Limbic lobe of the brain. The limbic system is more than a formation at the edge of the brain

– the broadest totality, which represents a morphofunctional association of systems. They are found in different parts of the brain.

Let's look at the functions and structure of the limbic system in the diagram below.

System structure

The limbic system includes:

• limbic and paralimbic formations
• anterior and medial nuclei of the thalamus
• medial and basal parts of the striatum
• hypothalamus
• oldest subcortical and mantle parts
• cingulate gyrus
• dentate gyrus
• hippocampus (seahorse)
• septum (septum)
• amygdala.

The diencephalon contains 4 main structures of the limbic system:

Then we have the hypothalamus, which is a vital part of the limbic system, which is responsible for the production of several chemical messengers called hormones. These hormones control the body's water levels, sleep cycles, body temperature and food intake. The hypothalamus is located below the thalamus.

Meanwhile, the flexural gyrus serves as a pathway that carries messages between the internal and external parts of the limbic system. The amygdala is one of two almond-shaped collections of nerve cells in the temporal lobe of the brain. Both amygdalae are responsible for preparing the body for emergency situations, such as "scared", and for storing memories of events for future recognition. The amygdala helps in the development of memories, especially those associated with emotional events and emergency situations.

• habenular nuclei (lead nuclei)
• thalamus
• hypothalamus
• mastoid bodies.

main functions of the limbic system

Connecting with Emotions

The limbic system is responsible for the following activities:

• sensual
• motivational
• vegetative
• endocrine

You can also add instincts here:

Michelds are also associated with the development of the emotions of fear and can be the cause of extreme expressions of fear, as in the case of panic. Additionally, the amygdala plays an important role in pleasure and sexual arousal and can vary depending on a person's sexual activity and maturity.

Components of the limbic system

The hippocampus is another section of the temporal lobe that is responsible for converting short-term memories into long-term memories. The hippocampus is thought to work with the amygdala to store memories, and damage to the hippocampus can lead to amnesia.

• food
• sexual
• defensive

The limbic system is responsible for regulating the wakefulness-sleep process. It develops biological motivations. They predetermine complex chains of effort. These efforts lead to the satisfaction of the above vital needs. Physiologists define them as the most complex unconditioned reflexes or instinctive behavior. For clarity, we can recall the behavior of a newborn baby when breastfeeding. This is a system of coordinated processes. As the child grows and develops, his instincts are increasingly influenced by consciousness, which develops as he learns and is raised.

Finally, we have the basal ganglia, which are a collection of nerve cell bodies that are responsible for coordinating muscle movement in posture. In particular, the basal ganglia help block unwanted movements from occurring and communicate directly with the brain for coordination.

Speculation about the development of the limbic system

It is believed that the limbic system developed from primitive mammals during human evolution. Therefore, many functions of the limbic system deal with instincts rather than learning behavior. Scientists debate whether this system should be considered a single unit biologically, as many of the original ideas that were used to develop the concept are considered obsolete. While they do not dispute the functions of the individual parts, many disagree about whether the pathways associated with these primitive functions are connected.

Interaction with the neocortex

The limbic system and neocortex are tightly and inextricably interconnected with each other and the autonomic nervous system. On this basis, it connects two of the most important activities of the brain - memory and feelings. Typically, the limbic system and emotions are linked together.

However, the limbic system is still discussed in many traditional biology and physiology courses as part of the nervous system. Limbic system structures are involved in many of our emotions and motivations, especially those related to survival. Such emotions include fear, anger, and emotions associated with sexual behavior. The limbic system is also associated with feelings of pleasure that are associated with our survival, such as those experienced from food and sex.

Functions of the limbic system

Certain structures of the limbic system are also involved in memory. Two large structures of the limbic system, and play an important role in memory. The Amygdala is responsible for determining what memories are stored and where the memories are stored. This definition is thought to be based on how much of an emotional response an event causes. The hippocampus sends memories to the appropriate part of the cerebral hemisphere for long-term storage and retrieves them when needed. Damage to this area of ​​the brain can result in an inability to form new memories.

Deprivation of part of the system leads to psychological inertia. The urge leads to psychological hyperactivity. Increased activity of the amygdala activates methods for provoking anger. These methods are regulated by the hippocampus. The system triggers eating behavior and awakens a sense of danger. These behaviors are regulated by both the limbic system and hormones. Hormones are in turn produced by the hypothalamus. This combination significantly influences life through the regulation of the functioning of the autonomic nervous system. Its significance is called the visceral brain. Determines the sensory-hormonal activity of the animal. Such activity is practically not subject to brain regulation either in animals, or even less so in humans. This demonstrates the relationship between emotions and the limbic system.

The part known as the "also" is included in the limbic system. The thalamus is involved in sensory perception and regulation of motor functions. It connects areas that are involved in sensory perception and movement with other parts of the brain, and that also play a role in sensation and movement. The hypothalamus is a very small but important component of the diencephalon. It plays an important role in regulating body temperature, and many other vital activities.

An almond-shaped mass of nuclei involved in emotional reactions, hormonal secretions and memory. Myggdala is responsible for the control of fear or the associative learning process through which we learn to fear something. - a fold in the brain associated with sensory input into emotion and the regulation of aggressive behavior. - arches, strips of axons that connect the hippocampus to the hypothalamus. - a tiny noob that acts as a memory indexer - sends memories to the appropriate part of the cerebral hemisphere for long-term storage and retrieves them when needed. - About the size of the pearl, this structure directs many important functions. The hypothalamus is also an important emotional center, controlling molecules that make you feel agitated, angry, or unhappy. - receives sensory information from the olfactory bulb and participates in the identification of odors. - a large, double-lobed mass of cells that transmit sensory signals in and out. It wakes you up in the morning and gets your adrenaline flowing. . Thus, the limbic system is responsible for controlling various functions in the body.

System functions

The main function of the limbic system is to coordinate actions with memory and its mechanisms. Short-term memory is usually combined with the hippocampus. Long-term memory comes from the neocortex. The manifestation of personal skills and knowledge from the neocortex occurs through the limbic system. For this purpose, sensory-hormonal stimulation of the brain is used. This provocation brings up all the information from the neocortex.

Some of these functions include interpreting emotional responses, storing memories, and regulation. More recently, Paul MacLean, accepting the basic principles of Papez's proposal, created the demonic limbic system and added new structures to the circuit: the orbitofrontal and medial frontal cortices, the paraphthopacambal gyrus and important subcortical groupings such as the amygdala, medial thalamic nucleus, septal area, prosencephalic basal ganglia and several brain stems.

Major areas related to emotions. It is important to emphasize that all of these structures are intensely connected to each other, and none of them is responsible for any specific emotional state. However, some contribute more than others to certain emotions. Below we will look, one at a time, at the most well-known structures of the limbic system.

The limbic system also performs the following significant function - verbal memory of incidents and experiences gained, skills, as well as knowledge. All this looks like a complex of effector structures.

In the works of specialists, the system and functions of the limbic system are depicted as an “anatomical emotional ring.” All aggregates connect with each other and other parts of the brain. The connections with the hypothalamus are especially multifaceted.

Lesions or stimulation of the medial dorsal and anterior nuclei of the thalamus are associated with changes in emotional reactivity. However, the importance of these nuclei for regulating emotional behavior is not due to the thalamus itself, but to the connection of these nuclei with other structures of the limbic system. The medial dorsal nucleus connects with the cortical areas of the prefrontal region and with the hypothalamus. The anterior nuclei connect to the mamillary bodies, and through them, through the plunger, to the hippocampus and dentate gyrus, thus participating in the Papez chain.

It defines:

• human sensual mood
• his motivation for action
• behavior
• processes of acquiring knowledge and remembering.

Violations and their consequences

If the limbic system is disturbed or there is a defect in these complexes, amnesia progresses in patients. However, it should not be defined as a place where certain information is stored. It connects all the separate parts of memory into generalized skills and incidents that are easy to reproduce. Disruption of the limbic system does not destroy individual fragments of memories. These damages destroy their conscious repetition. In this case, various pieces of information are stored and serve as a guarantee for procedural memory. Patients with Korsakoff's syndrome can learn some other new knowledge. However, they will not know how and what exactly they learned.

This structure has extensive connections with other prosencephalic areas and mesencephaly. Lesions of the hypothalamic nuclei interfere with several autonomic functions and some of the so-called motivated behaviors, such as thermal regulation, sexuality, alertness, hunger and thirst. The hypothalamus is thought to play a role in emotions. In particular, its lateral portions seem to be associated with pleasure and rage, while its median portion appears to be involved with disgust, displeasure, and a tendency to laugh uncontrollably and loudly.

Defects in its activities result from:

• brain injury
• neuroinfections and intoxications
• vascular pathologies
• endogenous psychoses and neuroses.

It all depends on how significant the defeat was, as well as the restrictions. Quite real:

• epileptic convulsive states
• automatisms
• changes in consciousness and mood
• derealization and depersonalization
• auditory hallucinations
• taste hallucinations
• olfactory hallucinations.

It is no coincidence that when the hippocampus is predominantly damaged by alcohol, a person’s memory for recent incidents suffers. Patients undergoing treatment for alcoholism in the hospital suffer from the following: they do not remember what they ate for lunch today, whether they had lunch at all or not, or when they last took medications. At the same time, they perfectly remember events that took place in their lives long ago.

The role of the limbic system in the formation of motivation, emotions, memory organization

However, in general terms, the hypothalamus is more associated with the expression of emotions than with the genesis of affective states. When physical symptoms of emotions appear, the threat they pose flows back through the hypothalamus to the limbic centers and therefore to the anterior frontal nucleus, increasing anxiety. This negative feedback mechanism can be so strong as to create a panic situation. As will be seen later, knowledge of this phenomenon is very important for clinical and therapeutic reasons.

