Self-repair of the brain
Changeable brainDenis Tulinov, "Trinity variant" No. 37-2009
One of the main conclusions of neurophysiological research of the last two decades is formulated as follows: you are able to change your brain. Now it is safe to say that the formed adult brain is capable of reorganization. Until recently, there were big doubts about this. However, recently, primarily due to the improvement of equipment and new scanning methods, it has become possible to move from the field of assumptions and hypotheses to experimental observations.
In the mid-1990s, neurologist Alvaro Pascual-Leone conducted an unusual experiment. He asked people to play the piano. A group of volunteers were offered simple exercises on a musical keyboard, which they had to perform every weekday for two hours. It was supposed to be played with one hand. Despite the relative ease, the tasks required a certain amount of training and the subjects did not get it right away. But by the end of the first week, after five days of classes, the number of errors had noticeably decreased. The brain gradually adapted to the task.
Pascual-Leone was interested in the question of how such an adaptation would be reflected in the brain tissue. Is it possible to detect traces of such adaptation in it using the available methods? Most likely, he believed, the changes should affect the motor areas of the cortex associated with the fingers of the trained hand. Therefore, at the beginning of the experiment, brain areas were identified in each volunteer, where signals from the flexor and extensor muscles of the middle finger of the hand are projected. For this purpose, the method of focal transcranial magnetic stimulation (TMS) was used, which allows you to build cortical maps with high resolution. The motor area associated with the middle finger was checked in all subjects every day, before and after playing music. For control purposes, cortical maps were constructed for the fingers of both hands. Similar indications were also taken from control groups that did not perform exercises. TMS measurements showed that as a result of the exercises, the motor area of the fingers of the trained hand grew rapidly. By the end of the first week, it had increased significantly (Fig. A).
The "materiality" of thought
It is obvious that in the first days the brain reacted to the new experience with a surge of neuronal connections. He activated the adjacent areas of the cortex, and more neurons were now engaged in finger movement. In this way, the control over the mechanics of movements was strengthened in order to ensure their accuracy. However, rapid expansion of the cortical "finger" zone was observed only in the first week. Over the next four weeks, its size gradually decreased (Fig. C), despite the fact that the subjects continued to study. As the training progressed, the exercises shifted more and more into the stereotype phase and less and less required corrective actions. According to Pascual-Leone, the rapid and short-term expansion of motor zones that he discovered represents the first necessary stage of learning, followed by a deeper reorganization of the cortex, translating the newly acquired skill into long-term automatism.
The volunteers of the other group received a similar task: to play with one hand on the keyboard every day for two hours. However, they were not provided with exercises, allowing them to play anything. Despite the similar load on the fingers with the main group, the growth of their cortical zones was much less pronounced. It followed from the experiment that motor activity itself does not lead to significant shifts in the excitation of the cortex. Apparently, the main component of the expansion of motor zones in the main group was focusing on the task and conscious control of movements.
Pascual-Leone developed this idea by excluding the influence of movements. He suggested that another group perform the same exercises in the same mode, only mentally. During the experiment, the fingers of the subjects remained motionless. As a result, the motor zones not only reacted to imaginary movements – their dynamics almost completely repeated the growth noted in the main group. The motor areas of people who performed exercises in the mind were similar in size to the corresponding areas of those who were really engaged on the keyboard (Fig. C). Mental training led to real training - to a change in the neurophysiological properties of brain tissue.
Since then, other experiments have been conducted; the concept of mental rehearsal (mental rehearsal) has entered scientific usage, and the method of mental visualization is used, among other things, to reduce phantom pains. It is now clear that replaying situations in the mind really enriches the brain with new experiences. In a certain sense, at the level of the physical substrate, consciousness does not distinguish between actual and simulated movements, initiating similar brain changes. The good news is that using this property, you can prepare yourself for the upcoming motor activity by developing the appropriate areas of the neocortex. This is especially useful for athletes, military personnel, rescuers, and other professionals. The bad news concerns everyone: imagining certain negative situations, scrolling them in the mind, the brain is really able to live them as real. And this is often reflected in the state of the nervous tissue.
See without eyes
Let's try to illustrate how far the brain's ability to rebuild its own information flows extends. As you know, signals coming from outside are processed in different areas of the brain, depending on the type of sensory system that transmitted the data. The names of the neocortex departments reflect this dependence: visual cortex, auditory cortex, somatosensory cortex. It is obvious that, for example, when the eyes are damaged, information ceases to flow to the visual centers and a person loses sight, despite the operability of the corresponding cortical field. How will the brain behave if visual signals start coming to it through a different type of sensory system? The current level of electronics development allows us to answer this question.
At the moment, a device has been developed and is being tested to help the blind see with the help of language. The device is called BrainPort and consists of a miniature video camera attached to the forehead, as well as a processor that fits in the hand, and a small grid of electrodes superimposed on the tongue. The video signal comes from the camera to the processor, which converts pixels into electrical pulses. Then they are directed to the surface of the tongue, and each electrode is connected to a certain beam of pixels. The intensity of light corresponds to the current strength and duration of the electrical signals that the tongue senses.
