The structure of the limbic system. limbic system

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

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

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

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

2) the formation of the emotional state of the organism;

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

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

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

6) participation in the organization of the cycle "sleep - wakefulness".

The limbic system, as a phylogenetically ancient formation, exerts a regulatory influence on the cerebral cortex and subcortical structures, establishing the necessary correspondence between their activity levels. Undoubtedly, an important role in the implementation of all the above functions of the limbic system is played by the receipt of information from the olfactory receptors (phylogenetically the most ancient way of obtaining information from the external environment) and its processing into this brain system.

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

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

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

Belt gyrus. Damage to the cingulate gyrus in monkeys is known to make them less shy; animals cease to be afraid of a person, do not show signs of affection, anxiety or hostility. This indicates the presence in the cingulate gyrus of neurons responsible for the formation of negative emotions.

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

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

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

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

The limbic system, as is known, includes the structures of the reticular formation of the midbrain, in connection with which some authors propose to speak of the limbic-reticular complex (LRC).

Limbic system: concept, functions. How is it related to our emotions?

What is the limbic system of the brain? What does it consist of? Joy, fear, anger, 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).

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), the hippocampus, the hypothalamus, 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 responses 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 bodily response, known as “fight or flight,” 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 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. Anger and calmness are also functions of the limbic system: anger responses 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 enter 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 linked to the causes of neurodegenerative diseases, 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.

2- Anxiety

Anxiety disorders are the result of disturbances in the regulation of amygdala activity. The scientific literature has detailed the fear circuit that involves the amygdala, the prefrontal cortex, and the anterior cingulate cortex of the brain. (Cannistraro, 2003).

3- Epilepsy

Epilepsy can manifest itself as a consequence of changes in the limbic system. Temporal lobe epilepsy is most common in adults and occurs as a result of sclerosis in the hippocampus. It is believed that this type of epilepsy is associated with dysfunction at the level of the limbic system.

4- Mood disorders

There are studies that show changes in the volume of the limbic system in relation to affective disorders such as bipolar disorder and depression. Functional studies have shown decreased activity in the prefrontal cortex and anterior cingulate cortex in affective disorders. The anterior cingulate cortex is the focus of attention and emotional integration, and is also involved in the regulation of emotions.

5- Autism

Autism and Asperger's syndrome lead to changes in social aspects. Some structures of the limbic system, such as the cingulate gyrus and the amygdala, undergo negative changes in these diseases.

Translation by Alexandra Dyuzheva

Notes:

Cannistraro, P.A., and Rauch, S.L. (2003). Neural circuitry of anxiety: Evidence from structural and functional neuroimaging studies. Psychopharmacol Bull, 37, 8–25

Rajmohan, V., y Mohandas, E. (2007). The limbic system. Indian Journal of Psychiatry 49(2):132-139

Maclean PD. The triune brain in evolution: Role in paleocerebral functions. New York: Plenum Press; 1990

Roxo, M.; Franceschini, P.R.; Zubaran, C.; Kleber, F.; and Sander, J. (2011). The Limbic System Conception and Its Historical Evolution. TheScientificWorldJOURNAL, 11, 2427–2440

Morgane, P.J., y Mokler, D.J. (2006). The limbic system: contiuing resolution. Neuroscience and Biobehavioral Reviews, 30: 119–125

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 work specifically on 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 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, which is 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).

limbic system (synonym: limbic complex, brain, rhinencephalon, thymencephalon)

a complex of structures of the middle, diencephalon and telencephalon involved in the organization of visceral, motivational and emotional reactions of the body.

The bulk of the L.S. structures. make up the formations of the brain related to the ancient, old and new cortex, located mainly on the medial surface of the cerebral hemispheres, as well as numerous subcortical structures closely associated with them.

At the initial stage of development of vertebrates, L.s. provided all the most important reactions of the body (food, orientation, sexual, etc.), which are formed on the basis of the most ancient distant sense - smell (Smell) . It acted as an integrating factor of many integral functions of the body and united the structures of the terminal, diencephalon and midbrain into a single morphofunctional complex. A number of structures L.s. on the basis of ascending and descending pathways forms closed systems.

Morphologically, HP in higher mammals includes ( rice. one ) areas of the old cortex (cingulate, or limbic, gyrus,), some formations of the new cortex (temporal and frontal regions, intermediate frontotemporal zone), subcortical structures (, caudate, putamen, septum, reticular formation of the midbrain, nonspecific nuclei of the thalamus) .

