Haldan Keffer Hartline
Haldan Keffer Hartline (
December 22,
1903 –
March 17,
1983) was an
American physiologist who was a cowinner (with
George Wald and
Ragnar Granit) of the
1967 Nobel Prize in Physiology or Medicine for his work in analyzing the neurophysiological mechanisms of vision.
Hartline began his study of retinal electrophysiology as a National Research Council Fellow at
Johns Hopkins University,
Baltimore, receiving his M.D. in
1927. After attending the universities of
Leipzig and
Munich as an Eldridge Johnson traveling research scholar, he became professor of
biophysics and chairman of the department at Johns Hopkins in
1949. One of Hartline's graduate students at Johns Hopkins,
Paul Greengard, later also won the Nobel Prize. Hartline joined the staff of
Rockefeller University,
New York City, in
1953 as professor of neurophysiology.
Hartline investigated the electrical responses of the
retinas of certain
arthropods,
vertebrates, and
mollusks because their
visual systems are much simpler than those of humans and are thus easier to study. He concentrated his studies on the eye of the
horseshoe crab (
Limulus polyphemus). Using minute electrodes in his experiments, he obtained the first record of the electrical impulses sent by a single
optic nerve fibre when the receptors connected to it are stimulated by light. He found that the
photoreceptor cells in the eye are interconnected in such a way that when one is stimulated, others nearby are depressed, thus enhancing the contrast in light patterns and sharpening the perception of shapes. Hartline thus built up a detailed understanding of the workings of individual photoreceptors and nerve fibres in the retina, and he showed how simple retinal mechanisms constitute vital steps in the integration of visual information.
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Nobel biography
