Here some black substance appears. Black substance

second higher education in psychology in MBA format

subject: Anatomy and evolution of the human nervous system.
Manual "Anatomy of the central nervous system"

8.1. Roof of the midbrain
8.2. Brain stems
The midbrain is a short section of the brain stem, forming the cerebral peduncles on its ventral surface and the quadrigeminal on the dorsal surface. On a cross section, the following parts are distinguished: the roof of the midbrain and the cerebral peduncles, which are divided by a black substance into the roof and base (Fig. 8.1).

Rice. 8.1. Midbrain formations

8.1. Roof of the midbrain
The roof of the midbrain is located dorsal to the aqueduct, its plate is represented by the quadrigeminal. The hills are flat and have alternating white and gray matter. The superior colliculus is the center of vision. From it there are pathways to the lateral geniculate bodies. Due to the evolutionary transfer of vision centers to the forebrain, the centers of the superior colliculi perform only reflex functions. The inferior colliculi serve as subcortical hearing centers and are connected by the medial geniculate bodies. From the spinal cord to the quadrigeminal region there is an ascending pathway, and downwards there are pathways that provide two-way communication between the visual and auditory subcortical centers with the motor centers of the medulla oblongata and spinal cord. The motor pathways are called the tegnospinal tract and the tegnobulbar tract. Thanks to these pathways, unconscious reflex movements are possible in response to sound and auditory stimuli. It is in the buffs of the quadrigeminal that the orienting reflexes are closed, which I. P. Pavlov called the “What is this?” reflexes. These reflexes play an important role in the implementation of the mechanisms of involuntary attention. In addition, two more important reflexes are closed in the upper tubercles. This is a pupillary reflex, which ensures optimal illumination of the retina, and a reflex associated with adjusting the lens for clear vision of objects located at different distances from a person (accommodation).

8.2. Brain stems
The cerebral peduncles look like two rollers, which, diverging upward from the pons, plunge into the thickness of the cerebral hemispheres.
The tegmentum of the midbrain is located between the substantia nigra and the aqueduct of Sylvius and is a continuation of the tegmentum of the pons. It is in it that there is a group of nuclei belonging to the extrapyramidal system. These nuclei serve as intermediate links between the cerebrum on the one hand, and on the other hand, with the cerebellum, medulla oblongata and spinal cord. Their main function is to ensure coordination and automaticity of movements (Fig. 8.2).

Rice. 8.2. Transverse section of the midbrain:

1 - roof of the midbrain; 2 - water supply; 3 - central gray matter; 5 - tegmentum; 6 - red nucleus; 7 - black substance

In the tegmentum of the midbrain, the largest are the elongated red nuclei. They stretch from the subthalamic region to the pons. The red nuclei reach their greatest development in higher mammals, in connection with the development of the cerebral cortex and cerebellum. The red nuclei receive impulses from the nuclei of the cerebellum and the globus pallidus, and the axons of the neurons of the red nuclei are directed to the motor centers of the spinal cord, forming the rubrospial tract.

In the gray matter surrounding the midbrain aqueduct, there are the nuclei of the III and IV cranial nerves, innervating the oculomotor muscles. In addition, groups of vegetative nuclei are also distinguished: the accessory nucleus and the unpaired median nucleus. These nuclei belong to the parasympathetic division of the autonomic nervous system. The medial longitudinal fascicle unites the nuclei of the III, IV, VI, XI cranial nerves, which ensures combined eye movements when deviated in one direction or another and their combination with head movements caused by irritation of the vestibular apparatus.

Under the tegmentum of the midbrain is the locus coeruleus - the nucleus of the reticular formation and one of the sleep centers. Laterally from the locus coeruleus there is a group of neurons that influence the release of releasing factors (liberins and statins) of the hypothalamus.

