Limbic system The brain is part of the higher nervous system, responsible for many body functions. The peculiarity of this part of the brain is that it represents a collection of structures. This explains its versatility. What structure does this part of the brain have and how dangerous are disturbances in its functioning?

This is a unique set of nerve structures that are interconnected. In total, the system includes about 12 “divisions,” although it was initially believed that this part of the brain was responsible solely for the sense of smell.

Undoubtedly, the human brain has a complex structure, but we should not forget that all structures have a certain connection with each other. Those “units” that are part of this system are “on the brink”. From the point of view of neurology and anatomy, this term indicates that the nervous structures have a connection with the cerebral cortex.

The connections between neurons in this part of the brain are dense, having a ring structure. This is also considered a feature.

History of the system

Descriptions of this part of the brain first appeared in 1952, but they were inaccurate. But as civilization progressed and developed, it was possible to correct the information and obtain an accurate understanding of the system and its functioning.

It was originally said that the main and only function of this part of the brain is to process information. In general, the description is correct, but not accurate. Since it was assumed that a person obtains information by analyzing smells.

Olfactory ability, assessment of the information received and connection with the cerebral cortex - that’s all that the discoverer of the system, P. McLean, managed to establish. He described a number of structures that formed a single whole and were “on the edge,” that is, in close proximity to the cerebral cortex. The location of the nerve structures influenced the name of the system.

Initially, the doctor assumed that several nerve structures connected in the limbic system of the brain, forming dense neural connections. Later we managed to obtain more complete information.

As medicine developed, it was possible to establish that the structure is responsible not only for the sense of smell, but also for memory, both short-term and long-term.

System structure

It is believed that this part of the brain has a special, “ancient” structure, since it is connected to the cortical part of the main organ, located on the inner hemispheres.

The system is responsible for vegetative functions and includes the following parts:

1. Cingulate gyrus.
2. Hippocampus
3. Almond-shaped nuclei, they are also called hemispheres.
4. Piriform gyrus.

Dense neural connections receive impulses from the following parts of the human brain:

• hypothalamus;
• pituitary;
• subcortical nuclei;
• thalamus;
• hippocampus

In animal studies, it was found that irritation various parts this system leads to behavioral changes:

1. Aggression appears and defensive functions intensify.
2. Irritation increases, social function changes.

Emotions and memory are the first to suffer. But at the same time, memories remain with a person.

Since the structure of this part of the brain is complex, a more common description is that it is a “bundle” of nerve structures that forms a system. Impulses are transmitted from the cerebral cortex, and not only. Various parts of this organ are involved in the “ligament”.

Functionality of the limbic system

This part of the autonomic nervous system, according to doctors, performs many functions. Through experiments, it was possible to prove that disruptions in the functioning of interconnected structures lead to problems with vital organs.

Let us describe in detail the functions of this part of the brain:

• responsible for memory and perception of information, for the ability to learn and cognition;
• regulates the work and analyzes the information received from the olfactory organs;
• participates in organizing simple motivational and informational activities;
• responsible for human socialization, in particular, communication and the emotional component;
• participates in the ability to shape research activities.

Through communication with the hypothalamus and cerebral cortex, neurons receive impulses that affect the functioning of vital organs. They also influence human hormonal levels through communication with the pituitary gland.

It is worth noting that the system is involved in the formation of food and sexual instincts. But this participation is considered indirect, not direct.

What else is the system responsible for, and what functions does it perform:

1. It is believed that neural connections form a link: wakefulness - sleep.
2. Regulates metabolic processes in the body, including water-salt balance.
3. Helps adapt to external stimuli.

It is believed that the structure of the system is such that it allows the brain not only to analyze the information received, but also to perceive commands and issue an adequate response. This allows us to judge the system’s ability to influence the perception and analysis of information received from outside. This means that in cases of change, the system helps a person adapt to environmental factors. This function is called adaptation.

The significant functionality allows us to assert that a set of structures is involved in the work of various organs responsible for the life support of the body.

Violations and their consequences

If they occur, the disorders affect the entire body. In most cases, this situation results from:

• development of infectious diseases affecting nervous system;
• serious poisonings leading to severe intoxication;
• prolonged and excessive consumption of alcoholic beverages;
• taking certain medications in case of overdose;
• development of psychological disorders;
• receiving serious head injuries.

