurons, nerve impulses began to be carried out along certain paths, which ensured the speed and accuracy of the body's reactions. So high quality new way The body's response is called a reflex type of reaction.
A tubular nervous system is characteristic of chordates. This type of system provides the greatest accuracy, speed and locality of responses. It is characteristic of him highest degree concentration of nerve cells. The central nervous system is represented by a tubular spinal cord and brain. In the process of evolution, the development of the head parts of the brain increased, and their regulatory role increased. In the brain of higher vertebrates, a new section has developed - the cerebral cortex. It collects information from all sensory and motor systems, carries out higher analysis and serves as an apparatus for conditioned reflex activity, and in humans as an organ of mental activity and thinking.
The “payment” for the centralization of the nervous system is its high vulnerability: damage to the centers leads, as a rule, to disruption of the functions of the body as a whole.
Types of nervous systems
There are several types of organization of the nervous system, represented in various systematic groups of animals.
Diffuse nervous system - presented in coelenterates. Nerve cells form a diffuse nerve plexus in the ectoderm throughout the animal's body, and when one part of the plexus is strongly stimulated, a generalized response occurs - the whole body reacts.
Stem nervous system (orthogon) - some nerve cells are collected into nerve trunks, along with which the diffuse subcutaneous plexus is preserved. This type of nervous system is represented in flatworms and nematodes (in the latter the diffuse plexus is greatly reduced), as well as many other groups of protostomes - for example, gastrotrichs and cephalopods.
The nodal nervous system, or complex ganglion system, is represented in annelids, arthropods, mollusks and other groups of invertebrates. Most of the cells of the central nervous system are collected in nerve nodes - ganglia. In many animals, the cells are specialized and serve individual organs. In some molluscs (for example, cephalopods) and arthropods, a complex association of specialized ganglia with developed connections between them arises - a single brain or cephalothoracic nerve mass (in spiders). In insects, some sections of the protocerebrum (“mushroom bodies”) have a particularly complex structure.
A tubular nervous system (neural tube) is characteristic of chordates.
The nervous system in the form of diffuse syncytial tissue first appears in multicellular organisms. It is a network of nerve cells, the so-called reticular tissue. The morphological homogeneity and peculiar “closedness” of the reticular tissue do not allow differentiation of external influences. To the action of all external agents Living being responds with the same type of reactions.
With the advent of the ganglion (nodal) nervous system(worms, mollusks, echinoderms) specialization of responses occurs. It becomes possible to transfer excitation from one node to another. The structure and function of the nervous system at this stage of evolution are in direct connection with receptor formations. Sensitive cells of the nervous system in the process of evolution were improved in parallel with the development of reception apparatuses. This was greatly facilitated by the morphological proximity of the reception apparatus and sensory nerve cells.
Further improvement of the functions of the nervous system, observed in chordates, is associated with the centralization of nerve ganglia. In the structure of the nervous system of vertebrates, specialized synapses develop, and with them multiple connections between nerve cells. The emergence of multisynaptic connections created the preconditions for qualitatively new forms of relationships between body systems, as well as between the body and the environment.
In fish The olfactory brain is well developed, the globus pallidus and the nerve centers of the midbrain are structurally separated - the red nucleus and the substantia nigra. In the regulation of the life activity of reptiles, the cerebral hemispheres and subcortical nuclei play a leading role. In individual representatives of this class, a new cortex appears, reaching perfection in mammals and their highest representative - humans.