It has already been scientifically substantiated - the limbic system (more precisely, the amygdala and the transparent septum) is responsible for processing certain information. This information was received from the olfactory organs. At first, the following was stated - this system is capable of exclusively olfactory function. But over time it became clear: it is also well developed in animals without the sense of smell. Everyone knows about the importance of biogenic amines for leading a full life and activity:

Humans show the largest network of connections between the prefrontal region and traditional limbic structures. Perhaps, therefore, they represent the greatest variety of feelings and emotions among all species. Although some signs of attachment can be perceived in birds, the limbic system only began to develop, in fact, after the first mammals, and is virtually non-existent in reptiles, amphibians and all other previous species.

Paul McLean uses it to say that "it is very difficult to imagine a solitary and more emotionally empty creature than a crocodile." Two behaviors with affective connotations that emerged in mammals deserve special attention because of their distinctiveness.

• dopamine
• norepinephrine
• serotonin.

The limbic system has them in huge quantities. The manifestation of nervous and mental illnesses is associated with the destruction of their balance.

The structure and functions of the limbic system have not yet been studied in many ways. Conducting new research in this area will make it possible to determine its current place among other parts of the brain and will allow our practitioners to treat diseases of the central nervous system with new methods.

The more a mammal develops, the more accentuated these behaviors become. Ablation of important parts of the limbic system of any animal causes it to completely lose both maternal affection and human interest. And the evolution of mammals leads us to humanity. Of course, our hominid ancestor could already establish differences between the sensations that he experienced in individual cases, for example, being in his cave, polishing a stone or bone, running after a weak animal, running away from a stronger one, hunting a female of his own species, etc. P.

Cytoarchitecture of the limbic system cortex

With the development of language, specific names were given to these sensations, allowing them to be identified and communicated with other members of the group. Because there is an important subjective component that is difficult to convey, even today there is no uniformity regarding the best terminology to be used to designate many of these sensations in particular.

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A set of nerve structures and their connections located in the mediobasal part, involved in the control of autonomic functions and emotional, instinctive behavior, and also influencing the change in phases of sleep and wakefulness.

Non-emotional functions of the limbic system

Therefore, the words “affect,” “emotion,” and “feeling” are used interchangeably and imprecisely, almost as synonyms. However, we believe that each of these words deserves a precise definition, for the sake of their etymology and because of the physical and mental reactions they cause.

Interestingly, there is a worldwide tendency to view only positive experiences as affecting them. Opposite emotions and feelings can be used to indicate both positive and negative phenomena: “she has good feelings; I had painful emotions." According to Nobre de Melo, denominations influence, in general, events experienced by emotions or feelings. Emotions, as their etymology shows, exhibit reactions to those emotional states that, due to their intensity, lead to some kind of action.

The limbic system includes the most ancient part of the cerebral cortex, located on the inner side of the cerebral hemispheres. It includes: hippocampus, cingulate gyrus, amygdala nuclei, piriform gyrus. Limbic formations belong to the highest integrative centers for the regulation of the vegetative functions of the body. Neurons of the limbic system receive impulses from the cortex, subcortical nuclei, thalamus, hypothalamus, reticular formation and all internal organs. A characteristic property of the limbic system is the presence of well-defined circular neural connections that unite its various structures. Among the structures responsible for memory and learning, the main role is played by the hippocampus and the associated posterior zones of the frontal cortex. Their activity is important for the transition of short-term memory to long-term memory. The limbic system is involved in afferent synthesis, in the control of electrical activity of the brain, regulates metabolic processes and provides a number of autonomic reactions. Irritation of various parts of this system in an animal is accompanied by manifestations of defensive behavior and changes in the activity of internal organs. The limbic system is also involved in the formation of behavioral reactions in animals. It contains the cortical section of the olfactory analyzer.

Structural and functional organization of the limbic system

Great Peipes circle:

• hippocampus;
• vault;
• mamillary bodies;
• mamillary-thalamic bundle of Vikd Azir;
• thalamus;
• cingulate gyrus.

Small circle of Nauta:

• amygdala;
• end strip;
• partition.

Limbic system and its functions

Consists of phylogenetically old parts of the forebrain. In the name (limbus- edge) reflects the peculiarity of its location in the form of a ring between the neocortex and the terminal part of the brain stem. The limbic system includes a number of functionally combined structures of the midbrain, diencephalon and telencephalon. These are the cingulate, parahippocampal and dentate gyri, hippocampus, olfactory bulb, olfactory tract and adjacent areas of the cortex. In addition, the limbic system includes the amygdala, anterior and septal thalamic nuclei, hypothalamus and mamillary bodies (Fig. 1).

The limbic system has multiple afferent and efferent connections with other brain structures. Its structures interact with each other. The functions of the limbic system are realized on the basis of integrative processes occurring in it. At the same time, individual structures of the limbic system have more or less defined functions.

Rice. 1. The most important connections between the structures of the limbic system and the brain stem: a - Pipetz circle, b - circle through the amygdala; MT - mamillary bodies

Main functions of the limbic system:

• Emotional and motivational behavior (with fear, aggression, hunger, thirst), which can be accompanied by emotionally charged motor reactions
• Participation in the organization of complex forms of behavior, such as instincts (food, sexual, defensive)
• Participation in orientation reflexes: reaction of alertness, attention
• Participation in the formation of memory and the dynamics of learning (development of individual behavioral experience)
• Regulation of biological rhythms, in particular changes in the phases of sleep and wakefulness
• Participation in maintaining homeostasis by regulating autonomic functions

Cingulate gyrus

Neurons cingulate cortex receive afferent signals from the association areas of the frontal, parietal and temporal cortex. The axons of its efferent neurons follow to the neurons of the associative cortex of the frontal lobe, hipiocampus, septal nuclei, and amygdala, which are connected to the hypothalamus.

One of the functions of the cingulate cortex is its participation in the formation of behavioral reactions. Thus, when its anterior part is stimulated, aggressive behavior occurs in animals, and after bilateral removal, the animals become quiet, submissive, and asocial - they lose interest in other individuals of the group, not trying to establish contact with them.

The cingulate gyrus can have regulatory effects on the functions of internal organs and striated muscles. Its electrical stimulation is accompanied by a decrease in breathing rate, heart contractions, a decrease in blood pressure, increased motility and secretion of the gastrointestinal tract, pupil dilation, and decreased muscle tone.

It is possible that the influence of the cingulate gyrus on animal behavior and the functions of internal organs is indirect and mediated by connections of the cingulate gyrus through the frontal lobe cortex, hippocampus, amygdala and septal nuclei with the hypothalamus and brain stem structures.

It is possible that the cingulate gyrus is related to the formation of pain. In people who had a cingulate gyrus dissection for medical reasons, the feeling of pain decreased.

It has been established that the neural networks of the anterior cingulate cortex are involved in the operation of the brain's error detector. Its function is to identify erroneous actions, the progress of which deviates from the program of their execution and actions, the completion of which did not achieve the parameters of the final results. Error detector signals are used to trigger error correction mechanisms.

Amygdala

Amygdala located in the temporal lobe of the brain, and its neurons form several subgroups of nuclei, the neurons of which interact with each other and other brain structures. Among these nuclear groups are the corticomedial and basolateral nuclear subgroups.

Neurons of the corticomedial nuclei of the amygdala receive afferent signals from neurons of the olfactory bulb, hypothalamus, thalamic nuclei, septal nuclei, taste nuclei of the diencephalon and pain pathways of the bridge, through which signals from large receptive fields of the skin and internal organs arrive to the neurons of the amygdala. Taking into account these connections, it is assumed that the corticomedial group of tonsil nuclei is involved in the control of the autonomic functions of the body.

Neurons of the basolateral nuclei of the amygdala receive sensory signals from neurons of the thalamus, afferent signals about the semantic (conscious) content of signals from the prefrontal cortex of the frontal lobe, the temporal lobe of the brain and the cingulate gyrus.

Neurons of the basolateral nuclei are connected with the thalamus, the prefrontal part of the cerebral cortex and the ventral part of the striatum of the basal ganglia, therefore it is assumed that the nuclei of the basolateral group of the tonsils are involved in the functions of the frontal and temporal lobes of the brain.

Amygdala neurons send efferent signals along axons predominantly to the same brain structures from which they received afferent connections. Among them are the hypothalamus, the mediodorsal nucleus of the thalamus, the prefrontal cortex, the visual areas of the temporal cortex, the hippocampus, and the ventral part of the striatum.

The nature of the functions performed by the amygdala is judged by the consequences of its destruction or by the effects of its irritation in higher animals. Thus, bilateral destruction of the tonsils in monkeys causes a loss of aggressiveness, a decrease in emotions and defensive reactions. Monkeys with their tonsils removed stay alone and do not seek to come into contact with other animals. In diseases of the tonsils, there is a disconnect between emotions and emotional reactions. Patients may experience and express great concern about any matter, but at this time their heart rate, blood pressure and other autonomic reactions are not changed. It is assumed that the removal of the tonsils, accompanied by a severance of its connections with the cortex, leads to a disruption in the cortex of the processes of normal integration of the semantic and emotional components of efferent signals.

Electrical stimulation of the tonsils is accompanied by the development of anxiety, hallucinations, experiences of previously occurring events, as well as reactions of the SNS and ANS. The nature of these reactions depends on the location of the irritation. When irritating the nuclei of the corticomedial group, reactions from the digestive organs prevail: salivation, chewing movements, bowel movements, urination, and when irritating the nuclei of the basolateral group, reactions of alertness, raising the head, dilating the pupil, and searching. With severe irritation, animals may develop states of rage or, conversely, fear.

In the formation of emotions, an important role is played by the presence of closed circles of circulation of nerve impulses between the formations of the limbic system. A special role in this is played by the so-called limbic circle of Peipetz (hippocampus - fornix - hypothalamus - mamillary bodies - thalamus - cingulate gyrus - parahippocampal gyrus - hippocampus). The streams of nerve impulses circulating along this circular neural circuit are sometimes called the “stream of emotions.”

