Eccles, << EHK uhlz, >> Sir John Carew (1903-1997), an Australian medical researcher, made important discoveries about the transmission of nerve impulses. Nerve impulses are signals that carry messages to and from the brain and other parts of the body. Eccles’s discoveries enabled scientists to learn more about how nerve impulse pathways are organized within the brain. For this work, he shared the 1963 Nobel Prize in physiology or medicine with the English scientists Alan L. Hodgkin and Andrew F. Huxley, who also studied nerve impulse transmission.
Eccles studied an aspect of nerve impulse transmission called the postsynaptic potential. Hodgkin and Huxley had shown that the transmission of a nerve impulse is an electrical and chemical process controlled by the outer membrane of the nerve cell. When an impulse reaches the end of one nerve cell, a chemical called a neurotransmitter is released into the gap between one nerve cell and the next nerve cell. This gap is called the synaptic cleft. The neurotransmitter moves to the next nerve cell and causes certain pores of the nerve membrane to open. Ions (electrically charged atoms) move through these pores, resulting in a voltage change—the postsynaptic potential.
The postsynaptic potential can be either excitatory or inhibitory. An excitatory postsynaptic potential spreads within a nerve cell and increases the likelihood that the cell will transmit a nerve impulse. Eccles determined that the inhibitory postsynaptic potential reduces the likelihood that a nerve cell will transmit a nerve impulse. By blocking certain nerve impulses, the inhibitory postsynaptic potential helps regulate and route the constant flow of impulses throughout the nervous system.
Eccles was born on Jan. 27, 1903, in Melbourne, Australia. He was educated in Warrnambool and Melbourne, and at Oxford University, in England, where he was a Rhodes scholar. He received a Ph.D. from Oxford in 1929 and remained there to teach until 1937, when he returned to Australia. He taught at universities in Sydney and Canberra in Australia and Dunedin in New Zealand. He was knighted in 1958. In 1963, he was named Australian of the Year. Eccles left Australia in 1966 to work in the United States before retiring in Switzerland in 1975. Eccles died on May 2, 1997.
