Specific features of the electroretinogram of vertebrates induced by X-rays.

The net electroretinograms of dark-adapted retinas of the common frog in situ were investigated on an automated experimental system with programmed control and electronic differentiation of biopotentials with respect to the first and second derivatives. It was demonstrated that X-rays elicit an electroretinogram consisting of two components, provisionally called the first and second X-ray reactions (X-1 and X-2), which differ with respect to their parameters from electroretinograms elicited under the same conditions by red and blue light. The administration of sodium azide, sodium nitrate, monoiodo-acetate and other substances alter the X-1 and X-2 as well as the photo-induced ERGs in different ways; this indicates their relative independence and different mechanisms of the occurrence and passing of excitation across the structures of the retina, and makes it possible to partially isolate these for individual study. Thus, the assertion of a number of investigators regarding the absence of specific features in the X-ray induced electroretinograms becomes problematical. The discovery of X-ray-specific reactions in the retina makes it possible to hope that the radiological phosphene (the X-ray phosphene) may serve as a test for the determination of the individual radiational excitability of the central nervous system.