The electrically evoked response of the visual system (EER).

Abstract

(1) A technique is described for recording with scalp electrodes the occipital response to electrical stimulation of the globe. This electrically evoked response of the visual system has been labeled EER. (2) The amplitude of EER is a function of the amount of stimulus current. (3) There is an apparent difference in EER caused by electrode polarity. (4) There is little difference in EER to square pulses of varying durations. However, sawtooth stimuli cause increase of latency of response equivalent to duration of the sawtooth. (5) Although there is considerable variation of EER from individual to individual the response for any one subject appears to be quite constant. (6) The EER differs from the VER to stimuli of the same subjective brightness in several ways. The amplitude of the EER is greater but only when measured at the occipital pole; the latency of the VER is greater. These findings suggest that the EER represents activation of many collateral circuits not directly connected with brightness perception. They also suggest that the electrical stimulus acts on structures between the receptor inner segments and the ganglion cell body.