Alan Lloyd Hodgkin, Sir | Biography

Alan Lloyd Hodgkin built the foundations of much of modern neuroloscience by defining the electrical and chemical characteristics of nerve impulses. Along with Andrew F. Huxley, the two described the firing of nerve impulses, for conducting the impulse along the axon, and for founding the new science of ion channels. The two performed experiments on the nerve fibers of squid and described the nerve impulses with a series of mathematical equations. For their research in this area, which resulted in the ionic theory of nerve impulses, the two men shared the 1963 Nobel Prize in physiology or medicine with John C. Eccles.

Hodgkin was born in Banbury, Oxfordshire, England, to George L. and Mary Wilson Hodgkin. Hodgkin's father died in Baghdad during World War I, only a few years after his birth. Hodgkin was educated at the Downs School in Malvern and the Gresham School in Holt. In 1932, he entered Trinity College, Cambridge, where he first became interested in physiology. Hodgkin became a fellow at Trinity in 1936, serving as lecturer and later as assistant director of research at the physiological laboratory.

Hodgkin began studying the electrical properties of the nerve fibers in the shore crab while at Cambridge. He spent a year at the Rockefeller Institute in New York City between 1937 and 1938, and while there he met scientists who had developed new methods for studying nerve fibers. Hodgkin brought these ideas back to Cambridge, where with Andrew Huxley He devised an experiment to test an hypothesis about nerve impulses first proposed by German physiologist Julius Bernstein.

Bernstein had hypothesized that nerve cells possess a resting or unstimulated potential and an action or stimulated potential. During the resting potential, he believed, the nerve cell membrane had an unequal distribution of positively and negatively charged ions, with more negative ones on the inside. During resting potential, the membrane was permeable to the positively charged ions, but the negatively charged ions could not permeate the cell membrane. When the cell was stimulated, Bernstein argued, the membrane "gates" were temporarily opened, allowing ions to pass in both directions. By using the nerve cells of the shore crab, Hodgkin was able to establish that the resting potential was due to an outward movement of potassium ions; during the action potential the cell membrane's gates allowed in the more concentrated sodium ions. He also discovered that the action potential was usually much larger than the resting potential.

Some of the researchers Hodgkin had met in the United States were working with squid, whose nerve fibers are larger than those of most organisms. Hodgkin and Huxley were able to develop a method to study these fibers using microelectrodes, and they were able to confirm the results of their earlier experiment. Their progress, however, came to a halt during World War II, when Hodgkin worked on radar systems for aircraft for the Air Ministry. Hodgkin and Huxley were back in Cambridge in 1945, and they formed a small research group to pursue their pre-war investigations into nerve fibers.

In 1951, Hodgkin and his colleagues published the results of their research. They found that the membrane is permeable only to specific ions during the resting potential, because of the differing concentrations of potassium and sodium. The concentration of the positively charged sodium ions is greater on the outside of the membrane and the concentration of negative potassium ions higher on the inside during resting potential. During the action potential, the negative and positive ions travel through the membrane, so that the interior charge becomes positive and the exterior negative. This is followed by an equilibrium charge, then a return to the resting potential charge state. All this happens in milliseconds.

The work done by Hodgkin and Huxley which was most responsible for bringing them to the attention of the Nobel Prize committee was the development of a series of mathematical formulae they published in 1952. The purpose of these equations was to synthesize the experimental information then available about the electrical and chemical nature of nerve transmissions. Their goal was to analyze and predict each stage in the passage of the nerve cell membrane from resting to action potential. They were awarded the 1963 Nobel Prize in physiology or medicine, which they shared with John C. Eccles, an Australian who advanced the British team's findings by showing what happens to nerve impulses transmitted across the synapses, or intersections, between nerve cells.

Hodgkin was appointed Foulerton Research Professor of the Royal Society in 1952, and was awarded the Royal Medal in 1958. He was knighted in 1972, and the following year was appointed to the Order of Merrit, a British honor restricted to only 24 people at any one time. He was John Humphrey Plummer Professor of Biophysics at Cambridge from 1970 to 1981, president of the Marine Biological Association from 1966 to 1976. From 1970 to 1975 he served as President of the Royal Society, and from 1978 to 1984 as Master of Trinity College.

Hodgkin married the daughter of American Nobel Laureate Peyton Rous in 1944. The couple met during Hodgkin's year at the Rockefeller Institute in New York, and eventually had four children.