Introduction

Amygdala is a small, round, almond-shaped collection of gray matter inside each hemisphere of the brain. Most of its fibers are connected to the olfactory organs; a number of nerve fibers also connect to the hypothalamus. The functions of the amygdala appear to have something to do with a person's mood, feelings, and possibly memory of recent events.

The amygdala has very good connections. When it is damaged by a probe, scalpel, or disease, or when it is experimentally stimulated, serious emotional changes are observed.

The amygdala is connected to the rest of the body nervous system and is very well located, so it acts as a center for regulating emotions. It receives all signals coming from motor cortex, the primary sensory cortex, from part of the association cortex, and from the parietal and occipital lobes of your brain.

Thus, the amygdala is one of the main feeling centers of the brain; it is connected to all parts of the brain.

The purpose of the work is to study the amygdala, as well as its significance.

1. Concept and structure of the amygdala

The amygdala, amygdala, is an anatomical structure of the telencephalon, shaped like an amygdala, belonging to the basal ganglia of the cerebral hemispheres, belongs to the subcortical part of the limbic system.

Figure 1 - Brain formations related to the limbic system: 1 - olfactory bulb; 2 - olfactory pathway; 3 - olfactory triangle; 4 - cingulate gyrus; 5 - gray inclusions; 6 - vault; 7 - isthmus of the cingulate gyrus; 8 - end strip; 9 - hippocampal gyrus; 11 - hippocampus; 12 - mastoid body; 13 - amygdala; 14 - hook

There are two tonsils in the brain - one in each hemisphere. They are located in the white matter inside the temporal lobe of the brain, anterior to the apex of the inferior horn lateral ventricle, approximately 1.5-2.0 cm posterior to the temporal pole, borders the hippocampus.

It consists of three groups of nuclei: basolateral, associated with the cortex big brain; corticomedial, related to structures olfactory system, and central, associated with the hypothalamus and brainstem nuclei that control the autonomic functions of the body.

Figure 2 - Location of the amygdala in humans

The amygdala is an important part limbic system brain Its destruction leads to aggressive behavior or an apathetic, lethargic state. Through its connections with the hypothalamus, the amygdala influences endocrine system, as well as on reproductive behavior.

2. The importance of the amygdala for humans

amygdala defensive body brain

The neurons of the amygdala are diverse in form, function and neurochemical processes in them.

The functions of the amygdala are associated with providing defensive behavior, vegetative, motor, emotional reactions, motivation of conditioned reflex behavior. The functions of the amygdala obviously have direct relation to a person’s mood, his feelings, instincts, and possibly to the memory of recent events.

The electrical activity of the tonsils is characterized by oscillations of different amplitudes and frequencies. Background rhythms can correlate with the rhythm of breathing and heart contractions.

Neurons have pronounced spontaneous activity, which can be enhanced or inhibited by sensory stimulation. Many neurons are multimodal and multisensory and fire synchronously with the theta rhythm.

Irritation of the nuclei of the amygdala creates a pronounced parasympathetic effect on cardiovascular activity, respiratory systems, leads to a decrease (rarely to an increase) in blood pressure, a decrease in heart rate, disruption of excitation through the conduction system of the heart, the occurrence of arrhythmias and extrasystoles. At the same time vascular tone may not change. The slowdown in the rhythm of heart contractions when affecting the tonsils has a long latent period and has a long aftereffect.

Irritation of the tonsil nuclei causes respiratory depression and sometimes a cough reaction.

With artificial activation of the tonsil, reactions of sniffing, licking, chewing, swallowing, salivation, and changes in peristalsis appear. small intestine, and the effects occur with great latent period(up to 30-45 s after irritation). Stimulation of the tonsils against the background of active contractions of the stomach or intestines inhibits these contractions. The various effects of irritation of the tonsils are due to their connection with the hypothalamus, which regulates the functioning of internal organs.

The amygdala plays a key role in the formation emotions. In humans and animals, this subcortical brain structure is involved in the formation of both negative (fear) and positive emotions(pleasure).

The amygdala plays an important role in the formation of memories associated with emotional events. Disturbances in the functioning of the amygdala cause in people various shapes pathological fear and other emotional disorders.

The amygdala is rich in glucocorticoid receptors and is therefore also particularly sensitive to stress. Overstimulation of the amygdala under conditions of depression and chronic stress is associated with increased anxiety and aggression. It is believed that conditions such as anxiety, autism, depression, post-traumatic shock and phobias are associated with abnormal functioning of the amygdala.

The amygdala has another feature. They are related to visual analyzers, mainly through the cortex, in the region of the posterior cranial fossa and affect information processing processes in the visual and arsenal structures. There are several mechanisms for this effect.

