Eccles, John( Australian physiologist, Nobel Prize in Physiology or Medicine, 1963)
Comments for Eccles, John
Biography Eccles, John
genus. January 27, 1903
Australian physiologist John Carew Eccles was born in Melbourne. His mother, Mary Eccles (Carew), and his father, William James Eccles, were teachers. John was the eldest of two children in the family. Within three years he went to school in Uornambule (Victoria), and then returned to Melbourne, where in 1919. and graduated from high school. Then John went to Melbourne University for medical education. It is also strongly attracted to philosophy, especially the 'nature of thinking and consciousness and their relationship with the activity of the brain'. Even then he set out to become a member of the prominent neurophysiologist Charles Sherrington. In 1925, Mr.. E. graduated with honors in medicine and the title of bachelor of medicine at the University of Melbourne. He then continued his education at Magdalen College in Oxford, two years later graduated with honors and began to work with Sherrington in the position of research assistant.
. By this time, Sherrington was already well known for its thorough and comprehensive studies of joint functioning of muscles and neural structures in the reflexes
. Based on their data and work of the founder neuroanatomy Santiago Ramon y Cajal Sherrington formulated the concept of the synapse, ie. of the structure in which an electrical nerve impulse (action potential) is passed from one nerve cell or neuron to another. In addition, he found that, although the main feature of nerve cells is their electrical excitability, not all nerve cells cause the excitation of other. It was found that the inhibition is equally important property of neural connections that excitation. However, at that time was not known how to apply the excitation of individual nerves and synapses, and the differences between inhibitory impulses from stimulating.
. Experiments performed by Otto and Leah Henry Dale in the late 20's and early 30's. Testified that the nerve signals are transmitted through synapses with chemical mediators (neurotransmitters) such as acetylcholine
. This behavior differs substantially from the distribution of electrical action potentials in the nerves themselves. E. did not agree with this hypothesis. He believed that the speed of a synapse is too high and so this behavior can not be achieved by the diffusion of chemical. Thus, he was a supporter of the electrical hypothesis of synaptic transmission.
In 1929, Mr.. E. was awarded a master's and doctoral degrees. In 1934, Mr.. He was appointed professor of physiology at Magdalen College. In those years in Europe felt the approach of war, and in 1937. E. returned to Australia, having received the post of Director of the Institute of Pathology Kanematsu behalf of Sydney Hospital. Here he created a research lab and soon attracted a number of prominent scientists, including Bernard Katz and Stephen Kuffler.
. E., Katz and Kuffler investigated the effect of chemicals on the transfer of excitation from nerve cells to muscle fibers (similar to the work carried out by Daniel Bovet, led to the discovery of modern anesthetics and muscle relaxants)
. Later E. wrote: 'The data on the impact of antiholinosteraznyh means [substances that inhibit the action of certain enzymes], which manifests itself by an increase of the intensity and duration of excitation in the neuromuscular junction, forced me to do in 1942. final conclusion that the neurotransmitter acetylcholine is nervous excitement '. This finding prompted E. abandon the hypothesis of electrical conducting, at least for the neuromuscular synapse.
After the Second World War Z. was forced to interrupt their studies and on the instructions of the commission of Australian armed forces from 1941 to 1943. worked on issues relating to vision, 'air sickness' (sickness) and processing of blood.
In 1944, Mr.. E. moved to New Zealand, where he received the post of professor of physiology at the Medical College, University of Otago. Here he met with Karl Popper - one of the greatest philosophers of the XX century. Dealing with science. Popper believed that the primary role in scientific progress is a refutation of hypotheses. His ideas inspired the E., who was concerned about the fate of the electrical hypothesis of synaptic transmission. Popper was able to convince E. try to disprove his own hypothesis, assuring him that it would be no less important than finding the arguments in its favor.
Inspired by the boards of Popper, E. developed a method of stimulation and recording activity of neurons of the spinal cord in cats. For this he introduced in these neurons the thinnest electrodes. To record the electrical activity of several neurons, . jointly involved in a reflex, . He used a special device - the so-called block electrical stimulation and recording, . designed by Jack Coombs, . one of his staff,
. Reflex arc - a path along which nerve impulses pass from the sensory nerve endings, which receive one or other stimulus to the nerve center and then to a muscle or gland, which carries out a response to stimulation.