As a result of such unfavorable circumstances, the following changes occur in the body:

1. Memory problems appear. Often the patient cannot build a logical chain of events or connect them together. At the same time, he has memories, but he finds it difficult to analyze events.
2. Problems with the sense of smell arise, the functioning of the organs of vision and hearing is disrupted. Problems can be local in nature, up to the development of blindness or deafness. A person may complain that he does not feel anything (smell, taste).
3. Violations affect fine motor skills, influence the correction of movements. The emotional component suffers the most. A person’s behavior changes, he begins to show aggression, but more often such people suffer from changes in mood.
4. There are problems with sleep (perhaps the most common disorder). Such problems are common, but you will have to pay attention to the presence of other manifestations.

However, other functions of the body can also “suffer”; disturbances affect the functioning of organs digestive system, hormonal background. It is difficult to say what disturbances will appear in the body’s functioning and what they will lead to.

List of possible complications:

• auditory and visual hallucinations, less often taste;
• loss of orientation in space;
• frequent mood swings with the development of depressive states;
• confusion;
• inability to perceive and analyze information;
• development of epileptic seizures (in special cases).

Disturbances can be of a different nature, ranging from problems in the intestines and stomach, ending with disruptions in the immune, cardiovascular and endocrine systems.

Interaction with the neocortex

The neocortex is the “new cortex” that covers the entire brain like a cloak. The interconnection of the system lies in the fact that the neural connections located “on the edge” and the new cortex form a connection by transmitting impulses.

Receiving “signals”, the brain begins to function, and this activity affects not the functional part, but the emotional part.

Since the limbic system is responsible for the emotional component, connecting through a neural connection with the neocortex makes a person “themselves.”

Neocortex

It is quite difficult to understand what this term classifies, its meaning will become clearer if we translate the word from Latin, literally - this is the new cortex. But something else is also possible
interpretation of the term "chosen cortex", but it is considered inaccurate. This is a part of the human brain that envelops the entire organ, like a cloak, forming a kind of “cap” that participates in neural processes and performs certain functions.

History of origin

The term has been known for quite some time, but the lack of information has been compensated for relatively recently.

A theory explaining the functionality of the neocortex was developed in Menlo Park. She explained the algorithm of work, and the theory was presented in the form computer presentation. This presentation helped to understand how the neocortex functions and was a real breakthrough.

The essence of the algorithm and the presented theory:

1. Unites all human senses into a single whole.
2. Neurons have memory and form large connections, a kind of cause-and-effect relationship.

What does it consist of?

This part of the brain consists of three types of neurons that form connections with other parts of the organ.

Includes:

• the first and, perhaps, the largest group, making up 70 percent or more of all neurons, are pyramidal;
• at the level of 15-20% there is a group of stellate neurons;
• spindle-shaped neurons account for only about 5%, this group is the smallest.

What functions does it perform?

It is believed that the brain performs many functions, which is true, but what role does the neocortex play in this system?

To put it simply, without going into scientific terms, then without the neocortex a person can easily exist and perform normal functions: eat, reproduce, get food. But his life will be subordinated to instincts akin to animals.

But when the new cortex “turns on” to work, thinking appears that distinguishes humans from primates.

The neocortex performs the following functions:

1. Responsible for the thinking and intellectual abilities of the individual.
2. Affects his creative development.
3. It affects the emotional component, allowing a person to experience feelings.
4. Fine motor skills were also influenced by this part of the brain.

To put it simply, without the neocortex a person would not be able to write, draw, play music, perceive and analyze information. His movements would be rough, sloppy, automatic.

We can use an example to consider the activity of the neocortex:

• in the brain, in a specific part of it, an impulse is “born”;
• it gradually reaches the muscles of the larynx and tongue;
• a sound is heard, a song appears.

The neocortex “works” approximately according to this algorithm. All mental activity responsible for the individual characteristics of a person is under his control.

Understanding the structure of the limbic system of the human brain and comparing it with the neocortex, do not forget that the first term is the ancient cortex, and the second is the new cortex. The relationship between these parts of the organ is even determined by terminology.

