Other

Brain

The personal qualities of a person and the nature of his character have long been under the guns of studying scientists. Recently, Oxford University assessed the level of generosity of the test group and concluded that this feeling is generated by a specific area of ​​the brain.

The experiment involved volunteers who were playing a computer game. For successfully completed missions, volunteers were asked to choose one of two actions - to give the award to one of the players or use it for their own purposes.

During the charity of the test, the anterior bone cortex of the brain was activated. Scientists succeeded in identifying a similar reaction by scanning the volunteers with an MRI machine.

Neuronal reaction was observed far from all members of the group, but only among the most sensitive and responsive. The experiment was conducted under the direction of Dr. Patricia Lockwood, who holds the position of Professor in the Department of Experimental Psychology.

She reports that participants with a more developed level of empathy made a choice in favor of other players more quickly. And the reaction of the bone cortex of the brain was more pronounced.

Past studies of the bottom zone of the brain have shown that the bone area is less active in those people who are prone to depression and bipolar disorders. This discovery will be useful for the psychological study of a person, allowing a better understanding of the motives of antisocial behavior.

Brain tissue

The brain is the main part of the central nervous system. Talking about the presence of the brain in the strict sense can only be applied to vertebrates, starting with fish. However, this term is used somewhat loosely to refer to similar structures of highly organized invertebrates — for example, in insects, the brain is sometimes called the accumulation of the glands of the pharyngeal nerve ring. When describing more primitive organisms, they speak of head ganglia, and not of the brain.

The weight of the brain as a percentage of body weight is 0.06—0.44% in modern cartilaginous fishes, 0.02—0.94% in bony fish, 0.29—0.36% in caudate amphibians, 0 in tailless 50—0.73%. In mammals, the relative size of the brain is much larger: 0.3% for large cetaceans, 1.7% for small cetaceans, 0.6-1.9% for primates. In humans, the ratio of brain mass to body weight is on average 2%.

The brain of mammals of the orders of cetaceans, proboscides, and primates has the largest sizes. The most complex and functional brain is considered to be a reasonable human brain.

The average mass of the brain in various living beings is given in the table.

GroupBrain weight, g
Sperm whale7800
Finval6930
Elephant4783
Killer whale5620
Humpback whale4675
Gray whale4317
Bowhead whale2738
Grinda2670
Bottle-nosed dolphin1500—1600
Adult1300—1400
Walrus1020—1126
Pithecanthropus850—1000
Camel762
Giraffe680
hippopotamus582
Sea leopard542
Horse532
Gorilla465—540
Polar bear498
Cow425—458
Chimpanzee420
Newborn people350—400
GroupBrain weight, g
Orangutan370
California Sea Lion363
Manatee360
Tiger263,5
a lion240
Grizzly234
Pig180
Jaguar157
Sheep140
Baboon137
Rhesus macaque90—97
Dog (beagle)72
Aardvark72
Beaver45
Great white shark34
Whiskered baby shark32
Cat30
Porcupine25
Squirrel monkey22
Marmot17
Rabbit10—13
Platypus9
GroupBrain weight, g
Alligator8,4
Squirrel7,6
Opossum6
Woolly6
Ant-eater4,4
The guinea pig4
Common Pheasant4,0
Hedgehog3,35
Tupaya3
Battleship2,5
Owl2,2
Rat (weighing 400 g)2
Gray partridge1,9
Hamster1,4
Jumper1,3
Sparrow1,0
European quail0,9
Turtle0,3—0,7
Bullfrog0,24
Viper0,1
gold fish0,097
Green lizard0,08

Brain tissue edit |

What are we laughing at?

First you need to identify the intellect, a very difficult task, think about it. According to the most modern definitions, intelligence consists of the skills of logical thinking, problem solving, critical thinking and adaptation. When is the brain considered dead?

