Transcript Ivan Pavlov - BDoughertyAmSchool

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 MathematicsPhysics 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 demonstration 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-shutdown 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=hhqumfpx
uzI
http://www.youtube.com/watch?v=yRLfRRN
oZzI
http://revver.com/video/118759/science-ofhumor-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