Ivan Pavlov By: Valentina Villeda

Influences in Early Life Ivan Petrovich Pavlov was born on September 14, 1849 in the small town of Ryazan, about 100 miles southeast of Moscow. He was the eldest of five children. His father was a priest in one of the poorer parishes. Pavlov lived most of is early life in extreme poverty. Pavlov was going to study to become a priest but he then changed his mind. So he entered school during the Russian cultural revolution of the 1860's and was exposed to the leaders of this revolution, such as Turgeanyev, Doskovsky, Tolstoy, etc. However, he was apparently most heavily influenced by Pisarev, from whom he learned of Darwin's theory of natural selection and the famous Russian physiologist Sechenov, who had just published Reflexes of the Brain in 1863. It is clear that these kinds of influences on Pavlov steered him in the direction of science and consequently because he left the ecclesiastical seminary and entered the Mathematics-Physics Department at St. Petersburg State University.

Early Life In 1875 Pavlov graduated from the University with a degree in natural sciences. However, due to his interest in physicology he started work as an assistant in the Department of Physiology in the Medical Surgery Academy and in 1879 received a medical diploma. He was then recommended for an appointment with Andre Botkin, who was the most renowned clinician in St. Petersburg at the time. Botkin assigned Pavlov the task of heading his recently established experimental research laboratory. Since Botkin had little interest in experimental work, Pavlov was able to work pretty much independently on problems of his choice. He worked here until 1890. He was heavily influenced by Botkin's theories on the role that the nervous system plays in the regulation of physiological function, and it was here that Pavlov began his studies of the peripheral nerves of the heart and where in 1883 he successfully defended his doctoral dissertation in this area.

Years 1891 - 1900 It was at the Institute of Experimental Medicine in the years 1891-1900 that Pavlov did the bulk of his research on the physiology of digestion. It was here that he developed the surgical method of the «chronic» experiment with extensive use of fistulas, which enabled the functions of various organs to be observed continuously under relatively normal conditions. This discovery opened a new era in the development of physiology, for until then the principal method used had been that of «acute» vivisection, and the function of an organism had only been arrived at by a process of analysis. This meant that research into the functioning of any organ necessitated disruption of the normal interrelation between the organ and its environment.

Studies Pavlov  realized his favorite subject was that of physiology, and it wasn't long before he produced his first paper with a felllow student. On The Physiology of the Pancreatic Nerves for which he was awarded a gold medal.  Pavlov completed his course and received the degree of Candidate of Natural Sciences. Pavlov was also Director of the Physiological Laboratory at the clinic of S. P. Botkin , a famed Russian physician.  It was there he produced his doctoral thesis on The Centrifugal Nerves of the Heart, for which he was later awarded the Nobel Prize in Medicine/ physiology in 1904.

Marriage and Working Life In St. Petersburg State University Pavlov met Seraphima Vasilievna, who was in her last year at the Pedagogical Institute. They were married in 1881. During the first years of their married life they lived in extreme poverty. Seraphima had a lot of miscarriges.Then they had four children. Based on Seraphima's memoirs published after Pavlov's death she apparently enjoyed a happy family life. In 1883 Pavlov spent two years working abroad in the laboratories of Heidenhain and Ludwig in Germany. On his return to St. Petersburg, he resumed his work in Botkin's laboratory and in 1890 was appointed Professor in the Pharmacology Department at the Military Medical Academy. Five years later he joined the Physiology Department there, which he headed for the rest of his career. He was later also appointed the Head of the Department of Physicology in the newly established Institute of Experimental Medicine. Pavlov worked in his laboratory until his death at the age of 87 in Leningrad February 27, 1936.

Research Pavlov's research into the physiology of digestion led him logically to create a science of conditioned reflexes. In his study of the reflex regulation of the activity of the digestive glands, Pavlov paid special attention to the phenomenon of «psychic secretion», which is caused by food stimuli at a distance from the animal. By employing the method - developed by his colleague D. D. Glinskii in 1895 - of establishing fistulas in the ducts of the salivary glands, Pavlov was able to carry out experiments on the nature of these glands. A series of these experiments caused Pavlov to reject the subjective interpretation of «psychic» salivary secretion and, on the basis of Sechenov's hypothesis that psychic activity was of a reflex nature, to conclude that even here a reflex - though not a permanent but a temporary or conditioned one - was involved.