Central nervous system (CNS):

I. Cervical nerves.
Ii. Thoracic nerves.
Iii. Lumbar nerves.
Iv. Sacral nerves.
V. Coccygeal nerves.

1. The brain.
2. The diencephalon.
3. The midbrain.
4. The bridge.
5. Cerebellum.
6. Oblong brain.
7. Spinal cord.
8. Cervical thickening.
9. Transverse thickening.
10. “Horse tail”

Brain weight as a percentage of body weight in modern cartilaginous fish is 0.06-0.44%, in bone fish 0.02-0.94%, in tailed amphibians 0.29-0.36%, in tailless 0, 50-0.73% In mammals, the relative size of the brain is much larger: 0.3% for large cetaceans, 1.7% for small cetaceans, 0.6-1.9% for primates. In humans, the ratio of brain mass to body weight is on average 2%.

Brain death is an irreversible ending of all brain activity due to complete necrosis of the brain neurons after loss of blood flow and oxygenation. A person who dies from the brain has no clinical signs of brain function during a physical examination. This does not affect the pain and lack of cranial nerve reflexes. Reflexes include pupillary response, oculocephalic reflex, corneal reflex, lack of response to the calorie reflex test, and lack of spontaneous respiration. The diagnosis of brain death must be rigorous to determine if the condition is irreversible.

The brain of mammals of the orders of cetaceans, proboscides, and primates has the largest sizes. The most complex and functional brain can be considered the human brain.

The brain is enclosed in a reliable shell of the skull (with the exception of simple organisms). In addition, it is covered with shells (lat. Meninges) of connective tissue - hard (lat. Dura mater) and soft (lat. Pia mater), between which there is a vascular, or arachnoid (lat. Arachnoidea) shell. Between the membranes and the surface of the brain and spinal cord is cerebrospinal (often called spinal) fluid - cerebrospinal fluid (lat. Liquor). Cerebrospinal fluid is also found in the ventricles of the brain. The excess of this fluid is called hydrocephalus. Hydrocephalus is congenital (more often) and acquired.

Legal criteria vary, but neurological examinations are usually required by two independent doctors. If the tests show brain activity, the patient may be in a coma or vegetative state. The brain does not show brain activity. It is important to distinguish between brain death and conditions that can mimic brain death. Some comatose patients may recover, and some patients with severe irreversible neurological dysfunction will nevertheless retain some lower brain functions, such as spontaneous breathing, despite losses of both the cerebral cortex and the functionality of the brain.

The brain of higher vertebrate organisms consists of a number of structures: the cerebral cortex, the basal ganglia, the thalamus, the cerebellum, the brainstem. These structures are interconnected by nerve fibers (pathways). The part of the brain, consisting mainly of cells, is called gray matter, of nerve fibers - white matter. White is the color of myelin, a substance that covers fibers. Demyelination of fibers leads to severe abnormalities in the brain (multiple sclerosis).

Thus, anencephaly, in which there is no higher brain, is usually not considered brain death, although it is certainly an irreversible condition under which it may be advisable to refuse life support. Today, both legal and medical communities use “brain death” as the legal definition of death. Using the criteria for death from death, the medical community can declare a person legally dead, even if life support equipment supports the body’s metabolic processes.

Brain cells include neurons (cells that generate and transmit nerve impulses) and glial cells that perform important additional functions. (We can assume that neurons are brain parenchyma, and glial cells are stroma). Neurons are divided into excitatory (i.e., activating discharges of other neurons) and inhibitory (preventing the excitation of other neurons).

Do brain supplements help enhance memory and brain capacity? As we age, our brains are more susceptible to memory loss and diseases, such as Alzheimer's disease. The functionality of the human brain can also be affected due to problems in the nervous system or insufficient blood supply to the brain. to assist the brain.

Your brain generates almost 25 watts of energy while you wake up, which is enough to light a light bulb. Alcohol affects brain processes, weakening the connections between neurons. Every time you have a new thought or a memory is remembered, a new connection of the brain occurs between two or more brain cells.

Communication between neurons occurs through synaptic transmission. Each neuron has a long process called an axon, through which it transmits impulses to other neurons. The axon forks and forms synapses at the site of contact with other neurons - on the body of neurons and dendrites (short processes). Axo-axonal and dendro-dendritic synapses are much less common. Thus, one neuron receives signals from many neurons and in turn sends pulses to many others.