At the border of the tegmentum with the basal part lies the substantia nigra; the cells of this substance are rich in the dark pigment melanin (where the name comes from). The substantia nigra has connections with the cortex of the frontal lobe of the cerebral hemispheres, with the nuclei of the subthalamus and reticular formation. Damage to the substantia nigra leads to disruption of fine coordinated movements associated with plastic muscle tone. The substantia nigra is a collection of neuron bodies that secrete the neurotransmitter dopamine. Among other things, dopamine appears to contribute to some pleasurable feelings. It is known to be involved in creating the euphoria for which drug addicts use cocaine or amphetamines. In patients suffering from Parkinsonism, neurons in the substantia nigra degenerate, which leads to a lack of dopamine.

The Sylvian aqueduct connects the III (diencephalon) and IV (pons and medulla oblongata) ventricles. The cerebrospinal fluid flow through it is carried out from the third to the fourth ventricle and is associated with the formation of cerebrospinal fluid in the ventricles of the hemispheres and diencephalon.
The basal part of the cerebral peduncle contains fibers of the descending pathways from the cerebral cortex to the underlying parts of the central nervous system.

Midbrain comprises:

Bugrov quadrigeminals,

red core,

black substance,

Seam cores.

Red core– provides the tone of skeletal muscles, redistribution of tone when changing posture. Just stretching is a powerful activity of the brain and spinal cord, for which the red nucleus is responsible. The red core ensures the normal tone of our muscles. If the red nucleus is destroyed, decerebrate rigidity occurs, with a sharp increase in the tone of the flexors in some animals and the extensors in others. And with absolute destruction, both tones increase at once, and it all depends on which muscles are stronger.

Black substance– How is excitation from one neuron transmitted to another neuron? Excitation occurs - this is a bioelectric process. It reaches the end of the axon, where a chemical substance is released - a transmitter. Each cell has its own mediator. A transmitter is produced in the substantia nigra in nerve cells dopamine. When the substantia nigra is destroyed, Parkinson's disease occurs (the fingers and head constantly tremble, or there is stiffness as a result of a constant signal being sent to the muscles) because there is not enough dopamine in the brain. The substantia nigra provides subtle instrumental movements of the fingers and influences all motor functions. The substantia nigra exerts an inhibitory effect on the motor cortex through the stripolidal system. If it is disrupted, it is impossible to perform delicate operations and Parkinson's disease occurs (stiffness, tremors).

Above are the anterior tubercles of the quadrigeminal, and below are the posterior tubercles of the quadrigeminal. We look with our eyes, but we see with the occipital cortex of the cerebral hemispheres, where the visual field is located, where the image is formed. A nerve leaves the eye, passes through a number of subcortical formations, reaches the visual cortex, there is no visual cortex, and we will not see anything. Anterior tubercles of the quadrigeminal- This is the primary visual area. With their participation, an indicative reaction to a visual signal occurs. The indicative reaction is the “reaction what is it?” If the anterior tubercles of the quadrigeminal are destroyed, vision will be preserved, but there will be no quick reaction to the visual signal.

Posterior tubercles of the quadrigeminal This is the primary auditory zone. With its participation, an indicative reaction to the sound signal occurs. If the posterior tubercles of the quadrigeminal are destroyed, hearing will be preserved but there will be no indicative reaction.

Seam cores– this is the source of another mediator serotonin. This structure and this mediator takes part in the process of falling asleep. If the suture nuclei are destroyed, the animal is in a constant state of wakefulness and quickly dies. In addition, serotonin takes part in positive reinforcement learning (this is when a rat is given cheese). Serotonin provides character traits such as unforgivingness, goodwill; aggressive people have a lack of serotonin in the brain.

12) The thalamus is a collector of afferent impulses. Specific and nonspecific nuclei of the thalamus. The thalamus is the center of pain sensitivity.