One of them is a kind of “coloring” of the incoming visual information due to its own high-energy structures. Firstly, a certain emotional background is superimposed on the information traveling through visual radiation to the cortex. If at this moment the amygdala is overloaded with negative information, then the funniest story will not amuse the person, since the emotional background is not prepared for its analysis.

Secondly, the prevailing emotional background, also associated with the amygdala, affects the body as a whole. Thus, the information returned by these structures and further processed in programs forces a person to switch, for example, from contemplating nature to reading a book, creating a certain mood. After all, if you’re not in the mood, you won’t admire even the most beautiful landscape.

Damage to the amygdala in animals reduces the adequate preparation of the autonomic nervous system for organization and implementation. behavioral reactions, leads to hypersexuality, disappearance of fear, calmness, inability to rage and aggression. Animals become gullible. For example, monkeys with a damaged amygdala calmly approach a viper that previously caused them horror and flight. Apparently, in case of damage to the tonsil, some congenital features disappear unconditioned reflexes, realizing the memory of danger.

Fear is one of the strongest emotions not only in humans, but also in other animals, especially mammals. Scientists It was possible to prove that the protein stathmin is responsible for the functioning of innate and the development of acquired forms of fear. And the highest concentration of this protein is observed in the so-called amygdala- an area of ​​the brain associated with feelings of fear and anxiety. In experimental mice, the gene responsible for the production of stathmin was blocked. Such mice ignored danger - even in situations where other mice sensed it instinctively. For example, they fearlessly walked through open areas of labyrinths, although usually their relatives try to stay in what they consider to be safer, cramped nooks where they are hidden from prying eyes. If ordinary mice, when repeating a sound that had been accompanied by an electric shock the day before, froze in horror, then mice without the “fear gene” reacted to it as if it were an ordinary sound. At the physiological level, a lack of stathmin led to a weakening of long-term synaptic connections between neurons (such connections are believed to ensure memory). The greatest weakening was noted in the segments of the nerve networks going to the amygdala. At the same time, the experimental mice did not lose the ability to learn: they, for example, remembered the path through the maze once found no worse than ordinary mice.

References

1. Kozlov V.I. Anatomy of the nervous system: Tutorial for students / V.I. Kozlov, T.A. Tsekhmistrenko. - M.: Mir: ACT Publishing House LLC, 2004. - 206 p.

2. Tishevskoy I.A. Anatomy of the central nervous system: Textbook / I.A. Tishevskaya. - Chelyabinsk: SUSU Publishing House, 2000. - 131 p.

3. Fedyukovich N.I. Human anatomy and physiology: Textbook / N.I. Fedyukovich. - Rostov n/d: publishing house: “Phoenix”, 2003. - 416 p.

Human physiology. In 2 volumes. T.1 / Ed. V.M. Pokrovsky, G.F. Briefly. - M.: Medicine, 1997 - 448 p.

corpus amygdaloideum) - a characteristic area of ​​the brain, shaped like an amygdala, located inside the temporal lobe (Lobus temporalis) of the brain. There are two tonsils in the brain - one in each hemisphere. The amygdala plays a key role in the formation of emotions and is part of the limbic system. In humans and other animals, this subcortical brain structure is thought to be involved in both negative (fear) and positive emotions (pleasure). Its size is positively correlated with aggressive behavior. In humans, this is the most sexually dimorphic brain structure - in men, after castration, it shrinks by more than 30%. Conditions such as anxiety, autism, depression, post-traumatic stress disorder and phobias are hypothesized to be associated with abnormal functioning of the amygdala.

Anatomical division

The amygdala is actually several separately functioning nuclei, which anatomists combine together due to the proximity of the nuclei to each other. Among these nuclei, the key ones are: the basal-lateral complex, the central-medial nuclei and the corticomedial nuclei.

Connections

The basal-lateral complex, necessary for the development of a conditioned fear reflex in rats, receives input signals from sensory systems.

The central-medial nuclei are the main output for the basal-lateral complex, and are included in emotional arousal in rats and cats.

Pathologies

Until recently, it was believed that patients whose amygdala was destroyed due to Urbach-Wiethe disease experience complete absence fear. However latest research showed that it is still possible to frighten such people by using air inhalation with high content carbon dioxide - about 35 percent.

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Notes

Literature

• // Human Physiology / Ed. V. M. Pokrovsky, G. F. Korotko.