Living brain is so soft that you can cut it with a table knife. Losing oxygen in as little as 5–10 minutes can lead to severe brain damage. The brain can stay alive for 4-6 minutes without oxygen. The human brain contains about 400 miles of blood vessels.

Inside the brain there is no sense of pain, which explains why brain surgeons can explore areas of the brain even when the patient is awake. The left side of your brain controls the right side of your body, and the right side of your brain controls the left side of your body.

In most synapses, signal transmission is carried out chemically - through neurotransmitters. Mediators act on postsynaptic cells by binding to membrane receptors, for which they are specific ligands. Receptors can be ligand-dependent ion channels, they are also called ionotropic receptors, or they can be associated with systems of intracellular second messengers (such receptors are called metabotropic). The currents of ionotropic receptors directly alter the charge of the cell membrane, which leads to its excitation or inhibition. Examples of ionotropic receptors include receptors for GABA (the inhibitory channel is a chloride channel), or glutamate (the excitatory, sodium channel). Examples of metabotropic receptors are the muscarinic receptor for acetylcholine, the receptors for norepinephrine, endorphins, serotonin. Since the action of ionotropic receptors directly leads to inhibition or excitation, their effects develop faster than in the case of metabotropic receptors (1-2 milliseconds versus 50 milliseconds - a few minutes).

Your cerebral cortex is about as thick as a depressor for doctors, and it gets fatter when you study more. You will lose consciousness 10 seconds after the loss of blood supply to the brain. Of all creatures on Earth, humans have the most complex brain.

Differences in weight and brain size do not coincide with differences in mental abilities. If you extend the cerebral cortex will be 23 square meters. M or 5 square. There are about 100 billion neurons in the human brain, as many stars in our galaxy. Questions that we all would like to answer.

How does memory work in the brain? How is memory stored and then remembered later, even decades later? What makes us dream and what is the purpose of dreams? While the dreaming brain tends to make up the time required for repair, thereby creating a virtual experience.

The shape and size of the neurons of the brain are very diverse, in each department there are different types of cells. There are principal neurons, the axons of which transmit impulses to other departments, and interneurons that communicate within each department. Examples of principal neurons are pyramidal cells of the cerebral cortex and Purkinje cells of the cerebellum. Examples of interneurons are cortical basket cells.

While dreaming the brain also refreshes saved memories by deciding which ones to save and which not. Why do we need to sleep and how does the brain enter and support the sleep phase? We sleep to restore damaged parts of the body and dream. How do we make decisions, come to conclusions and honor our course in life?

How do each of us have our own personalities and traits? How can memory be stored in a living cell or group of cells? Is any work done on creating a computer using living cells to store and retrieve information, perhaps to duplicate the brain.

The activity of neurons in some parts of the brain can also be modulated by hormones.

Until now, it has been known that nerve cells regenerate only in animals. However, scientists recently discovered that in the human brain, which is responsible for smelling, mature neurons are formed from progenitor cells. One day they will be able to help “fix” the injured brain. Source not specified 15 days

For more than a century, faith has become the belief that people do not fulfill their intellectual potential. Self-improvement gurus, advertisers and maybe even Albert Einstein said that 90 percent of our brains are idle. The idea turned out to be popular in Hollywood, when the last film by Luc Besson "Lucy" used it as the main plot device.

In the film, Samuel Norman, a fictional neurologist played by Morgan Freeman, says: "It is estimated that most people use only 10% of their brain." Just imagine if we can access 100 percent. Is the statement that we use only 10 percent of our fact or fiction?