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Brain |
Forebrain |
Finite brain |
Olfactory brain,Basal ganglia,Cerebral cortex,Lateral ventricles |
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Diencephalon |
Epithalamus,Thalamus,Hypothalamus,Third ventricle |
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Brain stem |
Midbrain |
Four Hills,Brain stems,Silviev water supply |
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Diamond brain |
hindbrain |
Varoliev Bridge,Cerebellum |
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Medulla |
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Spinal cord |
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The evolution of the nervous system is closely related to the evolution of muscle tissue. The cells of multicellular animals gradually specialize to perform different functions. Muscle cells appear earlier in evolution than nerve cells. These progenitors of muscle cells are located on the surface of the body and are able to respond to external influences by contracting. Khlopin called them myoneuroepithelial cells. During the further development of multicellular organisms, muscle cells move into deeper layers of the body, so there is a need for sensitive cells that are accessible to superficial stimulation by stimuli and capable of transmitting excitation to deeper lying muscle cells. This is how organisms appeared that have neurons on the surface of the body, the processes of which are in direct contact with muscle cells. The next stage in the development of the nervous system is the appearance of nerve circuits, first of 2 neurons, and then with a large number of neurons. For example, such 2-neuron circuits are present in each segment earthworm. The 1st neuron (afferent, sensitive) lies on the surface of the body, the axon of the 1st neuron transmits an impulse to the deeper lying 2nd neuron (efferent, motor), and the 2nd neuron causes contraction of the muscle cells of the segment. At the next stage, intersegmental neurons appear in segmented animals. This allows the coordinated actions of the segments to be coordinated. The increase in the number of these connections led to the appearance of a bundle stretching along the body close to the central axis, ultimately the spinal cord and brain. In general, the evolution of the nervous system is characterized by conservatism: the higher ones retain the signs of segmentation inherent in the lower ones; chemical transmission of impulses in synapses in both lower and higher ones. The higher the level of organization, the more pronounced the advanced development and maturation of the nervous system in the embryonic period. The higher the level of organization of the species, the greater the number of blastomeres of the embryo is used to lay down the nervous system. Thus, in humans, 1/3 of the surface area of the fertilized egg is the presumptive zone (future zone) of the neural tube.
Functions of animal play activity.
Functions of gaming activity according to Fabry. 1) Developmental activity. Using manipulation games as an example. Qualitative changes in the behavior of the cub are associated with the results of manipulative games, the maturation of the motor and sensory components of this primary manipulation. (the ability to take various objects into the mouth of a fox is associated with the primary grasping of the nipple) Significance - the formation of motor components is determined by qualitative transformations in the motor sphere, expansion of functions and the transition of some functions from the oral apparatus and vice versa (sometimes a change in functions from lapping to sucking). The biological conditionality of manipulation is that cats have multifunctional limbs, badgers have specialization for digging holes → the forelimbs are developed. →games are determined by the way of life. But the picture is contradictory in monkeys - the forelimbs are less specialized and their additional functions have received the utmost development among mammals. 1.2. Juvenile behavior and adult behavior The motor repertoire of an adult is formed by fouling and supplementing the instinctive, innate basis of behavior with species-typical individual experience, i.e., through obligatory learning. With age, manipulation acquires more and more species-typical features. Significance – motor-sensory experience increases, biologically significant connections are established with environmental components. 2. The function is the formation of communication. In the process of playing together, group behavior is formed. By joint we should understand those games where there is coordination of action. Joint games without objects. In joint manipulative games, some objects are included in the game as the object of the game; such games perform a communicative role and objects can also serve as a replacement for a natural food object. 2.2. Game signaling - coordination of actions is based on mutual innate signaling; these signals serve as key stimuli for game behavior. These are postures, movements, sounds that notify the partner that he is ready to play. Signals that prevent a serious outcome of the game without such a notification that aggression and fake play can turn into a fight are also important. 2.3. The significance of joint games for adult behavior is that if a child is deprived of play, he will be incompetent in adulthood. They learn sexual behavior, maternal behavior. Young monkeys learn to communicate with each other through play.3. The cognitive function of the game is that during the game the juveniles acquire information about the properties and qualities of objects in their environment. This makes it possible to clarify and supplement species experience in relation to specific living conditions. The least exploratory component in games involving only physical exercises is mostly where there is an active influence on the object, i.e. in manipulative games. A special method is indirect games - trophy games, i.e. joint cognition of an object follows communication m/w. So, during ontogenesis, cognitive activity expands and becomes more complex, an expansion of functions takes place, after leaving the nest, behavior turns to qualitatively new objects and we can say about the change of functions
Characteristics of types of learning in animals according to W. Thorpe.
The classification of types of learning, proposed in 1963 by W. Thorpe, is descriptive on a historical basis with points of generalization. Thorpe identifies the types of learning studied by animal psychologists at one time or another in the development of the science of animal psychology. Thorpe “believes that different species may have different mechanisms responsible for learning; it leaves open the question to what extent cases of similar learning in representatives of different taxonomic types are caused by similar mechanisms.
