Basal ganglia (basal ganglia) is a striopallidal system, consisting of three pairs of large nuclei, immersed in the white matter of the telencephalon at the base of the cerebral hemispheres, and connecting the sensory and associative zones of the cortex with the motor cortex.

Structure

The phylogenetically ancient part of the basal ganglia is the globus pallidus, the later formation is the striatum, and the youngest part is the cervix.

The globus pallidus consists of outer and inner segments; striatum - from the caudate nucleus and putamen. The fence is located between the putamen and the insular cortex. Functionally, the basal ganglia also include the subthalamic nuclei and substantia nigra.

Functional connections of the basal ganglia

Exciting afferent impulses enter predominantly the striatum (caudate nucleus) mainly from three sources:

1) from all areas of the cortex directly and indirectly through the thalamus;

2) from nonspecific nuclei of the thalamus;

3) from the substantia nigra.

Among the efferent connections of the basal ganglia, three main outputs can be noted:

• from the striatum, inhibitory pathways go to the globus pallidus directly and with the participation of the subthalamic nucleus; from the globus pallidus the most important efferent path of the basal ganglia begins, going mainly to the ventral motor nuclei of the thalamus, from them the excitatory path goes to the motor cortex;
• part of the efferent fibers from the globus pallidus and striatum goes to the centers of the brain stem (reticular formation, red nucleus and then to the spinal cord), as well as through the inferior olive to the cerebellum;
• from the striatum, inhibitory pathways go to the substantia nigra and, after switching, to the nuclei of the thalamus.

Therefore, the basal ganglia are an intermediate link. They connect the associative and, in part, sensory cortex with the motor cortex. Therefore, in the structure of the basal ganglia there are several parallel functioning functional loops that connect them with the cerebral cortex.

Fig.1. Diagram of functional loops passing through the basal ganglia:

1 – skeletal-motor loop; 2 – oculomotor loop; 3 – complex loop; DC – motor cortex; PMC – premotor cortex; SSC – somatosensory cortex; PFC – prefrontal association cortex; P8 – field of the eighth frontal cortex; P7 – field of the seventh parietal cortex; FAC – frontal association cortex; VLN – ventrolateral nucleus; MDN – mediodorsal nucleus; PVN – anterior ventral nucleus; BS – globus pallidus; SN – black substance.

The skeletal-motor loop connects the premotor, motor, and somatosensory cortices to the putamen. The impulse from it goes to the globus pallidus and substantia nigra and then through the motor ventrolateral nucleus returns to the premotor area of ​​the cortex. It is believed that this loop serves to regulate such movement parameters as amplitude, strength, direction.

The oculomotor loop connects the areas of the cortex that control gaze direction with the caudate nucleus. From there, the impulse goes to the globus pallidus and substantia nigra, from which it is projected, respectively, into the associative mediodorsal and anterior relay ventral nuclei of the thalamus, and from them returns to the frontal oculomotor field 8. This loop is involved in the regulation of saccadic eye movements (saccal).

It is also assumed that there are complex loops through which impulses from the frontal association zones of the cortex enter the caudate nucleus, globus pallidus and substantia nigra. Then, through the mediodorsal and ventral anterior nuclei of the thalamus, it returns to the associative frontal cortex. It is believed that these loops are involved in the implementation of higher psychophysiological functions of the brain: control of motivation, forecasting, cognitive activity.

Functions

Functions of the striatum

Influence of the striatum on the globus pallidus. The influence is carried out primarily by the inhibitory neurotransmitter GABA. However, some neurons of the globus pallidus give mixed responses, and some only EPSPs. That is, the striatum has a dual effect on the globus pallidus: inhibitory and excitatory, with a predominance of inhibitory action.

Influence of the striatum on the substantia nigra. There are bilateral connections between the substantia nigra and the striatum. Neurons of the striatum have an inhibitory effect on neurons of the substantia nigra. In turn, neurons of the substantia nigra have a modulating effect on the background activity of neurons in the striatum. In addition to influencing the striatum, the substantia nigra has an inhibitory effect on the neurons of the thalamus.