Thalamus- visual thalamus. He was the first to discover his relationship to visual impulses. It is a collector of afferent impulses, those that come from receptors. The thalamus receives signals from all receptors except the olfactory ones. The thalamus receives information from the cortex, the cerebellum, and the basal ganglia. At the level of the thalamus, these signals are processed, only the most important information for a person at a given moment is selected, which then enters the cortex. The thalamus consists of several dozen nuclei. The nuclei of the thalamus are divided into two groups: specific and nonspecific. Through specific nuclei of the thalamus, signals arrive strictly to certain areas of the cortex, for example, visual to the occipital lobe, auditory to the temporal lobe. And through nonspecific nuclei, information diffuses to the entire cortex in order to increase its excitability in order to more clearly perceive specific information. They prepare the BP cortex for the perception of specific information. The highest center of pain sensitivity is the thalamus. The thalamus is the highest center of pain sensitivity. Pain is formed necessarily with the participation of the thalamus, and when some nuclei of the thalamus are destroyed, pain sensitivity is completely lost; when other nuclei are destroyed, barely bearable pain occurs (for example, phantom pain is formed - pain in a missing limb).

13) Hypothalamic-pituitary system. The hypothalamus is the center of regulation of the endocrine system and motivation.

The hypothalamus and pituitary gland form a single hypothalamic-pituitary system.

Hypothalamus. The pituitary stalk departs from the hypothalamus, on which it hangs pituitary- main endocrine gland. The pituitary gland regulates the functioning of other endocrine glands. The hypoplamus is connected to the pituitary gland by nerve pathways and blood vessels. The hypothalamus regulates the work of the pituitary gland, and through it the work of other endocrine glands. The pituitary gland is divided into adenohypophysis(glandular) and neurohypophysis. In the hypothalamus (this is not an endocrine gland, it is a part of the brain) there are neurosecretory cells in which hormones are secreted. This is a nerve cell; it can be excited, it can be inhibited, and at the same time hormones are secreted in it. An axon extends from it. And if these are hormones, they are released into the blood, and then go to the decision organs, i.e. to the organ whose work it regulates. Two hormones:

- vasopressin – promotes the conservation of water in the body, it affects the kidneys, and with its deficiency, dehydration occurs;

- oxytocin – produced here, but in other cells, ensures contraction of the uterus during childbirth.

Hormones are secreted in the hypothalamus and released by the pituitary gland. Thus, the hypothalamus is connected to the pituitary gland via nerve pathways. On the other hand: nothing is produced in the neurohypophysis; hormones come here, but the adenohypophysis has its own glandular cells, where a number of important hormones are produced:

- ganadotropic hormone – regulates the functioning of the sex glands;

- thyroid-stimulating hormone – regulates the functioning of the thyroid gland;

- adrenocorticotropic – regulates the functioning of the adrenal cortex;

- somatotropic hormone, or growth hormone, – ensures the growth of bone tissue and the development of muscle tissue;

- melanotropic hormone – is responsible for pigmentation in fish and amphibians, in humans it affects the retina.

All hormones are synthesized from a precursor called proopiomellanocortin. A large molecule is synthesized, which is broken down by enzymes, and other hormones, smaller in number of amino acids, are released from it. Neuroendocrinology.

The hypothalamus contains neurosecretory cells. They produce hormones:

1) ADH (antidiuretic hormone regulates the amount of urine excreted)

2) oxytocin (provides contraction of the uterus during childbirth).

3) statins

4) liberins

5) thyroid-stimulating hormone affects the production of thyroid hormones (thyroxine, triiodothyronine)

Thyroliberin -> thyroid-stimulating hormone -> thyroxine -> triiodothyronine.

The blood vessel enters the hypothalamus, where it branches into capillaries, then the capillaries gather and this vessel passes through the pituitary stalk, branches again in the glandular cells, leaves the pituitary gland and carries with it all these hormones, which each go with the blood to its own gland. Why is this “wonderful vascular network” needed? There are nerve cells in the hypothalamus that end on the blood vessels of this wonderful vascular network. These cells produce statins And liberins - This neurohormones. Statins inhibit the production of hormones in the pituitary gland, and liberins it is strengthened. If there is an excess of growth hormone, gigantism occurs, this can be stopped with the help of samatostatin. On the contrary: the dwarf is injected with samatoliberin. And apparently there are neurohormones for any hormone, but they are not yet discovered. For example, the thyroid gland produces thyroxine, and in order to regulate its production, the pituitary gland produces thyroid-stimulating hormone, but in order to control thyroid-stimulating hormone, thyreostatin has not been found, but thyroliberin is used perfectly. Although these are hormones, they are produced in nerve cells, so in addition to their endocrine effects, they have a wide range of extraendocrine functions. Thyroid hormone is called panactivin, because it improves mood, improves performance, normalizes blood pressure, and accelerates healing in case of spinal cord injuries; it is the only thing that cannot be used for disorders of the thyroid gland.