The grid also provides spatial correlation: the flash in the center of the visual field will be displayed accordingly as a pulse in the middle of the grid.
The blind begin to see. Naturally, the resolution of their black-and-white field of view is limited by the number of electrodes, which is still low. But even in this case, they manage to see not spots, but objects. For example, a person is able to press the elevator button, read letters and numbers, or take a cup from the table without spilling the contents. The brains of people who had the opportunity to use BrainPort very quickly mastered the new situation. Probably, analyzing the incoming signals, the brain recognized a pattern in them, which in basic terms is characteristic of information usually coming from the organs of vision. By combining these signals with knowledge about the movements of the head, the brain tried to build a picture. When he was convinced of the feedback, he began to learn to interpret the impulses coming from the language as visual information. Roughly speaking, he recruited the tongue to perform the function of the eyes.
Language as an "eye" may seem like an exotic choice, but this is not a whim of researchers. Saliva serves as an excellent conductor of electrical impulses, and nerve fibers are located in the tongue very close to the surface. At the same time, their density per unit area is high, due to which the tongue is an extremely sensitive organ. Almost perfect for vision. After the eyes.
You can do it
Modern technologies allow us to demonstrate another facet of the brain's ability to rebuild its work. As in the first example with the Pascual-Leone experiment, we are talking about the possibility of consciously influencing the electrical activity of the brain. If you supply consciousness with information about the current physiological parameters of the body in real time (which usually remains inaccessible to it), then you can gradually learn how to change these indicators and bring them back to normal. As you know, in a natural situation, consciousness does not directly control many processes going on in the body. The autonomic nervous system monitors the activity of internal organs, glands, blood and lymphatic vessels, metabolism and the constancy of the environment. A person does not know how to willfully change his blood pressure, limb temperature or the value of the alpha rhythm of the brain. However, he can receive current information about the state of his body's systems through special visualizations, for example, geometric shapes or diagrams on a computer screen. To do this, sensors are connected to the subject, which take readings in real time and transmit them to the processor. After the necessary transformations, purification and amplification of the signals, the data is displayed on the screen. Observing them for quite a long time, a person is able to consciously bring these data to the desired values. This usually looks like a change in the color of the shapes or the height of the columns. Sound can also be involved. In other words, the brain learns to enter a state corresponding to "correct" visualizations and stay in it.
As in the previous example with language vision, the brain uses feedback to guess the purpose of incoming data and then rebuild its work. Conditioned reflex training of the autonomic nervous system occurs by reinforcement in the form of video, audio or tactile images. The described ability of the brain to self-regulation has given development to a separate direction of scientific medicine. In this regard, as a rule, the term neurofeedback (neurofeedback), or biofeedback, is used. Currently, therapy is used to correct various psychosomatic disorders, including epilepsy, neurosis, panic attacks, attention deficit, migraines, muscle clamps, etc.
Self-repair of the brain
The above examples illustrate the ability of the brain to respond quickly to changed circumstances and rebuild its work. Electrical activity (rhythms, passing signals, switching groups of neurons on and off) is something that can be corrected within minutes, hours. At the same time, there is another class of problems, primarily injuries, the consequences of which can be eliminated or at least to some extent compensated only by anatomical changes in the structure of the brain. The damaged part is not able to grow back, just as a lost finger or limb cannot grow back. But the brain is sometimes able to transform existing tissue, forming unique structures and paving new neural pathways. This is a much longer process, and it can take years.
Not so long ago, doctors were shocked by the case of an American Terry Wallis, who in 1984, at the age of 20, got into a car accident, after which he fell into a coma. The brain was seriously damaged, the doctors ruled out the possibility of any improvement in the situation in the future. Wallis was in the so-called "minimally conscious state" for 19 years and came to his senses in 2003. Within three days, he regained the ability to talk. He remembered his life well before the disaster and believed that he was in the mid-80s. Over time, most cognitive functions recovered, although memory problems remained. Twice his brain was studied by diffusion tensor imaging, diffusion tensor imaging (DTI). Studies have shown the presence of anatomically unique structures that are not characteristic of the ordinary brain. Wallace's brain was not ordinary. Faced with the task of restoring functions after extensive damage, he developed an alternative connection scheme, initiating the growth of axons in the preserved sections. For many years, unnoticed from the outside, there was a careful and painstaking construction of a new brain. And all this time, homeostasis and life support of the body were maintained.
The above examples illustrate only a small part of the phenomenal abilities of the brain to modify itself on the go. Not so long ago, this was considered unlikely. In recent years, with the advent of modern equipment, it has become possible to look into the ongoing transformations and investigate them by scientific methods. There is no doubt that more amazing cases are waiting for us in the future.
Having dealt with the mechanisms of plasticity, scientists will eventually learn to provoke beneficial changes in the brain to help it cope with problems of various kinds, such as: mental disorders, aging, trauma. This promises to improve the quality of life (and sometimes save it) of millions of people. The diagnosis will no longer sound like a verdict.
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28.09.2009