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pan Shi, Kate A. Godwin, Paul J. DeMarco; Temporal Interactions Between the b-wave and d-wave of the Human Electroretinogram. Invest. Ophthalmol. Vis. Sci. 2012;53(14):5709.
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We examined the temporal interactions between the b-wave and d-wave of the human electroretinogram (ERG) and the influence of each on the amplitude of the ERG response.
Data were collected from nine human subjects using increment and decrement flashes and standard ERG recording techniques. For increment flashes, intensities from 75 to 900 cd/m2 were presented on a 25 cd/m2 background using stimulus durations of 5 ms, 20 ms and 75 ms. For these conditions the amplitude of the b-wave was measured. For decrement flashes, flash intensities from -100 to -300 cd/m2 were presented on a 325 cd/m2 background with stimulus durations of 5 ms, 20 ms and 75 ms. For these conditions the amplitude of the d-wave was measured. The data were analyzed using a 2-factor repeated measures ANOVA.
For increment flashes, the amplitude of the b-wave increased as a function of flash intensity for all flash durations and showed a plateau at higher intensities, but the slope and morphology of the intensity-response functions differed for each flash duration. There was a statistical main effect for amplitude across duration, revealing that the b-wave amplitude decreased as duration increased. For decrement flashes, the slope of the d-wave intensity-response function was similar across flash durations and did not show a plateau. However, the d-wave amplitude was significantly lower for 5 ms duration flashes compared to both 20 and 75 ms duration flashes, which did not differ from one another. As flash duration is increased, the b-wave and d-wave responses become separate entities and the interaction between the two changes.
For short duration flashes, the b-wave and d-wave interact to influence the ERG response. For increment flashes, the amplitude of the b-wave is increased by the d-wave response to a brief flash, but for decrement flashes the d-wave is decreased by the b-wave response to a brief flash. The flash duration at which the two responses become independent differs, suggesting a temporally dependent interaction between the generators of the two waveforms. These results suggest that the standard, brief-flash, increment and decrement ERG is a result of both ON- and OFF-pathway activity.
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