The limbic system of the human brain provides. limbic system

limbic system (limbicus- border) - a complex of brain structures (Fig. 11) related to emotions, sleep, wakefulness, attention, memory, autonomic regulation, motivations, internal urges; motivation includes the most complex instinctive and emotional reactions, such as food, defensive And etc. The term "limbic system" was introduced by Mac Lean in 1952.

This system surrounds the brainstem like a sheath. It is commonly referred to as the "olfactory brain" as it is directly related to the sense of smell and touch. Mood-altering drugs affect the limbic system, which is why people who take them feel uplifted or depressed.

The limbic system consists of the thalamus, hypothalamus, pituitary, hippocampus, pineal, amygdala, and reticular formation. The presence of functional connections between limbic structures and the reticular formation allows us to speak of the so-called limbic-reticular axis, which is one of the most important integrative systems of the body.

Visual thalamus(thalamus) - a paired formation of the diencephalon. The thalamus of the right hemisphere is separated from the thalamus of the left by the third ventricle. The visual hillock is a switching "station" of all sensory pathways (pain, temperature, tactile, taste, visceral). Each nucleus of the thalamus receives impulses from the opposite side of the body, only the face area has bilateral representations in the thalamus. The visual hillock is also involved in affective-emotional activity. The defeat of individual nuclei of the thalamus leads to a decrease in the feeling of fear, anxiety and tension, as well as to a decrease in intellectual abilities, up to the development of dementia and disruption of the processes of sleep and wakefulness. Clinical symptoms with complete damage to the thalamus are characterized by the development of the so-called "thalamic syndrome". This syndrome was first described in detail by J. Dezherin and G. Rus in 1906 and is manifested by a decrease in all types of sensitivity, severe pain on the opposite side of the body and impaired cognitive processes (attention, memory, thinking, etc.)

Hypothalamus(hypothalamic region) - a part of the diencephalon, located downward from the thalamus. The hypothalamus is the highest vegetative center that regulates the work of internal organs, many body systems and ensures the constancy of the internal environment of the body (homeostasis). Homeostasis - maintaining the optimal level of metabolism (protein, carbohydrate, fat, mineral, water), temperature balance of the body, normal activity of the cardiovascular, respiratory, digestive, excretory and endocrine systems. Under the control of the hypothalamus are all endocrine glands, in particular the pituitary gland. The close relationship between the hypothalamus and the pituitary gland forms a single functional complex - the hypothalamic-pituitary system. The hypothalamus is one of the main structures involved in the regulation of sleep and wakefulness. Clinical studies have shown that damage to the hypothalamus leads to lethargic sleep. From a physiological point of view, the hypothalamus is involved in the formation of the behavioral reactions of the body. The hypothalamus plays the main role in the formation of the body's main drives (food, drink, sexual, aggressive, etc.), motivational and emotional spheres. The hypothalamus is also involved in the formation of such states of the body as hunger, fear, thirst, etc. Thus, the hypothalamus carries out autonomic regulation of internal organs, maintains the constancy of the internal environment of the body, body temperature, controls blood pressure, gives signals about hunger, thirst, fear and is the source of sexual feelings.

The defeat of the hypothalamic region and the hypothalamic-pituitary system, as a rule, leads primarily to a violation of the constancy of the internal environment of the body, which is accompanied by a wide variety of clinical symptoms (increased blood pressure, palpitations, increased sweating and urination, the appearance of a feeling of fear of death, pain in the heart , disruption of the digestive tract), as well as a number of endocrine syndromes (Itsenko-Cushing, pituitary cachexia, diabetes insipidus, etc.).

Pituitary. It is otherwise called - a cerebral appendage, pituitary gland - an endocrine gland that produces a number of peptide hormones that regulate the function of the endocrine glands (genital, thyroid, adrenal cortex). A number of hormones of the anterior pituitary gland are called triple (somatotropic hormone, etc.). They are related to growth. So, the defeat of this area (in particular, with a tumor - acidophilic adenoma) leads to gigantism or acromegaly. Deficiency of these hormones is accompanied by pituitary dwarfism. Violation of the production of follicle-stimulating and luteinizing hormones is the cause of sexual insufficiency or sexual dysfunction.