Another circle (amygdala - hypothalamus - midbrain - amygdala) is important in the regulation of aggressive-defensive, sexual and eating behavioral reactions and emotions.

The tonsils are one of the structures of the central nervous system, the neurons of which have the highest density of sex hormone receptors, which explains one of the changes in the behavior of animals after bilateral destruction of the tonsils - the development of hypersexuality.

Experimental data obtained on animals indicate that one of the important functions of the tonsils is their participation in establishing associative connections between the nature of the stimulus and its significance: the expectation of pleasure (reward) or punishment for actions performed. The neural networks of the tonsils, ventral striatum, thalamus and prefrontal cortex are involved in the implementation of this function.

Hippocampal structures

Hippocampus together with the dentate gyrus ( subiculun) and the olfactory cortex forms a single functional hippocampal structure of the limbic system, located in the medial part of the temporal lobe of the brain. There are numerous two-way connections between the components of this structure.

The dentate gyrus receives its main afferent signals from the olfactory cortex and sends them to the hippocampus. In turn, the olfactory cortex, as the main gate for receiving afferent signals, receives them from various associative areas of the cerebral cortex, hippocampal and cingulate gyri. The hippocampus receives already processed visual signals from extrastriate areas of the cortex, auditory signals from the temporal lobe, somatosensory signals from the postcentral gyrus, and information from polysensory associative areas of the cortex.

The hippocampal structures also receive signals from other areas of the brain - the brainstem nuclei, raphe nucleus, and locus coeruleus. These signals perform a predominantly modulatory function in relation to the activity of hippocampal neurons, adapting it to the degree of attention and motivation, which are critical to the processes of memorization and learning.

The efferent connections of the hippocampus are organized in such a way that they go mainly to those areas of the brain with which the hippocampus is connected by afferent connections. Thus, efferent signals from the hippocampus follow mainly to the association areas of the temporal and frontal lobes of the brain. To perform their functions, hippocampal structures require constant exchange of information with the cortex and other brain structures.

One of the consequences of bilateral disease of the medial temporal lobe is the development of amnesia - memory loss with a subsequent decrease in intelligence. In this case, the most severe memory impairments are observed when all hippocampal structures are damaged, and less pronounced when only the hippocampus is damaged. From these observations, it was concluded that the hippocampal structures are part of the brain structures, including the medial galamus, cholinergic neuron groups of the base of the frontal lobes, and the amygdala, which play a key role in the mechanisms of memory and learning.

A special role in the implementation of memory mechanisms by the hippocampus is played by the unique property of its neurons to maintain a state of excitation and synaptic signal transmission for a long time after their activation by any influence (this property is called post-tetanic potentiation). Post-tetanic potentiation, which ensures long-term circulation of information signals in closed neural circles of the limbic system, is one of the key processes in the mechanisms of long-term memory formation.

Hippocampal structures play an important role in learning new information and storing it in memory. Information about earlier events is retained in memory after damage to this structure. In this case, hippocampal structures play a role in the mechanisms of declarative or specific memory for events and facts. The mechanisms of non-declarative memory (memory for skills and faces) are largely involved in the basal ganglia, cerebellum, motor areas of the cortex, and temporal cortex.

Thus, the structures of the limbic system take part in the implementation of such complex brain functions as behavior, emotions, learning, and memory. The functions of the brain are organized in such a way that the more complex the function, the more extensive the neural networks involved in its organization. From this it is obvious that the limbic system is only part of the structures of the central nervous system that are important in the mechanisms of complex brain functions and contributes to their implementation.

Thus, in the formation of emotions as states that reflect our subjective attitude to current or past events, we can distinguish mental (experience), somatic (gestures, facial expressions) and vegetative (vegetative reactions) components. The degree of manifestation of these components of emotions depends on the greater or lesser involvement in emotional reactions of the brain structures with the participation of which they are realized. This is largely determined by which group of nuclei and structures of the limbic system is activated to the greatest extent. The limbic system acts in the organization of emotions as a kind of conductor, enhancing or weakening the severity of one or another component of the emotional reaction.

The involvement of limbic system structures associated with the cerebral cortex in responses enhances the mental component of emotion, and the involvement of structures associated with the hypothalamus and the hypothalamus itself as part of the limbic system enhances the autonomic component of the emotional response. At the same time, the function of the limbic system in organizing emotions in humans is under the influence of the frontal lobe of the brain, which has a corrective effect on the functions of the limbic system. It restrains the manifestation of excessive emotional reactions associated with the satisfaction of simple biological needs and, apparently, contributes to the emergence of emotions associated with the implementation of social relationships and creativity.

The structures of the limbic system, built between the parts of the brain that are directly involved in the formation of higher mental, somatic and autonomic functions, ensure their coordinated implementation, maintenance of homeostasis and behavioral reactions aimed at preserving the life of the individual and the species.

In 1878, the French neuroanatomist P. Broca described brain structures located on the inner surface of each cerebral hemisphere, which, like an edge, or limbus, border the brain stem. He called them the limbic lobe. Subsequently, in 1937, the American neurophysiologist D. Peipets described a complex of structures (Papetz circle), which, in his opinion, are related to the formation of emotions. These are the anterior nuclei of the thalamus, mammillary bodies, hypothalamic nuclei, amygdala, nuclei of the septum pellucida, hippocampus, cingulate gyrus, Gudden's mesencephalic nucleus and other formations. Thus, Peipetz's circle contained various structures, including the limbic cortex and the olfactory brain. The term “limbic system” or “visceral brain” was proposed in 1952 by the American physiologist P. McLean to refer to the Peipetz circle. Later, other structures were included in this concept, the function of which was associated with the archiopaleocortex. Currently, the term “limbic system” is understood as a morphofunctional association, including a number of phylogenetically old structures of the cerebral cortex, a number of subcortical structures, as well as structures of the diencephalon and midbrain, which are involved in the regulation of various autonomic functions of internal organs, in ensuring homeostasis, and in self-preservation species, in the organization of emotional-motivational behavior and the “wakefulness-sleep” cycle.

The limbic system includes the prepiriform cortex, periamygdala cortex, diagonal cortex, olfactory brain, septum, fornix, hippocampus, dentate fascia, base of the hippocampus, cingulate gyrus, parahippocampal gyrus. Note that the term “limbic cortex” refers to only two formations - the cingulate gyrus and the parahippocampal gyrus. In addition to the structures of the ancient, old and middle cortex, the limbic system includes subcortical structures - the amygdala (or amygdala complex), located in the medial wall of the temporal lobe, the anterior nuclei of the thalamus, mastoid or mamillary bodies, mastoid-thalamic fascicle, hypothalamus, and also the reticular nuclei of Gudden and Bekhterev, located in the midbrain. All the main formations of the limbic cortex cover the base of the forebrain in a ring-like manner and are a kind of boundary between the neocortex and the brainstem. A feature of the limbic system is the presence of multiple connections both between individual structures of this system and between the limbic system and other brain structures, through which information, moreover, can circulate for a long time. Thanks to these features, conditions are created for effective control of brain structures by the limbic system (“imposition” of limbic influence). Currently, such circles as, for example, the Peipets circle (hippocampus - mammillary or mamillary bodies - anterior nuclei of the thalamus - cingulate gyrus - parahippocampal gyrus - hippocampal base - hippocampus), which are related to memory processes and learning processes, are well known. A circle is known that connects such structures as the amygdala, hypothalamus and midbrain structures, regulating aggressive-defensive behavior, as well as eating and sexual behavior. There are circles in which the limbic system is included as one of the important “stations”, due to which important brain functions are realized. For example, a circle connecting the neocortex and limbic system through the thalamus into a single whole is involved in the formation of figurative, or iconic, memory, and a circle connecting the neocortex and limbic system through the caudate nucleus is directly related to the organization of inhibitory processes in the cerebral cortex .

Functions of the limbic system. Due to the abundance of connections within the limbic system, as well as its extensive connections with other brain structures, this system performs a fairly wide range of functions:

1) regulation of the functions of diencephalic and neocortical formations;

2) formation of the emotional state of the body;

3) regulation of vegetative and somatic processes during emotional and motivational activity;

4) regulation of the level of attention, perception, memory, thinking;

5) selection and implementation of adaptive forms of behavior, including such biologically important types of behavior as searching, feeding, sexual, defensive;

6) participation in the organization of the sleep-wake cycle.

The limbic system, as a phylogenetically ancient formation, has a regulatory influence on the cerebral cortex and subcortical structures, establishing the necessary correspondence of their activity levels. There is no doubt that an important role in the implementation of all the listed functions of the limbic system is played by the entry into this brain system of information from olfactory receptors (phylogenetically the most ancient method of receiving information from the external environment) and its processing.