Influence of the striatum on the thalamus. Irritation of the striatum causes the appearance of high-amplitude rhythms in the thalamus, characteristic of the slow-wave sleep phase. Destruction of the striatum disrupts the sleep-wake cycle by reducing sleep duration.

Influence of the striatum on the motor cortex. The caudate nucleus of the striatum “inhibits” degrees of freedom of movement that are unnecessary under given conditions, thereby ensuring the formation of a clear motor-defensive reaction.

Stimulation of the striatum. Stimulation of the striatum in its various parts causes different reactions: turning the head and torso in the direction opposite to the stimulation; delay in food-producing activity; suppression of the sensation of pain.

Damage to the striatum. Damage to the caudate nucleus of the striatum leads to hyperkinesis (excessive movements) - chorea and athetosis.

Functions of the globus pallidus

From the striatum, the globus pallidus receives predominantly inhibitory and partially excitatory influence. But it has a modulating effect on the motor cortex, cerebellum, red nucleus and reticular formation. The globus pallidus has an activating effect on the center of hunger and satiety. Destruction of the globus pallidus leads to adynamia, drowsiness, and emotional dullness.

Results of the activity of all basal ganglia:

• development, together with the cerebellum, of complex motor acts;
• control of movement parameters (force, amplitude, speed and direction);
• regulation of the sleep-wake cycle;
• participation in the formation mechanism conditioned reflexes, complex forms of perception (for example, comprehension of a text);
• participation in the act of inhibiting aggressive reactions.

Basal ganglia- this is a set of three paired formations located in the telencephalon at the base of the cerebral hemispheres: the phylogenetically more ancient part of it - the globus pallidus, the later formation - the striatum, and the youngest in evolutionary terms - the fence.

The globus pallidus consists of outer and inner segments. The striatum is made up of the caudate nucleus and putamen. The fence is a formation that is located between the shell and the insular cortex.

Functional connections of the basal ganglia. Excitatory afferent impulses enter the striatum mainly from three sources:

from all areas of the cerebral cortex directly through the thalamus;

from nonspecific intralaminar nuclei of the thalamus;

from the black substance.

Among the efferent connections of the basal ganglia, three main outputs can be distinguished:

from the striatum, inhibitory pathways go to the globus pallidus directly and with the participation of the subthalamic nucleus. The most important efferent path of the basal ganglia begins from the globus pallidus, going mainly to the thalamus (namely to its ventral motor nuclei), and from them the excitatory path goes to the motor cortex;

part of the efferent fibers from the globus pallidus and striatum goes to the centers of the brain stem (reticular formation, red nucleus and then to the spinal cord), as well as through the inferior olive to the cerebellum;

from the striatum, inhibitory pathways go to the substantia nigra, and after switching, to the nuclei of the thalamus.

Assessing the connections of the basal ganglia as a whole, scientists note that this structure is a specific intermediate link (switching station) connecting the associative and, in part, sensory cortex with the motor cortex.

In the structure of connections of the basal ganglia, there are several parallel functioning functional loops connecting the basal ganglia and the cerebral cortex.

Skeletal-motor loop. Connects the premotor, motor and somatosensory areas of the cortex with the shell of the basal ganglia, impulses from which go to the globus pallidus and substantia nigra and then return through the ventral motor nucleus to the premotor area of ​​the cortex. Scientists believe that this loop serves to regulate movement parameters such as amplitude, force and direction.

Oculomotor loop. Connects the areas of the cortex that control the direction of gaze (field 8 of the frontal cortex and field 7 of the parietal cortex) with the caudate nucleus of the basal ganglia. From there, the impulse enters the globus pallidus and substantia nigra, from which it is projected, respectively, into the associative mediodorsal and anterior relay ventral nuclei of the thalamus, and from them returns to the frontal oculomotor field 8. This loop takes part in the regulation, for example, of saccadic eye movements.