Blood supply to the brain

The functioning of the neurons of the brain requires a significant amount of energy that the brain receives through the blood supply network. The brain is supplied with blood from the basin of three large arteries - two internal carotid arteries (lat. A. Carotis interna) and the main artery (lat. A. Basilaris). In the cranial cavity, the internal carotid artery has a continuation in the form of the anterior and middle cerebral arteries (Latin aa. Cerebri anterior et media). The main artery is located on the ventral surface of the brain stem and is formed by the fusion of the right and left vertebral arteries. Its branches are the posterior cerebral arteries. The above three pairs of arteries (anterior, middle, posterior), anastomosing between themselves, form an arterial (Willis) circle. For this, the anterior cerebral arteries are interconnected by the anterior communicating artery (Latin a. Communicans anterior), and between the internal carotid (or, sometimes, the middle cerebral artery) and the posterior cerebral arteries, on each side, there is a posterior communicating artery (lat. Aa.communicans posterior). The absence of anastomoses between arteries becomes noticeable with the development of vascular pathology (strokes), when, due to the absence of a closed circle of blood supply, the lesion area increases. In addition, there are numerous variants of the structure (open circle, atypical division of vessels with the formation of trifurcation, etc.). If the activity of neurons in one of the departments increases, the blood supply to this area also increases.The methods of non-invasive neuroimaging such as functional magnetic resonance imaging and positron-emission tomography allow registration of changes in the functional activity of individual brain regions.

In it, as Professor James wrote, "as a rule, men usually use only a small part of their powers, which they actually possess and which they can use in appropriate conditions." The atlas of the human brain from Michigan State University allows you to watch films of each section of the functioning of the human brain.

Professor Stow agrees that "there is no truth" at the 10 percent requirement. But he also says that the brain has “some redundancy” in it. “We still understand how the brain works and how we learn, as well as the plasticity of the brain — it's fascinating,” he says.

Between the blood and the brain tissue, there is a blood-brain barrier that provides selective permeability of substances in the bloodstream to the cerebral tissue. In some parts of the brain, this barrier is absent (hypothalamic region) or different from other parts, which is associated with the presence of specific receptors and neuroendocrine formations. This barrier protects the brain from many types of infections. At the same time, many drugs that are effective in other organs cannot penetrate the brain through the barrier.

Brain function

The main component of the nervous system in general and the brain in particular is a neuron or nerve cell, the “brain cells” of a popular language. A neuron is an electrically excited cell that processes and transmits information through electrochemical signaling. Unlike other cells, neurons never divide, and they also do not die to be replaced by new ones. Similarly, they usually cannot be replaced after a loss, although there are a few exceptions.

The average human brain has about 100 billion neurons and many more neuroglia, which serve to support and protect neurons. A typical neuron has soma, dendrites and one axon. Each neuron maintains a voltage gradient on its membrane due to metabolic-induced differences in sodium, potassium, chloride and calcium ions within the cell, each of which has a different charge. If the voltage changes significantly, an electrochemical impulse is generated, called an action potential.

The functions of the brain include the processing of sensory information from the senses, planning, decision-making, coordination, motion control, positive and negative emotions, attention, memory. The human brain performs a higher function - thinking. One of the most important functions of the human brain is the perception and generation of speech.

This electrical activity can be measured and displayed as a waveform called a brainwave or brain rhythm. This impulse spreads rapidly along the cell axon and is transferred through a specialized compound known as a synapse to a neighboring neuron, which receives it through its feathered dendrites. A synapse is a complex membrane junction or gap used to transmit signals between cells, so this transmission is known as a synaptic connection. Although axon-dendritic synaptic connections are the norm, other options are possible.

The main parts of the human brain:

rhomboid (posterior) brain,
medulla,
back (actually back),
the bridge (contains mainly projection nerve fibers and groups of neurons, is an intermediate link in the control of the cerebellum),
cerebellum (consists of a worm and hemispheres, on the surface of the cerebellum nerve cells form the cortex),
the rhombic brain cavity is the IV ventricle (there are holes at the bottom of it that connect it with the other three ventricles of the brain, as well as with the subarachnoid space),
midbrain
chelovecholmie,
the cavity of the midbrain - brain water supply system (Silviev water supply system),
brain legs,
forebrain - consists of intermediate and end brain,
intermediate (through this department there is a switch of all information that goes from the lower parts of the brain to the cerebral hemispheres), the cavity of the intermediate brain is the III ventricle,
thalamus
epithalamus
epiphysis,
leash
gray strip,
hypothalamus (center of the autonomic nervous system),
pituitary,
pituitary funnel,
gray bump,
mastoid body
finite,
cloak (bark)
basal nuclei (striatum),
caudate nucleus
lenticular nucleus,
fence,
amygdala
"Olfactory brain",
olfactory bulb (passes the olfactory nerve),
olfactory tract,
the end-brain cavity is the lateral (I and II ventricles).