Since the main organ in the human body is the brain, its structure is a priori considered complex. The neocortex and ancient cortex are just part of the system responsible for the functioning of the body and the performance of its functions.

Limbic system of the brain:

the pressor zone leads to vasoconstriction, and stimulation of the depressor zone leads to their dilation. The vasomotor center and the nuclei of the vagus nerve constantly send impulses, thanks to which a constant tone is maintained: the arteries and arterioles are constantly somewhat narrowed, and cardiac activity is slowed down.

IN the medulla oblongata is locatedrespiratory center, which, in turn, consists of the centers of inhalation and exhalation. At the level of the bridge there is a breathing center (pneumotaxic center) more high level, which adapts breathing to changes physical activity. Breathing in humans can also be controlled voluntarily from the cerebral cortex, for example during speech.

IN In the medulla oblongata there are centers that stimulate the secretion of the salivary, lacrimal and gastric glands, the secretion of bile from the gallbladder, and the secretion of the pancreas. In the midbrain, under the anterior tubercles of the quadrigeminal, there are parasympathetic centers of accommodation of the eye and pupillary reflex. All of the above centers of the sympathetic and nervous parasympathetic system are subordinate to the higher vegetative center - hypothalamus. The hypothalamus, in turn, is influenced by a number of other centers

brain. All these centers form the limbic system.

LIMBIC SYSTEM OF THE BRAIN

The limbic system in the human brain performs a very important function called motivational and emotional. To make it clear what this function is, let us remember: every organism, including the human body, has a whole set of biological needs. These include, for example, the need for food, water, warmth, reproduction and much more. To achieve some specific biological need develops in the body functional system(Fig. 4.3). The leading system-forming factor is the achievement of a certain result that meets the body’s needs in this moment. The initial nodal mechanism of the functional system is afferent synthesis (the left part of the diagram in Fig. 4.3). Afferent synthesis includes dominant motivation (for example, food search and consumption), situational afferentation (events of the external and internal environment), trigger afferentation and memory. Memory is necessary to fulfill a biological need. For example, a puppy that has just been weaned cannot be fed meat because it does not perceive it as food. Only after a certain number of trials (the type of food, its smell and taste, the environment and much more is remembered) does the puppy begin to eat meat. The integration of these components leads to a decision. The latter, in turn, is associated with a specific action program; in parallel with it, an acceptor of the results of the action is also formed, i.e. neural model of future outcomes. Information about the result parameters is sent through feedback to the action acceptor for comparison with a previously formed model. If the result parameters do not correspond to the model, then excitation arises, which through the reticular formation of the brain stem activates the orienting reaction, and the action program is corrected. Examples of some biological motivations will be given below.

The body also has a special mechanism for assessing the biological significance of biological motivation. This is an emotion. “Emotions are a special class mental processes and states associated with instincts, needs and motives. Emotions perform the function of regulating the subject’s activity by reflecting the significance of external and internal situations for the implementation of his life activities” (Leontyev, 1970). The biological substrate for the implementation of these most important functions of the body is a group of brain structures interconnected by close connections and components limbic system of the brain.

A general diagram of the limbic brain structures is shown in Appendix 4. All these brain structures are involved in the organization of motivational-emotional behavior. One of the main structures of the limbic system is the hypothalamus. It is through the hypothalamus that most limbic structures are united into an integral system that regulates the motivational and emotional reactions of humans and animals to external stimuli and forms adaptive behavior based on dominant biological motivation. Currently, the limbic system includes three groups of brain structures. The first group includes phylogenetically older cortical structures: the hippocampus (old cortex), olfactory bulbs and olfactory tubercle (ancient cortex). The second group is represented by areas of the neocortex: the limbic cortex on the medial surface of the hemisphere, as well as the orbitofrontal cortex on the basal part of the frontal lobe of the brain. The third group includes the structures of the telencephalon, diencephalon and midbrain: amygdala, septum, hypothalamus, anterior group of thalamic nuclei, central gray matter of the midbrain.

Back in the middle of the last century, it was known that damage to the structures of the hippocampus, mammillary body and some others (now we know that these structures are part of the limbic system of the brain) causes profound disorders of emotions and memory. Currently, profound impairments in memory for recent events in the clinic of hippocampal damage are called Korsakoff's syndrome.