Scientists also suggest the existence of complex loops through which impulses from the frontal associative zones of the cortex enter the structures of the basal ganglia (caudate nucleus, globus pallidus, substantia nigra) and return through the mediodorsal and ventral anterior nuclei of the thalamus to the associative frontal cortex. It is believed that these loops are involved in the implementation of higher psychophysiological functions of the brain: control of motivation, predicting the results of actions, cognitive (cognitive) activity.

Along with identifying the direct functional connections of the basal ganglia as a whole, scientists also highlight the functions of individual formations of the basal ganglia. One of these formations, as noted above, is the striatum.

Functions of the striatum. The main objects of functional influence of the striatum are the globus pallidus, substantia nigra, thalamus and motor cortex.

Influence of the striatum on the globus pallidus. It is carried out mainly through thin inhibitory fibers. In this regard, the striatum has a mainly inhibitory effect on the globus pallidus.

Influence of the striatum on the substantia nigra. There are bilateral connections between the substantia nigra and the striatum. Neurons of the striatum have an inhibitory effect on neurons of the substantia nigra. In turn, neurons of the substantia nigra, through the neurotransmitter dopamine, have a modulating effect on the background activity of striatal neurons. The nature of this influence (inhibitory, excitatory, or both) has not yet been established by scientists. In addition to influencing the striatum, the substantia nigra has an inhibitory effect on thalamic neurons and receives excitatory afferent inputs from the subthalamic nucleus.

Influence of the striatum on the thalamus. In the mid-twentieth century, scientists found that irritation of areas of the thalamus causes the appearance of manifestations typical of the slow-wave sleep phase. Subsequently, it was proven that these manifestations can be achieved not only by irritating the thalamus, but also the striatum. Destruction of the striatum disrupts the sleep-wake cycle (reduces sleep time in this cycle).

Influence of the striatum on the motor cortex. Clinical studies conducted in the 1980s. O.S. Andrianov proved the inhibitory effect of the striatal tail on the motor cortex.

Direct stimulation of the striatum through implantation of electrodes, according to clinicians, causes relatively simple motor reactions: turning the head and torso in the direction opposite to stimulation, flexing a limb on the opposite side, etc. Stimulation of some areas of the striatum causes a delay in behavioral reactions (indicative, food-procuring and etc.), as well as suppression of the sensation of pain.

Damage to the striatum (in particular its caudate nucleus) causes excessive movements. The patient seems unable to control his muscles. Experimental studies conducted on mammals have shown that when the striatum is damaged, animals steadily develop hyperactivity syndrome. The number of aimless movements in space increases by 5–7 times.

Another formation of the basal ganglia is the globus pallidus, which also performs its functions.

Functions of the globus pallidus. Receiving predominantly inhibitory influences from the striatum, the globus pallidus has a modulating effect on the motor cortex, reticular formation, cerebellum and red nucleus. When stimulating the globus pallidus in animals, elementary motor reactions in the form of contraction of the muscles of the limbs, neck, etc. are predominant. In addition, the influence of the globus pallidus on some areas of the hypothalamus (hunger center and posterior hypothalamus) was revealed, as evidenced by the activation of eating behavior noted by scientists. Destruction of the globus pallidus is accompanied by a decrease in motor activity. There is an aversion to any movements (adynamia), drowsiness, emotional dullness, and it becomes difficult to carry out existing and develop new conditioned reflexes.

Thus, the participation of the basal ganglia in the regulation of movements is their main, but not their only function. The most important motor function is the development (along with the cerebellum) of complex motor programs, which are implemented through the motor cortex and provide the motor component of behavior. At the same time, the basal ganglia control movement parameters such as force, amplitude, speed and direction. In addition, the basal ganglia are involved in the regulation of the sleep-wake cycle, in the mechanisms of formation of conditioned reflexes, and in complex forms of perception (for example, comprehension of text).

Questions for self-control:

What are the basal ganglia represented by?

General characteristics of functional connections of the basal ganglia.

Characteristics of functional loops of the basal ganglia.

Functions of the striatum.

Functions of the globus pallidus.