L.S. Structures participate in the regulation of the most important biological needs associated with obtaining energy and plastic materials, maintaining water and salt balance, optimizing body temperature, etc.

It has been experimentally proven that an emotional animal, when stimulated by some parts of the HP. It is manifested mainly by reactions of aggression (anger), flight (fear) or mixed forms of behavior, such as defensive reactions. Emotions, unlike motivations, arise in response to sudden changes in the environment and perform the role of a tactical task of behavior. Therefore, they are transient and optional. Long-term unmotivated changes in emotional behavior may be the result of organic pathology or the action of certain antipsychotics. In different departments of HP. centers of "pleasure" and "displeasure" were opened, united in the systems of "reward" and "punishment". When the “punishment” system is stimulated, they behave in the same way as with fear or pain, and when the “reward” system is stimulated, they tend to resume and carry it out on their own, if such an opportunity presents itself. Reward effects are not directly related to the regulation of biological motivations or the inhibition of negative emotions and most likely represent a non-specific mechanism of positive reinforcement, the activity of which is perceived as pleasure or reward. This general non-specific positive reinforcement is connected to various motivational mechanisms and ensures the direction of behavior based on the “better - worse” principle.

Visceral reactions when exposed to HP, as a rule, are a specific component of the corresponding type of behavior. So, when the hunger center is stimulated in the lateral parts of the hypothalamus, abundant, increased motility and secretory activity of the gastrointestinal tract are observed; during provocation of sexual reactions -, ejaculation, etc., and against the background of different types of motivational and emotional behavior, changes in respiration, heart rate and magnitude, secretion, catecholamines, other hormones and mediators are recorded,

To explain the principles of integrative activity L.s. put forward about the cyclic nature of excitation processes in a closed network of structures, including the hippocampus, mastoid bodies, brain, anterior nuclei of the thalamus, cingulate gyrus - the so-called Peips circle ( rice. 2 ). Then it resumes. This "transit" principle of organizing the functions of L.s. confirmed by a number of facts. For example, food reactions can be elicited by stimulation of the lateral nucleus of the hypothalamus, the lateral preoptic region, and some other structures. Nevertheless, despite the multiplicity of localization of functions, it was possible to establish key, or pacemaker, mechanisms, the deactivation of which leads to the complete loss of the function.

Currently, the problem of consolidation of structures into a specific functional system is being solved from the standpoint of neurochemistry. It is shown that many formations of L.s. contain cells and terminals that secrete several types of biologically active substances. Among them, the most studied are monoaminergic neurons, which form three systems: dopaminergic, noradrenergic and serotonergic (see Mediators) . Neurochemical affinity of individual HP structures. largely determines the degree of their participation in a particular type of behavior. The activity of the reward system is provided by noradrenergic and dopaminergic mechanisms; of the corresponding cell receptors with drugs from a number of phenothiazines or bugarofenones is accompanied by emotional and motor retardation, and with excessive dosages - depression and motor disorders close to Parkinson's syndrome. In the regulation of sleep and wakefulness, along with monoaminergic mechanisms, GABAergic and neuromodulatory mechanisms are involved, specifically responding to gamma-aminobutyric acid () and delta sleep peptide. In the mechanisms of pain, the key role is played by the endogenous opiate system and morphine-like substances - and enkephalins (see Regulatory peptides) .

Violations of the functions of HP manifest themselves in various diseases (brain injuries, intoxications, neuroinfections, vascular pathology, endogenous psychoses, neuroses) and are extremely diverse in the clinical picture. Depending on the location and extent of the lesion, these disorders may be related to motivations, emotions, vegetative functions and be combined in different proportions. Low thresholds of convulsive activity HP cause different forms of epilepsy: major and minor forms of convulsive seizures, automatisms, changes in consciousness (and derealization), vegetative paroxysms preceded or accompanied by various forms of mood changes in combination with olfactory, gustatory and auditory hallucinations.

olfactory bulb; 3 - ; 4 - front; 5 - ; 6 - belt; 7 - anterior nuclei of the thalamus; 8 - end strip; 9 - vault of the brain; 10 - brain strip; 11 - nuclei of the habenular complex; 12 - interpeduncular nucleus; 13 - mastoid nucleus; 14 - amygdaloid area ">

Rice. 1. Schematic representation of the main structures of the human limbic system and the connections between them (indicated by arrows and dotted lines): 1 - cells of the olfactory epithelium; 2 - olfactory bulb; 3 - olfactory tract; 4 - anterior commissure; 5 - corpus callosum; 6 - cingulate gyrus; 7 - anterior nuclei of the thalamus; 8 - end strip; 9 - vault of the brain; 10 - brain strip; 11 - nuclei of the habenular complex; 12 - interpeduncular nucleus; 13 - mastoid nucleus; 14 - amygdaloid area.

