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D. Czop, J. Kremers, M.W. Stepien, Z. Zagorski; Photoreceptor Specific ERG in Trichromats at Different Adaptation Conditions and Different Temporal Frequencies . Invest. Ophthalmol. Vis. Sci. 2003;44(13):4172.
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Purpose: At photopic luminances, cone selective adaptation influences the 30 Hz ERG responses driven by the adapted but also by the non-adapted cones. Intrusion of rod driven signals is probably small. We previously found that even at relatively high retinal luminances, rod driven signals may contribute to the ERG responses at temporal frequencies below 30 Hz. To investigate the intrusion of rod and S-cone driven signals and adaptation to the total ERG, we performed ERG measurements at different temporal frequencies and different states of adaptation in color normals. Methods: We measured ERG amplitudes and phases in trichromats (trichromacy was established by standard color vision tests). ERGs were measured at 18 Hz and 30 Hz. At each frequency, the responses were measured at ten different adaptation conditions. At each condition two stimuli were presented: one stimulating the L-cones (15% cone contrast) with a silent substitution in the M-cones and vice versa. In five conditions the rods were also modulated and adapted. In the remaining five conditions, the S-cones were modulated and adapted in addition to the L- or the M-cones. Results: When rods were modulated and adapted together with the L-cones, the ERGs at 18 Hz had smaller amplitudes than at 30 Hz. Combined M-cone and rod driven ERGs were larger at 18 Hz than at 30 Hz temporal frequency. But the differences were relatively small. When S-cones were modulated in addition to the L- or the M-cones, large differences between the responses measured at 18 Hz and at 30 Hz were observed. Conclusions: At 18 Hz temporal frequency the intrusion of rod driven signals is relatively small. However, S-cone driven signals can be large at 18 Hz. CR: none Support: This research was supported by DFG Grant KR1317/5-2 to JK; by the European Commission under contract QLGA-1999-50423 to DC and MWS, Fellows of the Marie Curie Training site.
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