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Excerpt describing the Amygdala

And both friends told each other - one about their hussar revelry and military life, the other about the pleasures and benefits of serving under the command of high-ranking officials, etc.
- Oh guard! - said Rostov. - Well, let’s go get some wine.
Boris winced.
“If you really want to,” he said.
And, going up to the bed, he took out his wallet from under the clean pillows and ordered him to bring wine.
“Yes, and give you the money and the letter,” he added.
Rostov took the letter and, throwing the money on the sofa, leaned both hands on the table and began to read. He read a few lines and looked angrily at Berg. Having met his gaze, Rostov covered his face with the letter.
“However, they sent you a fair amount of money,” said Berg, looking at the heavy wallet pressed into the sofa. “That’s how we make our way, Count, with a salary.” I'll tell you about myself...
“That’s it, my dear Berg,” said Rostov, “when you receive a letter from home and meet your man, whom you want to ask about everything, and I’ll be here, I’ll leave now so as not to disturb you.” Listen, please go somewhere, somewhere... to hell! - he shouted and immediately, grabbing him by the shoulder and looking tenderly into his face, apparently trying to soften the rudeness of his words, he added: - you know, don’t be angry; my dear, my dear, I say this from the bottom of my heart, as if it were an old friend of ours.
“Oh, for mercy’s sake, Count, I understand very much,” said Berg, standing up and speaking to himself in a guttural voice.
“You go to the owners: they called you,” added Boris.
Berg put on a clean frock coat, without a stain or a speck, fluffed up his temples in front of the mirror, as Alexander Pavlovich wore, and, convinced by Rostov’s glance that his frock coat had been noticed, left the room with a pleasant smile.
- Oh, what a brute I am, however! - Rostov said, reading the letter.
- And what?
- Oh, what a pig I am, however, that I never wrote and scared them so much. “Oh, what a pig I am,” he repeated, suddenly blushing. - Well, let’s go get some wine for Gavrilo! Well, okay, let's do it! - he said...
The letters from relatives also included letter of recommendation to Prince Bagration, which, on the advice of Anna Mikhailovna, the old countess got through her friends and sent to her son, asking him to take it down for its intended purpose and use it.
- This is nonsense! “I really need it,” said Rostov, throwing the letter under the table.
- Why did you leave it? – asked Boris.
- Some kind of letter of recommendation, what the hell is there in the letter!
- What the hell is in the letter? – Boris said, picking up and reading the inscription. – This letter is very necessary for you.
“I don’t need anything, and I won’t go as an adjutant to anyone.”
- Why? – asked Boris.
- Lackey position!
“You’re still the same dreamer, I see,” Boris said, shaking his head.
– And you are still the same diplomat. Well, that’s not the point... Well, what are you talking about? - asked Rostov.
- Yes, as you see. So far so good; but I admit, I would very much like to become an adjutant, and not remain at the front.

The identity of the 44-year-old mother of three, referred to as SM, has not been revealed. Rare genetic disorderUrbach-Wiethe disease - completely destroyedamygdala her brain playing important role in the formation various kinds emotions. In the experiments we are talking about told earlier , it was found that damage to the amygdala makes humans and mice less cautious and causes them to take risks.

The case of SM has been studied for about twenty years. It is known, for example, that this woman cannot recognize the expression of fear on a person’s face and draw a frightened face. In 1995, a simple experiment was conducted in which the appearance of a blue square on the screen is accompanied by a loud sound; ordinary person begins to feel fear at the sight of this square, while SM remained calm. Last August in the magazine Nature Neuroscience another one appeared , which contained information that SM, when approaching very close to another person, feels quite comfortable, although she is familiar with the concept of personal space.

The patient, we note, has no problems with memory and mental development. The whole range of ordinary human emotions is available to her.

In his new job the authors tried to prove that SM still cannot experience fear. As part of the testing, the woman was shown fragments from The Silence of the Lambs, The Blair Witch Project, The Shining, The Ring and some other films; she noted that most people would probably find these fragments scary, but she herself was simply interested. SM was then taken to an abandoned tuberculosis sanatorium. Waverly Hills , where on All Hallows' Eve there are special performances designed to frighten visitors. The methods used are the simplest, but most effective: according to the scientists’ description, the five women accompanying SM screamed in horror, but everything they saw did not make much of an impression on the subject.

SM also claimed that she hates snakes and spiders. In the pet store, however, she held one of the snakes for a long time and was ready to touch larger and more dangerous animals and tarantulas. When asked why she reacted so calmly to the reptiles she hated, the woman admitted that she was simply gripped by curiosity. “Without the amygdala, the brain's 'alarm signal' obviously doesn't go off,” says study participant Justin Feinstein, who represents University of Iowa . “This woman understands perfectly well what to watch out for, but she does not observe the prohibitions. It's amazing that she's still alive."