Numerous clinical observations, as well as animal studies, have shown that the structures of the Pipetz circle play a leading role in the manifestation of emotions (Fig. 4.4). The American neuroanatomist Pipetz (1937) described a chain of interconnected neural structures as part of the limbic system. These structures ensure the emergence and flow of emotions. He drew Special attention on the existence of numerous connections between the structures of the limbic system and the hypothalamus. Damage to one of the structures of this “circle” leads to profound changes in the emotional sphere of the psyche.

It is now known that the function of the limbic system of the brain is not limited only to emotional reactions, but also takes part in maintaining the constancy of the internal environment (homeostasis), regulation of the sleep-wake cycle, learning and memory processes, regulation of autonomic and endocrine

functions. Below is a description of some of these functions of the limbic system.

PHYSIOLOGY OF HYPOTHALAMUS

The hypothalamus is located at the base of the human brain and forms the walls of the third cerebral ventricle. The walls to the base pass into a funnel, which ends with the pituitary gland (lower medullary gland). The hypothalamus is the central structure of the limbic system of the brain and performs numerous functions. Some of these functions relate to hormonal regulation, which is carried out through the pituitary gland. Other functions are associated with the regulation of biological motivations. These include food consumption and maintaining body weight, water consumption and water-salt balance in the body, temperature regulation depending on the external temperature, emotional experiences, muscle work and other factors, and the reproductive function. In women, it includes regulating the menstrual cycle, bearing and giving birth to a child, feeding and much more. In men - spermatogenesis, sexual behavior. Listed here are just some of the basic features that will be covered in the tutorial. The hypothalamus also plays a central role in the body's response to stress.

Despite the fact that the hypothalamus does not occupy much great place in the brain (its area, if you look at the brain from the base, does not exceed the area of ​​a fingernail in the adult brain thumb hands), it contains about four dozen cores. In Fig. 4.5 shows only some of them. The hypothalamus contains neurons that produce hormones or special substances, which subsequently, acting on the cells of the corresponding endocrine glands, lead to the release or cessation of the release of hormones (the so-called releasing factors from the English release - to release). All these substances are produced in the neurons of the hypothalamus, then transported along their axons to the pituitary gland. The nuclei of the hypothalamus are connected to the pituitary gland by the hypothalamic-pituitary tract, which consists of approximately 200,000 fibers. The property of neurons to produce special protein secretions and then transport them for release into the bloodstream is called neurocrinia.

The hypothalamus is part diencephalon and at the same time an endocrine organ. In certain areas of it, the transformation of nerve impulses into the endocrine process takes place. Large neurons of the anterior hypothalamus form vasopressin (supraoptic nucleus) and oxytocin (paraventricular nucleus). In other areas of the hypothalamus are formed releasing factors. Some of these factors play the role of pituitary stimulants (libirins), others - inhibitors (statins). In addition to those neurons whose axons project to the pituitary gland or to the pituitary portal system, other neurons in the same nucleus project axons to many areas of the brain. Thus, the same hypothalamic neuropeptide can act as a neurohormone and a mediator or modulator of synaptic transmission.

CONTROL OF ENDOCRINE SYSTEM FUNCTIONS

The endocrine system occupies one of the central places in the management of various vital processes at the level of the whole organism. This system, with the help of produced hormones, is directly involved in controlling the metabolism, physiology and morphology of various cells, tissues and organs (see Appendix 5).

Hormones are biological highly active substances formed in the endocrine glands, entering the blood and exerting a regulatory effect on the functions of organs and systems of the body remote from the place of their secretion.

Hormones determine the intensity of protein synthesis, cell size, their ability to divide, growth of the entire organism and its individual parts, sex formation and reproduction; various forms of adaptation and maintenance of homeostasis; higher nervous activity.

The principle of the physiological action of hormones is that, once they enter the bloodstream, they are distributed throughout the body. Hormones exert their physiological effects in minimal doses. For example, 1 g of adrenaline can activate the work of 100 million isolated hearts. Cell membranes contain receptors for many hormones. The molecule of each type of hormone can connect only with “its” receptor on cell membrane(principle: the hormone molecule fits the receptor like a “key to a lock”). Such cells are called target cells. For example, for sex hormones, the target cells will be the cells of the gonads, and for adrenocorticotropic hormone (ACTH), which is released during stress, the target cells will be the cells of the adrenal cortex.