Classification of learning according to W. Thorpe:
1. Habituation (habituation);
2. Associative learning:
a) classic conditioned reflex.
Synonyms: respondent learning, conditioned reflex of the first kind;
b) operant conditioned reflex.
Synonyms: “trial and error”, conditioned reflex of the second kind,
instrumental learning, Skinnerian learning;
3. Latent (hidden) learning;
4. Insight (illumination):
a) insight itself (“capturing relationships”);
b) imitation type of social facilitation;
c) true imitation (“copying behavioral acts”);
5. Imprinting (imprinting):
a) sealing affection;
b) sexual imprinting.
Thorpe distinguishes between non-associative and associative learning.
Non-associative habituation is characteristic of all animals, from single-celled organisms to humans. With associative learning, an associative connection is formed between two mental phenomena.
Learning: Imitation learning
Obligate imitation learning
Optional simulation training
Non-species-typical imitation manipulation
Simulation problem solving
Tolman studied and tried to explain latent, or hidden, learning by observing rats in a maze. This type of learning is based on research motivation. Exploratory behavior builds what Tolman called a cognitive map. The animal forms a mental image of the components of the environment and its own actions in the environment. After this, the animal can move on to normal daily life. In addition to these situations, latent learning occurs in young animals and children during play.
Insight is the highest form of learning, based on experience gained earlier under other similar circumstances. Inherent only in birds and mammals with intelligence. Finding itself in a problem situation, the animal remains motionless and only evaluates the situation without performing any actions, after which it begins to act taking into account the actually existing connections between the components of the environment.
Characteristics of obligate and facultative learning.
Obligate and optional learning.
Non-associative obligate learning . Obligate learning is an individual experience that occurs in the early postnatal period and, as it were, completes the innate instinctive programs. With this form of learning, key stimuli may not coincide with indifferent signals. Obligate forms of learning include: summation reaction, habituation, imprinting, imitation. Summation- increasing the sensitivity of nervous tissue to irritating agents in protozoan invertebrates in the form of development! route of movement, distinguishing between edible and inedible! products, implementation of protective motor reactions. Privychanting- weakening of the reaction to a repeatedly presented stimulus that is not biologically significant in the life of the animal, the simplest form of behavior in lower animals. Imprinting- a set of behavioral acts that establish the primary connection between a newborn and his parents. During the first social contact, according to the type of imprinting, location memory, sexual imprinting, as well as the reaction of following a moving object in brooding birds and ungulates are carried out. Imitation (imitation)- training, completion of genetic programs, species-typical actions by observing the behavior of another individual of its species and repeating these actions. This is especially true for a young animal, which, by imitating parental behavior, learns various behavioral repertoires of its species.
Associative elective education . Optional (associative) form - active form individual behavior based on the extraction of significant functional elements from the environment to perform certain acts. These include: 1) classical conditioned reflex and 2) instrumental conditioned reflex. Conditioned reflex- association of an indifferent stimulus and an unconditioned signal that causes an unconditioned response. Instrumental conditioned reflex- operant instrumental actions, supported by an unconditioned reflex reaction. The system of classical and instrumental conditioned reflexes significantly expands the adaptive capabilities of living organisms, providing an active factor of interaction with the environment. Cognitive learning. The highest cognitive form of learning is characteristic of animals with a highly developed nervous system. This is the ability to form a holistic image or functional structure environment on establishing regular connections and relationships between the components of this environment.
Analysis of animal behavior leads to the conclusion that all the richness and diversity of full-fledged mental reflection is associated with learning and the accumulation of individual experience.
The formation of behavior is the process of implementing species-typical behavioral acts and experiences. Therefore, the formation of new behavior, learning, is the integration of new elements into instinctive behavior, inherent genetically.
There are forms of learning that outwardly resemble instinctive behavior, but, nevertheless, represent accumulation personal experience, but within the strict framework of species-typical behavior. These are forms of obligate learning, experience necessary for the survival of a given species, regardless of particular living conditions.
In contrast to obligate learning, facultative learning is a form of purely individual adaptation.
