Erlanger , Joseph

(1874–1965) American neurophysiologist

Erlanger, the son of a German immigrant drawn to California in the gold rush, was born in San Francisco. He was educated at the University of California and at Johns Hopkins University in Baltimore, where in 1899 he obtained his MD. After working on the staff for a few years Erlanger moved to the University of Wisconsin (1906) to accept the chair of physiology. In 1910 he moved to Washington University, St. Louis, where he held the chair of physiology in the Medical School until his retirement in 1944.

Between 1921 and 1931 Erlanger carried out some fundamental research on the functions of nerve fibers with his former pupil and colleague, Herbert Gasser. They investigated the transmission of a nerve impulse along a frog nerve kept in a moist chamber at constant temperature. Their innovation was to study the transmission with the cathode-ray oscillograph, invented by Ferdinand Braun in 1897, which enabled them to picture the changes the impulse underwent as it traveled along the nerve.

Erlanger and Gasser found that on stimulating a nerve, the resulting electrical activity indicating the passage of an impulse was composed of three waves, as observed on the oscillograph. They explained this by proposing that the one stimulus activated three different groups of nerve fibers, each of which had its own conduction rate. They went on to measure these rates, concluding that the fastest fibers (the A-fibers) conduct with a speed of up to 100 meters per second (mps) while the slowest (the C-fibers) could manage speeds of no more than 2 mps. The intermediate B-fibers conducted in the range 2–14 mps. Erlanger and Gasser were able to relate this variation to the thickness of the different nerve fibers, A-fibers being the largest.

It was a short step from this to the theory of differentiated function, in which it was proposed that the slender C-fibers carry pain impulses whereas the thicker A-fibers transmit motor impulses. But it was soon demonstrated that while such propositions may be broadly true the detailed picture is more complex.

Erlanger and Gasser produced an account of their collaboration inElectrical Signs of Nervous Activity (1937); they were awarded the 1944 Nobel Prize for physiology or medicine for their work.