Gastric and pancreatic secretion The traditional teaching of the "cephalic phase" of gastric and pancreatic secretion originated with Pavlov. Students learn that stimulation of gastric secretion of acid and pepsin and stimulation of pancreatic secretion of digestive enzymes starts with the anticipation of the ingestion of a desirable meal and is mediated by input to the stomach and pancreas from efferent nerves of the vagus. Pavlov’s cephalic phase was a brilliant demon-stration of a brain-gut interaction. The stimulation of secretion evoked by linking environmental stimuli with presentation of appetizing food was discovered by Pavlov in his dogs and was called by what is now a classic term: a "conditioned reflex."

Gastric and pancreatic secretion The descriptions by the American army surgeon, William Beaumont of how the appearance of the gastric mucosa mirrored the emotional state of his patient Alexis St. Martin preceded Pavlov’s work on brain-gut interactions in dogs. Beaumont’s studies laid the groundwork for Pavlov’s work and are the beginning of the arrow of time that points to what modern physiologists now understand about the digestive tract as an integrated system. Pavlov was a master experimental surgeon. His development of the "Pavlov pouch" enabled the discovery of the cephalic phase of secretion and its role in the anticipatory preparation of the upper digestive tract for the ingestion of a meal.

Pavlov´s Experiment In the early twentieth century, Russian physiologist Ivan Pavlov did Nobel prize-winning work on digestion. While studying the role of saliva in dogs’ digestive processes, he stumbled upon a phenomenon he labeled “psychic reflexes.” While an accidental discovery, he had the foresight to see the importance of it. Pavlov’s dogs, restrained in an experimental chamber, were presented with meat powder and they had their saliva collected via a surgically implanted tube in their saliva glands. Over time, he noticed that his dogs who begin salivation before the meat powder was even presented, whether it was by the presence of the handler or merely by a clicking noise produced by the device that distributed the meat powder.

Pavlov´s Dog Experiment Fascinated by this finding, Pavlov paired the meat powder with various stimuli such as the ringing of a bell. After the meat powder and bell (auditory stimulus) were presented together several times, the bell was used alone. Pavlov’s dogs, as predicted, responded by salivating to the sound of the bell (without the food). The bell began as a neutral stimulus (i.e. the bell itself did not produce the dogs’ salivation). However, by pairing the bell with the stimulus that did produce the salivation response, the bell was able to acquire the ability to trigger the salivation response. Pavlov therefore demonstrated how stimulus-response bonds are formed. He dedicated much of the rest of his career further exploring this finding.

Pavlov´s Dog Experiment The concept of classical conditioning is studied by every entry-level psychology student, so it may be surprising to learn that the man who first noted this phenomenon was not a psychology at all. Ivan Pavlov was a noted Russian physiologist who went on to win the 1904 Nobel Prize for his work studying digestive processes. It was while studying digestion in dogs that Pavlov noted an interesting occurrence – his canine subjects would begin to salivate whenever an assistant entered the room.

Pavlov´s Dog Experiment In his digestive research, Pavlov and his assistants would introduce a variety of edible and non-edible items and measure the saliva production that the items produced. Salivation, he noted, is a reflexive process. It occurs automatically in response to a specific stimulus and is not under conscious control. However, Pavlov noted that the dogs would often begin salivating in the absence of food and smell. He quickly realized that this salivary response was not due to an automatic, physiological process.

Classical Conditioning Based on his observations, Pavlov suggested that the salivation was a learned response. The dogs were responding to the sight of the research assistants' white lab coats, which the animals had come to associate with the presentation of food. Unlike the salivary response to the presentation of food, which is an unconditioned reflex, salivating to the expectation of food is a conditioned reflex.

Pavlov´s Dog Experiment In technical terms, the meat powder is considered an unconditioned stimulus (UCS) and the dog’s salivation is the unconditioned response (UCR). The bell is a neutral stimulus until the dog learns to associate the bell with food. Then the bell becomes a conditioned stimulus (CS) which produces the conditioned response (CR) of salivation after repeated pairings between the bell and food.

