Photoreceptor and bipolar-cell contributions to the cat electroretinogram: A kinetic model for the early part of the flash response

The time course of the initial negative wave of the flash electroretinogram of the dark-adapted cat has been found to be critically dependent on contributions from cells of the inner retina, not only for very low-intensity flashes for which the negative scotopic threshold response is dominant but also when the stimulus is sufficiently intense for the rods themselves to contribute directly to the electroretinogram. However, if the inner-retinal responses are blocked pharmacologically or are suppressed by a steady adapting background, the initial negative wave of the remaining electroretinogram (the a wave) can be explained as the sum of photoreceptor and bipolar-cell components that can be modeled as described by Lamb and Pugh [J. Physiol. (London) 449, 717 (1992)] and Robson and Frishman [Vis. Neurosci. 12, 837 (1995)], respectively. (C) 1996 Optical Society of America