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November 23, 1963


JAMA. 1963;186(8):792. doi:10.1001/jama.1963.03710080064014

For many years it has been possible to record electrical potentials from the eye ( electroretinogram) in response to intense large area flashes of light. The reduction or absence of such electroretinal potentials in response to ocular illumination has been useful in diagnosing generalized and diffuse retinal disease such as retinal degenerations. Similarly, intense flickering illumination of the eye has been used to induce rhythmic changes in the occipital electroencephalogram. Such "photic driving" has also sometimes proved clinically helpful. In more recent years various techniques have been employed to extract neuroelectric potentials related in time to the stimulus from extraneous background potentials (noise).

The advent of computers has heralded a new era in the rapid, efficient extraction of small signals from larger background "noise." With conventional recording techniques, signals less than 20μv could not be separated from "noise," whereas presently, a number of investigators are recording neuroelectric potentials in the 1-μv