A Gold Rush family
Joseph Erlanger was born in San Francisco on January 5, 1874, the sixth of seven children of Herman and Sarah Erlanger. Both his parents were Jewish immigrants from the Kingdom of Württemberg in southern Germany; his father came from the town of Buchau. They met in California during the Gold Rush, part of the wave of German Jews who settled in the American West in the mid-nineteenth century and built businesses and communities in its new cities.
Erlanger grew up in San Francisco and studied chemistry at the University of California, Berkeley, graduating with a Bachelor of Science in 1895. He then crossed the country to study medicine at the new Johns Hopkins School of Medicine in Baltimore, the institution that was transforming American medicine by joining science and clinical training.
Johns Hopkins and the heart
Erlanger received his medical degree from Johns Hopkins in 1899, second in his class, and trained for a year at Johns Hopkins Hospital under the great physician William Osler. A paper he published in 1901 on digestion in dogs caught the attention of the physiologist William Henry Howell, who recruited him to the physiology department, where he rose to associate professor.
His early research was on the circulation. He studied the principles of measuring blood pressure and designed and patented a recording sphygmomanometer that measured pressure at the brachial artery of the arm, the site still used for blood pressure readings today; he used it to study how pulse pressure affects the kidneys. He also devised a clamp that could temporarily block the bundle of fibres that carries the heartbeat signal from the upper to the lower chambers of the heart, allowing him to produce and study heart block in animals, an important step in understanding a condition that is now treated with pacemakers.
He also investigated the mechanism by which sound is produced in arteries. These are the tapping sounds a nurse listens for through a stethoscope while letting the air out of a blood pressure cuff, and understanding where they come from was part of making blood pressure measurement reliable. Erlanger’s instruments let him study, in human subjects, how changes in pulse pressure affect the kidneys and conditions such as orthostatic albuminuria, in which protein appears in the urine after standing.
Building physiology departments
In 1906 Erlanger became the first professor of physiology at the newly established medical school of the University of Wisconsin in Madison. One of his students there was Herbert Spencer Gasser, who would become his closest collaborator. In 1910 he moved to Washington University in St. Louis, which was reorganising its medical school along the Johns Hopkins model and offered him more support for research. He chaired its physiology department for 36 years, until 1946.
Gasser soon joined him in St. Louis. During the First World War the two men worked on traumatic shock, the dangerous collapse of the circulation after severe injury, which was killing many wounded soldiers.
Gasser later became director of the Rockefeller Institute for Medical Research in New York, but the partnership that began in Wisconsin and St. Louis remained the core of both men’s scientific reputations. Their collaboration ended in 1931, when Gasser moved to Cornell, and Erlanger continued to study the excitability of nerves with his own students.
Watching a nerve signal
By the early 1920s physiologists knew that nerve impulses are electrical waves, but their instruments were too slow and insensitive to show the shape of a signal in a nerve. In 1922 Erlanger and Gasser took a Western Electric cathode-ray oscillograph, an instrument designed for electrical engineering, and adapted it, with amplifiers, to record the tiny, brief electrical impulses travelling along the sciatic nerve of a frog. For the first time the action potential of a nerve could be seen on a screen and measured in detail.
Their recordings showed that a nerve, which looks like a single cable, is really a bundle of fibres of many different thicknesses, and that its overall signal is made up of several separate waves arriving at different times. They demonstrated that the speed at which a fibre conducts an impulse depends on its diameter: the thicker the fibre, the faster the signal. This confirmed an idea that had been suggested but never proved.
Standing on the shoulders of giants
Erlanger and Gasser built on a century of discovery. In the mid-nineteenth century Emil du Bois-Reymond showed that the nerve impulse is a wave of electrical change, and Hermann von Helmholtz first measured its speed. In the 1920s Edgar Adrian, who received the Nobel Prize in 1932, showed that nerves signal by trains of identical impulses, faster or slower depending on the strength of a stimulus. In 1907 the Swedish physiologist Gustaf Göthlin had predicted, from the physics of electrical cables, that thicker fibres should conduct faster, and the French physiologist Louis Lapicque had found indirect evidence for it.