Inluences on Watson John B. Watson further extended Pavlov’s work and applied it to human beings. In 1921, Watson studied Albert, an 11 month old infant child. The goal of the study was to condition Albert to become afraid of a white rat by pairing the white rat with a very loud, jarring noise (UCS).  At first, Albert showed no sign of fear when he was presented with rats, but once the rat was repeatedly paired with the loud noise (UCS), Albert developed a fear of rats. It could be said that the loud noise (UCS) induced fear (UCR). The implications of Watson’s experiment suggested that classical conditioning could cause some phobias in humans.

Reflex System Search Pavlov contributed to many areas of physiology and neurology. Most of his work involved research in temperament, conditioning and involuntary reflex actions. Pavlov performed and directed experiments on digestion, eventually publishing The Work of the Digestive Glands in 1897, after 12 years of research. His experiments earned him the 1904 Nobel Prize in Physiology and Medicine. These experiments included surgically extracting portions of the digestive system from animals, severing nerve bundles to determine the effects, and implanting fisulas between digestive organs and an external pouch to examine the organ's contents. This research served as a base for broad research on the digestive system.

Reflex System Search Further work on reflex actions involved involuntary reactions to stress and pain. Pavlov extended the definitions of the four temperament types under study at the time: phlegmatic, choleric, sanguine, and melancholic, updating the names to "the strong and impetuous type, the strong equilibrated and quiet type, the strong equilibrated and lively type, and the weak type." Pavlov and his researchers observed and began the study of Transmarginal inhibition (TMI), the body's natural response of shutting down when exposed to overwhelming stress or pain by electric shock. This research showed how all temperament types responded to the stimuli the same way, but different temperaments move through the responses at different times. He commented "that the most basic inherited difference. .. was how soon they reached this shutdown point and that the quick-to-shut-down have a fundamentally different type of nervous system."

Pavlov´s Legacies Pavlov forever clung to the strong belief that chronic studies in surgically prepared conscious animals were most likely to yield new insights into the integrated physiology of organ systems in general and the digestive system in particular. Leading up to the Pavlovian period, acute preparations in anesthetized animals were the norm for experimental physiology. Pavlov believed, and one might say proved, that sequentially repetitive studies in surgically prepared conscious animals are most likely to advance knowledge basic to humans. That we must understand the normal functioning of an organ in the alert animal, as well as its anatomy, histology, and cellular biology, to know disease has been the standard since Pavlov. Pavlov’s legacy in experimental surgery, which could equally well be referred to as "applied surgical physiology," embraces too many subsequent pioneers to mention even a few.

1890 important year 1890 was an important year for Pavlov, as he was asked to oversee the organization and run the Department of Physiology at the Institute of Experimental Medicine.  It was there he would conduct his most historically significant research, and also where he would remain for the rest of his life.  That same year, Pavlov was also appointed Professor of Pharmacology at the Military Medical Academy.

Most Imortant Research Pavlov's main area of research throughout his scientific career was on the digestive process, which brought on a series of experiments exploring the correlation between the nervous system and the autonomic functions of the body.  Pavlov experimented with dogs, studying the relationship between salivation and digestion. By applying stimuli to the animals in a variety of ways, using sound, visual, and tactile stimulation, he was able to make the animals salivate whether they were in the presence of food or not; a phenomenon he called the conditioned reflex.

Honors Pavlov was also elected a corresponding member of the Russian Academy of Sciences in 1901, the Nobel prize in 1904,  he was elected Academician of the Russian Academy of Sciences in 1907, given an honorary doctorate at Cambridge University in 1912, and awarded the Order of the Legion of Honour in 1915, the recommendation of the Medical Academy of Paris. 

Videos http://www.youtube.com/watch?v=hhqumfpxuzI http://www.youtube.com/watch?v=yRLfRRNoZzI http://revver.com/video/118759/science-of-humor-pavlovs-dog/

Quote "Science demands from a man all his life. If you had two lives that would not be enough for you. Be passionate in your work and in your searching."

Bibliography http://www.thewatershipdown.com/Pavlov's%20Biography.htm http://nobelprize.org/nobel_prizes/medicine/laureates/1904/pavlov-bio.html http://psychology.about.com/od/classicalconditioning/a/pavlovs-dogs.htm http://www.ivanpavlov.com/ http://physiologyonline.physiology.org/cgi/content/full/19/6/326 http://www.learning-theories.com/classical-conditioning-pavlov.html http://en.wikipedia.org/wiki/Ivan_Pavlov http://psychology.about.com/od/profilesofmajorthinkers/p/pavlov.htm