Each biology textbook says that the founder of reflex theory is Ivan Pavlov. This is true, however, even before the famous Russian physiologist, the nervous system was studied by many researchers. Of these, the teacher Pavlova Ivan Sechenov made the largest contribution.
Prerequisites for reflex theory
The term "reflex" means the stereotypical response 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 XVII century. He tried to explain with the help of mathematics those laws by which the world of living organisms exists.
Rene Descartes is not the founder of 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 in the form of a mechanical system. Later, Descartes will use this method. If Harvey transferred his principle to the internal structure of the body, then his French colleague applied this design to the interaction of the body with the outside world. He described his theory using the term âreflexâ, 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 came from him. When external factors affect the ends of these threads, the signal enters the brain. It was Descartes who became the founder of the principle of materialistic determinism in reflex theory. This principle is that any nervous process that occurs in the brain is caused by the action of an irritant.
Much later, the Russian physiologist Ivan Sechenov (founder of reflex theory) rightly called Descartes one of those scientists on whom he relied in his research. At the same time, the Frenchman had many misconceptions. 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 in humans.
Ivan Sechenov
Another person who made an important contribution to the development of reflex theory is Ivan Sechenov (1829â1905). He was an educator and creator of domestic 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, possibly, all the mental processes of the human body are physiological in 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.
The formation of reflex theory
In 1863, Ivan Sechenov published the book âReflexes of the brain,â which removes the question of who the founder of reflex theory is. 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 comes down to a reaction within the nervous system.
Sechenov not only discovered new facts, but also did a great job of summarizing the already known information about physiological processes within the body. He proved that the influence of the external environment is necessary both for the usual pulling of the hand, and for the emergence of thoughts or feelings.
Criticism of Sechenov's ideas in Russia
Society (especially Russian) did not immediately accept the theory of a brilliant physiologist. After the book âBrain Reflexesâ was published, some of the scientistâs articles were no longer published in Sovremennik. Sechenov boldly attacked theological church ideas. He was a materialist and tried to prove everything in terms of physiological processes.
Despite an ambiguous assessment in Russia, the basics of the theory of reflex activity were warmly received by the scientific community of the Old World. Sechenovâs books began to be published in Europe in gigantic print runs. The scientist even for some time transferred his main research activity to Western laboratories. He worked productively with the French physician Claude Bernard.
Receptor theory
In the history of science, one can find many examples of how scientists took the wrong path, proposing ideas that were not true. Such a case can be called the receptor theory of sensations, which contradicts the views of Sechenov and Pavlov. What is their difference? The receptor and reflex theory of sensations differently explain the nature of the body's reaction to external stimuli.
Both Sechenov and Pavlov believed that reflex is an active process. This point of view is entrenched in modern science and today is considered to be conclusively proven. The activity of the reflex is that living organisms react more sharply to some stimuli than others. Nature separates the necessary from the unnecessary. The receptor theory, on the contrary, says that the sensory organs react passively to the environment.
Ivan Pavlov
Ivan Pavlov - the founder of 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 reflex theory were proved by a physiologist experimentally. Even people far from biology and medicine have heard the phrase "Pavlovâs dog." Of course, we are not talking about one animal. This refers to 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. For ten years Pavlov studied the digestive system and had in his laboratory many dogs that he loved very much. Once a scientist wondered: why does an animal have saliva even before it is given food. Further observations showed an amazing connection. Saliva began to stand out when the dog heard the clatter of dishes or the voice of the person bringing her food. Such a signal triggered a mechanism causing 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 reflex theory come to then? Descartes in the XVII century 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 the dogs, the scientist came up with the idea of ââunconditioned and conditioned reflexes. The first group included congenital characteristics of the body, transmitted by inheritance. For example, swallowing, sucking, etc. Pavlov called those conditioned reflexes that a living creature receives after being born through personal experience and environmental features.
These qualities are not inherited - they are strictly individual. At the same time, the body may lose such a reflex if, for example, environmental conditions have changed, and it is no longer necessary. The most famous example of a conditioned reflex is Pavlovâs experiment with one of the laboratory dogs. The animal was taught that they bring food after the light is turned on in the room. Further, the physiologist monitored the appearance of new reflexes. And indeed, soon the dog began to salivate by itself when she saw the light on. However, she was not brought food.
The three principles of theory
The generally recognized principles of Sechenov-Pavlov reflex theory are reduced to three rules. What are they? The first of these 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 structurality. This rule states that the structure of the departments of the nervous system directly depends on the quantity and quality of their functions. In practice, this is as follows. If the body 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 in some neurons inhibition occurs, and in others - excitation. This process is a physiological analysis. As a result of it, a living organism can distinguish surrounding objects and phenomena.