Sometimes, after the defeat of the pituitary gland, a disorder in the regulation of sexual functions is combined with disorders of fat metabolism (adipose-genital dystrophy, in which a decrease in sexual function is accompanied by obesity of the pelvic region, thighs and abdomen). In other cases, on the contrary, premature puberty develops. With lesions of the lower parts of the pituitary gland, a dysfunction of the adrenal cortex develops, which leads to obesity, increased hair growth, voice changes, etc. The pituitary gland, closely connected through the hypothalamus with the entire nervous system, unites the endocrine system into a functional whole, which is involved in ensuring the constancy of the internal environment body (homeostasis), in particular the constancy of hormones in the blood and their concentrations.

Since the pituitary gland is the most important link in the system of internal organs, a violation of its function leads to violations of the autonomic nervous system that regulates the functioning of internal organs. The main causes of pituitary pathology are tumors, infectious diseases, vascular pathology, skull injuries, venereal diseases, radiation, pregnancy pathology, congenital insufficiency, etc. The defeat of various parts of the pituitary gland leads to a variety of clinical syndromes. So, excessive production of somatotropic hormone (growth hormone) leads to gigantism or acromegaly, and its deficiency is accompanied by pituitary dwarfism. Violation of the production of follicle-stimulating and luteinizing hormones (sex hormones) is the cause of sexual insufficiency or sexual dysfunction. Sometimes the dysregulation of the gonads is combined with a violation of fat metabolism, which leads to adipose-genital dystrophy. In other cases, precocious puberty is manifested. Often, the pathology of the pituitary gland leads to an increase in the functions of the adrenal cortex, which is characterized by hyperproduction of adrenocorticotropic hormone and the development of Itsenko-Cushing's syndrome. Extensive destruction of the anterior pituitary gland leads to pituitary cachexia, in which the functional activity of the thyroid gland and the function of the adrenal cortex are reduced. This leads to metabolic disorders and to the development of progressive emaciation, bone atrophy, the extinction of sexual functions and atrophy of the genital organs.

Destruction of the posterior pituitary gland leads to the development of diabetes insipidus (diabetes insipidus).

Hypoplasia and atrophy - a decrease in the size and weight of the pituitary gland - develop in old age, which leads to arterial hypertension (increased blood pressure) in the elderly. The literature describes cases of congenital hypoplasia of the pituitary gland with clinical manifestations of pituitary insufficiency (hypopituitarism). People exposed to radiation often develop hycocorticism (Addison's disease). A change in the functioning of the pituitary gland can also be of a temporary, functional nature, in particular during pregnancy, when hyperplasia of the pituitary gland is noted (an increase in its size and weight).

The main clinical symptoms of diseases arising from lesions of the hypothalamic-pituitary complex are described in the section "Clinical features of individual nosological forms".

hippocampus translated from Greek - a sea monster with the body of a horse and a fish tail. It is otherwise called - Ammon's horn. It is a paired formation and is located on the wall of the lateral ventricles. The hippocampus is involved in the organization of the orienting reflex and attention, the regulation of autonomic reactions, motivations and emotions, in the mechanisms of memory and learning. When the hippocampus is affected, human behavior changes, it becomes less flexible, difficult to rebuild in accordance with changing environmental conditions, and short-term memory is also sharply impaired. At the same time, the ability to memorize any new information disappears (anterograde amnesia). Thus, the so-called general memory factor suffers - the possibility of the transition of short-term memory into long-term memory.

Pineal body(pineal gland, pineal gland) - endocrine gland, is an unpaired rounded formation weighing 170 mg. It is located deep in the brain under the cerebral hemispheres and is adjacent to the back of the third ventricle. The pineal gland takes part in the processes of homeostasis, puberty, growth, as well as in the relationship of the internal environment of the body with the environment. Hormones of the pineal gland inhibit neuropsychic activity, providing a hypnotic, analgesic and sedative effect. Thus, a decrease in the production of melatonin (the main hormone of the gland) leads to persistent insomnia and the development of a depressive state. Disturbances in the hormonal function of the pineal gland are also manifested in an increase in intracranial pressure, and often in a manic-depressive syndrome with severe intellectual disorders.

amygdala(amygdaloid region) - a complex complex of brain nuclei, located in the depths of the temporal lobe and which is the center of "aggression". So, irritation of this area leads to a typical awakening reaction with elements of anxiety, anxiety (the pupils dilate, the heart rate, breathing, etc. become more frequent), and symptoms of the oral complex of movements are also observed - salivation, sniffing, licking, chewing, swallowing. The amygdala also has a significant influence on sexual behavior, leading to hypersexuality. The amygdaloid region has a certain effect on higher nervous activity, memory and sensory perception, as well as on the emotional and motivational environment.

