THE MECHANISM OF DARK ADAPTATION: A Critical Resume

Lythgoe, R. J.

doi:10.1136/bjo.24.1.21

Cited by 82 publications

(17 citation statements)

References 24 publications

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“…Electrophysiological work on receptive fields of retinal ganglion cells (Hartline, 1940) has made us familiar with the concept of pooling, and the findings of Barlow, FitzHugh & Kuffler (1957) show that the nature of these pools may change during adaptation. Earlier theoretical analyses (Broca, 1901; Lythgoe, 1940;Craik & Vernon, 1941;Pirenne & Denton, 1952) had sought to account for various adaptational phenomena by postulating changes in summation areas in the retina, but the studies of Barlow et al make clear that such summation may involve both excitatory and inhibitory signals.…”

Section: (Received 14 June 1965)mentioning

confidence: 99%

Spatial interaction in the human retina during scotopic vision.

Westheimer¹

1965

The Journal of Physiology

235

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The eye's sensitivity to light decreases with increasing background luminances. It was once thought that this could be simply explained by the decrease in the reservoir of available photolabile pigments in the receptors, but recent measurements have shown that changes in sensitivity are far too large to be accounted for by a simple theory involving concentration of visual pigments. A limit to the performance of the eye in detecting differences in brightness is set by quantum variability; but this existence of a theoretical limit tells us how well the eye could do in distinguishing brightness differences, not how it in fact achieves this.

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Section: (Received 14 June 1965)mentioning

confidence: 99%

Spatial interaction in the human retina during scotopic vision.

Westheimer¹

1965

The Journal of Physiology

235

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“…An increase in the area of a test stimulus results in a bigger drop in the threshold intensity in a dark-adapted eye than in a light-adapted eye (Lythgoe, 1940;Craik & Vernon, 1941;Barlow, 1957). This led to the idea that the retinal summation area was bigger in dark adaptation, which was attributed to increased interconnexion between receptors (Broca, 1901;Lythgoe, 1940), but the present experiments show that in these retinal units in the cat the most pronounced change on dark-adapting is the disappearance of lateral inhibition.…”

Section: Receptive Fields In Dark Adaptationmentioning

confidence: 99%

“…One aspect of this is the reduction of resolving power which has been measured in man in psychophysical experiments (Koenig, 1897(Koenig, , 1903Broca, 1901; Hecht, 1928;Pirenne & Denton, 1952). Another aspect is the increased amount of area summation that occurs at low intensities (Lythgoe, 1940;Craik & Vernon, 1941;Barlkw, 1957). These changes in performance might result, in part at least, from changes in the nervous pathways in the retina.…”

mentioning

confidence: 99%

Change of organization in the receptive fields of the cat's retina during dark adaptation

Barlow¹,

Fitzhugh²,

Kuffler³

1957

The Journal of Physiology

741

338

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“…For, though change of wave-length may simply result in the vertical shift of the curve (as discussed above) an increase in the area or duration of the flash does increase somewhat the extent of dark-adaptation and prolong the recovery time (Craik & Vernon, 1941;Arden & Weale, 1954). Other factors, therefore, besides the regeneration of rhodopsin must contribute to the increase of excitability during dark-adaptation-presumably a reorganization of nerve connexions, as Lythgoe (1940) pointed out long ago, and as electrophysiology has since confirmed (Barlow, Fitzhugh & Kuffler, 1957a, b).…”

mentioning

confidence: 96%

Dark‐adaptation and the regeneration of rhodopsin

Rushton¹

1961

The Journal of Physiology

121

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Ever since Kohlrausch (1922) measured dark-adaptation by plotting the logarithm of the threshold against the time in the dark, it has been clear that the recovery of visual sensitivity occurs in two stages. For, in general, the curve plotted exhibits two quasi-independent branches which meet at a pretty sharp kink. As Kohlrausch demonstrated, the early and faster process is associated with day vision: the later process with night vision. An enormous amount of subsequent work has substantiated this interpretation, but we are on much less secure grounds if we conclude (as is often done) that the first branch is concerned with cones only, the second with rods only and that there is no rod-cone interaction.The 'cone branch' is obtainable from the rod-free fovea; it has the spectral sensitivity of daylight vision, monochromatic test flashes are usually seen as coloured, acuity is good, and a large Stiles-Crawford effect is found. This is strong evidence that cones are involved, but weak evidence that rods are not involved. To be sure, they are not involved at the central fovea, but the cone branch there is not quite the same shape as that found at the parafovea, where rods are anatomically present (Hecht, Haig & Wald, 1935;Sloan, 1950).The 'rod branch' is obtainable from all parts of the retina where rods are present and is absent from the only places (fovea and blind spot) where they are not. This branch exhibits the spectral sensitivity of twilight vision which (after correction for absorption by the ocular media) corresponds very closely to the absorption spectrum of rhodopsin (Crescitelli & Dartnall, 1953), a photosensitive pigment which can be seen contained in the living rods (Boll, 1876). Test flashes appear colourless whatever their wave-length, acuity is poor and the Stiles-Crawford effect is small or absent. This is strong proof that rods are involved, but evidence is not so clear whether cones contribute or not. If rhodopsin is the only pigment which absorbs quanta at threshold throughout the second branch, then after any * Present address: Physiological Laboratory, University of Cambridge.

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THE MECHANISM OF DARK ADAPTATION: A Critical Resume

Cited by 82 publications

References 24 publications

Spatial interaction in the human retina during scotopic vision.

Spatial interaction in the human retina during scotopic vision.

Change of organization in the receptive fields of the cat's retina during dark adaptation

Dark‐adaptation and the regeneration of rhodopsin

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