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.