What was missing was a way to see the signals of individual groups of fibres directly. The fibres in a nerve range from less than a thousandth of a millimetre to just over two hundredths of a millimetre across. The Nobel committee described Erlanger and Gasser’s papers as remarkable both for their technique and for the wealth of new information they revealed, and called their work the third great milestone in the understanding of nerve physiology.
A, B and C fibres
Erlanger and Gasser sorted nerve fibres into three main groups. The thickest, the A fibres, conduct impulses at up to about 100 metres per second and carry the signals for muscle movement, position sense and touch. The B fibres conduct at about 3 to 14 metres per second. The thinnest, the C fibres, conduct at less than 2 metres per second, and, as their work and later research showed, carry much of the sensation of pain, especially slow, burning pain. They also showed that sensory and motor fibres differ in how easily they are excited. They also mapped how the three types of fibre are distributed among the sensory and motor roots that enter and leave the spinal cord.
This classification gave physiology a new picture of the nervous system as a highly differentiated network rather than a set of identical wires. In 1937 they summarised their work in a book, Electrical Signs of Nervous Activity. In 1944 they shared the Nobel Prize in Physiology or Medicine “for their discoveries relating to the highly differentiated functions of single nerve fibres.” Because of the Second World War, no ceremony was held in Stockholm that year.
Presenting the prize, the Swedish neurophysiologist Ragnar Granit said that as soon as their first results gave them the key, discovery followed hard upon discovery, until colleagues everywhere came to realise that a great new synthesis had been born in nerve physiology, one on which the future study of the brain and spinal cord would be built.
How patients benefit
Erlanger and Gasser’s findings are the foundation of the nerve conduction study, a routine hospital test in which small electrical pulses are applied to a nerve and the speed and size of the response are measured. Doctors use it every day to diagnose carpal tunnel syndrome, nerve damage from diabetes, Guillain-Barré syndrome and many other disorders, because damaged or demyelinated fibres conduct more slowly.
Their discovery that different sensations travel on fibres of different size also explains everyday medical experience. Local anaesthetics block thin pain fibres before thicker fibres, which is why a dental injection can stop pain while some sensation of pressure remains, and anaesthetists use this knowledge when they plan nerve blocks and spinal anaesthesia. The A, B and C classification is still taught to every medical student, and modern pain research, including the search for non-opioid painkillers that target the small fibres that carry pain, builds on it.
Jewish roots and family
Erlanger was the son of two Jewish immigrants from Württemberg, and his family story is part of the history of the Jewish pioneers of California. He is counted among Jewish Nobel laureates by the Jewish Virtual Library and Wikipedia. Little is recorded about his own religious practice.
In 1906 he married Aimée Hirstel. They had three children: Margaret, born in 1908; Ruth Josephine, born in 1910; and Herman, born in 1912, who died in 1959, the same year as his mother. The Joseph Erlanger House in St. Louis was designated a National Historic Landmark in 1976.
Later years and legacy
Erlanger received honorary doctorates from the universities of California, Wisconsin, Pennsylvania and Michigan and was elected to the National Academy of Sciences in 1922 and the American Philosophical Society in 1927. After retiring as department chairman in 1946 he remained at Washington University as professor emeritus and continued to work on nerve physiology. He died of heart disease in St. Louis on December 5, 1965, at the age of 91.
In 2009 the International Astronomical Union named a crater on the Moon after him. His more practical monument is in every neurology clinic: whenever a doctor measures how fast a patient’s nerves conduct, or explains why some nerves carry sharp pain and others dull ache, they are using the map of the nervous system that Erlanger and Gasser first drew with an engineer’s oscilloscope in St. Louis.
Sources & further reading
Joseph Erlanger, Biographical, NobelPrize.org · Award ceremony speech, Nobel Prize in Physiology or Medicine 1944, NobelPrize.org · Joseph Erlanger, Jewish Virtual Library · Joseph Erlanger, Wikipedia · Researched from the sources above and checked against them. Spotted an error? Tell us.
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