The hippocampus (seahorse, or Ammon's horn) is located deep in the temporal lobes of the brain and is an elongated elevation (up to 3 cm long) on ​​the medial wall of the lower, or temporal, horn of the lateral ventricle. This elevation, or protrusion, is formed as a result of a deep depression from the outside into the cavity of the inferior horn of the hippocampal sulcus. The hippocampus is considered as the main structure of the archiocortex and as an integral part of the olfactory brain. In addition, the hippocampus is the main structure of the limbic system; it is connected with many brain structures, including through commissural connections (commissure of the fornix) with the hippocampus of the opposite side, although in humans a certain independence in the activity of both hippocampuses has been found. Hippocampal neurons are distinguished by pronounced background activity, and most of them are characterized by polysensory properties, i.e., the ability to respond to light, sound and other types of stimulation. Morphologically, the hippocampus is represented by stereotypically repeating neuron modules connected to each other and to other structures. The connection of the modules creates the conditions for the circulation of electrical activity in the hippocampus during learning. At the same time, the amplitude of synaptic potentials increases, the neurosecretion of hippocampal cells and the number of spines on the dendrites of its neurons increase, which indicates the transition of potential synapses to active ones. The modular structure determines the ability of the hippocampus to generate high-amplitude rhythmic activity. The background electrical activity of the hippocampus, as studies in humans have shown, is characterized by two types of rhythms: fast (15 - 30 oscillations per second) low-voltage rhythms such as the beta rhythm and slow (4 - 7 oscillations per second) high-voltage rhythms such as the theta rhythm. At the same time, the electrical rhythmicity of the hippocampus is in a reciprocal relationship with the rhythmicity of the neocortex. For example, if during sleep a theta rhythm is recorded in the neocortex, then during the same period a beta rhythm is generated in the hippocampus, and during wakefulness the opposite picture is observed - in the neocortex - an alpha rhythm and a beta rhythm, and in the hippocampus it is predominantly registered theta rhythm. It has been shown that activation of neurons in the reticular formation of the brainstem increases the severity of the theta rhythm in the hippocampus and the beta rhythm in the neocortex. A similar effect (increased theta rhythm in the hippocampus) is observed when a high level of emotional stress is formed (during fear, aggression, hunger, thirst). It is believed that the theta rhythm of the hippocampus reflects its participation in the orienting reflex, in reactions of alertness, increased attention, and in the dynamics of learning. In this regard, the theta rhythm of the hippocampus is considered as an electroencephalographic correlate of the awakening reaction and as a component of the orienting reflex.

The role of the hippocampus in the regulation of autonomic functions and the endocrine system is important. It has been shown that especially hippocampal neurons, when excited, can have a pronounced effect on cardiovascular activity, modulating the activity of the sympathetic and parasympathetic nervous system. The hippocampus, like other structures of the archiopaleocortex, is involved in the regulation of the activity of the endocrine system, including the regulation of the release of glucocorticoids and thyroid hormones, which is realized with the participation of the hypothalamus. The gray matter of the hippocampus belongs to the motor area of ​​the olfactory brain. It is from here that descending impulses arise to the subcortical motor centers, causing movement in response to certain olfactory stimuli.

Involvement of the hippocampus in the formation of motivation and emotions. It has been shown that removal of the hippocampus in animals causes the appearance of hypersexuality, which, however, does not disappear with castration (maternal behavior may be disrupted). This suggests that changes in sexual behavior modulated from the archiopaleocortex are based not only on hormonal origin, but also on changes in the excitability of neurophysiological mechanisms that regulate sexual behavior. It has been shown that irritation of the hippocampus (as well as the forebrain bundle and the cingulate cortex) causes sexual arousal in the male. There is no clear evidence regarding the role of the hippocampus in modulating emotional behavior. However, it is known that damage to the hippocampus leads to a decrease in emotionality, initiative, a slowdown in the speed of basic nervous processes, and an increase in the thresholds for evoking emotional reactions. It has been shown that the hippocampus, as a structure of the archiopaleocortex, can serve as a substrate for the closure of temporary connections, and also, by regulating the excitability of the neocortex, contributes to the formation of conditioned reflexes at the level of the neocortex. In particular, it has been shown that removal of the hippocampus does not affect the rate of formation of simple (food) conditioned reflexes, but inhibits their consolidation and differentiation of new conditioned reflexes. There is information about the participation of the hippocampus in the implementation of higher mental functions. Together with the amygdala, the hippocampus is involved in calculating the probability of events (the hippocampus records the most likely events, and the amygdala records the unlikely ones). At the neural level, this can be ensured by the work of novelty neurons and identity neurons. Clinical observations, including those of W. Penfield and P. Milner, indicate the involvement of the hippocampus in memory mechanisms. Surgical removal of the hippocampus in humans causes memory loss for events in the immediate past while retaining memory for distant events (retroanterograde amnesia). Some mental illnesses that occur with memory impairment are accompanied by degenerative changes in the hippocampus.

Cingulate gyrus. It is known that damage to the cingulate cortex in monkeys makes them less fearful; animals cease to be afraid of humans, and do not show signs of affection, anxiety or hostility. This indicates the presence in the cingulate gyrus of neurons responsible for the formation of negative emotions.

Nuclei of the hypothalamus as a component of the limbic system. Stimulation of the medial nuclei of the hypothalamus in cats causes an immediate rage reaction. A similar reaction is observed in cats when the part of the brain located in front of the hypothalamic nuclei is removed. All this indicates the presence in the medial hypothalamus of neurons that participate, together with the nuclei of the amygdala, in organizing emotions accompanied by rage. At the same time, the lateral nuclei of the hypothalamus are, as a rule, responsible for the appearance of positive emotions (saturation centers, pleasure centers, positive emotion centers).

The amygdala, or corpus amygdaloideum (synonyms - amygdala, amygdala complex, almond-shaped complex, amygdala), according to some authors, belongs to the subcortical, or basal, nuclei, according to others - to the cerebral cortex. The amygdala is located deep in the temporal lobe of the brain. The neurons of the amygdala are varied in shape, their functions are associated with the provision of defensive behavior, autonomic, motor, emotional reactions, and the motivation of conditioned reflex behavior. The involvement of the amygdala in the regulation of the processes of urine formation, urination and contractile activity of the uterus has also been shown. Damage to the amygdala in animals leads to the disappearance of fear, calmness, and inability to rage and aggression. Animals become gullible. The amygdala regulates eating behavior. Thus, damage to the amygdala in a cat leads to increased appetite and obesity. In addition, the amygdala also regulates sexual behavior. It has been established that damage to the amygdala in animals leads to hypersexuality and the emergence of sexual perversions, which are removed by castration and reappear with the introduction of sex hormones. This indirectly indicates control by the neurons of the amygdala in the production of sex hormones. Together with the hippocampus, which has novelty neurons that reflect the most likely events, the amygdala calculates the probability of events, since it contains neurons that record the most unlikely events.

From an anatomical point of view, the septum pellucidum (septum) is a thin plate consisting of two sheets. The transparent septum passes between the corpus callosum and the fornix, separating the anterior horns of the lateral ventricles. The plates of the transparent septum contain nuclei, i.e., accumulations of gray matter. The septum pellucidum is generally classified as a structure of the olfactory brain; it is an important component of the limbic system.

It has been shown that the septal nuclei are involved in the regulation of endocrine function (in particular, they influence the secretion of corticosteroids by the adrenal glands), as well as the activity of internal organs. The septal nuclei are related to the formation of emotions - they are considered as a structure that reduces aggressiveness and fear.

The limbic system, as is known, includes the structures of the reticular formation of the midbrain, and therefore some authors propose to talk about the limbic-reticular complex (LRC).

LIMBIC SYSTEM(syn.: visceral brain, limbic lobe, limbic complex, thymencephalon) - a complex of structures of the final, intermediate and middle parts of the brain, constituting the substrate for the manifestation of the most general states of the body (sleep, wakefulness, emotions, motivations, etc.). The term “limbic system” was introduced by P. McLane in 1952.

There is no consensus on the exact composition of the structures that make up the HP. Most researchers, in particular, consider the hypothalamus (see) as an independent formation, distinguishing it from HP. However, such a distinction is conditional, since it is on the hypothalamus that convergence of influences emanating from structures involved in the regulation of various autonomic functions and the formation of emotionally charged behavioral reactions occurs. Connection of functions of HP. with the activity of internal organs gave rise to some authors to designate this entire system of structures as the “visceral brain”, but this term only partially reflects the function and meaning of the system. Therefore, most researchers use the term “limbic system,” thereby emphasizing that all structures of this complex are phylogenetically, embryologically and morphologically related to Broca’s major limbic lobe.

The main part of HP. consist of structures related to the ancient, old and new cortex, located mainly on the medial surface of the cerebral hemispheres, and numerous subcortical formations closely associated with them.

At the initial stage of development of vertebrates, the structure of the HP. provided all the most important reactions of the body (nutritional, orientation, defensive, sexual). These reactions were formed on the basis of the first distant sense - smell. Therefore, the sense of smell (see) acted as the organizer of many integral functions of the body, combining morphol, their basis is the structure of the final, intermediate and middle parts of the brain (see).

HP is a complex interweaving of ascending and descending paths, forming within this system many closed concentric circles of different diameters. Of these, the following circles can be distinguished: amygdaloid region - stria terminalis - hypothalamus - amygdaloid region; hippocampus - fornix - septal region - mammillary (mammillary, T.) bodies - mastoid-thalamic fascicle (Vic d'Azira) - thalamus - cingulate gyrus - cingulate fasciculus - hippocampus (Papes circle, Fig. 1).

Ascending paths of L. s. anatomically insufficiently studied. It is known that, along with the classical sensory pathways, they also include diffuse ones that are not part of the medial lemniscus. The descending pathways of the bloodstream, connecting it with the hypothalamus, the reticular formation (see) of the midbrain and other structures of the brain stem, pass mainly as part of the medial bundle of the forebrain, the terminal (terminal, etc.) strip and fornix. The fibers coming from the hippocampus (see) end in ch. arr. in the area of ​​the lateral part of the hypothalamus, in the infundibulum, preoptic zone and mamillary bodies.

Morphology

Pm. includes the olfactory bulbs, the olfactory legs, which pass into the corresponding tracts, the olfactory tubercles, the anterior perforated substance, the diagonal band of Broca, which limits the anterior perforated substance at the back, and two olfactory gyri - the lateral and medial with the corresponding stripes. All these structures are united by the common name “olfactory lobe”.

On the medial surface of the brain to the L. s. include the anterior part of the brain stem and interhemispheric commissures, surrounded by a large arcuate gyrus, the dorsal half of which is occupied by the cingulate gyrus, and the ventral half by the parahippocampal gyrus. Posteriorly, the cingulate and parahippocampal gyri form the retrosplenial region, or isthmus. Anteriorly, between the anterior-inferior ends of these gyri, there is the cortex of the posterior orbital surface of the frontal lobe, the anterior part of the insula and the pole of the temporal lobe. The parahippocampal gyrus should be distinguished from the hippocampal formation, formed by the body of the hippocampus, the dentate gyrus, or dentate fascia, the pericallosal remnant of the old cortex and, according to some authors, the subiculum and presubiculum (i.e., the base and foundation of the hippocampus).

