Ichiji Tasaki

Dr. Ichiji Tasaki (田崎一二) is a Japanese biophysicist and physician involved in research relating to the electical impulses in the nervous system. He is crediting 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. Tasaki was born in Japan in 1910 where he attended medical school at the urging of his mother and received his M.D. in 1938. However, instead of practicing medicine, he 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 [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.] . His description of this process, termed saltatory conduction, is prominent in every biology textbook.

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 [ [Tasaki I. Nerve impulses in individual auditory nerve fibers of guinea pig. J Neurophysiol. 17(2): 97-122, 1954. PMID 13143414] . This effort led to the development of the field of audiology, indirectly providing the basis for diagnosing and treating many hearing disorders.

Research Interests

Tasaki began his NIH career in 1953, at NINDS, then called the National Institute of Neurological Disorders and Blindness. Later, when NIMH separated from that institute, he moved with the new institute, where he was a lab chief for 22 years. He is currently on detail to NICHD. Since coming to NIH, Tasaki has been studying the physical and chemical processes that occur in nerve membranes. [Tasaki I. Rapid structural changes in nerve fibers and cells associated with their excitation processes. Jpn J Physiol. 1999 Apr;49(2):125-38.PMID 10393347] [Tasaki I, Matsumoto G. On the cable theory of nerve conduction. Bull Math Biol. 2002 Nov;64(6):1069-82. PMID 12508531] [Tasaki I. On the conduction velocity of nonmyelinated nerve fibers. J Integr Neurosci. 2004 Jun;3(2):115-24.PMID 15285049]

References

Further reading

[http://intramural.nimh.nih.gov/research/pi/pi_tasaki_i.html Principal Investigator Ichiji Tasaki at the National Institutes of Health]