Rod and L-cone interactions in a deuteranope at different temporal frequencies

The dynamics of interactions between rods and L-cones in a deuteranopic hum an observer at different temporal frequencies were studied, by measuring fl icker detection thresholds for different ratios of rod to L-cone modulation . Retinal illuminance was 7.4 td and retinal eccentricity was 5 degrees. Mo dulation frequency varied between 1-15 Hz. A model, based on a vector addit ion of responses originating in the rods and the L-cones, can describe the threshold data. We found that up to 9 Hz temporal frequency the rods and th e L-cones interacted additively, whereas at larger frequencies (10-15 Hz) t he interaction was inhibitory. The phase difference between the rods and th e L-cones increased linearly with temporal frequency, indicating a differen ce in delay time of about 26 ms. (C) 2000 John Wiley & Sons, Inc. Col Res A ppl, 26, S76-S78, 2001.