Animals on our planet possess a marvelous adaptation mechanism which helps them to study their environment and accumulate knowledge throughout their lives. This mechanism partly depends on the functions of the sense organs. Their characteristic feature is that they soon become ‘accustomed’ to stimuli of continuous action and stop responding to them, but react at the same time very actively to all new stimuli.
This is probably a phenomenon with which everyone is familiar. If you go into premises from outside and smell a pungent or offensive odor, within a few minutes the odour ceases to irritate you. Your nose becomes accustomed to the odor and stops sending messages about it to the brain. But, if you leave the room for a short time and then come back again, you are immediately aware of the odor again.
Owing to this feature of the sense organs, the brain always receives information on all the new events occurring in the environment. Besides, every new stimulus evokes the orientation reflex, which helps the organism to prepare for any surprise. If a new stimulus, inessential to the animal, is followed by some important events, a conditioned reflex is formed, and the new stimulus becomes a signal announcing the coming of an important event.
Temporary connections are established when two events — one important for the organism and the other inessential — coincide in time. If a dog hears the rattle of its bowl each time before it is given food, it will very soon develop a conditioned reflex, and the rattle alone will eventually be sufficient to evoke salivation and the other reactions previously caused only by food.
Conditioned reflexes are a summary of elementary knowledge of the world around the animal. They reflect the basic laws governing the animal’s environment. When the feeding process is preceded by the rattle of a bowk and this happens several, times, the dog develops a conditioned reflex which means that the animal has ‘noticed’ the interconnection of the two events.
The conditioned stimulus (the rattle of the bowl) has become something like a signal for the second stimulus, and can now evoke all the responses that were formerly only induced by food.
The signalling activity (the formation of temporary connections) is a universal phenomenon common to all animals on our planet. Moreover, there are grounds for believing that this principle is even more universal and valid for any organism, so that even on other planets we may find animals with temporary connections. There is every reason to assume that the formation of temporary connections is one of the basic and universal laws of nature, inherent in all forms of highly organized matter. The specific properties of temporary connections can, of course, vary in each particular case.
The human brain is the greatest wonder Nature has ever wrought on this planet. Science was unable to cope with its astonishing complexity till the twentieth century. The great Russian physiologist Ivan Pavlov and his numerous disciples were responsible for the first major achievements in the study of the brain. Pavlov’s success may be explained by the fact that he fortunately chose to study a phenomenon which, on the one hand, could be regarded a simple physiological act and investigated by conventional physiological methods of research, but which was, on the other hand, a psychic phenomenon. Moreover, this phenomenon was later found to be the very elementary psychic act which, according to Pavlov, provides the cornerstone of the immense edifice of mental activity and became known as a conditioned reflex.
It would be an exaggeration to say that the theory of conditioned reflexes was generally recognized from the very start. The older generation of scientists have not forgotten the time when very few people believed that it would ever be possible to comprehend the extremely involved functions of the human brain. The situation has changed since then. But even now there are still those who doubt that mental activity is based only on systems of conditioned reflexes (or temporary connections), that is on extremely simple reactions in the organism.
Our brain doubtlessly has many mechanisms of mental activity so far obscure to us, but they are all dependent on conditioned reflexes. Any cell in the body, and, of course, any unicellular organism, is more or less capable of retaining traces of the previous stimulations and modifying its reactions according to past experiences, that is it is capable of associating one event with another. This function is more pronounced in the nerve cells whose development made it the prerogative of the nervous apparatus.