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. 1966 Mar;183(2):481–496. doi: 10.1113/jphysiol.1966.sp007878

The separation of cone mechanisms in dark adaptation

J J Du Croz, W A H Rushton
PMCID: PMC1357590  PMID: 5942821

Abstract

1. In dark adaptation the threshold is raised as though the bleaching of visual pigment generated an equivalent background. Now Stiles has shown that real coloured backgrounds act selectively upon the various colour mechanisms, so we ask: `Do equivalent backgrounds from coloured bleachings also act selectively?'

2. When dark adaptation was plotted using a blue test flash (Fig. 1b) following bleaching by orange light a kinked curve was obtained. The upper branch was shown to have the same dark adapted threshold as Stiles blue (π1) mechanism and the lower branch as his green (π4) mechanism. The π4 dark adaptation curve alone (unkinked) was obtained using a white instead of an orange bleach.

3. Dark adaptation curves were obtained in which the test flash was presented upon various steady backgrounds. In conditions where only π4 was involved (Fig. 3) the experimental results fitted the curves calculated on the assumption that the equivalent background of bleaching simply adds to the real background in raising the threshold—a condition already established for rods.

4. In conditions where π4 and π1 were both present (blue test, yellow-green background and white bleach) kinked dark adaptation curves were obtained (Fig. 2) where the upper branch (π4) coincided with those of Fig. 3 and the lower were due to π1.

5. The blue mechanism recovers in dark adaptation at about the same rate as red and green, or slightly slower.

6. Dark adaptation curves with red (π5) and green (π4) limbs can be obtained after a deep red bleach (Fig. 4) using a red test flash and a green background. The red and the green limbs were also plotted alone in their entirety by slightly changing the conditions.

7. We are led to the idea of three colour mechanisms that adapt as independently one of another after bleaching as they do with backgrounds.

8. Though this simple independence accounts for the wide and conspicuous range of adaptive phenomena, we have encountered some special conditions (not here described) that seem to imply a measure of interaction between the different colour mechanisms.

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Selected References

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

  1. AUERBACH E., WALD G. Identification of a violet receptor in human color vision. Science. 1954 Sep 10;120(3115):401–405. doi: 10.1126/science.120.3115.401. [DOI] [PubMed] [Google Scholar]
  2. BAKER H. D., RUSHTON W. A. THE RED-SENSITIVE PIGMENT IN NORMAL CONES. J Physiol. 1965 Jan;176:56–72. doi: 10.1113/jphysiol.1965.sp007535. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. BARLOW H. B., SPARROCK J. M. THE ROLE OF AFTERIMAGES IN DARK ADAPTATION. Science. 1964 Jun 12;144(3624):1309–1314. doi: 10.1126/science.144.3624.1309. [DOI] [PubMed] [Google Scholar]
  4. Blakemore C. B., Rushton W. A. Dark adaptation and increment threshold in a rod monochromat. J Physiol. 1965 Dec;181(3):612–628. doi: 10.1113/jphysiol.1965.sp007786. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Blakemore C. B., Rushton W. A. The rod increment threshold during dark adaptation in normal and rod monochromat. J Physiol. 1965 Dec;181(3):629–640. doi: 10.1113/jphysiol.1965.sp007787. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. FUORTES M. G., HODGKIN A. L. CHANGES IN TIME SCALE AND SENSITIVITY IN THE OMMATIDIA OF LIMULUS. J Physiol. 1964 Aug;172:239–263. doi: 10.1113/jphysiol.1964.sp007415. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. RUSHTON W. A. A FOVEAL PIGMENT IN THE DEUTERANOPE. J Physiol. 1965 Jan;176:24–37. doi: 10.1113/jphysiol.1965.sp007532. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. RUSHTON W. A. CONE PIGMENT KINETICS IN THE PROTANOPE. J Physiol. 1963 Sep;168:374–388. doi: 10.1113/jphysiol.1963.sp007198. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. RUSHTON W. A. Dark-adaptation and the regeneration of rhodopsin. J Physiol. 1961 Apr;156:166–178. doi: 10.1113/jphysiol.1961.sp006666. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Rushton W. A. Bleached rhodopson and visual adaptation. J Physiol. 1965 Dec;181(3):645–655. doi: 10.1113/jphysiol.1965.sp007789. [DOI] [PMC free article] [PubMed] [Google Scholar]

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