Pavlov, Ivan Petrovich

Pavlov, Ivan Petrovich (1849-1936), Russian physiologist and psychologist. Pavlov was the first Russian winner of the Nobel Prize for Physiology or Medicine (1904) for his work on the physiology of digestion, out of which developed his work on behaviour and conditioned reflexes.

Pavlov was born in Ryazan. He initially attended the local theological seminary before turning to medicine. He studied at the University of St Petersburg (1870-1875), where Elie Cyon developed Pavlov’s early interest in physiology (as a boy, he had read I. M. Sechenov’s Cerebral Reflexes and later spoke of its formative influence). Pavlov completed a course in physiology, followed by a two-year fellowship at the St Petersburg Military Medical Academy and qualified as a doctor in 1879, but was already concentrating on a career as a “pure physiologist” (his own description), working in and then eventually leading S. P. Botkin’s laboratory at the Military Medical Academy (1878-1890). Pavlov also spent two years (1884-1886) working abroad with Karl Ludwig in Leipzig and Rudolf Heidenhain in Breslau (now Wrocław).

Botkin’s interest in nervous rather than hormonal control of physiological functions influenced Pavlov. In the course of his long career he succeeded in applying “nervism” (his theory that the “nervous system controls the greatest possible number of bodily activities”) to three areas of physiological research: circulation of the blood (1874-1888), digestion (1879-1897), and the brain and higher nervous activity (1897-1936). These overlapped in time and each project helped generate the next. In all his research, Pavlov concentrated on the relationship between organs and/or organ systems and the whole organism. He did not disregard cellular and molecular reductionism, and the kinds of questions that research at these levels could answer, but it did not interest him. Pavlov continued his work despite the momentous political upheavals that beset Russia during his lifetime, and his later, open criticism of the ruling Communist Party.

Partly in preparation for his doctoral dissertation (1883), he investigated the nervous control of blood pressure and the heart. Here he began to shape his crucial method, the long-term experiment. He surgically prepared animals (usually dogs) to permit qualitative and quantitative investigation of their physiological functions. He considered the use of such whole, neurologically intact, un-anaesthetized animals an advance on vivisection. He was a skilled surgeon who rigorously applied the new antiseptic and aseptic techniques.

In 1890 Pavlov became pharmacology professor in the Military Medical Academy (professor of physiology, 1895) and director of a newly founded St Petersburg Institute of Experimental Investigation. Here he built a loyal team of workers and extended research on his new interest in the physiology of digestion, for which he won the 1904 Nobel Prize. The experimental preparation of the dogs’ digestive tracts yielded much new information including an understanding of the relationship between ingested food and saliva production (Pavlov’s salivary secretion curves), and the discovery of the enzyme enterokinase (with N. P. Shepovalnikov). His research also led to clinical advances in gastroenterology.

At the Nobel Prize presentation ceremony, Pavlov chose to talk about the new research that had arisen from his study of digestion: the use of the salivary reflex as a means to understand the higher mental processes. During his measurement of salivary secretions, Pavlov had become aware that his experimental dogs salivated in response not just to ingested food (what he termed an “unconditioned reflex”) but also to mere presentation of food (a “conditioned reflex”), and later to an unrelated external stimulus, for instance the sound of a bell. As the reflex, salivation, could be measured quantitatively, he believed he had found a way of analysing and explaining behaviour from an external, objective perspective—the perspective of a physiologist. He published his magnum opus Conditioned Reflexes in 1926 (trans. 1927). In time, his research and that of his laboratory (at the Institute of Physiology of the Soviet Academy of Sciences and the Biological Station at Koltushy) became interested in neuroses and increasingly speculative. His views dominated Russian psychiatry, and in the United States, especially, his work inspired the behaviourist school of psychology.