A typical neuron shoots 5-50 times per second. Each individual neuron can form thousands of connections with other neurons in this way, giving a typical brain over 100 trillion synapses. Functionally connected neurons connect with each other, forming neural networks. The connections between neurons are not static, although they change over time. The more signals sent between two neurons, the stronger the connection increases, and therefore, with each new experience and each memorable event or fact, the brain slightly rebuilds its physical structure.

The flow of signals to and from the brain is carried out through the spinal cord that controls the body, and through the cranial nerves. Sensory (or afferent) signals come from the sense organs to the subcortical (that is, preceding the cortex of the hemispheres) nuclei, then to the thalamus, and from there to the highest section - the cortex of the big hemispheres.

The cortex consists of two hemispheres connected by a bundle of nerve fibers - the corpus callosum. The left hemisphere is responsible for the right half of the body, the right - for the left. In humans, the right and left hemispheres have different functions.

Visual signals enter the visual cortex (in the occipital lobe), tactile in the somatosensory cortex (in the parietal lobe), olfactory - in the olfactory cortex, etc. In the associative regions of the cortex, various sensory signals (modalities) are integrated.

Motor areas of the cortex (primary motor cortex and other areas of the frontal lobes) are responsible for the regulation of movements.

The prefrontal cortex (developed in primates) is responsible for mental functions.

The areas of the cortex interact with each other and with the subcortical structures - the thalamus, the basal ganglia, the nuclei of the brain stem and the spinal cord. Each of these structures, although lower in hierarchy, performs an important function, and can also act autonomously. Thus, the basal ganglia, the red core of the brain stem, the cerebellum and other structures are involved in movement management, amygdala in emotions, the reticular formation in attention management, in the short-term memory the hippocampus.

On the one hand, there is a localization of functions in the brain, on the other - they are all connected in a single network.

The brain has the property of plasticity. If one of its departments is affected, other departments can compensate for its function over time. Brain plasticity also plays a role in learning new skills.

One of the oldest methods of studying the brain is the method of ablation, which consists in the fact that one of the parts of the brain is removed, and scientists are watching the changes to which such an operation leads.

Not every area of ​​the brain can be removed without killing the body. Thus, many parts of the brain stem are responsible for vital functions, such as breathing, and their defeat can cause immediate death. Nevertheless, the defeat of many departments, although it affects the viability of the organism, is not lethal. This, for example, applies to areas of the cerebral cortex. An extensive stroke causes paralysis or loss of speech, but the body continues to live. A vegetative state in which most of the brain is dead can be maintained through artificial feeding.

Studies with the use of ablations have a long history and are ongoing. If scientists of the past removed areas of the brain surgically, then modern researchers use toxic substances that selectively affect brain tissue (for example, cells in a certain area, but not nerve fibers passing through it).

After removal of the brain, some functions are lost, and some are preserved. For example, a cat whose brain is cut above the thalamus retains many postural reactions and spinal reflexes. An animal whose brain is dissected at the level of the brain stem (decerebrated) maintains the tone of the extensor muscles, but loses postural reflexes.

Conducted monitoring and people with lesions of brain structures. Thus, cases of gunshot wounds to the head during World War II provided a wealth of information for researchers. Studies are also conducted on patients with stroke and brain damage as a result of injury.

Electrophysiologists register the electrical activity of the brain - with the help of thin electrodes, which allow recording discharges of individual neurons, or using electroencephalography (a technique for extracting brain potentials from the surface of the head).

The thin electrode can be made of metal (covered with an insulating material that exposes only a sharp tip) or glass. The glass electrode is a thin tube filled inside with saline. The electrode can be so thin that it penetrates inside the cell and allows you to record intracellular potentials. Another way to record the activity of neurons is extracellular.

