An electrically evoked slow potential of the frog's retina. II. Identification with PII component of electroretinogram.

1. To show conclusively that the electrically evoked retinal response (EERG) is in fact an electrically evoked component of the usual ERG, it is necessary to show that the two responses have the same intraretinal pattern of current generators. A method for determining when two responses have the same origin has been developed. This method utilizes measurements from a single microelectrode penetrating the retina. 2. The method was sensitive enough to detect differences in the origins of two responses when they were present. 3. The EERG had the same intraretinal origin as the PII component of the ERG, and thus is the PII component evoked by electricity rather than by light. 4. The hypothesis that electrical stimuli act on the synaptic terminals of the photoreceptor cells predicts that electrical current will evoke components of the ERG. The fact that the EERG is an electrically evoked component of the ERG fulfills that prediction.