According to T. Tembrok, facultative learning is the most flexible, labile component of animal behavior. But this lability is not the same in various forms optional learning. Concretization of species experience by adding individual experience to instinctive behavior is present at all stages of the behavioral act. So the American ethologist R.A. Hyde points to a change in instinctive behavior through learning, through a change in the combination of stimuli, isolating them from the general background, strengthening, etc.
It is also significant that the changes cover both the effector and sensory spheres.
In the effector sphere, examples of learning can be both recombinations of innate motor elements and newly acquired ones. In higher animals, acquired movements of effectors play a large role in the process of cognitive activity, the intellectual sphere of functioning.
Modification of behavior in the sensory sphere significantly expands the animal’s orientation capabilities, due to the acquisition of new groups of signals from the external world. Such an example is cases when a signal that is biologically unimportant for an animal as a result of personal experience in combination with a biologically important one acquires the same degree of importance. And this process is not just the simple formation of new conditioned reflexes.
The basis of learning in this case is dynamic processes in the nervous system, especially in its external parts, where afferent synthesis of various reactions caused by external and internal factors. These stimuli are then compared with early individual experience, and, as a result, a readiness to perform variable responses to the situation is formed. The analysis of the results that follows is a trigger for new afferent synthesis, etc.
Thus, in addition to specific programs, individual programs are formed on which the learning processes are based. The animal is not a passive learner in this process, but actively participates itself, having the “freedom of choice” of interaction.
The basis of learning is the formation of effector programs for upcoming actions, during which there is a comparison and assessment of external and internal stimuli, specific and individual experience, registration of parameters and verification of the results of the actions performed. The implementation of species experience in individual behavior to a greater extent requires learning processes in initial stages search behavior, because reactions to single, random signs of each specific situation cannot be programmed in the process of evolution.
And since without the inclusion of newly acquired elements in instinctive behavior, the implementation of species experience is impossible, which means that these inclusions are hereditarily fixed, therefore, the range of learning is strictly species-typical.
This framework of disposition to learning in higher animals is much wider than what is required in real life conditions, therefore they have greater opportunities for individual adaptation to extreme situations. The level of plasticity of an animal's behavior in the implementation of instinctive experience can serve as an indicator of general mental development.
In this process of development, the difference in behavior between lower and higher animals is not a change from simple behavior to a more complex one, but on the contrary, more complex ones are added to the simplest forms, which leads to an increase in the variability of behavior
Characteristics of the perceptual psyche of animals.
Characteristics of the perceptual psyche . Lowest level. It is the highest stage of development of psychic reflection. This stage is characterized by a change in the structure of the activity - highlighting the content of the activity related to the conditions in which the object of the activity is given in the environment (operation)that we encounter genuine skills and perceptions. The subject components of the environment are reflected as integral elements. Object perception presupposes a certain degree of generalization; sensory generalizations appear. At this level - arthropods, molluscs, crustaceans, arachnids. Instinctive behavior does not lose its relevance in the process of evolution since it cannot be replaced by learning. Instinctive behavior is a species behavior, and learning is individualthe progress of instinctive behavior is associated with the progress of individual behavior. changeable behavior. In higher vertebrates, the psyche has acquired the importance of a decisive factor in evolution thanks to a strong learning process and, in its highest manifestations, intellectual actions, but at the same time the instinctive foundations of behavior are preserved. In higher vertebrates, instinctive components serve for the spatiotemporal orientation of the most important behavioral acts. Spatial orientation is carried out on the basis of taxis - tropo - body - and menotaxis - i.e. typically innate elements of behavior + mnemotaxis is the memorization of landmarks. Also instinctive behaviorbiological adequacy of response to environmental components. An adequate response to biological situations is possible if it is guided by the constant characteristics of these objects and situations; this is what happens on a genetically fixed, innate basis when it reacts to key stimuli.instinctive actions acquire cognitive significance for them. Instinctive behavior reaches a particularly high level of development in vertebrates in ritualized communication with each other; full communication is a necessary condition for higher integration in the field of behavior - the integration of individuals and communities. The great role of learning in the formation of individual characteristics of sound communication and acoustic imitationindividuals of different species can communicate.the ability of higher vertebrates to expand their communicative abilities through learning should have become an important prerequisite for the emergence of human forms of communication. Skills are formed on the basis of unconditioned reflex connections and always include conservative motor elements. Learned automated actions play a large role in the life of higher mammals + monkeys and humans. Complex plastic skills perform the function of quickly adapting the body to environmental conditions. The plasticity of higher-order skills complements the rigidity of lower-order skills and instinctive actions. This plasticity manifests itself when a positive or negative stimulus is transformed into its opposite. Another important feature is the ability to transfer a skill to new conditions (i.e., adequate use of experience). Complex skills are motor receptor systems that provide the development of plastic motor programs based on orienting activity. Process of orientation + motor activity and finding the right decision tasks are formed during this activity on the basis of sensory generalization.complex skills have become the prerequisite and basis for the development of higher forms of mental activity - intellectual actions.
