The oscillatory potentials in response to stimuli of photopic intensities delivered in dark-adaptation: an explanation for the conditioning flash effect.

Previous studies reported that the oscillatory potentials (OPs) evoked to the first flash of a series were always smaller than those produced by the later flashes. This conditioning flash effect (CFE) was suggested to arise from rod inhibition of cone-mediated OPs. We investigated this CFE with the use of two stimulus intensities: 10 cd sec m-2 and 1 cd sec m-2. While the highest intensity did yield the previously reported CFE, the dimmest intensity did not. Our results further indicated that with the brightest stimulus, there is a significant increase in the interpeak interval of the OPs, while dimmest stimuli failed to reveal a similar marked increase. We also noted a significant correlation between the frequency domain of the OPs (as estimated with the interpeak interval) and the amplitude of the OPs (individual or collective: SOPs). Our results would also suggest that the observed CFE could result from a cone inhibition of rod-mediated OPs.