Clinical observations show that in patients with epilepsy, convulsive syndrome is often combined with fear, longing or severe unmotivated depression. The defeat of this area leads to the so-called temporal lobe epilepsy, in which psychomotor, vegetative and emotional symptoms are expressed. In such patients, many basic motivations are violated (increase or decrease in appetite, hyper- or hyposexuality, bouts of displeasure, unmotivated fear, anger, rage, and sometimes aggressiveness).

- the widest set, which is a morphofunctional association of systems. They are located in different parts of the brain.

Consider 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
• the oldest subcrustal and mantle parts
• cingulate gyrus
• dentate gyrus
• hippocampus (seahorse)
• septum (partition)
• amygdala bodies.

There are 4 main structures of the limbic system in the diencephalon:

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

The flexural gyrus, meanwhile, serves as a pathway that relays messages between the inner and outer parts of the limbic system. The amygdala is one of two almond-shaped clusters of nerve cells in the temporal lobe of the brain. Both amygdala are responsible for preparing the body for emergencies, such as being 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 emergencies.

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

main functions of the limbic system

Connection with emotions

The limbic system is responsible for the following activities:

• sensual
• motivational
• vegetative
• endocrine

Instincts can also be added here:

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

Components of the limbic system

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

• food
• sexual
• defensive

The limbic system is responsible for regulating the wake-sleep process. It develops biological motivations. They predetermine complex chains of efforts to be made. 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. It is a system of coordinated processes. With the growth and development of the child, his instincts are increasingly influenced by consciousness, which develops in the course of study and education.

Finally, we have the basal ganglia, which are the 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 assumed that the limbic system developed from primitive mammals during human evolution. Therefore, many of the functions of the limbic system deal with instincts and not with the study of behavior. Scholars 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 do not agree on whether the paths associated with these primitive functions are related.

Interaction with the neocortex

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

However, the limbic system is still discussed in many traditional biology and physiology courses as part of the nervous system. The 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 connected to 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. The two large structures of the limbic system play an important role in memory. The amygdala is responsible for determining which 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 elicits. The hippocampus sends memories to the appropriate part of the brain hemisphere for long-term storage and retrieves them when needed. Damage to this area of ​​the brain can lead to an inability to form new memories.

Deprivation of a part of the system leads to psychological inertia. The urge leads to psychological hyperactivity. Strengthening the activity of the amygdala triggers ways to provoke anger. These methods are regulated by the hippocampus. The system triggers eating behavior and arouses a sense of danger. These behaviors are regulated by both the limbic system and hormones. Hormones, in turn, are produced by the hypothalamus. This combination largely affects the vital activity through the regulation of the functioning of the autonomic nervous system. Its meaning is hugely called the visceral brain. Determines the sensory-hormonal activity of the animal. Such activity is practically not subject to brain regulation either in an animal, or even more so in humans. This shows the relationship between emotions and the limbic system.

The part known as "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 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 regulation, body temperature, and many other vital activities.

Almond-shaped mass of nuclei involved in emotional reactions, hormonal secretions and memory. Myggdala is responsible for the harnessing of fear, or the associative learning process by which we learn to be afraid of something. a fold in the brain associated with sensory input to emotions and the regulation of aggressive behavior. - arches, bands 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 brain hemisphere for long-term storage and retrieves them when needed. - about the size of pearls, this structure directs many important functions. The hypothalamus is also an important emotional center, controlling the molecules that make you feel excited, angry, or unhappy. - receives sensory information from the olfactory bulb and is involved 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 gives you an adrenaline rush. . 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 associated with the hippocampus. Long-term memory - with the neocortex. The manifestation of personal skill and knowledge from the neocortex occurs through the limbic system. For this, sensual-hormonal provocation 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 regulating. More recently, Paul McLean, taking the basic foundations of Papez's proposal, created the demonative limbic system and added new structures to the schema: the orbitofrontal and medial-frontal cortex, the paraftopacambic gyrus, and important subcortical groupings such as the amygdala, medial thalamic nucleus, septal region, prosencephalic basal nuclei and several brain stems.

The main areas associated with emotions. It is important to emphasize that all these structures are intensely connected to each other, and none of them is responsible for any particular emotional state. However, some of them contribute more than others to certain emotions. Below we consider, one by one, the most well-known structures of the limbic system.

The limbic system also performs the following significant function - the verbal memory of incidents and the experience gained, skills, and 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 are connected to each other and other parts of the brain. Connections with the hypothalamus are especially multifaceted.

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

It defines:

• sensual mood of a person
• his motivation to work
• behavior
• processes of acquiring knowledge and memorization.