The functions associated with neurosecretory cells and cells that produce neurofebtides were previously discussed.

The hypothalamus produces statins and liberins, which are included in the body's stress response. If the body is affected by some harmful factor, then the body must somehow respond - this is the stress reaction of the body. It cannot occur without the participation of statins and liberins, which are produced in the hypothalamus. The hypothalamus necessarily takes part in the response to stress.

The following functions of the hypothalamus are:

It contains nerve cells that are sensitive to steroid hormones, i.e. sex hormones, both female and male sex hormones. This sensitivity ensures formation of a female or male type. The hypothalamus creates the conditions for motivating behavior according to the male or female type.

A very important function is thermoregulation; the hypothalamus contains cells that are sensitive to blood temperature. Body temperature can change depending on the environment. Blood flows through all structures of the brain, but thermoreceptive cells, which detect the slightest changes in temperature, are found only in the hypothalamus. The hypothalamus turns on and organizes two responses of the body: heat production or heat transfer.

Food motivation. Why does a person feel hungry?

The signaling system is the level of glucose in the blood, it should be constant ~120 milligrams% - s.

There is a mechanism of self-regulation: if our blood glucose level decreases, liver glycogen begins to break down. On the other hand, glycogen reserves are not enough. The hypothalamus contains glucoreceptive cells, i.e. cells that record the level of glucose in the blood. Glucoreceptive cells form hunger centers in the hypothalamus. When blood glucose levels drop, these blood glucose-sensing cells become excited and a feeling of hunger occurs. At the level of the hypothalamus, only food motivation arises - a feeling of hunger; to search for food, the cerebral cortex must be involved, with its participation a true food reaction arises.

The satiety center is also located in the hypothalamus, it inhibits the feeling of hunger, which protects us from overeating. When the saturation center is destroyed, overeating occurs and, as a result, bulimia.

The hypothalamus also contains a thirst center - osmoreceptive cells (osmatic pressure depends on the concentration of salts in the blood). Osmoreceptive cells record the level of salts in the blood. When salts in the blood increase, osmoreceptive cells are excited, and drinking motivation (reaction) occurs.

The hypothalamus is the highest control center of the autonomic nervous system.

The anterior sections of the hypothalamus mainly regulate the parasympathetic nervous system, the posterior sections mainly regulate the sympathetic nervous system.

The hypothalamus provides only motivation and goal-directed behavior to the cerebral cortex.

14) Neuron – structural features and functions. Differences between neurons and other cells. Glia, blood-brain barrier, cerebrospinal fluid.

I Firstly, as we have already noted, in their diversity. Any nerve cell consists of a body - soma and processes. Neurons are different:

1. by size (from 20 nm to 100 nm) and shape of the soma

2. by the number and degree of branching of short processes.

3. according to the structure, length and branching of axon endings (laterals)

4. by the number of spines

II Neurons also differ in functions:

A) perceivers information from the external environment,

b) transmitting information to the periphery,

V) processing and transmitting information within the central nervous system,

G) exciting,

d) brake.

III Differ in chemical composition: various proteins, lipids, enzymes are synthesized and, most importantly, - mediators .

WHY, WHAT FEATURES IS THIS ASSOCIATED WITH?

Such diversity is determined high activity of the genetic apparatus neurons. During neuronal induction, under the influence of neuronal growth factor, NEW GENES are turned on in the cells of the ectoderm of the embryo, which are characteristic only of neurons. These genes provide the following features of neurons ( the most important properties):

A) The ability to perceive, process, store and reproduce information

B) DEEP SPECIALIZATION:

0. Synthesis of specific RNA;

1. No reduplication DNA.

2. The proportion of genes capable of transcriptions, make up in neurons 18-20%, and in some cells – up to 40% (in other cells - 2-6%)

3. The ability to synthesize specific proteins (up to 100 in one cell)

4. Unique lipid composition

B) Privilege of nutrition => Dependence on level oxygen and glucose in blood.

