Every biology textbook says that the founder of the reflex theory is Ivan Pavlov. This is true, but even before the famous Russian physiologist, many researchers studied the nervous system. Of these, Pavlov's teacher Ivan Sechenov made the biggest contribution.
Premises of the reflex theory
The term "reflex" means a stereotyped reaction of a living organism to an external stimulus. Surprisingly, this concept has mathematical roots. The term was introduced into science by the physicist Rene Descartes, who lived in the 17th century. He tried to explain with the help of mathematics the laws by which the world of living organisms exists.
Rene Descartes is not the founder of the reflex theory in its modern form. But he discovered much of what later became part of it. Descartes was helped by William Harvey, an English physician who was the first to describe the circulatory system in the human body. However, he also presented it as a mechanical system. Later this method will be used by Descartes. If Harvey transferred his principle to the internal structure of the body, then his French colleague applied thisconstruction on the interaction of the organism with the external world. He described his theory using the term "reflex", taken from the Latin language.
The importance of Descartes' discoveries
The physicist believed that the human brain is the center responsible for communication with the outside world. In addition, he suggested that nerve fibers come from it. When external factors affect the ends of these threads, a signal is sent to the brain. It was Descartes who became the founder of the principle of materialistic determinism in the reflex theory. This principle is that any nervous process occurring in the brain is caused by the action of an irritant.
Much later, the Russian physiologist Ivan Sechenov (the founder of the reflex theory) rightly called Descartes one of those scientists on whom he relied in his research. At the same time, the French had many delusions. For example, he believed that animals, unlike humans, act mechanically. The experiments of another Russian scientist - Ivan Pavlov - showed that this is not so. The nervous system of animals has the same structure as that of humans.
Ivan Sechenov
Another important contributor to the development of reflex theory is Ivan Sechenov (1829–1905). He was an educator and creator of Russian physiology. The scientist was the first in world science to suggest that the higher parts of the brain work only on reflexes. Before him, neurologists and physiologists did not raise the question that, perhaps, allthe mental processes of the human body are of a physiological nature.
During research in France, Sechenov proved that the brain affects motor activity. He discovered the phenomenon of central inhibition. His research made a splash in the then physiology.
Formation of the reflex theory
In 1863, Ivan Sechenov published the book "Reflexes of the Brain", which removes the question of who is the founder of the reflex theory. In this work, many ideas were formulated that formed the basis of the modern doctrine of the higher nervous system. In particular, Sechenov explained to the public what the reflex principle of regulation is. It lies in the fact that any conscious and unconscious activity of living organisms is reduced to a reaction within the nervous system.
Sechenov not only discovered new facts, but also did a great job of summarizing already known information about the physiological processes inside the body. He proved that the influence of the external environment is necessary both for the usual pulling of the hand, and for the appearance of a thought or feeling.
Criticism of Sechenov's ideas in Russia
Society (especially Russian) did not immediately accept the theory of a brilliant physiologist. After the book "Reflexes of the Brain" was published, some of the scientist's articles were no longer published in Sovremennik. Sechenov boldly attacked the theological ideas of the Church. He was a materialist and tried to prove everything in terms of physiological processes.
Despite the ambiguous assessment in Russia, the fundamentals of the theoryreflex activity were warmly welcomed by the scientific community of the Old World. Sechenov's books began to be published in Europe in gigantic editions. The scientist even moved his main research activities to Western laboratories for some time. He worked productively with the French physician Claude Bernard.
Receptor theory
In the history of science, one can find many examples of scientists going down the wrong path, offering ideas that did not correspond to reality. The receptor theory of sensations, which contradicts the views of Sechenov and Pavlov, can be called such a case. What is their difference? The receptor and reflex theory of sensations explain the nature of the body's reaction to external stimuli in different ways.
Both Sechenov and Pavlov believed that the reflex is an active process. This point of view has been entrenched in modern science and today is considered finally proven. The activity of the reflex lies in the fact that living organisms react more sharply to some stimuli than to others. Nature separates the necessary from the unnecessary. The receptor theory, on the contrary, says that the sense organs react passively to the environment.
Ivan Pavlov
Ivan Pavlov is the founder of the reflex theory along with Ivan Sechenov. He studied the nervous system all his life and developed the ideas of his predecessor. This phenomenon attracted the scientist with its complexity. The principles of the reflex theory have been proven empirically by a physiologist. Even people far from biology and medicine have heard the phrase "Pavlov's dog." Of course, it is notabout one animal. This refers to the hundreds of dogs that Pavlov used for his experiments.
The impetus for the discovery of unconditioned reflexes and the final formation of the entire reflex theory was a simple observation. Pavlov had been studying the digestive system for ten years and had many dogs in his laboratory, whom he loved very much. One day, a scientist wondered why an animal would salivate even before it was given food. Further observations showed a surprising connection. Saliva began to flow when the dog heard the clink of dishes or the voice of the person who brought her food. Such a signal triggered a mechanism that caused the production of gastric juice.
Unconditioned and conditioned reflexes
The above case interested Pavlov, and he began a series of experiments. What conclusions did the founder of the reflex theory come to then? As far back as the 17th century, Descartes spoke about the body's reactions to external stimuli. The Russian physiologist took this concept as a basis. In addition, Sechenov's reflex theory helped him. Pavlov was his direct student.
Watching dogs, the scientist came to the idea of unconditioned and conditioned reflexes. The first group included congenital features of the organism, transmitted by inheritance. For example, swallowing, sucking, etc. Pavlov called conditioned reflexes those that a living being receives after birth due to personal experience and environmental characteristics.
These qualities are not inherited - they are strictly individual. In the same timethe organism may lose such a reflex if, for example, environmental conditions have changed, and it is no longer needed. The most famous example of a conditioned reflex is Pavlov's experiment with one of the laboratory dogs. The animal was taught that food is brought after the light bulb turns on in the room. Next, the physiologist monitored the appearance of new reflexes. And indeed, soon the dog began to salivate by itself when he saw the light bulb turned on. At the same time, they did not bring food to her.
Three principles of theory
The generally accepted principles of Sechenov-Pavlov's reflex theory boil down to three rules. What are they? The first of them is the principle of materialistic determinism, formulated by Descartes. According to him, each nervous process is caused by the action of an external stimulus. The reflex theory of mental processes is based on this rule.
The second is the principle of structure. This rule states that the structure of the parts of the nervous system directly depends on the quantity and quality of their functions. In practice, it looks like this. If an organism does not have a brain, then its higher nervous activity is primitive.
The last principle is the principle of analysis and synthesis. It lies in the fact that inhibition occurs in some neurons, while excitation occurs in others. This process is a physiological analysis. As a result, a living organism can distinguish between surrounding objects and phenomena.
