Interaction of slow potentials of the retina evoked by photic and electric stimuli.

In a previous paper1) it was shown that a slow potential similar to the so-called dendritic potential of the cerebral cortex occurs in reponse to direct electric stimulation of the carp's retina. Based on various experiments it was inferred that this potential originates in the retinal network intervening between the receptor cell layer and the ganglion cell layer. In the normal photoreceptive processes some electrical change must be induced from the receptor cell layer into the retinal network. Therefore, the retinal network represents a common path for photic and electric excitation of the retina. The present paper deals with the interaction between slow potentials caused by photic and electric stimuli. The conduction velocity of the potentials evoked by direct electric stimulation of the cortex was measured by a number of investigators, 2-6) and values ranging from 0.1 to 2 m./sec. were obtained. In the present experiment we measured the conduction velocity of the negative slow potential to direct electric stimulation of the retina.