SM has indeed had a lot of unpleasant situations in her past: she lives in a poor area and has been threatened many times and was almost killed once. At the same time, her only memories associated with fear relate to early childhood- to the period when the amygdalae were not yet damaged.

Some experts consider the new data very unreliable, suggesting that SM may - consciously or not - adjust behavior and assessments of their emotions to meet the authors' expectations. According to the employee New York University Elizabeth Phelps, who also worked with people whose amygdala function was impaired, found that her patients retained the ability to experience fear. “I think colleagues are jumping to conclusions,” Ms. Phelps said. “However, the differences may be due to the fact that the amygdala fails at different ages.”

In addition, in SM, not only the amygdala is affected, but also several other areas of the brain. Perhaps this is what makes her case unique.

Amygdala (amygdala) of the brain

M brain indala, amygdala or m tonsil-shaped body (lat. Corpus amygdoloideum) - This is a subcortical structure of the limbic system, located deep in the temporal lobe of the brain.

"Wrong" tonsils - pharyngeal tonsils

The amygdala, as a brain formation, should not be confused with other tonsils - the pharyngeal tonsils!

Tonsils of the mouth (lat. tonsillae) - these are clusters lymphoid tissue located in the nasopharynx and oral cavity. They perform protective and hematopoietic functions, participate in the development of immunity - they are a first-line protective mechanism against inhaled and ingested foreign substances. harmful substances and antigens. The full immunological role of the tonsils still remains unclear. The commonly known term "tonsils" refers only to the palatine tonsils.

Both types of tonsils - cerebral and pharyngeal - act completely independently of each other and each in its own area, and the only thing they have in common is the same name.

And if your pharyngeal tonsils (tonsils) are suddenly removed, then do not be afraid that your brain activity will be disrupted in the same manner as in the unfortunate monkeys in experiments where their brain tonsils - amygdalae - were removed!

“Those same” tonsils - brain ones

So, amygdala is an almond-shaped accumulation of gray matter deep in the temporal lobe of the brain, measuring on average 10x8x5 mm.

The amygdala-amygdala belongs to the basal ganglia of the brain and is part of the limbic system, which controls emotions.

There are two tonsils in total - one in each hemisphere. The neurons of the amygdala are diverse in form, function and neurochemical processes in them.

Functions of the amygdala

The functions of the amygdala are associated with the provision of defensive behavior, autonomic, motor, emotional reactions, and the motivation of conditioned reflex behavior.

Moreover, the main thing, apparently, is motivation, i.e. encouragement to action.

The cerebral cortex allows you to create sensory (sensory) images, i.e. see, hear or feel something. The hippocampus (part of the limbic system, which “manages” memory) makes it possible to store a sensory image and remember it after some time. But the amygdala determines which emotional feelings we experience for a given sensory image.

The amygdala is actually several separately functioning nuclei, which anatomists unite together due to their proximity to each other. Among these nuclei, the key ones are: the basal-lateral complex, the central medial nuclei and the corticomedial nuclei.
The basal-lateral complex, necessary for the development of a conditioned fear reflex in rats, receives input signals from sensory systems.
The central-medial nuclei are the main output for the basal-lateral complex, and are included in emotional arousal in rats and cats.
The amygdala is connected to the rest of the nervous system and is strategically located, so it acts as a center for regulating emotions. It receives all the signals coming from the motor cortex, the primary sensory cortex, part of the association cortex, and the parietal and occipital lobes of your brain. In other words, from almost every available source. if you destroy it and look at the vegetative functions, nothing changes. But if it is irritated, a disruption occurs in the functioning of internal organs.
Axons emerging from the amygdala are concentrated in the reticular nuclei of the thalamus, which process signals from the sensory organs. Therefore, the amygdala can influence the work of the thalamus with sensory information: giving some information increased significance, and making others insignificant.