The parahippocampal gyrus is divided into the following three parts: 1. The pear-shaped area (area piriformis), which in macrosmatics forms the pear-shaped lobe (lobus piriformis), which occupies the largest part of the hook (uncus). It is divided, in turn, into the periamygdaloid and prepiriform regions: the first covers the nuclear mass of the amygdaloid region and is very poorly separated from it, the second merges in front with the lateral olfactory gyrus. 2. Entorhinal area (area entorhinalis), occupying the middle part of the gyrus below and behind the hook. 3. Subicular and presubicular areas, located between the entorial cortex, hippocampus and retrosplenial region and occupying the medial surface of the gyrus.

The subcallosal (paraterminal) gyrus, together with the rudimentary anterior hippocampus, septal nuclei and gray precommissural formations, is sometimes called the septal area, as well as the pre- or paracommissural area.

From the formations of the new cortex to L. s. Some researchers include its temporal and frontal sections and the intermediate (frontotemporal) zone. This zone lies between the prepiriform and periamygdaloid cortex, on the one hand, and the orbitofrontal and temporopolar cortex, on the other. It is sometimes called the orbitoinsulotemporal cortex.

Phylogenesis

All brain formations that make up the human brain belong to the most phylogenetically ancient regions of the brain and therefore can be found in all vertebrates (Fig. 2).

The evolution of limbic structures in a number of vertebrates is closely related to the evolution of the olfactory analyzer and those brain formations that receive impulses from the olfactory bulb. In lower vertebrates (cyclostomes, fish, amphibians and reptiles), the first acceptors of such olfactory impulses are the septal and amygdaloid areas, the hypothalamus, as well as the old, ancient and interstitial areas of the cortex. Already at the earliest stages of evolution, these structures were closely connected with the nuclei of the lower brain stem and performed the most important integrative functions, which provided the body with adequate adaptation to environmental conditions.

In the process of evolution, due to the extremely intensive growth of the neocortex, neostriatum and specific nuclei of the thalamus, the relative (but not absolute) development of limbic structures decreased somewhat, but did not stop. They only underwent certain morphol and topographical changes. So, for example, in lower vertebrates the archistriatum, or amygdala, occupies an almost median position in the region of the telencephalon, in marsupials it is located at the bottom of the temporal horn of the lateral ventricle, and in most mammals it moves to the temporal end of the horn of the lateral ventricle, acquiring the shape of an almond, in due to which it received the name amygdala. In humans, this structure occupies the pole region of the temporal lobe.

The septal region in all animals except primates is a large part of the telencephalon, constituting the medial surface of the hemispheres. In humans, the entire nuclear mass of the septal region is displaced in the ventral direction, and therefore the superomedial wall of the lateral ventricle is formed not by ganglion elements of the brain, but by a kind of film - a transparent septum (septum pellucidum).

Ancient cortical formations underwent such serious changes in the process of evolution that they turned from surface structures like a cloak into separate discrete formations of the most bizarre shape. Thus, the old cortex acquired the shape of a horn and began to be called the horn of ammon, the ancient and interstitial areas of the cortex turned into the olfactory tubercle, isthmus, and cortex of the pyriform gyrus.

During evolution, limbic structures came into close contact with younger brain formations, providing highly organized animals with a more subtle adaptation to increasingly complex and constantly changing conditions of existence.

Cytoarchitecture of the limbic system cortex

The ancient cortex (paleocortex), according to I. N. Filimonov, is characterized by a primitively constructed cortical plate, the edges of which are not clearly separated from the underlying subcortical cell accumulations. It consists of the pyriform region, the olfactory tubercle, the diagonal region, and the basal part of the septum. On top of the molecular layer of the ancient cortex are afferent fibers, which in other cortical areas run in the white matter under the cortex. Therefore, the cortex is not so clearly separated from the subcortex. Under the fiber layer there is a molecular layer, then a layer of giant polymorphic cells, even deeper - a layer of pyramidal cells with brush-shaped dendrites at the base of the cell (bouquet cells) and, finally, a deep layer of polymorphic cells.

The old cortex (archicortex) has an arched shape. Surrounding the corpus callosum and fimbria of the hippocampus, it is in front, its posterior end in contact with the periamygdaloid, and its anterior end with the diagonal regions of the ancient cortex. The old cortex includes the hippocampal formation and the subicular region. The old bark differs from the ancient one in the complete separation of the cortical plate from the underlying formations, and from the new one in its simpler structure and the absence of a characteristic division into layers.

The intermediate cortex is the area of ​​the cortex that separates the new cortex from the old (periarchicortical) and ancient (peripaleocortical).

The cortical plate of the periarchicortical zone, which separates the old cortex from the new along its entire length, is divided into three main layers: outer, middle and inner. The interstitial cortex of this type includes the presubicular, entorhinal and peritectal regions. The latter is part of the cingulate gyrus and is in direct contact with the supracallosal rudiment of the hippocampus.

The peripaleocortical, or transitional insular, zone surrounds the ancient cortex, separating it from the new cortex, and closes posteriorly with the periarchicortical zone. It consists of a number of fields that carry out a consistent but intermittent transition from the ancient cortex to the new one and occupy the outer-inferior surface of the insular cortex.

In the literature, you can often find another classification of the cortical structures of the bloodstream - from a cytoarchitectonic point of view. Thus, Vogt (S. Vogt) and O. Vogt (1919) together call the archi- and paleocortex the allocortex or heterogenetic cortex. K. Broad May (1909), Rose (M. Rose, 1927) and Rose (J. E. Rose, 1942) the limbic cortex, retrosplenial and certain other areas (for example, the insula), forming the intermediate cortex between the neocortex and allocortex is called mesocortex. I. N. Filimonov (1947) calls the intermediate cortex paraallocortex (juxtallocortex). Pribram, Kruger (K.N. Pribram, L. Kruger, 1954), Kaada (B.R. Kaada, 1951) consider the mesocortex only as part of the paraallocortex.

Subcortical structures. To the subcortical formations of L. s. include the basal ganglia, nonspecific nuclei of the thalamus, hypothalamus, leash and, according to some authors, the reticular formation of the midbrain.

Neurochemistry

Based on data obtained in recent decades using histochemical research methods, mainly the fluorescent microscopy method, it has been shown that almost all structures of HP. receive terminals of neurons secreting various biogenic amines (so-called monoaminergic neurons). The cell bodies of these neurons lie in the lower brain stem. In accordance with the secreted biogenic amine, three types of monoaminergic neuronal systems are distinguished - dopaminergic (Fig. 4), noradrenergic (Fig. 5) and serotonergic. The first identifies three paths.

1. Nigroneostriatal begins in the substantia nigra and ends on the cells of the caudate nucleus and putamen. Each neuron of this pathway has many terminals (up to 500,000) with a total length of processes up to 65 cm, which makes it possible to instantly influence a large number of neostriatal cells. 2. Mesolimbic begins in the ventral tegmental region of the midbrain and ends on the cells of the olfactory tubercle, septal and amygdaloid areas. 3. Tubero-infundibular originates from the anterior part of the arcuate nucleus of the hypothalamus and ends on the cells of the eminentia mediana. All these pathways are mononeuronal and do not contain synaptic switches.

Ascending projections of the noradrenergic system are represented in two ways: dorsal and ventral. The dorsal one starts from the locus coeruleus, and the ventral one starts from the lateral reticular nucleus and the red nucleus spinal tract. They extend forward and end on the cells of the hypothalamus, preoptic area, septal and amygdaloid areas, olfactory tubercle, olfactory bulb, hippocampus and neocortex.

Ascending projections of the serotonergic system begin from the raphe nuclei of the midbrain and the reticular formation of the tegmentum. They extend forward along with the fibers of the medial forebrain bundle, giving off many collaterals to the tegmental area at the border of the diencephalon and midbrain.

Shute and Lyois (G. S. D. Shute, P. R. Lewis, 1967) showed that in L. s. there are a large number of substances associated with acetylcholine metabolism; They traced clear cholinergic pathways from the reticular and tegmental nuclei of the brain stem to many forebrain formations, and primarily to the limbic ones, the so-called. dorsal and ventral tegmental pathways, which directly or with one or two synaptic switches reach many thalamo-hypothalamic nuclei, structures of the striatum, amygdaloid and septal areas, olfactory formation, hippocampus and neocortex.

In HP, especially in the olfactory structures, a lot of glutamine, aspartic and gamma-aminobutyric acids were found, which may indicate the mediator function of these substances.

L.S. contains a significant amount of biologically active substances belonging to the group of enkephalins and endorphins. Most of them are found in the striatum, amygdala, leash, hippocampus, hypothalamus, thalamus, interpeduncular nucleus and other structures. Only in these structures are receptors found that perceive the action of substances of this group - the so-called. opiate receptors [S. I. Snyder], 1977].

In 1976, Weindlom et al. (A. Weindl) it was found that, in addition to the hypothalamus, the septal and amygdaloid regions, and partly the thalamus, contain neurons capable of secreting neuropeptides such as vasopressin, etc.

Physiology

Combining the formations of the terminal, intermediate and middle parts of the brain, HP. ensures the formation of the most general functions of the body, realized through a whole range of individual or associated partial reactions. In the structures of HP. there is an interaction between exteroceptive (auditory, visual, olfactory, etc.) and interoceptive influences. Even with the most primitive influence on almost all structures of the HP. (mechanical, chemical, electrical) one can detect a whole series of isolated simple or fragmentary responses, varying in severity and latent period depending on which structure is subject to irritation. Vegetative reactions such as salivation, piloerection, defecation, etc., changes in the functioning of the respiratory, cardiovascular and lymphatic systems, changes in pupillary reaction, thermoregulation, etc. are often observed. The duration of these reactions is sometimes very significant, which indicates inclusion of individual endocrine devices in the work. Often such autonomic reactions are observed together with coordinated motor manifestations (eg, chewing, swallowing and other movements).