In some cases, thin electrodes (from one to several hundred) are implanted in the brain, and researchers record activity for a long time. In other cases, the electrode is inserted into the brain only for the duration of the experiment, and at the end of the recording is removed.

Using a thin electrode, it is possible to record both the activity of individual neurons and local potentials (local field potentials), which are formed as a result of the activity of many hundreds of neurons. With the help of EEG electrodes, as well as surface electrodes, which are directly applied to the brain, only global activity of a large number of neurons can be recorded. It is believed that the activity recorded in this way consists of both neural action potentials (i.e., neural impulses) and subthreshold depolarisations and hyperpolarizations.

When analyzing the potentials of the brain, they often produce their spectral analysis, and the different components of the spectrum have different names: delta (0.5-4 Hz), theta 1 (4-6 Hz), theta 2 (6-8 Hz), alpha (8- 13 Hz), beta 1 (13-20 Hz), beta 2 (20-40 Hz), gamma waves (includes the frequency of beta 2 rhythm and above).

One method of studying brain function is electrical stimulation of specific areas. Using this method, for example, the “motor homunculus” was investigated - it was shown that, by stimulating certain points in the motor cortex, one could induce hand movement, stimulating other points — leg movements, etc. The resulting map is called the homunculus. Different parts of the body are represented by areas of the cerebral cortex that differ in size. Therefore, the homunculus has a large face, thumbs and palms, but a small body and legs.

If you stimulate the sensory regions of the brain, you can cause sensations. This was shown both on man (in Penfield's famous experiments) and on animals.

Currently, non-invasive focal magnetic stimulation is widely used to stimulate the brain. The problem with this method is that it activates rather large areas of the brain, and in some cases it is required to stimulate local areas.

Electrical stimulation is also used in medicine - from electric shock, shown in many movies about the horrors of psychiatric clinics, to the stimulation of structures in the depths of the brain, which has become a popular treatment for Parkinson's disease.

To study the anatomical structures of the brain, X-ray CT and MRI are used. PET and single-photon emission computed tomography (SPECT), functional MRI are also used in anatomical and functional studies of the brain. It is possible to visualize the structures of the brain by ultrasound diagnostics (ultrasound) in the presence of an ultrasound “window” - a defect in the cranial bones, for example, a large spring in young children.

In the era of modern technology, people hardly think about the fact that they have a far more advanced tool than numerous computers, smartphones and other wonders of technology. The brain, by right, is one of the most mysterious and poorly studied organs of the human body. This article contains the most interesting facts about the human brain.

Our memory

Scientists are just beginning to be selected to solve the mystery of our memories. Why do we remember something well and something else bad? Using modern technology, the academic world found out that a person has ordinary and false memories. And both of these types of memories force the same parts of the brain to be active.

Therefore, it cannot be said that only the hippocampus plays the largest role in human memory (it participates in the formation of emotions, memory consolidation), as scientists assumed earlier. Yes, it certainly is of great importance, but not exceptional. When researching the mechanisms of memory, scientists ask subjects to recall the situation in context in order to distinguish between false and ordinary memories. These facts about the human brain are still not fully understood.

Phantom sensation

A large percentage of people whose body parts are amputated feel heat, pain, or pressure in a non-existent limb. Scientists have not come to a single conclusion that would explain this phenomenon. Some say that the nerve endings that led to the amputated limb make new connections and send signals there, as if it were there. Others assume that there is a memory of the whole organism in the human brain, and therefore it works with the limb even after its loss.

Ability to recover lost functions

The human brain has another amazing ability - the ability to restore functions that have been lost. In the event that an injury occurred at an early age and important parts of the cerebral cortex were damaged, the functions of these sections are in most cases transferred to other areas. Of course, recovery takes place gradually and is not always fully implemented. However, these facts about the human brain indicate that the brain is a single system, all of whose elements are interconnected.

The brain never rests

Our brain never rests, even when we sleep, the brain continues to work actively. There are various interesting theories about where our dreams come from. One of the theories says that our brain in a dream strengthens memories, processes the information received in a day. And the second theory makes the assumption that our brain in a dream activates various channels and checks connections. Scientists from around the world still do not know where dreams come from a person. Only the fact that dreams always come during the so-called “REM sleep phase” has been established.