The part of the brain located below the cortex is mainly composed, as I already mentioned, of white matter, of which the myelin-covered nerve fibers are composed. For example, directly above the ventricles - the cavities of the brain - is the corpus callosum, which connects the right and left hemispheres of the brain.

Nerve fibers crossing the corpus callosum unite the brain into a single functional whole, but potentially the hemispheres can work independently of each other.

For clarification, we can use the example of the eyes. We have two eyes that usually work together as one. However, if we close one eye, we can see quite well with one eye. A one-eyed person should never be considered blind. Likewise, removing one hemisphere from an experimental animal does not render it brainless. The remaining hemisphere, to one degree or another, takes on the functions of the remote one. Usually, each hemisphere is primarily responsible for “its” half of the body. If, leaving both hemispheres in place, the corpus callosum is crossed, then coordination of the halves of the brain is lost, and both halves of the body come under more or less independent control of the unrelated hemispheres of the brain. Literally, an animal develops two brains. Such experiments were performed on monkeys. (After cutting the corpus callosum, some more fibers of the optic nerves were cut so that each eye was connected to only one hemisphere of the brain.) After this operation, each eye could be trained separately to perform different tasks. For example, a monkey can be taught to focus on a cross in a circle as a marker for a food container. If only the left eye is left open during training, only it will be trained to solve the problem. If you then close the monkey’s left eye and open the right one, then it will not cope with the task and will look for food by trial and error. If each eye is trained to solve opposite problems, and then both eyes are opened, the monkey will solve them one by one, changing activities. It seems that the hemispheres of the brain politely pass the baton to each other every time.

Naturally, in such an ambiguous situation, when the functions of the body are controlled by two independent brains, there is always the danger of confusion and confusion. internal conflicts. To avoid this situation, one of the hemispheres (in humans, almost always the left) becomes dominant, that is, dominant. The speech-controlling Broca's area that I mentioned is located in the left hemisphere, not the right. Left hemisphere controls the right half of the body, and this explains the fact that the vast majority of people on Earth are right-handed. Moreover, even left-handers dominant hemisphere is still left. Ambidexters, who do not have a clear dominance of any one hemisphere, sometimes have difficulty forming speech in early childhood. The subcortical areas of the brain consist of more than just white matter. Beneath the cortex there are also compact areas of gray matter. These are called the basal ganglia1.

1 The word "ganglion" is of Greek origin and means "knot". Hippocrates and his followers used this word to refer to nodule-like subcutaneous tumors. Galen, a Roman physician around 200 AD, began using the term to refer to clusters of nerve cells protruding along nerve trunks. This word is still used in this sense today.

Above the other basal ganglia, in the subcortex, is the caudate nucleus. The gray matter of the caudate nucleus bends downward, forming the amygdala nucleus. To the side of the amygdala is the lenticular nucleus, and between them is a layer of white matter called internal capsule. The nuclei are not completely homogeneous formations; they also contain white matter of the pathways through which myelinated nerve fibers pass, which gives the basal ganglia a striated appearance. Because of this, both nuclei received the unifying name of the striatum.

Inside the dome, formed by the complex of the striatum, caudate nucleus and lentiform nucleus, there is another large area of ​​​​gray matter called the thalamus or thalamus.

The basal ganglia are difficult to study because they are hidden deep beneath the cerebral cortex. big brain. There are indications, however, that the subcortical basal ganglia play a major role in brain function, both active and passive. The white matter of the striatum can be considered in some sense a narrow bottleneck. All motor nerve fibers coming from the cortex and all sensory nerve fibers ascending to the cortex must pass it. Therefore, any damage to this area will result in widespread damage to bodily functions. Such a lesion can, for example, deprive the sensitivity and ability to move the entire half of the body opposite the hemisphere in which the damage to the subcortical ganglia occurred. Such a unilateral lesion is called heminlegia (“stroke of half the body”, Greek). (The loss of the ability to move is called the Greek term "paralysis", which means "relaxation". The muscles, so to speak, relax. The disease that leads to the sudden onset of paralysis is often called a stroke or stroke because the person affected by this disease suddenly falls off his feet, as if struck on the head by an invisible blunt object.)

