Human beings and other animals are born with certain abilities (e.g. sucking, crying etc.), but the vast number of techniques that they will later need have to be learned. On of the ways in which this is done is by building on the natural physical abilities (reflex actions) to produce new and different abilities (conditioned reflexes). The most famous experiments relating to this were carried out on dogs by the Russian physiologist Ivan Petrovitch Pavlov.

Ivan Petrovitch Pavlov noted that a dog produced saliva in its mouth when offered food. Every time Ivan Petrovitch Pavlov fed the dog h sounded a bell. Eventually he found that the dog produced saliva when the bell was sounded, even though no food was offered. In other words a new ‘conditioned reflex’ had been ‘learned’, which was not a natural reflex action. Ivan Petrovitch Pavlov’s theory of ‘conditioned reflexes’ helps to explain only some of the ways in which we learn. Also, his later theories on the role of the brain in the formation of ‘conditioned reflexes’ are not supported by experimental evidence. However, there can no doubt that Ivan Petrovitch Pavlov’s work opened up new fields of investigation in nervous physiology and psychology.

Ivan Petrovitch Pavlov was born at Ryazan in 1849. He studied at the University of St. Petersburg and at the Medico-Surgical Academy, graduating in 1883. During his early researches he discovered the nerve fibres supplying the heart and also those to the pancreas. For  twenty years he continued his study of digestive glands, showing that the mere presence of food in the mouth was sufficient to cause gastric juice to be released  in the stomach : the food does not have to reach the stomach.

By means of an ingenious operation Ivan Petrovitch Pavlov was able to isolate part of the stomach, creating a pouch  a Pavlov pouch – that had an opening to the outside through the abdominal wall. He took care not to disrupt the blood or the nerve supply of the pouch or to interfere with the passage of food through the rest of the stomach. On taking food therefore, or merely by the animal looking at it, a rich supply of gastric juice was obtained through the abdominal opening.

For his outstanding work on the physiology of the digestive glands Ivan Petrovitch Pavlov was awarded the Nobel Prize for medicine in 1904. From 1907 onwards he turned his attentions to ‘conditioned reflexes’.

By means of a series of brilliant experiments he showed that such reflexes are linked to certain regions of the forebrain and thus he mapped out areas with different functions.

Ivan Petrovitch Pavlov undoubtedly owed much of his success to his great operative skill. In his later years he devoted much of his time to psychiatric work, examining many patients with diseased brains. This work, with that of Freud, contributed much to the science of psychology. He died in 1936.

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