Along with the vegetative reactions of HP. determines vestibulosomatic functions, as well as such somatic reactions as postural and vocal reactions. Apparently, L. s. should be considered as a center for the integration of vegetative and somatic components of reactions of a hierarchically higher level - emotional and motivational states, sleep, orientation-exploratory activity, etc. These complex reactions manifest themselves in animals or humans upon stimulation of very specific structures of the HP. It has been shown that irritation or destruction of the amygdala, septum, frontotemporal cortex, hippocampus and other parts of the limbic system can lead to an increase or, conversely, a decrease in food-procuring, defensive and sexual reactions. Particularly evident in this regard is the destruction of the temporal, orbital and insular cortex, the amygdala and the adjacent part of the cingulate gyrus, causing the emergence of the so-called. Klüver-Bucy syndrome, in which the ability of animals to evaluate both their internal state and the usefulness or harmfulness of external stimuli is impaired. Animals after such an operation become tame; continuously examining the surrounding objects, they indiscriminately grab everything they come across, lose their fear even of fire and, even when burned, continue to touch it (so-called visual agnosia arises). They often become hypersexual, exhibiting sexual reactions even towards animals of a different species. Their attitude towards food also changes.

The wealth of relationships within L. s. determines the other side of emotional activity - the possibility of a significant increase in emotion, the duration of its retention and often its transition to a stagnant patol state. Peips (J. W. Papez), for example, believes that the emotional state is the result of the circulation of excitations through the structures of the HP. from the hippocampus through the mamillary bodies (see) and the anterior nuclei of the thalamus to the cingulate gyrus, and the latter, in his opinion, is the truly receptive zone of the experienced emotion. However, an emotional state that manifests itself not only subjectively, but also contributes to one or another purposeful activity, i.e., reflecting one or another motivation of the animal, appears, apparently, only when excitation from the limbic structures spreads to the neocortex, and primarily in its frontal regions (Fig. 6). Without the participation of the neocortex, emotion is incomplete; it loses its biol, meaning and appears as false.

The motivational states of animals, arising in response to electrical stimulation of the hypothalamus and closely related limbic formations, can manifest themselves behaviorally in all their natural complexity, i.e. in the form of rage and organized reactions of attack on another animal or, conversely, in the form of defense reactions and avoiding an unpleasant stimulus or running away from an attacking animal. Particularly noticeable is the participation of L. s. in the organization of food-procuring behavior. Thus, bilateral removal of the tonsil leads either to a long-term refusal of food by animals or to hyperphagia. As shown by K.V. Sudakov (1971), Noda (K. Noda) et al. (1976), Paxinos (G. Paxinos, 1978), changes in food-procuring behavior and thirst-quenching reactions are also observed in the case of irritation or destruction of the septum pellucidum, piriform cortex and certain mesencephalic nuclei.

Removal of the amygdala and piriform cortex leads to the gradual development of pronounced hypersexual behavior, which can be weakened or removed by destruction of the inferomedial nucleus of the hypothalamus or septal region.

Impact on HP. may lead to higher order motivational changes that manifest at the community level. The most demonstrative emotional and motivational states of animals are manifested in the case of their reactions of self-irritation or avoidance of an unfavorable stimulus, when various formations of the physical system are exposed to influence.

The formation of a behavioral act based on any motivation (see) begins with an indicative-exploratory reaction (see). The latter, as experimental data show, is also realized with the obligatory participation of HP. It has been established that the action of indifferent stimuli causing a behavioral reaction of alertness is accompanied by characteristic electrographic changes in the structures of the bloodstream. While desynchronization of electrical activity is recorded in the cerebral cortex, in certain structures of the bloodstream, for example, in the amygdaloid region, hippocampus and piriform cortex, other changes in electrical activity occur. Against the background of rather reduced activity, paroxysmal bursts of high-frequency oscillations are detected; a slow regular rhythm is recorded in the hippocampus with a frequency of 4-6 per 1 second. This reaction, typical of the hippocampus, occurs not only with sensory stimulation, but also with direct electrical stimulation of the reticular formation and any limbic structure, leading to a behavioral reaction of alertness or anxiety.

Numerous experiments show that weak stimulation of limbic structures in the absence of a specific emotional reaction always causes alertness or an indicative-exploratory reaction in the animal. Closely related to the orienting exploratory reaction is the animal’s identification in the environment of signals that are significant for a given situation and their memorization. In the implementation of these mechanisms of orientation, learning and memory, a large role is assigned to the hippocampus and amygdaloid region. Destruction of the hippocampus sharply impairs short-term memory (see). During stimulation of the hippocampus and for some time after it, animals lose the ability to respond to conditioned stimuli.

Wedge, observations show that bilateral removal of the medial surface of the temporal lobes also causes severe memory disorders. Patients experience retrograde amnesia, they completely forget the events that preceded the operation. In addition, the ability to remember deteriorates. The patient cannot remember the name of the item in which it is located. Short-term memory suffers sharply: patients lose the thread of a conversation, are unable to keep track of the score of sports games, etc. In animals after such an operation, previously acquired skills are impaired, and the ability to develop new, especially complex ones, deteriorates.

According to O. S. Vinogradova (1975), the main function of the hippocampus is to register information, and according to M. L. Pigareva (1978), it is to provide reactions to signals with a low probability of reinforcement in cases where there is a deficit of pragmatic information, i.e. e. emotional stress.

L.S. closely related to sleep mechanisms (see). Hernandez-Peon et al. showed that with injections of small doses of acetylcholine or anticholinesterase substances into various parts of the HP. Animals develop sleep. The following sections of the lungs are especially effective in this regard: the medial preoptic area, the medial bundle of the forebrain, the interpeduncular nuclei, ankylosing spondylitis, and the medial part of the pontine tegmentum. These structures make up the so-called. hypnogenic limbic-midbrain circle. Excitation of the structures of this circle produces a function that blocks the ascending activating influences of the reticular formation of the midbrain on the cerebral cortex, which determine the state of wakefulness. At the same time, it has been shown that sleep can occur with the application of acetylcholine and anticholinesterase substances to the overlying formations of the lung system: the prepiriform and periamygdaloid regions, the olfactory tubercle, the striatum and the cortical areas of the blood cell located on the anterior and medial surfaces of the hemispheres brain The same effect can be obtained by irritating the cerebral cortex, especially its anterior sections.

It is characteristic that the destruction of the medial forebrain bundle in the preoptic area prevents the development of chemically induced sleep. irritation of the upper parts of the HP. and cerebral cortex.

Some authors [Winter (P. Winter) et al., 1966; Robinson (V. W. Robinson), 1967; Delius (J. D. Delius), 1971] believe that in L. s. are so-called centers of communication of animals (their vocal manifestations), clearly correlated with their behavior in relation to their relatives. These centers are formed by the structures of the amygdaloid, septal and preoptic areas, the hypothalamus, the olfactory tubercle, certain nuclei of the thalamus and the tegmentum. Robinson (1976) suggested that humans have two speech centers. The first, phylogenetically older, is located in L. s.; it is closely related to motivational-emotional factors and provides low-information signals. This center is controlled by the second - higher center, located in the neocortex and associated with the dominant hemisphere.

Participation of L. s. in the formation of complex integrative functions of the body is confirmed by examination data of mentally ill patients. So, for example, senile psychoses are accompanied by clear degenerative changes in the septal and amygdaloid areas, hippocampus, fornix, medial parts of the thalamus, entorhinal, temporal and frontal areas of the cortex. In addition, in the structures of L. s. in patients with schizophrenia, large amounts of dopamine, norepinephrine and serotonin are found, i.e., biogenic amines, disruption of normal metabolism is associated with the development of a number of mental illnesses, including schizophrenia.

Particularly noticeable is the participation of L. s. in the development of epilepsy (see) and various epileptoid conditions. Patients suffering from psychomotor epilepsy, as a rule, have organic damage in areas involving limbic structures. These are primarily the orbital part of the frontal and temporal cortex, the parahippocampal gyrus, especially in the area of ​​the uncinus, the hippocampus and dentate gyrus, as well as the amygdala nuclear complex.

The wedge described above are usually accompanied by a clear electrographic indicator - electrical convulsive discharges are recorded in the corresponding parts of the brain. This activity is most clearly recorded in the hippocampus, although it also appears in other structures, for example, in the amygdala and septum. The presence in them of diffuse plexuses of nerve processes and multiple feedback circuits creates conditions for multiplication, retention and prolongation of activity. Hence the characteristic of the structures of L. s. extremely low threshold for the occurrence of the so-called. after-discharges, which can continue after the cessation of electrical or chemical. irritation for a long time.

The lowest threshold for electrical afterdischarge was found in the hippocampus, amygdala, and piriform cortex. A characteristic feature of these after-discharges is their ability to spread from the site of irritation to other structures of the bloodstream.

Wedge, and experimental data show that during the period of convulsive discharges in HP. memory processes are disrupted. In patients with temporo-diencephalic lesions, complete or partial amnesia is observed or, conversely, violent outbreaks of paroxysms of sensation of what has already been seen, heard, experienced.

Thus, occupying a middle position within c. And. pp., the limbic system is able to quickly “get involved” in almost all functions of the body, aimed at actively adapting it (in accordance with existing motivation) to environmental conditions. L.S. receives afferent excitation messages from formations of the lower trunk, which in each case can be very specific, from the rostral (olfactory) structures of the brain and from the neocortex. These excitations, through a system of mutual connections, quickly reach all the necessary areas of the HP. and instantly (through the fibers of the medial forebrain bundle or direct neostriatal-tegmental pathways) activate (or inhibit) the executive (motor and autonomic) centers of the lower trunk and spinal cord. This achieves the formation of a “specialized” function for these specific conditions, a system with a clear morphology and neurochemistry, architectonics, which ends with the body achieving the necessary useful result (see Functional systems).

