Discoveries are rarely made unintentionally. Even if the encounter with a new, yet unknown phenomenon occurred completely by accident, it is most often possible to comprehend it only on the basis of ideas and concepts that already exist in science. When the level of our knowledge is not yet mature enough to appreciate the discovery, it goes unnoticed.
Only at the beginning of the 19th century did scientists seriously study the human brain. F. Gall and G. Spurzheim were among the first to publish their works, who stated that the nature of mental disorders depends on the place of brain damage. The topic became fashionable, and the theory began to be widely discussed among doctors that the development of certain abilities, inclinations, character traits leads to such an overgrowth of the corresponding parts of the brain - brain centers - that the bones of the skull above this place are forced to bend like a bump. According to them, one can supposedly judge the character of a person and his abilities. Gall indicated the location of 37 cones, including cones of cowardice, aggressiveness, patriotism.
Get out of the church
Gall's work provoked a heated discussion, and, of course, the church took up arms against him. How dare he refute the unknowability of the human soul !? How can you determine where the divine soul has “legs” and where is “head” and where (Oh, horror!) Are the centers of religious faith or unbelief !? And how dare this heretic say that vices are not the fruit of the instigation of the devil, but the constituent parts of the same soul given by God ?! And only the priests would have pounced on the scientist! So also Napoleon raised his voice: he achieved from the Austrian emperor the expulsion of the scientist from Vienna and the prohibition of his experiments. Yes, it was dangerous to study the brain the century before last. Only brave men undertook to write about the localization of certain mental functions in different parts of the brain. Their position was strengthened by the results of a detailed physiological study by P. Fleurance,which is still often quoted by modern neurophysiologists.
Doves of peace
Flurance conducted his experiments on pigeons. The scientist removed various parts of the cerebral hemispheres from them and watched how the behavior of the birds changed. He found that the large hemispheres of pigeons solely control their behavior. However, Fleurance did not notice any separation of functions in the cerebral hemispheres and came to the conclusion that the intelligence of birds was disturbed in exactly the same way, no matter what area was damaged. Only the amount of brain matter removed mattered: the more it was removed, the more the birds' behavior was disturbed. Thus, according to Flurance, the cerebral hemispheres function as a whole. All their parts are equal, in much the same way as a soccer ball: wherever the ball is hit, it will bounce with the same force. This conclusion of his has divided scientists into two irreconcilable, warring camps:supporters of the localization of functions in the brain and supporters of the equality of all parts and departments of the cerebral hemispheres.
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Cut it boldly
Scientists obtained all the basic information about the functions of the human brain by studying patients. Clinical observations of mental changes in various forms of lesions of the cerebral hemispheres made it possible to judge the distribution of responsibilities between their separate areas. However, it became possible to really understand this issue only now, after the advent of new diagnostic methods, surgical and therapeutic treatment. Observations of doctors made in the course of using these methods (carrying out experiments on humans, of course, is unacceptable), have significantly expanded our understanding of the organization of higher mental functions of a person. Further - more: they found out that the nerve cells of the brain exchange information with each other using weak electrical impulses. It is quite understandablethat a stronger current completely disrupts the brain. Irritation by electric current disorganizes the generation of electrical impulses to such an extent that normal brain activity stops for a while. Outwardly, it looks like the loss of individual functions. Significant changes in its electrical reactions also indicate disruption of the brain. Then the Japanese researcher Wada established: if the question arises about the need for an operation on one of the cerebral hemispheres, the surgeon, before deciding on such a step, must know exactly which of the hemispheres is dominant. Is the patient's speech centers really in the left hemisphere? And what awaits him after the upcoming surgery? For this purpose, drugs are used. If the drug affects only one hemisphere of the brain,functions mainly of this hemisphere will drop out.
They are so different
It was possible to find ways to study the distribution of functions in normal, perfectly healthy people. To do this, sound and visual stimuli of varying complexity are presented in such a way that information falls into only one hemisphere, and how it is perceived by the subject is studied. Another way is to compare the electrical reactions that unfold in the right and left hemispheres when performing various tests. This makes it possible to judge which half of the brain is in charge of a given task.
Both of these methods, as well as other methods of studying the higher mental functions of a person, made it possible to make many interesting observations. The study of the distribution of functions between the cerebral hemispheres not only made it possible to make a significant step forward in understanding the physiological mechanisms of higher mental functions of the brain, but served as the basis for the development of new methods for diagnosing its diseases and the subsequent rehabilitation of patients.
Konstantin Kuraev