This project involves the study of neurons of the visual system of primates, including humans, using electrophysiological techniques. The data of a large electroretinography (ERG) survey of normal volunteers previously collected over a five-year period using standardized Ganzfeld ERG recordings are being statistically analyzed. The results will provide normative values for dark-adapted rod responses, dark-adapted cone responses, and light-adapted cone responses obtained in standardized conditions in a clinical setting.