Rice. 2a). Morphofunctional characteristics of the limbic system - a schematic representation of the structures of the limbic system (indicated in a darker color; in the center - the so-called Peips circle): 1 - cingulate gyrus; 2 - prewedge; 3 - parahippocampal gyrus (arrows show the relationship of structures).

bark; the blue arrows indicate the morphological connections of the Peips circle, the purple arrows indicate the connections that are not included in it"\u003e

Rice. 2b). Morphofunctional characteristics of the limbic system - the scheme of interaction between the structures of the Peips circle: 1 - amygdaloid region; 2 - olfactory system; 3 - partition; 4 - arch 5 - cingulate gyrus 6 - hippocampus 7 - anterior nucleus of the thalamus 8 - hypothalamus 9 - entorhinal cortex; blue arrows indicate the morphological connections of the Peips circle, purple - connections that are not included in it.


1. Small medical encyclopedia. - M.: Medical Encyclopedia. 1991-96 2. First aid. - M.: Great Russian Encyclopedia. 1994 3. Encyclopedic dictionary of medical terms. - M.: Soviet Encyclopedia. - 1982-1984.

  • limbic area

See what the "Limbic system" is in other dictionaries:

    In the brain. The limbic system (from lat. limbus border, edge) is the totality of a number of brain structures. Participates in the regulation of the functions of internal organs, smell, instinctive behavior, emotions, memory, sleep, wakefulness and ... ... Wikipedia

    LIMBIC SYSTEM, a complex of structures within the BRAIN. The limbic system is located in a semicircle around the hypothalamus. It is believed to be involved in emotional responses such as fear, aggression, and mood changes, as well as... ... Scientific and technical encyclopedic dictionary

    - (from lat. limbus border), limbic lobe, the totality of a number of brain structures (final, intermediate and middle sections), united by anatomical. and func. signs. Includes phylogenetically young cortical structures ... ... Biological encyclopedic dictionary

    The totality of a number of brain structures. Participates in the regulation of the functions of internal organs, smell, instinctive behavior, emotions, memory, sleep, wakefulness, etc ... Big Encyclopedic Dictionary

    The totality of a number of brain structures. Participates in the regulation of the functions of internal organs, smell, instinctive behavior, emotions, memory, sleep, wakefulness, etc. * * * LIMBIC SYSTEM LIMBIC SYSTEM, a combination of a number of structures ... ... encyclopedic Dictionary

    limbic system- a complex of structures of the final, intermediate and middle parts of the brain, which constitute the substrate for the manifestation of the most general states of the body (sleep, wakefulness, emotions, motivation, etc.). The term "limbic system" was introduced by P. Mac Lane in ... ... Human psychology: glossary of terms

    limbic system- (lat. limbus edge, border) - a system that is formed evolutionarily by relatively old formations of the forebrain and is located in a depression under the corpus callosum. It includes: 1. hippocampus, 2. amygdala, 3. olfactory ... ... Encyclopedic Dictionary of Psychology and Pedagogy

    - (from lat. limbus border) olfactory, or visceral, brain, a set of parts of the brain, united according to anatomical (spatial relationship) and functional (physiological) features. The main part of L. s. ... ... Great Soviet Encyclopedia

    The totality of a number of brain structures. Participates in the regulation of internal functions. organs, sense of smell, instinctive behavior, emotions, memory, sleep, wakefulness, etc ... Natural science. encyclopedic Dictionary

- a set of nervous structures and their connections located in the mediobasal part of the cerebral hemispheres, involved in the control of autonomic functions and emotional, instinctive behavior, as well as influencing the change in the phases of sleep and wakefulness.

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 are among 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 vegetative 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.

Structural and functional organization of the limbic system

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 title (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. Fig. 1. The most important connections between the structures of the limbic system and the brain stem: 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. Thus, when its anterior part is stimulated, animals develop aggressive behavior, 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 respiratory rate, 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 frontal cortex, 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 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 pain sensitivity pathways of the pons, through which signals from the 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, so 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 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, we can distinguish mental (experience), somatic (gestures, facial expressions) and vegetative (vegetative reactions) components. The degree of manifestation of these components of emotions depends on the greater or lesser involvement in 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 the 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 the species.

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