Do we need sleep?

Almost a third of our lives we spend in a dream. People, animals, insects are sleeping. It is not known for certain why we need sleep. Scientists can only speculate. They found that sleep is very important for the life of mammals. After all, if you deprive sleep for a long time, it can lead to various health disorders, and even death.

According to scientists, in a long phase of sleep a person rests, stores energy, as the brain at this time almost does not show activity. And in the fast phase, the brain processes the memories received by a person in a day, and transfers these memories from short-term to long-term memory. However, scientists have not been able to explain the fact why our dreams are so rarely associated with our memories?

Brain loves to workout

Physical training helps keep the brain in good shape. Regular athletic stress contributes to an increase in the number of capillaries in the brain, which accordingly improves the access of oxygen and glucose. Enough regular sessions of 30 minutes 2-3 times a week.

Intellectual training is also helpful. “Live Computer” is amenable to development at any age. The more it loads with complex puzzles, the “smarter” it becomes. So do not be lazy to "pump over brains" - this will save you from senile dementia and mental disorders.

Two hemispheres

Many people know that the human brain consists of two hemispheres, while few people know that the functions of the right and left hemispheres are different.

By the way, the left hemisphere in women, as a rule, is larger than in men. This scientifically substantiates the fact that women are more successful in the humanities, and men in technical and mathematical.

I remember - I do not remember

No less interesting facts about the brain are connected with memory, or rather with its loss. Most people are aware of the phenomenon of amnesia. It is often mentioned in fiction, cinema, serials. Few people know that amnesia is different. Most often, it occurs after any traumatic effect, whether it is a traumatic brain injury, intoxication or a tumor, and the person does not remember the period after exposure.

However, amnesia can affect the period before the impact, this is the case when the patient forgets all the facts of his life before the injury. A special place is occupied by amnesia associated with affects, strong emotional states, when a person forgets some traumatic event, an unpleasant incident from his own life.

In addition to amnesia, there are other memory disorders, such as hypermnesia, i.e. memory gain, often accompanied by astounding abilities for arithmetic counting. There is also the phenomenon of hypomnesia, i.e. deterioration or weakening of memory.

Evgeny Shevchenko pinned post
Evgeny Shevchenko pinned post

Human brain:
1. Hemisphere of the big brain (final brain)
2. Thalamus (diencephalon)
3. Hypothalamus (diencephalon)
4. Midbrain
Show full story ...
5. Bridge
6. Cerebellum
7. Medulla Brain
8. Spinal cord
The brain (lat. Cerebrum, ancient Greek ἐγκέφαλος) is the main organ of the central nervous system of the vast majority of chordates, its head end, in vertebrates, is inside the skull. In the anatomical nomenclature of vertebrates, including man, the brain as a whole is most often referred to as encephalon - a Latinized form of the Greek word, originally Latin cerebrum became synonymous with the large brain (telencephalon).

The brain consists of a large number of neurons connected by synaptic connections. By interacting through these connections, neurons form complex electrical impulses that control the activity of the whole organism.

Despite significant progress in the study of the brain in recent years, much of his work still remains a mystery. The functioning of individual cells is well explained, but an understanding of how the brain functions as a whole as a result of the interaction of thousands and millions of neurons is available only in a very simplified form and requires further in-depth research.

See also: Human brain

Human brain (fixed in formalin)
The brain is the main part of the central nervous system. Talking about the presence of the brain in the strict sense can only be applied to vertebrates, starting with fish. However, this term is used somewhat loosely to refer to similar structures of highly organized invertebrates — for example, in insects, the brain is sometimes called the accumulation of the glands of the pharyngeal nerve ring. When describing more primitive organisms, they speak of head ganglia, and not of the brain.

The weight of the brain as a percentage of body weight is 0.06—0.44% in modern cartilaginous fishes, 0.02—0.94% in bony fish, 0.29—0.36% in caudate amphibians, 0 in tailless 50—0.73%. In mammals, the relative size of the brain is much larger: 0.3% for large cetaceans, 1.7% for small cetaceans, 0.6-1.9% for primates. In humans, the ratio of brain mass to body weight is on average 2%.