Several examples of the relationship between pituitary hormones and target organs are shown in Fig. 4.6. Disruption of one or another link of the endocrine system can significantly change the normal course of physiological processes, leading to deep pathology, often incompatible with life.

There is a functional close interdependence between the nervous and endocrine systems, which is ensured various types connections (Fig. 4.7).

The central nervous system influences the endocrine system in two ways: through autonomic (sympathetic and parasympathetic) innervation and changes in the activity of specialized neuroendocrine centers. Let us illustrate this important point using the example of maintaining blood glucose levels during sharp decline plasma glucose concentrations (hypoglycemia). Since glucose is absolutely necessary for brain function, hypoglycemia cannot last long. Endocrine cells of the pancreas respond to hypoglycemia by secreting the hormone glucagon, which stimulates the release of glucose from the liver. Other endocrine cells of the pancreas respond to hypoglycemia, on the contrary, by reducing the release of another hormone, insulin, which leads to a decrease in glucose utilization by all tissues, with the exception of the brain. Glucoreceptors in the hypothalamus respond to hypoglycemia by increasing the release of glucose from the liver through activation of the sympathetic nervous system. In addition, the adrenal medulla is activated and adrenaline is released, which reduces the utilization of glucose by body tissues and also promotes the release of glucose from the liver. Other hypothalamic neurons respond to hypoglycemia by stimulating the release of the hormone cortisol from the adrenal cortex, which increases glucose synthesis in the liver when this store is depleted. Cortisol also inhibits insulin-activated glucose utilization in all tissues except the brain. The result of joint reactions of the nervous and endocrine systems is a return to normal concentrations of glucose in the blood plasma within 60 - 90 minutes.

Under certain conditions, the same substance can act as a hormone and a mediator, and the mechanism in both cases comes down to the specific interaction of the molecule with the target cell receptor. Signals from the endocrine glands, whose role is played by hormones, are perceived by specialized nervous structures and are ultimately transformed into changes in the body's behavior and into responses of the endocrine system. The latter become part of the regulatory reactions that form neuroendocrine integration. In Fig. 4.7 shows possible types of relationships between the nervous and endocrine systems. In any given case, only some of these paths are actually used.

The pituitary gland, the lower medullary gland, is a complex endocrine organ located at the base of the skull in the sella turcica of the main bone, anatomically connected by a leg to the hypothalamus. It consists of three lobes: anterior, middle and posterior. The anterior and middle lobes are collectively called the adenohypophysis, and the posterior lobe is called the neurohypophysis. The neurohypophysis is divided into two sections: the anterior neurohypophysis, or median eminence, and the posterior neurohypophysis, or posterior lobe of the pituitary gland.

The pituitary gland contains a very developed network of capillaries, the walls of which have a special structure, the so-called fenestrated (perforated) epithelium. This network of capillaries is called the “miraculous capillary network” (Fig. 4.8). The axons of hypothalamic neurons end in synapses on the walls of capillaries. Thanks to this, neurons release synthesized protein molecules from the synapses on the walls of these vessels directly into the bloodstream. All neurohormones are hydrophilic compounds for which there are corresponding receptors on the surface of the target cell membrane. At the first stage, the interaction of the neurohormone with the corresponding membrane receptor occurs. Further signal transmission is carried out by intracellular second messengers. A diagram of the neuroendocrine system of the human body is presented in Appendix 5.

Control of secretion of the posterior lobe of the pituitary gland. The posterior lobe, or neurohypophysis, is an endocrine organ that accumulates and secretes two hormones synthesized in the magnocellular nuclei of the anterior hypothalamus (paraventricular and supraoptic), which are then transported along axons to the posterior lobe. Neuropituitary hormones in mammals include vasopressin, or antidiuretic hormone, which regulates water metabolism, and oxytocin, a hormone involved in labor.