Violations and their consequences

In case of violation of the limbic system or a defect in these sets, 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. Disturbance 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 preserved and serve as a guarantee for procedural memory. Patients with Korsakov's syndrome can learn some other new knowledge for themselves. However, they will not know how and what exactly they learned.

This structure has extensive connections with other proencephalic areas and mesencephaly. Lesions in 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 believed to play a role in emotions. In particular, its lateral parts seem to be associated with pleasure and rage, while the median part seems to be associated with disgust, displeasure, and a tendency to uncontrollable and loud laughter.

Defects in its activities lead to:

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

It all depends on how significant the defeat was, as well as the limitations. 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 with the predominant defeat of the hippocampus by alcohol, a person suffers from memory in relation to recent incidents. Patients undergoing treatment for alcoholism in the hospital suffer from the following: they do not remember what they ate for lunch today and dined at all, or not, and when they last took medication. At the same time, they perfectly remember the events that took place in their lives for a long time.

The role of the limbic system in the formation of motivations, 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 the physical symptoms of emotions appear, the threat they pose returns through the hypothalamus to the limbic centers and therefore to the anterior frontal nuclei, increasing anxiety. This negative feedback mechanism can be strong enough to create a panic situation. As will be seen later, knowledge of this phenomenon is very important for clinical and therapeutic reasons.

Already scientifically substantiated - the limbic system (more precisely, the amygdala and the transparent septum) is responsible for processing certain information. This information is taken 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 smell. Everyone knows the importance of biogenic amines for leading a full life and activity:

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

Paul McLean uses to say that "it's very hard to imagine a lonely and more emotionally empty creature than a crocodile." Two behaviors with affective connotations that have appeared in mammals deserve special attention because of their peculiarity.

• dopamine
• norepinephrine
• serotonin.

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

The structure and functions of the limbic system are largely unknown. Conducting new research in this area will make it possible to determine its real 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 are. Ablation of important parts of the limbic system of any animal causes it to completely lose both maternal affection and lunar interest. And the evolution of mammals leads us to humanity. Of course, our hominid ancestor could already distinguish between the sensations he experienced on occasion, such as 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 kind, etc. P.

Cytoarchitectonics of the limbic system cortex

With the development of language, specific names were given to these sensations, allowing their definition and communication with other members of the group. Because there is an important subjective component that is difficult to convey, even today there is no consensus on the best terminology to be used to refer to many of these sensations in particular.

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A set of nervous structures and their connections located in the mediobasal part, involved in the control of autonomic functions and emotional, instinctive behavior, as well as influencing the change in the 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 evoke.

Curiously, there is a worldwide tendency to regard only positive experiences as affecting. Opposite emotions and feelings can be used to refer to 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, show reactions to those emotional states that, due to their intensity, turn to some kind of action.

The limbic system is the most ancient part of the cerebral cortex, located on the inside 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 autonomic functions of the body. The 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 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 the electrical activity of the brain, regulates metabolic processes and provides a number of autonomic reactions. Irritation of various sections 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 responses in animals. It contains the cortical section of the olfactory analyzer.

Great Circle of Peipes:

• hippocampus;
• vault;
• mamillary bodies;
• mamillary-thalamic bundle Wikd "Azira;
• thalamus;
• 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 new cortex and the final part of the brain stem. The limbic system includes a number of functionally integrated structures of the middle, diencephalon, and telencephalon. These are the cingulate, parahippocampal and dentate gyrus, the hippocampus, the olfactory bulb, the 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 the integrative processes taking place in it. At the same time, more or less defined functions are inherent in individual structures of the limbic system.

Rice. 1. The most important connections between the structures of the limbic system and the brainstem: a - the circle of Paipez, b - the circle through the amygdala; MT - mammillary bodies

The main functions of the limbic system:

• Emotional-motivational behavior (with fear, aggression, hunger, thirst), which may be accompanied by emotionally colored motor reactions
• Participation in the organization of complex behaviors, such as instincts (food, sexual, defensive)
• Participation in orienting reflexes: reaction of alertness, attention
• Participation in the formation of memory and the dynamics of learning (the 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 gyrus receive afferent signals from the association areas of the frontal, parietal and temporal cortex. The axons of its efferent neurons follow the neurons of the associative cortex of the frontal lobe, the hipiocampus, the septal nuclei, the amygdala, which are connected with the hypothalamus.

