Physiology. It is uncertain why the pair had such a sudden shift in interest to neuroscience, as Erlanger was already widely respected in the cardiology field. Erlanger and Gasser were able to modify a Western Electric oscilloscope to run at low voltages. Prior to this modification, the only method available to measure neural activity was the electroencephalograph, which could only show large-scale electrical activity. With this technology, they were able to observe that action potentials occurred in two phases—a spike (initial surge) followed by an after-spike (a sequence of slow changes in potential). They discovered that neurons were found in many forms, each with their own potential for excitability. With this research, the pair discovered that the velocity of action potentials was directly proportional to the diameter of the nerve fiber. The partnership ended in 1931, when Gasser accepted a position at Cornell University. In 1944, they won the Nobel Prize in Medicine or Physiology for these discoveries. He died of heart disease on December 5, 1965 at St. Louis, Missouri. The Joseph Erlanger House in St. Louis was designated a National Historic Landmark on December 8, 1976 as a building of national significance. On January 22, 2009, the International Astronomical Union named a crater on the moon after him. Citations References External links including the Nobel Lecture on December 12, 1946 The Discovery of Vitamin K, Its Biological Functions and Therapeutical Application National Academy of Sciences Biographical Memoir 1874 births 1965 deaths Nobel laureates in Physiology or Medicine American Nobel laureates American people of German-Jewish descent American physiologists American neuroscientists Jewish American scientists Johns Hopkins School of Medicine alumni Johns Hopkins University faculty Lowell High School (San Francisco) alumni People from San Francisco Scientists from St. Louis Scientists from Missouri Nobel laureates affiliated with Missouri Washington University in St. Louis faculty University of California, Berkeley alumni