It has been suggested that one of the functions of the basal ganglia is to control the activity of the motor cortex of the cerebral hemispheres. (This function is inherent in the extrapyramidal system, of which the basal ganglia are part.) The subcortical ganglia keep the cortex from acting too rashly and quickly. When there are disturbances in the basal ganglia, the corresponding areas of the cortex begin to discharge uncontrollably, which leads to convulsive involuntary muscle contractions.

Typically, such disorders affect the muscles of the neck, head, hands and fingers. As a result, the head and hands constantly tremble slightly. This tremor is especially noticeable at rest. It decreases or disappears when any purposeful movement begins. In other words, the tremor disappears when the cortex begins real actions, and does not produce individual rhythmic discharges.

The muscles of other groups become abnormally immobile in such cases, although there is no real paralysis. Facial expressions lose their liveliness, the face becomes mask-like, the gait is constrained, the arms hang motionless along the body, without making movements characteristic of walking. This combination of reduced mobility of the shoulders, forearms and face with increased pathological mobility of the head and hands has received the controversial name of shaking palsy. Shaking palsy was first described in detail by the English physician James Parkinson in 1817 and has since been called Parkinson's disease.

Some relief comes from intentionally damaging specific basal ganglia that appear to be the cause of "shivering dog." One way is to touch the affected area with a thin probe, which stops the tremor (shaking) and rigidity (stiffness). Then this area is destroyed with liquid nitrogen at a temperature of -50 °C. If symptoms recur, the procedure can be repeated. Obviously, a non-functioning node is better than a poorly functioning one.

In some cases, damage to the basal ganglia leads to more extensive disorders, manifested in the form of spastic contractions of large muscle masses. It seems that the patient is performing an awkward, convulsive dance. These movements are called chorea (“trochea” - “dance”, Greek). Chorea can affect children after suffering from rheumatism, when the infectious process affects the subcortical formations of the brain. This form of the disease was first described by the English physician Thomas Sydenham in 1686, which is why it is called Sydenham's chorea.

In the Middle Ages, there were even epidemic outbreaks of “dance mania,” which at times covered regions and provinces. These were probably not epidemics of true chorea; the roots of this phenomenon must be sought in mental disorders. One must think that mental mania was the result of observing cases of true chorea. Some fell into the same state due to hysterical mimicry, others followed his advice.

measure, which led to outbreaks. A belief was born that one could be cured of this mania by making a pilgrimage to the tomb of St. Vitus. For this reason, Sydenham's chorea is also called "St. Vitus's dance."

There is also hereditary chorea, often called Huntington's chorea, named after the American physician George Summer Huntington, who first described it in 1872. It's more serious illness than the dance of St. Vitus, which ultimately heals spontaneously. Gentiigton's chorea first appears in adulthood (between 30 and 50 years). At the same time, they are developing mental disorders. The condition of the patients gradually worsens, and eventually death occurs. This is a hereditary disease, as one of its names suggests. Two brothers who suffered from Huntington's chorea once migrated from England to the United States. It is believed that all patients in the United States are descendants of these brothers.

The thalamus is the center of somatosensory sensitivity - the center of perception of touch, pain, heat, cold and muscle feeling. It is a very important component of the reticular activating formation, which receives and sifts incoming sensory data. The strongest stimuli, such as pain or extremely hot or cold temperatures, are filtered out in the thalamus, while milder stimuli such as touch, warmth or coolness are passed on to the cortex. The impression arises that the cortex can only be trusted with minor stimuli that allow for leisurely consideration and a leisurely reaction. Rough stimuli that require an immediate response and cannot be delayed are quickly processed in the thalamus, followed by a more or less automatic response.