Not a single tissue in the body is in such a dramatic dependence on the level of oxygen in the blood: 5-6 minutes of stopping breathing and the most important structures of the brain die, and first of all the cerebral cortex. A decrease in glucose levels below 0.11% or 80 mg% - hypoglycemia may occur and then coma.

On the other hand, the brain is fenced off from the blood flow by the BBB. It does not allow anything into the cells that could harm them. But, unfortunately, not all of them - many low-molecular toxic substances pass through the BBB. And pharmacologists always have a task: does this drug pass through the BBB? In some cases this is necessary, if we are talking about brain diseases, in others it is indifferent to the patient if the drug does not damage nerve cells, and in others it should be avoided. (NANOPARTICLES, ONCOLOGY).

The sympathetic nervous system is excited and stimulates the adrenal medulla - the production of adrenaline; in the pancreas - glucagon - breaks down glycogen in the kidneys to glucose; glucocarticoids produced in the adrenal cortex - provides gluconeogenesis - the formation of glucose from ...)

And yet, with all the diversity of neurons, they can be divided into three groups: afferent, efferent and intercalary (intermediate).

15) Afferent neurons, their functions and structure. Receptors: structure, functions, formation of an afferent volley.

The nigra substance is an integral part of the pallidal system, which is part of the striopallidum in the extrapyramidal system. Ch.s. located in the cerebral peduncles, has close connections with various parts of the cerebral cortex, with the striatum, globus pallidus and reticular formation; together with the red nuclei and reticular formation, it participates in the regulation of muscle tone, incl. vocal and articulatory apparatus, in performing precise and subtle movements of the fingers; has to do with coordinating the acts of swallowing and chewing. Defeat of Ch. causes an increase in plastic muscle tone

Psychomotorics: dictionary-reference book. - M.: VLADOS.

V.P. Dudiev.

2008. See what “BLACK SUBSTANCE” is in other dictionaries:

Lingbao- Taoism History People Schools Temples Terminology Texts ... Wikipedia Emergency

Midbrain- a section of the stem part of the brain (See Brain), located between the diencephalon (See Diencephalon) (anteriorly), the pons and the cerebellum (See Cerebellum) (posteriorly). Represented by a quadrigeminal structure consisting of two... ...

Extrapyramidal system- (from Extra... and Greek pyramis pyramid) a set of brain structures located in the cerebral hemispheres and brain stem and involved in the center, control of movements, bypassing the corticospinal, or pyramidal system (See Pyramidal ... Great Soviet Encyclopedia

MIDDLE BRAIN- mesencephalon, a section of the brain stem located between the diencephalon (anteriorly), the pons and the cerebellum (posteriorly). Formed from cf. brain bladder. Consists of the quadrigeminal peduncle and cerebral peduncles. Ch. his education... Biological encyclopedic dictionary

Atypical antipsychotics- (atypical antipsychotics) a new class of drugs, the most common difference of which from classical (typical) antipsychotics is a lower degree of affinity for dopamine D2 receptors and the presence of a multireceptor binding profile ... ... Wikipedia

Extrapyramidal system- (Latin: extra outside, outside, to the side + pyramis, Greek: πϋραμίς pyramid) a set of structures (formations) of the brain involved in controlling movements, maintaining muscle tone and posture, bypassing the corticospinal ... ... Wikipedia

Tardive dyskinesia- – a complication in the form of hyperkinesia that occurs as a result of long-term therapy (after a year or more) with antipsychotics during treatment with the latter or after their withdrawal. Occurs somewhat more often in elderly patients or against the background of residual... ... Encyclopedic Dictionary of Psychology and Pedagogy

Pathological changes affect the substantia nigra of the midbrain.