Under the influence of vasopressin, the permeability of the collecting ducts of the kidney and the tone of the arterioles increase. Vasopressin in some synapses of hypothalamic neurons performs a mediator function. Its entry into the general bloodstream occurs when the osmotic pressure of the blood plasma increases, as a result of which osmoreceptors are activated - neurons of the supraoptic nucleus and the perinuclear zone of the hypothalamus. With a decrease in blood plasma osmolarity, the activity of osmoreceptors is inhibited and the secretion of vasopressin decreases. With the help of the described neuroendocrine interaction, including a sensitive feedback mechanism, the constancy of the osmotic pressure of the blood plasma is regulated. If the synthesis, transportation, secretion or action of vasopressin is disrupted, diabetes insipidus. The leading symptoms of this disease are discharge large quantity urine with low relative density (polyuria) and a constant feeling of thirst. In patients, diuresis reaches 15 - 20 liters per day, which is no less than 10 times higher than normal. When water intake is limited, patients become dehydrated. The secretion of vasopressin is stimulated by a decrease in the volume of extracellular fluid, pain, some emotions, stress, as well as a number of drugs - caffeine, morphine, barbiturates, etc. Alcohol and an increase in the volume of extracellular fluid reduce the secretion of the hormone. The effect of vasopressin is short-lived because it is quickly destroyed in the liver and kidneys.

Oxytocin is a hormone that regulates labor and milk secretion by the mammary glands. Sensitivity to oxytocin increases with the introduction of female sex hormones. The maximum sensitivity of the uterus to oxytocin is observed during ovulation and on the eve of childbirth. During these periods, the greatest release of the hormone occurs. The descent of the fetus along the birth canal stimulates the corresponding receptors, and afferentation enters the

paraventricular nuclei of the hypothalamus, which increase the secretion of oxytocin. During sexual intercourse, the secretion of the hormone increases the frequency and amplitude of uterine contractions, facilitating the transport of sperm into the oviducts. Oxytocin stimulates milk production by causing contraction of the myoepithelial cells lining the mammary ducts. As a result of increased pressure in the alveoli, milk is squeezed into large ducts and is easily released through the nipples. When the tactile receptors of the mammary glands are stimulated, impulses are sent to the neurons of the paraventricular nucleus of the hypothalamus and cause the release of oxytocin from the neurohypophysis. The effect of oxytocin on milk production occurs 30-90 s after the start of nipple stimulation.

Control of secretion of the anterior pituitary gland. Most of the hormones of the anterior pituitary gland act as specific regulators of other endocrine glands; these are the so-called “tropic” hormones of the pituitary gland.

Adrenocorticotropic hormone(ACTH) is the main stimulator of the adrenal cortex. This hormone is released during stress, spreads through the bloodstream and reaches target cells of the adrenal cortex. Under its action, catecholamines (adrenaline and norepinephrine) are released from the adrenal cortex into the blood, which have a sympathetic effect on the body (this effect was described in more detail above). Luteinizing hormone is the main regulator of the biosynthesis of sex hormones in male and female gonads, as well as a stimulator of growth and maturation of follicles, ovulation, formation and functioning of the corpus luteum in the ovaries. Follicle stimulating hormone increases the sensitivity of the follicle to the action of luteinizing hormone, and also stimulates spermatogenesis. Thyroid-stimulating hormone is the main regulator of the biosynthesis and secretion of thyroid hormones. The group of tropic hormones includes growth hormone, ilisomatotropin, the most important regulator of body growth and protein synthesis in cells; also participates in the formation of glucose and the breakdown of fats; Some of the hormonal effects are mediated through increased liver secretion of somatomedin (growth factor I).

In addition to tropic hormones, hormones are produced in the anterior lobe that perform an independent function similar to the functions of hormones of other glands. These hormones include: prolactin, or lactogenic hormone, regulating lactation (milk formation) in a woman, differentiation of various tissues, growth and metabolic processes, instincts of nursing offspring in representatives of various classes of vertebrates. Lipotropins are regulators of fat metabolism.

The functioning of all parts of the pituitary gland is closely related to the hypothalamus. The hypothalamus and pituitary gland form a single structural and functional complex, which is often called the “endocrine brain.”