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E. M. Bogomolova.

The limbic section of the cerebral hemispheres currently includes the cortical zones of the olfactory analyzer (hippocampus - gyrus hippocampi, transparent septum - septum pellucidum, cingulate gyrus - gyrus cinguli, etc.), and partly also the taste analyzer (circular sulcus of the insula). These sections of the cortex are connected with other mediobasal areas of the temporal and frontal lobes, with the formations of the hypothalamus and the reticular formation of the brain stem. The listed formations are united by numerous bilateral connections into a single limbic-hylotalamo-reticular complex, which plays a major role in the regulation of all autonomic-visceral functions of the body. The oldest sections of the cerebral cortex, which are included in this complex, differ in their cytoarchitectonics (three-layer type of cellular structure) from the rest of the cortex, which has a six-layer type of structure.

R. Vgosa (1878) considered the phylogenetically old telencephalic areas located around the brain stem as the “large limbic lobe.”

These same structures were designated as the “olfactory brain,” which does not reflect their leading function in organizing complex behavioral acts. The identification of the role of these formations in the regulation of vegetative-visceral functions led to the emergence of the term “visceral brain”. Further clarification of the anatomical and functional features and physiological role of these structures led to the use of a less specific definition - “limbic system”. The limbic system includes anatomical formations united by close functional connections. The structures that make up the limbic system differ phylogenetically:

• ancient cortex (paleocortex) - hippocampus, piriform gyrus, piriform, periamygdaloid cortex, entorhinal region, olfactory bulb, olfactory tract, olfactory tubercle;
• paraallocortex - an area occupying an intermediate position between the old and new cortex (cingulate gyrus, or limbic lobe, presubiculum, frontoparietal cortex);
• subcortical formations - amygdala complex, septum, anterior nuclei of the thalamus, hypothalamus;
• reticular formation of the midbrain.

The central parts of the limbic system are the amygdala complex and the hippocampus.

The amygdala receives afferent impulses from the olfactory tubercle, septum, piriform cortex, temporal pole, temporal gyri, orbital cortex, anterior insula, intralaminar nuclei of the thalamus, anterior hypothalamus and reticular formation.

There are two efferent pathways: dorsal - through stria terminalis to the anterior hypothalamus and ventral - to the subcortical formations, temporal cortex, insula and along the polysynaptic path to the hippocampus.

Afferent impulses come to the hippocampus from the anteriobasal formations, the frontotemporal cortex, the insula, the cingulate sulcus, and from the septum through the diagonal ligament of Broca, which connects the reticular formation of the midbrain with the hippocampus.

The efferent pathway from the hippocampus goes through the fornix to the mamillary bodies, through the mastoid-thalamic fascicle (Vic d'Azir fascicle) to the anterior and intralaminar nuclei of the thalamus, then to the midbrain and pons.

The hippocampus is closely connected with other anatomical structures included in the limbic system, and together with them forms the circle of Papez: hippocampus - fornix - septum - mamillary bodies - anterior nuclei of the thalamus - cingulate gyrus - hippocampus.

Thus, there are two main functional neuronal circles of the limbic system: the major circle of Papez and the minor circle, which includes the amygdala complex - stria terminalis- hypothalamus.

There are several classifications of limbic structures. According to the anatomical classification of N. Gastaut, N. Lammers (1961), two parts are distinguished - basal and limbic; according to the anatomical and functional classification - the oromedial-basal area, which regulates vegetative-visceral functions, behavioral acts associated with food function, sexual, emotional sphere, and the posterior area (posterior part of the cingulate sulcus, hippocampal formation), which takes part in the organization of more complex behavioral acts, mnestic processes. P. McLean distinguishes two groups of structures: rostral (orbital and insular cortex, temporal pole cortex, piriform lobe), which ensures the preservation of life for a given individual, and caudal (septum, hippocampus, lumbar gyrus), which ensures the preservation of the species as a whole, regulating generative functions.

K. Pribram, L. Kruger (1954) identified three subsystems. The first subsystem is considered as the primary olfactory system (olfactory bulb and tubercle, diagonal fasciculus, corticomedial nuclei of the amygdala), the second provides olfactory-gustatory perception, metabolic processes and emotional reactions (septum, basal-lateral nuclei of the amygdala, frontotemporal basal cortex) and the third is involved in emotional reactions (hippocampus, entorhinal cortex, cingulate cortex). The phylogenetic classification also distinguishes two parts: the old one, consisting of mammillary structures closely associated with the formations of the midline and neocortex, and the later one - the temporal neocortex. The first carries out vegetative-endocrine-somato-emotional correlations, the second - interpretive functions. According to the concept of K. Lissak, E. Grastian (1957), the hippocampus is considered as a structure that has inhibitory effects on the thalamocortical system. At the same time, the limbic system plays an activating and modeling role in relation to a number of other brain systems.

The limbic system is involved in the regulation of vegetative-visceral-hormonal functions aimed at ensuring various forms of activity (eating and sexual behavior, species preservation processes), in the regulation of systems that ensure sleep and wakefulness, attention, the emotional sphere, memory processes, thus carrying out somato-vegetative integration.

The functions in the limbic system are presented globally and are poorly differentiated topographically, however, certain departments have relatively specific tasks in organizing holistic behavioral acts. Including neural closed circles, this system has a large number of “inputs” and “outputs” through which its afferent and efferent connections are made.

Damage to the limbic part of the hemispheres primarily causes various disorders of autonomic-visceral functions. Many of these disorders of the central regulation of autonomic functions, which were previously attributed only to pathology of the hypothalamic region, are associated with lesions of the limbic region, especially the temporal lobes.

Pathology of the limbic region can manifest itself as symptoms of prolapse with vegetative asymmetry or symptoms of irritation in the form of vegetative-visceral attacks, usually of a temporal origin, less often of a frontal origin. Such attacks are usually shorter in duration than hypothalamic ones; they may be limited to short auras (epigastric, cardiac, etc.) before a general convulsive attack.

When the limbic zone is damaged, there are fixation amnesia (memory impairment similar to Korsakoff's syndrome) and pseudoreminiscences (false memories). Emotional disorders (phobias, etc.) are very common. Disorders of the central regulation of autonomic-visceral functions entail a violation of adaptation to changing environmental conditions.

Corpus callosum

In the corpus callosum (corpus callosum) - a massive formation of white matter - there are commissural fibers connecting the paired sections of the hemispheres. In the anterior section of this large commissure of the brain - in the knee (genu corporis callosi) - there are connections between the frontal lobes, in the middle section - in the trunk (truncus corporis callosi) - between the parietal and temporal lobes, in the posterior section - in the thickening (splenium corporis callosi ) - between the occipital lobes.

Lesions of the corpus callosum manifest as mental disorders. With lesions in the anterior parts of the corpus callosum, these disorders have features of the “frontal psyche” with confusion (disturbances in behavior, actions, criticism). Frontal-callous syndrome is distinguished (akinesia, amymia, aspontaneity, astasia-abasia, oral automatism reflexes, decreased criticism, memory impairment, grasping reflexes, apraxia, dementia). Disconnection of connections between the parietal lobes leads to distorted perceptions of the “thermal circuit” and the appearance of motor apraxia in the left upper limb; changes in the psyche of a temporal nature are associated with impaired perceptions of the external environment, with a loss of correct orientation in it (the “already seen” syndrome, amnestic disorders, confabulations); lesions in the posterior parts of the corpus callosum lead to complex types of visual agnosia.

Pseudobulbar symptoms (violent emotions, reflexes of oral automatism) are also common with lesions of the corpus callosum. At the same time, pyramidal and cerebellar disorders, as well as disorders of cutaneous and deep sensitivity, are absent, since their projection innervation systems are not damaged. Of the central movement disorders, dysfunction of the pelvic organs sphincters is most often observed.

One of the features of the human brain is the so-called functional specialization of the cerebral hemispheres. The left hemisphere is responsible for logical, abstract, thinking, the right hemisphere is responsible for concrete, figurative. His individuality and characteristics of perception (artistic or thinking type of character) depend on which of the hemispheres is most morphologically developed and dominant in a person.

When the right hemisphere is turned off, patients become verbose (even talkative), talkative, but their speech loses intonation expressiveness, it is monotonous, colorless, dull, and acquires a nasal (nasal) tint. Such a violation of the intonation-voice component of speech is called disprosody (prosody - melody). In addition, such a patient loses the ability to understand the meaning of the speech intonations of the interlocutor. Therefore, along with the preservation of the formal vocabulary of speech (vocabulary and grammar) and an increase in speech activity, a “right-hemisphere” person loses the imagery and concreteness of speech that intonation and vocal expressiveness gives it. The perception of complex sounds is impaired (auditory agnosia), a person ceases to recognize familiar melodies, cannot hum them, and finds it difficult to recognize male and female voices (imaginative auditory perception is impaired). Inferiority of figurative perception is also revealed in the visual sphere (does not notice the missing detail in unfinished drawings, etc.). The patient finds it difficult to perform tasks that require orientation in a visual, figurative situation, where it is necessary to take into account specific features of the object. Thus, when the right hemisphere is turned off, those types of mental activity that underlie imaginative thinking suffer. At the same time, those types of mental activity that underlie abstract thinking are preserved or even strengthened (facilitated). This state of mind is accompanied by a positive emotional tone (optimism, a tendency to joke, faith in recovery, etc.).

