Transmission of information by light to the brain. Scientific library - abstracts - principles of information transfer and structural organization of the brain
At the same time, despite the fractions of a second delay, the brain-computer-internet-computer-brain interface implemented by scientists allowed one person to control the movements of another person. Since this work is carried out under the auspices of the US Army Research Office, it is not surprising that the latest demonstration used a shooting game and simulated actions with explosive devices. The US military sees this technology as an opportunity to bypass the language barrier and differences in experience between two people who need to work together to do some potentially dangerous work with the help of direct information transmission.
The first demonstration of the performance of this system was held last year. And the current demonstration not only confirmed the efficiency of the idea itself, but also showed some of its advanced features. As before, one of the participants, the one who remotely controls the actions of another person, puts on EEG sensors, with the help of which the computer reads patterns of brain activity in certain areas of the brain. This data is digitized and transmitted over the Internet to another computer, which performs the entire sequence in reverse. The second person, the performer, is under the influence of a magnetic field induced by a coil directed to the area of the brain that controls hand movements. A human operator can send a command to another person and for this he does not even need to move, he only needs to imagine that he is moving his hand. The human performer receives commands from the outside with the help of transcranial magnetic excitation technology and his hands move independently of his consciousness.
In their experiments, the researchers tested the performance of the system on three pairs of participants. The operator and performer were always in two buildings, the distance between which was equal to 1.5 kilometers and between which only one digital communication line was laid. “The first operator was involved in a computer game in which he had to protect the city from attack, using various types of weapons and shooting down rockets launched by the enemy. At the same time, he was completely deprived of the possibility of physical impact on the gameplay. The only way the operator could play the game was by mentally controlling the movements of his hands and fingers, write the Washington researchers. - The accuracy of the game from pair to pair varied greatly and ranged from 25 to 83 percent. And the highest level of errors fell on the share of errors in the execution of the fire command.
The researchers are currently receiving a $1 million grant from the W. M. Keck Foundation to help them continue and expand their research. As part of the new stage, researchers are going to learn how to decipher and transmit more complex brain processes, expand the number of types of transmitted information, which will allow for the transfer of concepts, thoughts and rules. Thanks to this, at least scientists are counting on it, it will be possible in the near future to realize such fantastic technologies, with the help of which, for example, brilliant scientists will be able to transfer their knowledge directly to students, or virtuoso musicians or surgeons will be able to remotely perform operations using the hands of others. of people.
The composition of the human brain includes structural and functionally interconnected neurons. This mammalian organ, depending on the species, contains from 100 million to 100 billion neurons.
Each neuron of mammals consists of a cell - an elementary unit of structure, dendrites (short process) and an axon (long process). The body of an elementary structural unit contains a nucleus and cytoplasm.
axon leaves the cell body and often gives rise to many small branches before reaching the nerve endings.
Dendrites extend from the body of the nerve cell and receive messages from other units of the nervous system.
synapses- these are contacts where one neuron connects to another. Dendrites are covered with synapses, which are formed by the ends of axons from other structural and functional units of the system.
The composition of the human brain is 86 billion neurons, consisting of 80% water and consuming about 20% of the oxygen intended for the whole organism, although its mass is only 2% of the body weight.
How signals are transmitted in the brain
When units of the functional system neurons receive and send messages, they transmit electrical impulses along their axons, which can vary in length from a centimeter to one meter or more. it appears to be very complex.
Many axons are covered with a multilayered myelin sheath that speeds up the transmission of electrical signals along the axon. This shell is formed with the help of specialized elementary units of the glia structure. In the organ central system, glia are called oligodendrocytes, and in the peripheral nervous system are called Schwann cells. The brain center contains at least ten times more glia than units of the nervous system. Glia performs many functions. Importance of glium in transportation nutrients to neurons, purification, processing of a part of dead neurons.
To transmit signals, the functional units of the body system of any mammal do not work alone. In a neural circuit, the activity of one elementary structural unit directly affects many others. To understand how these interactions control brain function, neuroscientists study the connections between nerve cells and how they transmit signals in the brain and change over time. This study may lead scientists to a better understanding of how nervous system develops, is exposed to diseases or injuries, the natural rhythms of brain connections are disturbed. Thanks to new technology Imaging scientists are now better able to visualize the circuits that connect the regions and composition of the human brain. 
Development of methods, microscopy and computer science allow scientists to begin mapping the connections between individual nerve cells in animals better than ever before.
By studying the composition of the human brain in detail, scientists can shed light on brain disorders and errors in the development of the neural network, including autism and schizophrenia.
From the retina, signals are sent to the central part of the analyzer along the optic nerve, which consists of almost a million nerve fibers. At the level of the optic chiasm, about half of the fibers go to the opposite hemisphere of the brain, the remaining half go to the same (ipsilateral) hemisphere. The first switching of the optic nerve fibers occurs in the lateral geniculate bodies of the thalamus. From here, new fibers are sent through the brain to the visual cortex of the brain (Fig. 5.17).
Compared with the retina, the geniculate body is a relatively simple formation. There is only one synapse here, since the incoming optic nerve fibers terminate on cells that send their impulses to the cortex. The geniculate body contains six layers of cells, each of which receives input from only one eye. The top four are small-celled, the bottom two are large-celled, so the top layers are called parvocellular(parvo - small, cellula - cell, lat.) and the bottom ones magnocellular(magnus - big, lat.)(Fig. 5.18).