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

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

It is possible that the effects of the cingulate gyrus on the behavior of animals and the functions of internal organs are indirect and mediated by connections of the cingulate gyrus through the cortex of the frontal lobe, hippocampus, amygdala and septal nuclei with the hypothalamus and brainstem structures.

It is possible that the cingulate gyrus is related to the formation of pain sensations. People who underwent a cingulate gyrus dissection for medical reasons experienced a reduction in pain.

It has been established that the neural networks of the anterior part of the cingulate gyrus are involved in the operation of the brain error detector. Its function is to identify erroneous actions, the progress of which deviates from the program of their execution and actions, at the completion of which the parameters of the final results were not achieved. Error detector signals are used to trigger mechanisms for correcting erroneous actions.

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 corticomesial and basolateral subgroups of the nuclei.

The neurons of the corticomesial nuclei of the amygdala receive afferent signals from the neurons of the olfactory bulb, hypothalamus, nuclei of the thalamus, septal nuclei, gustatory nuclei of the diencephalon, and pathways of pain sensitivity of the pons, along which signals from large receptive fields of the skin and internal organs arrive at the amygdala neurons. Taking into account these connections, it is assumed that the corticomedial group of tonsil nuclei is involved in the control of the implementation of the vegetative functions of the body.

The neurons of the basolateral nuclei of the amygdala receive sensory signals from the 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.

The neurons of the basolateral nuclei are associated with the thalamus, the prefrontal cortex of the cerebral hemispheres, and the ventral striatum of the basal ganglia; therefore, it is assumed that the nuclei of the basolateral group of the tonsils are involved in the implementation of 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 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, the bilateral destruction of the tonsils in monkeys causes a loss of aggressiveness, a decrease in emotions and defensive reactions. Monkeys with removed tonsils are kept alone, do not seek to make 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 for any reason, but at this time the heart rate, blood pressure and other autonomic reactions are not changed. It is assumed that the removal of the tonsils, accompanied by a rupture of its connections with the cortex, leads to a disruption in the processes of normal integration of the semantic and emotional components of efferent signals in the cortex.

Electrical stimulation of the tonsils is accompanied by anxiety, hallucinations, past experiences, and SNS and ANS reactions. The nature of these reactions depends on the localization of irritation. When the nuclei of the cortico-medial group are irritated, reactions from the digestive organs prevail: salivation, chewing movements, bowel movements, urination, and when the nuclei of the basolateral group are irritated, reactions of alertness, raising the head, pupil dilation, search. With strong irritation, animals can develop states of rage or, conversely, fear.

In the formation of emotions, an important role belongs to 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 Paipez (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 (almond - hypothalamus - midbrain - amygdala) is important in the regulation of aggressive-defensive, sexual and nutritional behavioral reactions and emotions.

The tonsils are one of the structures of the CNS, on the neurons of which there is 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 links between the nature of the stimulus and its significance: the expectation of pleasure (reward) or punishment for the 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 along 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 bilateral links 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 gateway for receiving afferent signals, receives them from various associative areas of the cerebral cortex, the hippocampal and cingulate gyrus. The hippocampus receives already processed visual signals from the 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 stem nuclei, the raphe nucleus, and the bluish spot. These signals perform a predominantly modulatory function in relation to the activity of hippocampal neurons, adapting it to the degree of attention and motivations that are crucial for the processes of memorization and learning.

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

One of the consequences of a bilateral disease of the medial part of the temporal lobe is the development of amnesia - memory loss with a subsequent decrease in intelligence. At the same time, 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 structures of the brain, including the medial halamus, cholinergic neuronal groups of the base of the frontal lobes, the amygdala, which play a key role in the mechanisms of memory and learning.

A special role in the implementation of memory mechanisms in 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 they are activated by any influences (this property is called post-tetanic potentiation). Post-tetanic potentiation, which ensures long-term circulation of information signals in closed neural circuits 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 stored in memory after damage to this structure. At the same time, 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 more involved in the basal ganglia, the cerebellum, the motor areas of the cortex, and the temporal cortex.

Thus, the structures of the limbic system are involved in the implementation of such complex brain functions as behavior, emotions, learning, 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 a part of the structures of the central nervous system that are important in the mechanisms of complex brain functions, and contributes to their implementation.

So, in the formation of emotions as states that reflect our subjective attitude to current or past events, one 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 the 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 an emotional reaction.