Characteristics of the sensory psyche of animals.
Characteristics of the sensory psyche of animals. Lowest level of mental development. See above for the movements of protozoa. About the psyche, we say that protozoa actively react to changes in the environment and react to biologically not directly significant properties of environmental components as signals about the appearance of vital environmental conditions. It is important for understanding the conditions for the origin of the psyche - the reaction of protozoa to temperature (the reaction to temp. is a property of all protoplasm). But they do not have thermoreceptors; the coexistence of the pre-psychic and the psychic. The quality of psychic reflection is determined by how developed the abilities of movement, spatio-temporal orientation and changes in innate behavior. At a primitive level, protozoa have instinctive behavior - kinesis. Orientation - taxis. The search phase of instinctive behavior (kinesis) is underdeveloped. Only negative components of the environment are recognized remotely at this level; biologically neutral ones are not perceived as signaling, that is, they do not exist for the animal as such. Plasticity of behavior is the most primitive form - habituation and, in some cases, the ability to associative learning. Why is that? The environment of the microcosm is less stable, the life of microorganisms is short, frequent changes of generationsexcessive accumulation of individual experience. In this microenvironment there are no complex and varied conditions to which one must adapt. The highest level of sensory psyche. Perception - the ability to perceive objects is still absent. Annelids their behavior is still dominated by avoidance of unfavorable external conditions, but an active search for positive stimuli already exists and this is characteristic of the highest level of the elementary sensory psyche. Kinesis and elementary taxis play a big role in their lives. The rudiments of complex forms of instinctive behavior are already encountered - leeches, snails, and higher taxis appear, which provide more accurate orientation in spacefull use of food resources. In higher invertebrates, the rudiments of constructive activity, aggressive behavior, and communication appear. General assessment - the primary main function of the primitive nervous system was to coordinate the internal processes of life in connection with the increasing specialization of cells and new formations - tissues from which all organs and systems of a multicellular organism are built. The external functions of the nervous system are determined by the degree of external activity, which in these systems is at a low level. At the same time, the structure and functions of receptors and the external activity of the nervous system become more complicated in leading active image life. Stereotyping forms of response is a defining feature of all their behavior.
The evolutionary necessity of the appearance of psychic reflection in the organic world.
Appearing only at a certain stage of development of the organic world, the psyche is inherent only in highly organized living beings. It is expressed in their ability to reflect the world around them with their condition. The beginning of this stage in the evolution of the organic world should be considered the appearance of the animal form of life, for it was the specific living conditions of animals that gave rise to the need for a qualitatively new, active reflection of objective reality, capable of regulating the increasingly complex relationship of the organism with the environment.
Thus, The psyche is a form of reflection that allows an animal organism to adequately orient its activity in relation to the components of the environment. At the same time, serving as an active reflection of objective reality, matter, the psyche itself is a property of highly developed organic matter. This matter is the nervous tissue of animals (or its analogues). The vast majority of animals have a brain - the central organ of neuropsychic activity.
The psyche of animals is inseparable from their behavior, by which we mean all a set of manifestations of external, mainly motor, activity of an animal, aimed at establishing vital connections between the body and the environment. Mental reflection is carried out on the basis of this activity during the animal’s influence on the surrounding world. In this case, not only the components of the environment themselves are reflected, but also the animal’s own behavior, as well as the changes it makes in the environment as a result of these influences. Moreover, in higher animals (higher vertebrates), which are characterized by genuine cognitive abilities, the most complete and profound reflection of objects in the surrounding world occurs precisely in the course of their change under the influence of the animal.