When the left hemisphere is damaged, a person’s speech capabilities are sharply limited, the vocabulary is impoverished, words denoting abstract concepts drop out of it, the patient does not remember the names of objects, although he recognizes them. Speech activity decreases sharply, but the intonation pattern of speech is preserved. Such a patient recognizes the melodies of songs well and can reproduce them. Thus, if the function of the patient’s left hemisphere is impaired, along with a deterioration in verbal perception, all types of figurative perception are preserved. The ability to remember words is impaired, he is disoriented in place and time, but notices the details of the situation; a clear, specific orientation is maintained. In this case, a negative emotional background arises (the patient’s mood deteriorates, he is pessimistic, it is difficult to be distracted from sad thoughts and complaints, etc.).

References

1. Lectures on human anatomy and physiology with the basics of pathology – Baryshnikov S.D. 2002
2. Atlas of Human Anatomy – Bilich G.L. – Volume 1. 2014
3. Anatomy according to Pirogov – V. Shilkin, V. Filimonov – Atlas of human anatomy. 2013
4. Atlas of Human Anatomy – P.Tank, Th. Gest – Lippincott Williams & Wilkins 2008
5. Atlas of Human Anatomy – Team of authors – Diagrams – Drawings – Photographs 2008
6. Fundamentals of medical physiology (second edition) – Alipov N.H. 2013

In this article we will talk about the limbic system, the neocortex, their history, origin and main functions.

Limbic system

The limbic system of the brain is a set of complex neuroregulatory structures of the brain. This system is not limited to just a few functions - it performs a huge number of tasks that are essential for humans. The purpose of the limbus is the regulation of higher mental functions and special processes of higher nervous activity, ranging from simple charm and wakefulness to cultural emotions, memory and sleep.

History of origin

The limbic system of the brain formed long before the neocortex began to form. This oldest hormonal-instinctive structure of the brain, which is responsible for the survival of the subject. Over a long period of evolution, 3 main goals of the system for survival can be formed:

• Dominance is a manifestation of superiority in a variety of ways
• Food - Subject's nutrition
• Reproduction - transferring your genome to the next generation

Because man has animal roots, the human brain has a limbic system. Initially, Homo sapiens possessed only affects that influenced the physiological state of the body. Over time, communication developed using the type of scream (vocalization). Individuals who were able to convey their state through emotions survived. Over time, the emotional perception of reality was increasingly formed. This evolutionary layering allowed people to unite into groups, groups into tribes, tribes into settlements, and the latter into entire nations. The limbic system was first discovered by American researcher Paul McLean back in 1952.

System structure

Anatomically, the limbus includes areas of the paleocortex (ancient cortex), archicortex (old cortex), part of the neocortex (new cortex) and some subcortical structures (caudate nucleus, amygdala, globus pallidus). The listed names of the various types of bark indicate their formation at the indicated time of evolution.

Weight specialists in the field of neurobiology, they studied the question of which structures belong to the limbic system. The latter includes many structures:

In addition, the system is closely related to the reticular formation system (the structure responsible for brain activation and wakefulness). The anatomy of the limbic complex is based on the gradual layering of one part onto another. So, the cingulate gyrus lies on top, and then descending:

• corpus callosum;
• vault;
• mamillary body;
• amygdala;
• hippocampus

A distinctive feature of the visceral brain is its rich connection with other structures, consisting of complex pathways and two-way connections. Such a branched system of branches forms a complex of closed circles, which creates conditions for prolonged circulation of excitation in the limbus.

Functionality of the limbic system

The visceral brain actively receives and processes information from the surrounding world. What is the limbic system responsible for? Limbus- one of those structures that works in real time, allowing the body to effectively adapt to environmental conditions.

The human limbic system in the brain performs the following functions:

• Formation of emotions, feelings and experiences. Through the prism of emotions, a person subjectively evaluates objects and environmental phenomena.
• Memory. This function is carried out by the hippocampus, located in the structure of the limbic system. Mnestic processes are ensured by reverberation processes - a circular movement of excitation in the closed neural circuits of the seahorse.
• Selecting and correcting a model of appropriate behavior.
• Training, retraining, fear and aggression;
• Development of spatial skills.
• Defensive and foraging behavior.
• Expressiveness of speech.
• Acquisition and maintenance of various phobias.
• Function of the olfactory system.
• Reaction of caution, preparation for action.
• Regulation of sexual and social behavior. There is a concept of emotional intelligence - the ability to recognize the emotions of others.

At expressing emotions a reaction occurs that manifests itself in the form of: changes in blood pressure, skin temperature, respiratory rate, pupil reaction, sweating, reaction of hormonal mechanisms and much more.

Perhaps there is a question among women about how to turn on the limbic system in men. However answer simple: no way. In all men, the limbus works fully (with the exception of patients). This is justified by evolutionary processes, when a woman in almost all time periods of history was engaged in raising a child, which includes a deep emotional return, and, consequently, a deep development of the emotional brain. Unfortunately, men can no longer achieve the development of limbus at the level of women.

The development of the limbic system in an infant largely depends on the type of upbringing and the general attitude towards it. A stern look and a cold smile do not contribute to the development of the limbic complex, unlike a tight hug and a sincere smile.

Interaction with the neocortex

The neocortex and limbic system are tightly connected through many pathways. Thanks to this unification, these two structures form one whole of the human mental sphere: they connect the mental component with the emotional one. The neocortex acts as a regulator of animal instincts: before committing any action spontaneously caused by emotions, human thought, as a rule, undergoes a series of cultural and moral inspections. In addition to controlling emotions, the neocortex has an auxiliary effect. The feeling of hunger arises in the depths of the limbic system, and the higher cortical centers that regulate behavior search for food.

The father of psychoanalysis, Sigmund Freud, did not ignore such brain structures in his time. The psychologist argued that any neurosis is formed under the yoke of suppression of sexual and aggressive instincts. Of course, at the time of his work there was no data on the limbus, but the great scientist guessed about similar brain devices. Thus, the more cultural and moral layers (super ego - neocortex) an individual had, the more his primary animal instincts (id - limbic system) are suppressed.

Violations and their consequences

Based on the fact that the limbic system is responsible for many functions, this very many can be susceptible to various damages. The limbus, like other structures of the brain, can be subject to injury and other harmful factors, which include tumors with hemorrhages.

Syndromes of damage to the limbic system are rich in number, the main ones are:

Dementia– dementia. The development of diseases such as Alzheimer's and Pick's syndrome is associated with atrophy of the limbic complex systems, and especially in the hippocampus.

Epilepsy. Organic disorders of the hippocampus lead to the development of epilepsy.

Pathological anxiety and phobias. Disturbance in the activity of the amygdala leads to a mediator imbalance, which, in turn, is accompanied by a disorder of emotions, which includes anxiety. A phobia is an irrational fear of a harmless object. In addition, an imbalance of neurotransmitters provokes depression and mania.

Autism. At its core, autism is a deep and serious maladjustment in society. The inability of the limbic system to recognize the emotions of other people leads to serious consequences.

Reticular formation(or reticular formation) is a nonspecific formation of the limbic system responsible for the activation of consciousness. After deep sleep, people wake up thanks to the work of this structure. In cases of its damage, the human brain is subject to various disorders of blackout, including absence and syncope.

Neocortex

The neocortex is a part of the brain found in higher mammals. The rudiments of the neocortex are also observed in lower animals that suck milk, but they do not reach high development. In humans, the isocortex is the lion's part of the general cerebral cortex, having an average thickness of 4 millimeters. The area of ​​the neocortex reaches 220 thousand square meters. mm.

History of origin

At the moment, the neocortex is the highest stage of human evolution. Scientists were able to study the first manifestations of the neobark in representatives of reptiles. The last animals in the chain of development that did not have a new cortex were birds. And only a person is developed.

Evolution is a complex and long process. Every species of creature goes through a harsh evolutionary process. If an animal species was unable to adapt to a changing external environment, the species lost its existence. Why does a person was able to adapt and survive to this day?

Being in favorable living conditions (warm climate and protein foods), human descendants (before the Neanderthals) had no choice but to eat and reproduce (thanks to the developed limbic system). Because of this, the mass of the brain, by the standards of the duration of evolution, gained a critical mass in a short period of time (several million years). By the way, the brain mass in those days was 20% greater than that of a modern person.

However, all good things come to an end sooner or later. With a change in climate, descendants needed to change their place of residence, and with it, start looking for food. Having a huge brain, descendants began to use it to find food, and then for social involvement, because. It turned out that by uniting into groups according to certain behavioral criteria, it was easier to survive. For example, in a group where everyone shared food with other members of the group, there was a greater chance of survival (Someone was good at picking berries, someone was good at hunting, etc.).

From this moment it began separate evolution in the brain, separate from the evolution of the whole body. Since those times, a person’s appearance has not changed much, but the composition of the brain is radically different.

What does it consist of?

The new cerebral cortex is a collection of nerve cells that form a complex. Anatomically, there are 4 types of cortex, depending on its location - , occipital, . Histologically, the cortex consists of six balls of cells:

• Molecular ball;
• external granular;
• pyramidal neurons;
• internal granular;
• ganglion layer;
• multiform cells.

What functions does it perform?

The human neocortex is classified into three functional areas:

• Sensory. This zone is responsible for higher processing of received stimuli from the external environment. So, ice becomes cold when information about the temperature arrives in the parietal region - on the other hand, there is no cold on the finger, but only an electrical impulse.
• Association zone. This area of ​​the cortex is responsible for information communication between the motor cortex and the sensitive one.
• Motor area. All conscious movements are formed in this part of the brain.
  In addition to such functions, the neocortex provides higher mental activity: intelligence, speech, memory and behavior.

Conclusion

To summarize, we can highlight the following:

• Thanks to two main, fundamentally different, brain structures, a person has duality of consciousness. For each action, two different thoughts are formed in the brain:
  • “I want” - limbic system (instinctive behavior). The limbic system occupies 10% of the total brain mass, low energy consumption
  • “Should”—neocortex (social behavior). Neocortex occupies up to 80% of total brain mass, high energy consumption and limited metabolic rate