20-HZ FLICKER STIMULUS CAN ISOLATE THE CONE FUNCTION IN RAT RETINA

Cone electroretinograms (ERGs) are typically isolated in humans by fli cker stimuli against rod-desensitizing adapting fields. To investigate the manner in which adapting-field luminance affects the cone ERGs, w e recorded ERGs in normal albino Sprague-Dawley rats with flicker stim uli presented against adapting fields that ranged in luminance from -i nfinity to 1.75 log cd/m(2). A flicker rate of 20 Hz was used to isola te the cone ERGs under all adaptation conditions. We found the amplitu des of cone ERGs to increase with increasing adapting-field luminance. These response characteristics are similar to human ERGs using 30-Hz flicker stimuli, which suggests that flicker stimuli are a useful tech nique to isolate the cone function in rats.