Because of this, there is a tendency to distinguish between the cortex, the center of cold thinking, and the thalamus, the seat of hot emotions. Indeed, it is the thalamus that controls the activity of the facial muscles under conditions of emotional stress, so that even if the cortical control of the same muscles is affected and the face remains mask-like in a calm state, it can suddenly become distorted by a spasm in response to strong emotion. In addition, animals with the bark removed become angry very easily. Despite these facts, the idea of ​​such a division of functions between the cortex and thalamus is an unacceptable simplification. Emotions cannot arise from just one, very small part of the brain - this must be clearly recognized. The emergence of emotions is a complex integrative process that includes the activity of the cortex of the frontal and temporal lobes. Removing the temporal lobes in experimental animals weakens emotional reactions, although the thalamus remains intact.

IN last years The researchers paid close attention to the most ancient, in evolutionary terms, areas of the subcortical structures of the old olfactory brain. These structures are associated with emotions and stimuli that provoke strong emotions - sexual and food. This region appears to coordinate sensory input with bodily needs, in other words, visceral needs. Parts of the visceral brain were called Broca's limbic lobes ("limb" is Latin for "border") because this region surrounds and delimits the corpus callosum from the rest of the brain. For this reason, the visceral brain is sometimes called the limbic system.

See Ganglion, Brain. Large psychological dictionary. M.: Prime EUROZNAK. Ed. B.G. Meshcheryakova, acad. V.P. Zinchenko. 2003 ... Great psychological encyclopedia

BASAL GANGLIA- [cm. basal] the same as the basal ganglia, subcortical ganglia (see Basal ganglia) ...

Basal ganglia- (basal Greek ganglion - tubercle, tumor) - subcortical nuclei, including the caudate nucleus, putamen and globus pallidus. They are part of the extrapyramidal system, responsible for the regulation of movements. Damage to the basal ganglia and their connections with the cortex,... ... encyclopedic Dictionary in psychology and pedagogy

BASAL GANGLIA- Three large subcortical nuclei, including the caudate nucleus, putamen and globus pallidus. These structures and some associated structures of the midbrain and hypothalamus constitute the extrapyramidal system and are directly responsible for the regulation... ... Dictionary in psychology

- (nuclei basalis), subcortical nuclei, basal ganglia, accumulations of gray matter in the thickness of the white matter of the cerebral hemispheres of vertebrates, involved in motor coordination. activity and formation of emotions. reactions. B. i. together with… … Biological encyclopedic dictionary

Several large accumulations of gray matter located in the thickness of the white matter of the cerebrum (see figure). They include the caudate (caudate) and lenticular nuclei (they form the striatum (corpus striatum)), and... ... Medical terms

BASAL GANGLIA, BASAL NUCLEI- (basal ganglia) several large accumulations of gray matter located in the thickness of the white matter of the cerebrum (see figure). They include the caudate (caudate) and lenticular nuclei (they form the striatum (corpus... Explanatory dictionary of medicine

BASAL GANGLIA- [from Greek. ganglion tubercle, node, subcutaneous tumor and basis] subcortical accumulations of nerve cells taking part in various reflex acts (see also Ganglion (in 1) meaning), Subcortical nuclei) ... Psychomotorics: dictionary-reference book

- (n. basales, PNA; synonym: basal ganglia outdated, subcortical I.) I. located at the base of the cerebral hemispheres; to Ya. b. include the caudate and lenticular ego, the fence and the amygdala... Large medical dictionary

A set of structures in the body of animals and humans, uniting the activities of all organs and systems and ensuring the functioning of the body as a whole in its constant interaction with the external environment. N. s. perceives... ... Great Soviet Encyclopedia

The basal ganglia include the following anatomical structures:

striatum (striatum), consisting of the caudate nucleus and putamen; globus pallidus (pallidum), divided into internal and external sections; substantia nigra and Lewis's subthalamic nucleus.

BG functions:

1. Complex centers unconditioned reflexes and instincts
2. Participation in the formation of conditioned reflexes
3. Coordination of muscle tone and voluntary movements. Control of amplitude, strength, direction of movements
4. Coordination of combined motor acts
5. Control of eye movements (saccades).
6. Programming complex goal-directed movements
7. Inhibition centers for aggressive reactions
8. Higher mental functions (motivation, forecasting, cognitive activity). Complex shapes perception of external information (for example, comprehension of text)
9. Participation in sleep mechanisms

Afferent connections of the basal ganglia.