. In the quiescent state in the nerve cells of the inner surface of the membrane is in relation to the outer surface of the negative charge of about 60 millivolts
. This potential difference is called the resting potential. When excited by the same inner surface of the membrane acquires a positive charge to the outside, and then quickly restored the original resting potential. This phenomenon was discovered and explained in the 40's - early 50-ies. Alan Hodgkin and Andrew Huxley. Investigating the synaptic interconnected neurons, e. showed that the excitation of 'irritating' (presynaptic) neuron is in the 'stimulated' (postsynaptic) neuron excitatory postsynaptic potential (EPSP).
. In a typical case, EPSP membrane potential deviates from the resting level (- 60 mV) to about - 50 millivolts
. This postsynaptic cell is approaching a state of, . in which there is an action potential, but the action potential appears, . when the potential of postsynaptic neuron reaches the so-called threshold level (about - 40 mV), . a single EPSP is usually not enough for,
. E. and his colleagues showed that action potentials arise as a result of addition of several EPSP.
In the study of neural circuits E. discovered that some of these chains are not exciting, and brake. In these cases, the excitation of the presynaptic neuron causes the so-called inhibitory postsynaptic potential (IPSP), exceeding the resting potential of about 15 millivolts. In 1951, Mr.. E. reported his discovery, . calling it a fatal blow to the hypothesis of electrical synapses in, . because from the perspective of this hypothesis could not be explained, . how 'positive' action potential presynaptic cells in the synapse may become negative IPSP postsynaptic cells.,
. In the same year, E
. left New Zealand because his research hampered by too much teaching load. During the year, he lectured at Magdalen College, then went to Canberra and joined the newly established Australian National University. In Canberra moved and Jack Coombs, and they continued their joint work on the processes of excitation and inhibition. However, they found that the discharge of the neuron depends on the arithmetic sums arising in its IPSP and EPSP. In addition, it was shown that each neuron can have either inhibitory or excitatory effect, but not both. This means that each neuron provides only one type of neurotransmitter. Later E. studied the movement of various ions in the excitatory or inhibitory synapses (ions - atoms or a group of atoms that carry positive or negative electrical charge).
In 1963, Mr.. E. received the Nobel Prize in Physiology or Medicine jointly with Alan Hodgkin and Andrew Huxley 'for their discoveries concerning the ionic mechanisms of excitation and inhibition in the peripheral and central portions of the nerve cells'. In his speech at the awards ceremony a researcher at the Karolinska Institute said Ragnar Granit, . referring to the winners: 'Set the singular nature of electrical processes, . occurring in the peripheral and central nervous system, . you have such clarity in our understanding of the activities of neural structures, . to which our contemporaries do not dream to live '.,
. By that time, when E
. was awarded the Nobel Prize, he took up the study of the cerebellum - part of the brain that controls coordination of muscle movements. The main cells of the cerebellum have been described by Ramon y Cajal at the beginning of the century. E. analyzed their mutual relations and concluded that the inhibition in the cerebellum plays a particularly important role. Reaching the mandatory age of retirement, E. resigned from the Australian National University, but wishing to continue their studies in 1966. moved to Chicago and was appointed Director of the Institute of Biomedical Research of the American Medical Association. Due to the personal and administrative conflicts Z. in 1968. had to leave Chicago and take the post of honorary professor of physiology and medicine at the University of New York at Buffalo. Here E. continued his research activities of the cerebellum until 1975, when he retired and moved to Switzerland, where he finally was able to engage those philosophical issues that interest him from a young age.
In 1928, Mr.. E. married Irene Francis Miller. In their family were four sons and five daughters. In 1968. couple divorced, and in the same year, E. married Helene Taborikovoy, medical scientists from Czechoslovakia. Taborikova participated in many subsequent works E.
E. is a foreign member of the American Academy of Arts and Sciences and the Italian National Academy of Sciences. In addition, he is a member of the Pontifical Academy, the American Philosophical Society, the American National Academy of Sciences, Indian National Academy of Sciences and the Belgian Royal Academy of Sciences. He was awarded the Royal Medal of the Royal Society of London (1962) and a medal Koteniusa Germanskoy Academy of Natural Scientists 'Leopoldina'.