Hartline continued and extended the work initiated by Adrian and Matthews on electrical discharges from the optic nerve. See also his later papers In the same journal, 1940, 130, 690-711. Reprinted with historical introduction by Hartline in F. Ratliff (ed.). Studies on excitation and inhibition in the retina, New York, [1974].

In 1967 Hartline shared the Nobel Prize in Physiology or Medicine with Granit (No. 1534) and G. Wald (No. 1535) "for his discovery of the optical nerve network."