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OBITUARY: ICHIJI TASAKI
Dr. Ichiji Tasaki passed away in Bethesda,
Maryland on Jan 4, 2009 at age 98, six days after
falling and hitting his head. Most of his research
career was devoted to nerve conduction and
excitation and he is known for his discovery of
saltatory conduction in myelinated neurons. In the
auditory community he is recognized for introducing
micropipette electrodes to study the inner ear and
for demonstrating that the endocochlear pontential
is generated by the stria vascularis.
He started his scientific career at Keio
University Medical School, isolating a single nerve
fiber from the frog sciatic nerve. This technique
later lead him to discover saltatory conduction of
myelinated nerve fibers. He demonstrated that
excitation of a node or Ranvier induces a local
current which stimulates the next node of Ranvier,
which is one insulating myelin sheath away. This
finding explains why myelinated nerve fibers
conduct nerve impulses so fast.
His work on hearing was initiated while he was
at the Central Institute for the Deaf in St Louis,
MO in 1951 before he moved to NIH in 1953. Among
other works, Tasaki introduced microelectrode
recording method to the cochlea and published a
paper with Hallowell Davis and Eldredge in 1954,
which clarified the electroanatomy of the cochlea
by describing the endocochlear potential,
intracellular potential, and junction potential.
His demonstration that the source of the
endocochlear potential is the stria vascularis,
coauthored by Spyropoulos, was published in
1959.
He was an early pioneer of using internal
perfusion of squid giant axon for studying nerve
excitation. He later found various changes
associated with nerve excitation including changes
in fluorescence and pressure, a phenomenon somewhat
similar to outer hair motility but with much
smaller magnitude. He is the author of three
monographs, Nervous Transmission (1953), Nerve
Excitation: A Macromolecular Approach (1969), and
Physiology and Electrochemistry of Nerve fibers
(1982).
He had an amazing knack of thinking about
science while watching football games on TV. He
claimed that he needed to play golf to stop
thinking about science. He kept working well into
his 90's studying phase transitions in
polyelectrolyte gels. He was featured in NIH Record
as the oldest working scientist at NIH and retired
on August 1 last year at age 97. He was survived by
his two sons, Akira, a physicist in Tsukuba and
Keiji, a computer scientist in Bethesda, with whose
family he lived after the death of Nobuko, his wife
and long-time assistant, five years ago.
Kuni H. Iwasa
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