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. 1970 Apr;207(2):449–461. doi: 10.1113/jphysiol.1970.sp009072

The attenuation of rod signals by bleachings

M Alpern, W A H Rushton, S Torii
PMCID: PMC1348717  PMID: 5499030

Abstract

1. Contrast flash technique allows the rod threshold to be measured even when it lies far above the cone threshold. In this way the rod dark adaptation curve after rhodopsin bleaching can be measured over 6 log units.

2. By retinal densitometry the regeneration of rhodopsin can be measured in the same subject. It is found that the log threshold is raised 1·2 units for each 10% of rhodopsin in the bleached state.

3. We have tried to discover whether bleaching raises the threshold by desensitizing the rods, or (like backgrounds) by attenuating their signals. Neither suggestion satisfies all conditions.

4. All are satisfied by [Formula: see text], where N is the size of rod signal, constant for threshold; θ, θD are steady backgrounds of light and receptor noise; ϕ is the threshold flash with σ a constant of about 2·5 log td sec; B the fraction of pigment in the bleached state.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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