The brain of mammals of the orders of cetaceans, proboscides, and primates has the largest sizes. The most complex and functional brain is considered to be a reasonable human brain.

Brain tissue Edit

The brain is enclosed in a solid shell of the skull (with the exception of simple organisms). In addition, it is covered with shells (lat. Meninges) of connective tissue - hard (lat. Dura mater) and soft (lat. Pia mater), between which there is a vascular, or arachnoid (lat. Arachnoidea) shell. Between the membranes and the surface of the brain and spinal cord is cerebrospinal (often called spinal) fluid - cerebrospinal fluid (lat. Liquor). Cerebrospinal fluid is also found in the ventricles of the brain. The excess of this fluid is called hydrocephalus. Hydrocephalus is congenital (more often) and acquired.

The brain of higher vertebrate organisms consists of a number of structures: the cerebral cortex, the basal ganglia, the thalamus, the cerebellum, the brainstem. These structures are interconnected by nerve fibers (pathways). The part of the brain, consisting mainly of cells, is called gray matter, of nerve fibers - white matter. White is the color of myelin, a substance that covers fibers. Demyelination of fibers leads to severe abnormalities in the brain (multiple sclerosis).

Brain cells Edit

Brain cells include neurons (cells that generate and transmit nerve impulses) and glial cells that perform important additional functions. (We can assume that neurons are parenchyma of the brain, and glial cells - stroma). There are afferent neurons (sensitive neurons), efferent neurons (some of them are called motor neurons, sometimes this is not a very accurate name applies to the entire group of efferents) and interneurons (intercalary neurons).

Communication between neurons occurs through synaptic transmission. Each neuron has a long process called an axon, through which it transmits impulses to other neurons. The axon forks and forms synapses at the site of contact with other neurons - on the body of neurons and dendrites (short processes). Axo-axonal and dendro-dendritic synapses are much less common. Thus, one neuron receives signals from many neurons and, in turn, sends pulses to many other

In most synapses, signal transmission is carried out chemically - through neurotransmitters. Mediators act on postsynaptic cells by binding to membrane receptors, for which they are specific ligands. Receptors may be ligand-dependent ion channels, they are also called ionotropic receptors, or may be associated with systems of intracellular secondary mediators (such receptors are called metabotropic). The currents of ionotropic receptors directly alter the charge of the cell membrane, which leads to its excitation or inhibition. Examples of ionotropic receptors include receptors for GABA (the inhibitory channel is a chloride channel), or glutamate (the excitatory, sodium channel). Examples of metabotropic receptors are the muscarinic receptor for acetylcholine, the receptors for norepinephrine, endorphins, serotonin. Since the action of ionotropic receptors directly leads to inhibition or excitation, their effects develop faster than in the case of metabotropic receptors (1-2 milliseconds versus 50 milliseconds - a few minutes).

The shape and size of the neurons of the brain are very diverse, in each department there are different types of cells. There are principal neurons, the axons of which transmit impulses to other departments, and interneurons that communicate within each department. Examples of principal neurons are pyramidal cells of the cerebral cortex and Purkinje cells of the cerebellum. Examples of interneurons are cortical basket cells.

The activity of neurons in some parts of the brain can also be modulated by hormones.

Until now, it has been known that nerve cells regenerate only in animals. However, scientists recently discovered that in the human brain, which is responsible for smelling, mature neurons are formed from progenitor cells. One day they will be able to help “fix” the injured brain. Stem cells located in the brain stop dividing, some chromosome regions are reactivated, and neuron-specific structures and connections begin to form. From this point on, the cell can be considered a full-fledged neuron. At present, only 2 regions of active neuron growth are known. One of them is a memory zone. The other is the area of ​​the brain responsible for movement. This explains the partial and complete restoration over time of the corresponding functions after damage to this part of the brain.

Watch the video: How the Brain Works Part 1 UCLA (January 2020).

Loading...