Involvement in responses of the structures of the limbic system associated with the cerebral cortex enhances the mental component of emotion in them, 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 reaction. At the same time, the function of the limbic system in the organization of emotions in humans is under the influence of the cortex of the frontal lobe of the brain, which has a corrective effect on the functions of the limbic system. It inhibits the manifestation of excessive emotional reactions associated with the satisfaction of the simplest 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 vegetative functions, ensure their coordinated implementation, maintenance of homeostasis and behavioral responses aimed at preserving the life of the individual and species.

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

limbic system

The limbic system of the brain is a collection of complex neuroregulatory structures of the brain. This system is not limited to just a few functions - it performs a huge number of the most important tasks for a person. 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 occurrence

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

• Dominance - a manifestation of superiority in a variety of ways
• Food - subject nutrition
• Reproduction is the transfer of one's genome to the next generation.

Because a person has animal roots, a limbic system is present in the human brain. Initially, Homo sapiens had only affects that affect the physiological state of the body. Over time, communication was formed by the type of cry (vocalization). Individuals who knew how to convey their state with the help of emotions survived. Over time, an emotional perception of reality has been formed more and more. Such evolutionary stratification allowed people to unite into groups, groups into tribes, tribes into settlements, and the latter into entire peoples. 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 structures of the subcortex (caudate nucleus, amygdala, globus pallidus). The listed names of various types of bark indicate their formation at the indicated time of evolution.

Weight specialists in the field of neuroscience, they dealt with 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 scheme of the anatomy of the limbic complex rests on the gradual layering of one part on another. So, on top lies the cingulate gyrus, 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 vicious circles, which creates conditions for a long-term circulation of excitation in the limbus.

Functionality of the limbic system

The visceral brain actively receives and processes information from the outside 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 the phenomenon of the environment.
• Memory. This function is carried out by the hypocampus, located in the structure of the limbic system. Mnestic processes are provided by the processes of reverberation - a circular movement of excitation in the closed neural circuits of the sea horse.
• Selection and correction of a model of suitable behavior.
• Training, retraining, fear and aggression;
• Development of spatial skills.
• Defensive and foraging behavior.
• Expressiveness of speech.
• Acquisition and maintenance of various phobias.
• The work 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 those around you.

At expression of emotions a reaction occurs, which 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: none. In all men, the limbus works to the full (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 reach the level of development of a woman's limbus.

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

Interaction with the neocortex

The neocortex and the limbic system are tightly connected by 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: human thought usually goes through a series of cultural and moral inspections before taking any action spontaneously evoked by emotions. In addition to controlling emotions, the neocortex has an auxiliary effect. The feeling of hunger arises in the depths of the limbic system, and already the higher cortical centers that regulate behavior search for food.

The father of psychoanalysis, Sigmund Freud, did not bypass such brain structures in his time. The psychologist argued that every neurosis is formed under the yoke of the suppression of sexual and aggressive instincts. Of course, at the time of his work, there were no data on the limbus yet, but the great scientist guessed about such brain devices. So, 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 set can be susceptible to various damages. The limbus, like other structures of the brain, can be subject to injuries and other harmful factors, which include tumors with hemorrhages.

Syndromes of lesions of the limbic system are rich in number, the main ones are as follows:

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

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

pathological anxiety and phobias. Violation of the activity of the amygdala leads to a mediator imbalance, which, in turn, is accompanied by a disorder of emotions, including 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 dire consequences.

Reticular formation(or mesh formation) is a non-specific 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 subjected to various disorders of turning off consciousness, including absence and syncope.

neocortex

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

History of occurrence

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

Evolution is a complex and long process. Every kind of creature goes through a harsh evolutionary process. If an animal species could not adapt to a changing environment, the species would lose its existence. Why is a person was able to adapt and survive to this day?

Being in favorable living conditions (warm climate and protein food), the descendants of man (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 mass of the brain in those days was 20% more than that of a modern person.

However, all good things come to an end sooner or later. With climate change, the descendants had to change their place of residence, and with it, start looking for food. Having a huge brain, the descendants began to use it for searching for food, and then for social involvement, because. It turned out that by uniting in groups according to certain criteria of behavior, it was easier to survive. For example, in a group where everyone shared food with other members of the group, they were more likely to survive (Someone picked berries well, and someone hunted, etc.).

From that moment began separate evolution in the brain, separate from the evolution of the whole body. Since then, the appearance of a person has not changed much, but the composition of the brain differs dramatically.