The epiphysis, or superior pineal gland, is part of the epithalamus. The pineal gland produces the hormone melatonin, which regulates pigment metabolism in the body and has an antigonadotropic effect. The blood supply to the pineal gland is carried out through a circulatory network formed by the secondary branches of the middle and posterior cerebral arteries. Having entered the connective tissue capsule of the organ, the vessels break up into many capillaries of the organ with the formation of a network characterized by big amount anastomoses. The blood from the pineal gland is partially drained into the system of the great cerebral vein of Galen, some of it enters the veins of the choroid plexus of the third ventricle. Neurosecretion of the pineal gland depends on illumination. The main link in this chain is the anterior hypothalamus (suprachiasmatic nucleus), which receives direct input from the optic nerve fibers. Next, a descending path is formed from the neurons of this nucleus to the superior sympathetic node and then, as part of a special (pineal) nerve, enters the pineal gland.

In the light, the production of neurohormones in the pineal gland is inhibited, while during the dark phase of the day it increases. Melatonin affects the functions of many parts of the central nervous system and some behavioral reactions. For example, in humans, an injection of melatonin induces sleep.

Another physiologically active substance of the pineal gland that claims to be a neurohormone is serotonin, a precursor of melatonin. Animal studies have shown that the content of serotonin in the pineal gland is higher than in other organs, and depends on the species, age of the animal, as well as the light regime; it is subject to daily fluctuations with maximum levels during the daytime. Daily rhythm of serotonin content in the pineal gland

The limbic system, also called the visceral brain, rhinencephalon, thymencephalon, contains a whole complex of structures of different middle, intermediate, final, which are involved in the organization of motivational, visceral and emotional reactions of the body.

The limbic system of the brain has a very complex structure; it unites such sections of the old cortex as the hippocampus, limbic and cingulate gyri; sections of the new cortex: frontal, temporal sections and frontotemporal intermediate zone; subcortical structures: globus pallidus, putamen, septum, hypothalamus, nonspecific nuclei of the thalamus, reticular formation of the midbrain. All subcortical structures are very closely connected with the main structures of the cortex big brain. The structures of the system are localized mainly on the cerebral hemispheres.

The limbic system, the functions of which at the initial stage of the evolution of the animal world were formed on the basis of smell, provides many vital reactions of the body, such as orientation, sex and food. The sense of smell not only acted as the main integrating factor, but also united the structures of the brain into a single integral complex. Therefore, in higher vertebrates, including humans, the structures of the limbic system, built on the basis of descending and ascending pathways, have a closed system of functioning.

The limbic system controls many of the most important processes occurring in the body - regulation of water-salt balance, maintaining a constant body temperature, as well as behavioral reactions, in particular food reactions, aimed at obtaining energy and nutrients. It determines a person’s emotional behavior, sexual behavior, processes of sleep and wakefulness, learning and memory. This system determines and controls the motivation of behavior and ensures the purposefulness of all actions. As a result, the body adapts to changes in conditions environment is constantly being improved. And first of all, this concerns the social environment, since man is a purely social being.

The limbic system also provides another important function - verbal or carrying information about any events, existing knowledge or acquired skills and experience. In clinical practice, it has been revealed that when the limbic structures are impaired or damaged, patients develop amnesia. But scientists argue that the limbic system is not a repository of information because memory fragments are dispersed throughout the association cortex. And the limbic system only functionally unites them and makes them available for reproduction. When limbic structures are violated, the memory is not erased, its fragments remain and are preserved, but only its conscious reproduction fails. Therefore, almost all people with damage to the limbic system are able to instantly master many motor or perceptual skills and abilities, but at the same time they cannot remember where they could have learned this before.

Dysfunctions of the limbic system can cause brain injuries, neuroinfections and intoxications, vascular pathologies, endogenous psychoses and neuroses. Depending on the volume of the lesion or its localization, epileptic convulsive states, automatisms, changes in consciousness and mood, derealization and depersonalization, as well as auditory, gustatory and olfactory hallucinations may occur.

Sadness, disgust. Emotions. Even though we sometimes feel depressed due to their intensity, but in fact, life without them is impossible. What would we do, for example, without fear? Perhaps we would turn into reckless suicides. This article explains what the limbic system is, what it does, its functions, components, and possible states. What does the limbic system have to do with our emotions?

