Haldan Keffer Hartline

Haldan Keffer Hartline

[hahrt-lahyn]
Hartline, Haldan Keffer, 1903-83, American physiologist, b. Bloomsburg, Pa., M.D. Johns Hopkins, 1927. From 1931 to 1949 (except for 1940-41), he was a researcher at the Eldridge Reeves Johnson Foundation for Medical Physics, Univ. of Pennsylvania. He was a professor at Johns Hopkins from 1949 to 1953, when he joined the faculty of the Rockefeller Institute (now Rockefeller Univ.). Hartline was a co-recipient of the 1967 Nobel Prize in physiology or medicine with George Wald and Ragnar Granit for their discoveries concerning the primary physiological and chemical visual processes in the eye. Hartline studied the eye of the horseshoe crab and determined that stimulation of one of the receptor cells in the eye is accompanied by depression of the nearby cells, resulting in enhanced contrast and shape perception.
Haldan Keffer Hartline (December 22, 1903March 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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