The amygdala reacts with many of its nuclei to visual, auditory, interoceptive, olfactory, and skin irritations, and all these irritations cause a change in the activity of any of the amygdala nuclei, i.e., the amygdala nuclei are polysensory. The reaction of the nucleus to external stimulation lasts, as a rule, up to 85 ms, i.e., significantly less than the reaction to similar stimulation of the neocortex.
The neurons of the amygdala have well-defined spontaneous activity, which can be enhanced or inhibited by sensory stimulation. Many neurons are multimodal and multisensory and fire synchronously with the theta rhythm.
If you destroy the amygdala and look at the autonomic functions, nothing changes. But if it is irritated, a disruption occurs in the functioning of internal organs. Irritation of the nuclei of the amygdala creates a pronounced parasympathetic effect on the activity of the cardiovascular and respiratory systems, leading to a decrease (rarely to an increase) blood pressure, a decrease in heart rate, disruption of the conduction of excitation through the conduction system of the heart, the occurrence of arrhythmias and extrasystoles. In this case, vascular tone may not change.
The slowdown in the rhythm of heart contractions when affecting the tonsils has a long latent period and has a long aftereffect.
Irritation of the tonsil nuclei causes respiratory depression and sometimes a cough reaction.
With artificial activation of the tonsil, reactions of sniffing, licking, chewing, swallowing, salivation, and changes in small intestinal motility appear, and the effects occur with a long latent period (up to 30-45 s after irritation). Stimulation of the tonsils against the background of active contractions of the stomach or intestines inhibits these contractions.
The various effects of irritation of the tonsils are due to their connection with the hypothalamus, which regulates the functioning of internal organs.
The amygdala provides emotional support for autonomic reactions. During an indicative reaction, when something new has arisen, as a rule, such a reaction is accompanied by a change vegetative functions, such as changes in heart function, increased breathing, changes in blood pressure. If the amygdala is destroyed, then this emotional accompaniment is absent, an indicative reaction occurs, but the autonomic nervous system does not turn on, and the autonomic reactions do not change. If you destroy the amygdala of a dominant male, then his career is over. The amygdala is responsible for recognizing a person by face. If scalerosis occurs temporal region, and the amygdala is located exactly there, this especially often happens with epilepsy, the disease prosopagnosia occurs, Prosop - face, agnosia - forget. As a result of this disease, a person does not even recognize himself in the mirror.
The amygdala has a low convulsive threshold; if an injury occurs in the amygdala, the focus of epilepsy very often occurs, the source of pathological impulses. The person develops post-traumatic amygdalar epilepsy, which is not related to glutamate or GABA. Pathological impulses arise in the amygdala and go to the cortex cerebral hemispheres there is increased excitability from there to motor neurons spinal cord, and severe motor spasms occur. This happens often birth trauma. Damage to the amygdala in animals reduces the adequate preparation of the autonomic nervous system for the organization and implementation of behavioral reactions, leading to hypersexuality, the disappearance of fear, calmness, and inability to rage and aggression. Animals become gullible. For example, monkeys with a damaged amygdala calmly approach a viper that previously caused them horror,
escape. Apparently, in case of damage to the amygdala, some innate unconditioned reflexes that implement the memory of danger disappear.
In humans and other animals, this subcortical brain structure is involved in the formation of both negative (fear) and positive emotions (pleasure). Its size is positively correlated with aggressive behavior. In humans, this is the most sexually dimorphic brain structure - in men, after castration, it shrinks by more than 30%. Conditions such as anxiety, autism, depression, post-traumatic shock and phobias are thought to be associated with abnormal functioning of the amygdala.

Scheme of action of the amygdala
↙ ↘
With an intact tonsil With a damaged tonsil
Monkey + fire = fear, flight Monkey + fire = indifference

Fence

The fence (Claustrum) is an elongated plate up to 2 mm thick, the front part of which thickens. The medial edge of the plate is smooth, and along the lateral edge there are small protrusions of gray matter. Located under the cerebral cortex, deep white matter.
The deep localization and small size of the fence present certain difficulties for its physiological study. This structure contains polymorphic neurons different types. It forms connections primarily with the cerebral cortex.
Stimulation of the fence causes an indicative reaction, turning the head in the direction of irritation, chewing, swallowing, and sometimes vomiting movements. Irritation from the fence inhibits the conditioned reflex to light and has little effect on conditioned reflex to the sound. Stimulation of the fence during eating inhibits the process of eating food.
It is known that the thickness of the fence of the left hemisphere in humans is somewhat greater than that of the right; When the right hemisphere fence is damaged, speech disorders are observed.

In the studies of E.N. Panakhova (2006) found that the role of the amygdala is not limited to its regulation of perceptual and cognitive processes - it takes part in controlling the conduction of integrated information throughout visual path both channels for the entry of specific signals into the visual cortex of the cerebral cortex - retinogeniculocortical and retinocolliculogeniculocortical. By the nature of the influence on structures visual system two phylogenetically heterogeneous sections of the amygdala are in opposing relationships and have a phasic effect of opposite directions on these structures. It has been established that the basolateral amygdala (BLA) leads to the actualization of the visual signal, and the more ancient phylogenetically, the corticomedial amygdala (CMA), has an inhibitory effect on the transmission of visual information to the cortex along the main retinogeniculocortical pathway.