What does it consist of

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

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

What functions does

The human neocortex is classified into three functional areas:

• touch. This zone is responsible for the highest processing of stimuli received from the external environment. So, ice becomes cold when information about temperature enters the parietal region - there is no cold on the finger, but there is only an electrical impulse.
• association zone. This area of ​​the cortex is responsible for the information connection between the motor and sensory cortex.
• motor zone. All conscious movements are formed in this part of the brain.
  In addition to such functions, the neocortex provides higher mental activity: intellect, speech, memory and behavior.

Conclusion

Summing up, we can highlight the following:

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

The limbic system is a functionally unified complex of nervous structures responsible for emotional behavior, urges to action (motivation), learning and memory processes, instincts (food, defensive, sexual) and regulation of the sleep-wake cycle. Due to the fact that the limbic system perceives a large amount of information from the internal organs, it received a second name - the "visceral brain".

The limbic system consists of three structural complexes: the ancient cortex (paleocortex), the old cortex (archicortex), and the median cortex (mesocortex). The ancient cortex (paleocortex) includes preperiform, periamygdala, diagonal cortex, olfactory bulbs, olfactory tubercle, and transparent septum. The second complex, the old cortex (archicortex), consists of the hippocampus, dentate fascia, and cingulate gyrus. The structures of the third complex (mesocortex) are the insular cortex and the parahippocampal gyrus.

The limbic system includes such subcortical formations as the tonsils of the brain, the septal nuclei, the anterior thalamic nucleus, the mammillary bodies, and the hypothalamus.

The main difference between the limbic system and other parts of the central nervous system is the presence of bilateral reciprocal connections between its structures, which form closed circuits through which impulses circulate, providing functional interaction between various parts of the limbic system.

The so-called Peipes twist includes: the hippocampus - the mamillary bodies - the anterior nuclei of the thalamus - the cortex of the cingulate gyrus - the parahippocampal gyrus - the hippocampus. This circle is responsible for emotions, memory formation and learning.

Another circle: amygdala - hypothalamus - mesencephalic structures - the amygdala regulates aggressive-defensive, food and sexual forms of behavior.

The limbic system forms connections with the neocortex through the frontal and temporal lobes. The latter transmit information from the visual, auditory, and somatosensory cortex to the amygdala and hippocampus. It is believed that the frontal areas of the brain are the main cortical regulator of the activity of the limbic system.

Functions of the limbic system

Numerous connections of the limbic system with the subcortical structures of the brain, the cerebral cortex and internal organs allow it to take part in the implementation of various functions, both somatic and vegetative. It controls emotional behavior and improves the adaptive mechanisms of the body in the new conditions of existence. With the defeat of the limbic system or experimental impact on it, eating, sexual and social behavior is disturbed.

The limbic system, its ancient and old cortex are responsible for olfactory functions, and the olfactory analyzer is the most ancient. It triggers all kinds of activities of the cerebral cortex. The limbic system includes the highest vegetative center - hypothalamus, creating vegetative support for any behavioral act.

The most studied structures of the limbic system are the amygdala, hippocampus, and hypothalamus. The latter was described earlier (see p. 72).

Amygdala (amygdala, amygdala) is located deep in the temporal lobe of the brain. The neurons of the amygdala are polysensory and ensure its participation in defensive behavior, somatic, vegetative, homeostatic and emotional reactions, and in the motivation of conditioned reflex behavior. Irritation of the amygdala leads to changes in the cardiovascular system: fluctuations in heart rate, the appearance of arrhythmias and extrasystoles, a decrease in blood pressure, as well as reactions from the gastrointestinal tract: chewing, swallowing, salivation, changes in intestinal motility.

After the bilateral removal of the tonsils, the monkeys lose the ability for social intragroup behavior, they avoid the rest of the group members, behave aloofly, seem to be anxious and insecure animals. They do not distinguish edible objects from inedible ones (mental blindness), their oral reflex becomes pronounced (they take all objects in their mouths) and hypersexuality occurs. It is believed that such disorders in amygdalaectomized animals are associated with impaired bilateral connections between the temporal lobes and the hypothalamus, which are responsible for acquired motivational behavior and emotions. These brain structures compare newly received information with already accumulated life experience, i.e. with memory.

Currently, a fairly common emotional disorder associated with pathological functional changes in the structures of the limbic system is state of anxiety which manifests itself in motor and vegetative disorders, feeling of fear facing real or imagined danger.

hippocampus - one of the main structures of the limbic system is located deep in the temporal lobes of the brain. It forms a complex of stereotypically repeating interconnected micro-networks or modules that allow information to circulate in this structure during learning, i.e. the hippocampus is directly related to memory. Damage to the hippocampus leads to retroanterograde amnesia or impaired memory for events close to the moment of damage, a decrease in emotionality, and initiative.