These two types of layers receive information from different ganglion cells associated with various types bipolar cells and receptors. Each cell of the geniculate body is activated from the receptive field of the retina and has "on" or "ofrV" centers and periphery of the opposite sign. However, between the cells of the geniculate body and the ganglion cells of the retina, there are
Rice. 5 17 Transmission of visual information to the brain. 1- eye; 2 - retina; 3 - optic nerve; 4 - optic chiasm; 5 - external geniculate body, 6 - visual radiation; 7 - visual cortex; 8 - occipital lobes (Lindsney, Norman, 1974)
brain - physical basis vision. Most of the pathways leading from the retina to the visual cortex in the back of the hemispheres pass through the lateral geniculate body. On a transverse section of this subcortical structure, six cell layers are visible, two of which correspond to magnocellular connections (M), and four correspond to parvocellular (P) (Zeki, 1992).
There are differences, of which the most significant is the much more pronounced ability of the periphery of the receptive field of the geniculate cells to suppress the effect of the center, i.e., they are more specialized (Huebel, 1974).
The neurons of the lateral geniculate bodies send their axons to the primary visual cortex, also called zoneVI (visual - visual, English). primary visual (striate) the cortex consists of two parallel and largely independent systems, magnocellular and parvocellular, named according to the layers of the geniculate bodies of the thalamus (Zeki and Shopp, 1988). The magnocellular system is found in all mammals and is therefore of an earlier origin. The parvocellular system is found only in primates, which indicates its later evolutionary origin (Carlson, 1992). The magnocellular system is included in the analysis of shapes, movement and depth of visual space. The parvocellular system is involved in visual functions developed in primates, such as color perception and fine detail detection (Merigan, 1989).
The connection of the geniculate bodies and the striate cortex is carried out with high topographic accuracy: zone VI actually contains a “map” of the entire surface of the retina. The defeat of any part of the nerve pathway connecting the retina with zone VI leads to the appearance fields of absolute blindness, the dimensions and position of which exactly correspond to the length and lo-
localization of damage in zone VI. S. Henschen called this zone cortical retina (Zeki, 1992).
The fibers coming from the lateral geniculate bodies are in contact with the cells of the fourth layer of the cortex. From here, information eventually spreads to all layers. Cells in the third and fifth layers of the cortex send their axons to deeper brain structures. Most of the connections between the cells of the striate cortex run perpendicular to the surface, the lateral connections are mostly short. This suggests the presence of locality in the processing of information in this area.
The area of the retina that acts on a simple cell of the cortex (the receptive field of the cell), like the fields of neurons in the retina and geniculate bodies, is divided into “on” and “offr” areas. However, these fields are far from a regular circle. In a typical case, the receptive field consists of a very long and narrow "op" region, which is adjoined on both sides by wider "o! G" regions (Huebel, 1974).
Here we will also talk about information. But in order not to get confused in different interpretations of the same word, let's immediately clearly define what information will be discussed. So, the brain is able to fix only connections. This type of information (connection) the brain remembers. The process by which it does this is called the "Memory" process. But we are accustomed to calling information that the brain cannot remember. These are really existing objects of the world around us. This is all that we have to learn at school or college. We will talk about this information now. Let's figure out how the brain reacts to real objects, to textual information, and to a very special type of information - symbolic (or exact) information. The listed types of information - real objects, texts, telephone numbers (and similar information) the brain cannot remember. But experience suggests that we can still remember something from the above. How does the memorization and reproduction of such information take place?
1. IMAGES 2. TEXT INFORMATION 3. SIGN INFORMATION
First, let's analyze the reaction of the brain to real-life objects. How does the brain manage to reproduce them if none of the researchers can detect visual images in the brain? Nature has acted very cunningly. Any real-life object has internal connections. The brain is able to identify and remember these connections. Have you ever wondered why, in fact, a person needs several sense organs? Why do we know how to smell, taste, see an object and hear it (if it emits sounds)? A real-life object emits physical and chemical signals into space. This is the light reflected from it or emitted by it, these are all kinds of vibrations in the air, the object can have a taste, and the molecules of this object can fly far away from it. If a person had only one sense organ, then the memory system of the brain, fixing connections, would not be able to remember anything. But one general information field from an object is divided by our brain into several components. Information enters the brain through different channels of perception. The visual analyzer conveys the outlines of the object (let it be an apple). The auditory analyzer perceives the sounds made by the object: when you bite into an apple, a characteristic crunch is heard. The taste analyzer perceives taste. The nose, a few meters away, is able to catch the molecules emitted by ripe apples. Part of the information about the object can enter the brain through the hands (touch). As a result of breaking the information about the object into parts, the brain gets the opportunity to form connections. And these connections are formed naturally. Everything that is in the mind at one moment of time is connected, that is, remembered. As a result, while we are studying an apple, while we are examining it, twisting it in our hands, tasting it, the brain identifies various characteristics of this natural object and automatically forms connections between them. None of the characteristics is memorized by itself. Only connections are remembered. In the future, when our nose smells the smell of apples - that is, a stimulus enters the brain - the previously formed connections will work and the brain will create other characteristics of this object in our minds. We will remember the holistic image of an apple. The mechanism of natural memorization is so obvious that it is even strange to talk about it. This method of memorization gives us the opportunity to RECOGNIZE the objects of the world around us only by a small part of the information about them.
