Ichiji Tasaki (田崎 一二 Tasaki Ichiji, October 10, 1910 – January 4, 2009) was a Japanese-born American biophysicist and physician involved in research relating to the electrical impulses in the nervous system.
Tasaki is credited with discovering the insulating function of the myelin sheath. His discoveries provided the foundation for a better understanding of diseases such as multiple sclerosis, in which myelin is lost or damaged.
Early life and education
In 1910, Tasaki was born in Japan. Here and at the urging of his mother, he attended medical school, from which he received his M.D. in 1938. Rather than practising medicine, however, Tasaki decided to pursue his first love; biophysics.
While in Japan, he studied vertebrate nerve fibers and discovered the insulating function of the myelin sheath, a material that speeds the conduction of nerve impulses. He also was the first to show that electrical impulses traveling along myelinated nerve cells actually "jump" between the breaks in the myelin wrapping, called nodes of Ranvier. This process, termed saltatory conduction, is featured in a majority of physiology textbooks.
After World War II, Tasaki's research took him to England and to Switzerland, where he further studied the properties of nerve fibers. In 1951, he came to the United States to work at Washington University in St. Louis. While there, Tasaki and his colleagues demonstrated how vibrations that occur in the cochlea in response to sound are translated into electrical signals that the brain can interpret. This effort led to the development of the field of audiology, indirectly providing the basis for diagnosing and treating many hearing disorders.
Tasaki began his career at the National Institutes of Health in 1953, at NINDS, then called the National Institute of Neurological Disorders and Blindness. In 1957, he became a naturalized U.S. citizen.
Later, he moved to the NIMH, where he was a lab chief for 22 years. At the time of his death, he was on detail to the Eunice Kennedy Shriver National Institute of Child Health and Human Development. Since coming to NIH, Tasaki studied the physical and chemical processes that occur in nerve membranes.
- "Ichiji Tasaki Neurophysiologist". Washington Post. January 20, 2009. Retrieved 15 August 2011.
- van Hollen, Chris (11 September 2008). "Tribute to Dr. Ichiji Tasaki". United States House of Representatives. Retrieved 15 August 2011.
- Tasaki, I. The electro-saltatory transmission of the nerve impulse and the effect of narcosis upon the nerve fiber. Am J Physiol 127: 211-227, 1939.
- Tasaki, I. and Takeuchi, T. Der am Ranvierschen Knoten entstehende Aktionsstrom und seine Bedeutung für die Erregungsleitung. Pflügers Arch ges Physiol. 244: 696-711, 1941.
- "Biophysicist Tasaki Leaves Extraordinary Scientific Legacy". National Institute of Health. Archived from the original on 21 July 2011. Retrieved 15 August 2011.
- Tasaki, I (1954). "Nerve impulses in individual auditory nerve fibers of guinea pig". Journal of Neurophysiology. 17 (2): 97–122. PMID 13143414.
- Tasaki, I (1999). "Rapid structural changes in nerve fibers and cells associated with their excitation processes". The Japanese journal of physiology. 49 (2): 125–38. doi:10.2170/jjphysiol.49.125. PMID 10393347.
- Tasaki, I; Matsumoto, G (2002). "On the cable theory of nerve conduction". Bulletin of mathematical biology. 64 (6): 1069–82. doi:10.1006/bulm.2002.0310. PMID 12508531.
- Tasaki, I (2004). "On the conduction velocity of nonmyelinated nerve fibers". Journal of integrative neuroscience. 3 (2): 115–24. doi:10.1142/S0219635204000415. PMID 15285049.