Hartline, Haldan Keffer

Hartline, Haldan Keffer

(born Dec. 22, 1903, Bloomsburg, Pa., U.S.—died March 17, 1983, Fallston, Md.) U.S. physiologist. He received his M.D. from Johns Hopkins University. Experimenting on horseshoe crabs, he was the first to record the electrical impulses sent by a single optic-nerve fibre. He found that when one of the eye's receptor cells is stimulated, others nearby are depressed, enhancing contrast and sharpening perception of shapes. He showed how simple retinal mechanisms constitute vital steps in the integration of visual information. In 1967 he shared a Nobel Prize with George Wald and Ragnar Arthur Granit.