Morphology

MR signs (T2, T2 gradient echo):

• disappearance of the normal reduced signal from the reticular part of the substantia nigra and red nuclei due to the death of melanin-containing neurons;
• fusion of normally hypointense zones in these modes due to the deposition of iron in the compact and reticular parts of the substantia nigra, as well as the red nuclei, accompanied by a slight increase in MRS on T1.

With a targeted study of the midbrain in T1 and T2 (with a decrease in FOV), especially T1 gradient echo, these changes are better identified. Pinpoint areas of increased signal in the T2 mode may appear in the compact part of the substantia nigra.

MPT in axial projection (T2 mode) at the level of the midbrain in normal conditions (a) and in Parkinson’s disease (b, c). a - normally there is a reduced signal from the reticular part of the substantia nigra (long thin arrow) and the red nucleus (thick arrow), a weakly hyperintense signal from the compact part of the reticular formation separating them (thin short arrow). In Parkinson's disease, there is death of melanin-containing neurons of the reticular part of the substantia nigra and red nucleus with an increase in the signal from them and smoothing of the boundaries between these three formations (b), or accumulation of iron in the midbrain with a decrease in the signal from all three of these formations with their merging into one zone hypointense signal in T2 mode (c).

Differential diagnosis

• Wilson's disease
• chronic hepatitis,
• manganese intoxication - an altered MR signal covers large regions - the subcortical nuclei (putamen, caudate nucleus). In this case, the phenomena of demyelination involve strionigral pathways in the process.

Clinical picture

Triad of symptoms: resting tremor, muscle rigidity, hypokinesia.

Pathogenesis

Degeneration and death of dopaminergic pigmented (melanin-containing) neurons, gliosis of these nuclear groups, atrophy of the adjacent parts of the midbrain tegmentum, secondary degeneration of dopaminergic and noradrenergic pathways connecting these nuclei with the cerebral cortex. In the substantia nigra, the deposition of iron ions in high concentrations is determined.

Ecology of life. Educational: Today we offer you a story about the dark, but irreplaceable substance (or substance) of our brain.

Today we offer you a story about the dark, but irreplaceable substance (or substance) of our brain.

Black substance(or Substantia nigra) does not take up as much space as the white matter. It is located in the midbrain, one of the oldest structures in the center of the brain. Namely, it is hidden under four of its hills. To be completely precise, each of us has two Substantia nigra - left and right.

Midbrain. Animation from Life Science Databases(LSDB).

Cross section of the midbrain at the quadrigeminal level. The substantia nigra is shown in guess what color.

Despite the fact that the Substantia nigra, like the gray matter, contains the bodies of neurons, it is much darker due to its “coloring” with neuromelanin (by the way, another form of this pigment - melanin - gives color to our eyes, skin and hair).

Neuromelanin monomer

In total, there are two layers in the substantia nigra: compact layer (pars compacta) and ventral (pars reticulata). Here we need to clarify the word “ventral”.

Doctors use two spatial antonyms: ventral and dorsal. "Ventral" means "abdominal". This does not mean at all that the ventral layer of the substantia nigra is located in the stomach. It is simply located more “in front” in the body. “Ventral” is anterior, “dorsal” is posterior (dorsal).

If we talk about the functionality of the layers, then the compact one is in some sense similar to a computer processor - it processes information and transmits it to the thalamus and quadrigeminal region of the midbrain, and the ventral one ensures the production of the neurotransmitter dopamine. The layers are arranged vertically, the pars compacta is located closer to the body axis than the pars reticulata.

Dopamine

Thanks to the substantia nigra, we can move our eyes, perform small and precise movements, in particular with our fingers, chew and swallow. And our body can carry out breathing, cardiac activity, and keep blood vessels in good shape.

Disturbances in the functioning of the substantia nigra lead to various diseases. There is a hypothesis that the secret of schizophrenia lies in it. And Parkinson’s disease, which we often write about on the portal, is caused precisely by a disruption in the production of dopamine in the substantia nigra: it causes the death of neurons there.

Histology of the corpus nigra in a patient with Parkinson's disease

Researchers have even found the neurotoxin MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine), which, just like Parkinson's disease, destroys dopamine neurons, and are now actively using it in mice to model the disease and searching for ways to treat it. published