What is the limbic system? Since the time of Aristotle, scientists have been researching mysterious world human emotions. Historically, this area of ​​science has always been the subject of much controversy and intense debate; Bye scientific world has not come to accept that emotions are an integral part of human nature. In fact, science now confirms that there is a certain brain structure, namely the limbic system, that regulates our emotions.

The term “limbic system” was proposed by American scientist Paul D. MacLean in 1952 as the neural substrate for emotions (MacLean, 1952). He also proposed the concept of the triune brain, according to which the human brain consists of three parts, impaled on one another, like in a nesting doll: the ancient brain (or reptilian brain), the midbrain (or limbic system) and the neocortex (cerebral cortex).

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Components of the limbic system

What does the limbic system of the brain consist of? What is its physiology? The limbic system has many centers and components, but we will focus only on those that have the most significant functions: the amygdala (hereinafter referred to as the amygdala), and the cingulate gyrus.

“The hypothalamus, the anterior cingulate nucleus, the cingulate cortex, the hippocampus and its connections represent a coherent mechanism that is responsible for central emotional functions and also takes part in the expression of emotions.” James Paperc, 1937

Functions of the limbic system

Limbic system and emotions

The limbic system in the human brain performs the following function. When we talk about emotions, we automatically have a feeling of some rejection. It's about about the association that still takes place from that time when the concept of emotions looked like something dark, clouding the mind and intellect. Some groups of researchers have argued that emotions reduce us to the level of animals. But in fact, this is absolutely true, because, as we will see later, emotions (not so much themselves, but the system they activate) help us survive.

Emotions have been defined as interrelated responses evoked by situations of reward and punishment. Rewards, for example, promote responses (satisfaction, comfort, well-being, etc.) that attract animals to adaptive stimuli.

• Autonomic reactions and emotions depend on the limbic system: The relationship between emotions and autonomic reactions (body changes) is important. Emotions are essentially a dialogue between the brain and body. The brain detects a significant stimulus and sends information to the body so that it can respond appropriately to those stimuli. The last step is that the changes in our body occur consciously, and thus we acknowledge our own emotions. For example, fear and anger responses begin in the limbic system, which causes diffuse effects on the sympathetic nervous system. The body's fight-or-flight response prepares a person for threatening situations so that he can defend or flee, depending on the circumstances, by increasing his heart rate, breathing and blood pressure.
• Fear depends on the limbic system: fear reactions are formed as a result of stimulation of the hypothalamus and amygdala. This is why destroying the amygdala eliminates the fear response and its associated bodily effects. The amygdala is also involved in fear-based learning. Likewise, neuroimaging studies show that fear activates the left amygdala.
• and calmness are also functions of the limbic system: Anger reactions to minimal stimuli are observed after removal of the neocortex. Destruction of both some areas of the hypothalamus and the ventramedial nucleus and septal nuclei also causes anger reactions in animals. Anger can also be generated by stimulating wider areas of the midbrain. Conversely, bilateral destruction of the amygdala disrupts anger responses and leads to excessive calmness.
• Pleasure and addiction originate in the limbic system: neural networks responsible for pleasure and addictive behavior are included in the structure of the amygdala, nucleus accumbens and hippocampus. These circuits are involved in the motivation to use drugs, determine the nature of impulsive consumption and possible relapses. Learn more about the benefits of cognitive rehabilitation in addiction treatment.

Non-emotional functions of the limbic system

The limbic system takes part in the formation of other processes related to survival. Its neural networks, specializing in functions such as sleep, sexual behavior or memory, are widely described in the scientific literature.

As you might expect, memory is another important function, which we need to survive. Although there are other types of memory, emotional memory refers to stimuli or situations that are vital. The amygdala, prefrontal cortex, and hippocampus are involved in the acquisition, maintenance, and disappearance of phobias from our memory. For example, the fear of spiders that humans have to ultimately make it easier for them to survive.

The limbic system also controls eating behavior, appetite, and the functioning of the olfactory system.

Clinical manifestations. Disturbances in the limbic system

1- Dementia

The limbic system is associated with the causes of, in particular, Alzheimer's disease and Pick's disease. These pathologies are accompanied by atrophy in the limbic system, especially in the hippocampus. In Alzheimer's disease, senile plaques and neurofibrillary tangles (tangles) appear.