Most of the afferent signals coming to the basal ganglia enter the striatum. These signals come almost exclusively from three sources:

- from all areas of the cerebral cortex;

- from the intralamellar nuclei of the thalamus;

- from the substantia nigra (along the dopaminergic pathway).

Efferent fibers from the striatum go to the globus pallidus and substantia nigra. From the latter, not only the dopaminergic path to the striatum begins, but also the paths going to the thalamus.

The most important of all efferent tracts of the basal ganglia originates from the internal part of the globus pallidus, ending in the thalamus, as well as in the roof of the midbrain. Through the stem formations with which the basal ganglia are connected, centrifugal impulses follow to the segmental motor apparatus and muscles along descending conductors.

- from the red nuclei - along the rubrospinal tract;

- from the Darkshevich nucleus - along the posterior longitudinal fasciculus to the nuclei of nerves 3, 4,6 and through it to the nucleus of the vestibular nerve;

- from the nucleus of the vestibular nerve - along the vestibulospinal tract;

— from the quadrigeminal region — along the tectospinal tract;

- from the reticular formation - along the reticulospinal tract.

Thus, the basal ganglia play mainly the role of an intermediate link in the chain connecting the motor areas of the cortex with all its other areas.

Symptoms of damage to the basal ganglia.

Damage to the basal ganglia is accompanied by a wide variety of movement disorders. Of all these disorders, Parkinson's syndrome is the most famous.

Gait - cautious, small steps, slow, reminiscent of an old man's gait. The initiation of movement is impaired: it is not possible to move forward immediately. But in the future, the patient cannot stop immediately: he still continues to be pulled forward.

Facial expressions– extremely poor, her face takes on a frozen, mask-like expression. A smile, a grimace of crying with emotions appear belatedly and disappear just as slowly.

Normal pose- the back is bent, the head is tilted to the chest, the arms are bent at the elbows, at the wrists, the legs are at knee joints(supplicant pose).

Speech- quiet, monotonous, dull, without sufficient modulation and sonority.

Akinesia- (hypokinesia) - great difficulties in the manifestation and motor initiation: difficulty in starting and completing movements.

Muscle stiffness- constant increase muscle tone, independent of the position of the joints and movements. The patient, having adopted a certain position, maintains it for a long time, even if it is not comfortable. “Frozen” in the accepted position - plastic or waxy rigidity. During passive movements, the muscles do not relax gradually, but intermittently, as if in steps.

Rest tremor- trembling, which is observed at rest, is expressed in the distal parts of the limbs, sometimes in the lower jaw and is characterized by low amplitude, frequency and rhythm. The tremor disappears during purposeful movements and resumes after their completion (difference from cerebellar tremor, which appears during movement and disappears at rest).

Parkinson's syndrome is associated with the destruction of the pathway (inhibitory) running from the substantia nigra to the striatum. In the region of the striatum, the neurotransmitter dopamine is released from the fibers of this pathway. The manifestations of parkinsonism and, in particular, akinesia are successfully treated by introducing the dopamine precursor - dopa. On the contrary, destruction of the areas of the globus pallidus and thalamus (ventrolateral nucleus), in which the paths to the motor cortex are interrupted, leads to the suppression of involuntary movements, but does not relieve akinesia.

When the caudate nucleus is damaged, athetosis develops - slow, worm-like, writhing movements are observed in the distal parts of the limbs at certain intervals, during which the limb takes on unnatural positions. Athetosis can be limited or widespread.

When the shell is damaged, chorea develops - it differs from athetosis in the rapidity of twitching and is observed in the proximal parts of the limbs and on the face. Characterized by rapid changes in the localization of convulsions, then the facial muscles twitch, then the muscles of the leg, at the same time the eye muscles and the arm, etc. In severe cases, the patient becomes like a clown. Grimacing, smacking, and speech disturbances are often observed. Movements become sweeping, excessive, and the gait becomes dancing.