The hippocampus is involved in the orienting reflex, the reaction of alertness, increasing attention. He is responsible for the emotional accompaniment of fear, aggression, hunger, thirst.

In the general regulation of human and animal behavior, the relationship between the limbic and monoaminergic brain systems. The latter include dopaminergic, noradrenergic And serotonergic systems. They begin in the trunk and innervate various parts of the brain, including some structures of the limbic system.

So, noradrenergic neurons send their axons from the locus coeruleus, where they are in large numbers, to the amygdala, hippocampus, cingulate gyrus, entorhinal cortex.

dopaminergic neurons in addition to the substantia nigra and basal nuclei, they innervate the amygdala, septum and olfactory tubercle, frontal lobes, cingulate gyrus and entorhinal cortex.

Serotonergic neurons are located mainly in the median and near-median nuclei (nuclei of the median suture) of the medulla oblongata and, as part of the medial bundle of the forebrain, innervate almost all parts of the diencephalon and forebrain.

Experiments with self-irritation using implanted electrodes or on a person during neurosurgical operations "proved that stimulation of innervation zones by catecholaminergic neurons located in the limbic system leads to pleasant sensations. These zones are called pleasure centers. Next to them are clusters of neurons, the irritation of which causes an avoidance reaction, they were called "centers of displeasure".

Many mental disorders are associated with monoaminergic systems. Over the past decades, for the treatment of disorders of the limbic system, psitropic drugs have been developed that affect the monoaminergic systems and indirectly on the functions of the limbic system. These include tranquilizers of the benzodiazepine series (seduxen, elenium, etc.), which relieve constipation (imizin), neuroleptics (aminosine, haloperidol, etc.

Sadness, disgust. Emotions. Despite the fact that we sometimes feel overwhelmed by 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 is responsible for, what its functions, components and possible states are. What does the limbic system have to do with our emotions?

What is the limbic system? Since the time of Aristotle, scientists have been exploring the mysterious world of human emotions. Historically, this area of ​​science has always been the subject of much controversy and intense debate; until the scientific world came to recognize that emotions are an integral part of human nature. Indeed, science is now confirming that there is a brain structure, namely the limbic system, that regulates our emotions.

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

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Components of the limbic system

What is the limbic system of the brain made up 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 nucleus of the anterior cingulate gyrus, the cingulate gyrus, the hippocampus and its connections are a well-coordinated mechanism that is responsible for central emotional functions, and also takes part in the expression of emotions.” James Peipets, 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, automatically we have a feeling of some rejection. We are talking about the association that still takes place from the time when the concept of emotions looked like something dark, clouding the mind and intellect. Some groups of researchers have argued that emotions bring us down to the level of animals. But in fact, this is absolutely true, because, as we will see later, emotions (not so much in themselves, but in the system that 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 responses (body changes) is important. Emotions are essentially a dialogue between the brain and the body. The brain detects a significant stimulus and sends information to the body so that it can respond to these stimuli in the appropriate way. The last step is that the changes in our body happen consciously, and thus we acknowledge our own emotions. For example, fear and anger responses start in the limbic system, which causes a diffuse effect on the sympathetic nervous system. The body's response, known as "fight or flight," prepares a person for threatening situations so that he can defend or flee, as the case may be, by increasing his heart rate, breathing rate, and blood pressure.
• Fear depends on the limbic system: fear reactions are formed as a result of stimulation of the hypothalamus and amygdala. That is why destruction of the amygdala eliminates the fear response and its associated bodily effects. The amygdala is also involved in fear-based learning. Similarly, 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 some areas of the hypothalamus, as well as the ventromedial nucleus and septal nuclei, also causes an anger response in animals. Anger can also be generated through stimulation of wider areas of the midbrain. Conversely, bilateral destruction of the amygdala impairs anger responses and leads to excessive calmness.
• Pleasure and addiction originate in the limbic system: the neural networks responsible for pleasure and addictive behavior are part of 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 for addiction treatment.

Non-emotional functions of the limbic system

The limbic system is involved in the formation of other processes associated with survival. Its neural networks are widely described in the scientific literature, specializing in functions such as sleep, sexual behavior, or memory.

As you might expect, memory is another important function 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 removal of phobias from our memory. For example, the fear of spiders that people have in order to ultimately make it easier for them to survive.

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

Clinical manifestations. Limbic system disorders

1- Dementia

The limbic system is associated with causes, 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 plexuses (tangles) appear.