Rod and cone receptor mechanisms in typical and atypical congenital achromatopsia

Blackwell, H. Richard; Blackwell, O M

doi:10.1016/0042-6989(61)90022-0

Cited by 127 publications

(59 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…They have generally exhibited some features resembling a limited cone vision (Lewis & Mandelbaum, 1943;Hecht, Schlaer, Smith, Haig & Peskin, 1948). The degree and the manner in which cones enter varies considerably in reported cases and the cone spectral sensitivity may be maximal either at 440 mfl (Blackwell & Blackwell, 1959), 510 m,u (Sloan, 1954(Sloan, , 1958Alpern, Falls & Lee, 1960) or in our case at 550 m,u. There is no reason to believe that all these represent the same genetic condition, and indeed the mode of inheritance of the 'blue cone' type appears to be different from that of the 'rhodopsin cone' type (H. F. Falls, personal communication).…”

mentioning

confidence: 97%

Increment thresholds in a subject deficient in cone vision

Fuortes¹,

Gunkel²,

Rushton³

1961

The Journal of Physiology

View full text Add to dashboard Cite

It is well recognized, particularly from the work of Hecht (1937), that measurements of visual function at different levels of illumination generally fall into two categories, a low intensity scotopic portion and a high intensity photopic portion. Thus in the time course of dark-adaptation, and in the curves where log. increment threshold, log. acuity or fficker fusion frequency is plotted against log. field intensity, the results are found to fall upon two distinct branches. The low-intensity branch has the spectral sensitivity of rhodopsin, and it is not seen in measurements made upon the fovea centralis; it is therefore considered to be due to rod function. The other branch has a-different spectral sensitivity, it is found upon the rod-free fovea and hence it is considered to be due to cone function. Now though there are considerable difficulties in distinguishing the functions of the various types of cone, it is easy to separate cone curves from rod curves over the whole intensity range of the cones. For not only may measurements be made upon the fovea where rods are absent, but even elsewhere it turns out that cones have an increment sensitivity and fusion frequency so much higher than rods that the plotted curves generally show the cone branch substantially in its entirety. It is otherwise with rod curves, for not only is there no part of the human retina which contains rods without cones, but the very features which make cone measurements outstanding in a mixed population make rod measurements unavailable. In fact, we can only measure rods at intensities below the cone threshold. This does not mean that rods are necessarily inactive at higher intensities, but their activity cannot be measured by ordinary threshold procedures, and we are left wondering what course the rod branch may take after it disappears behind the cone branch.This question could be answered if we were able to investigate a subject who had no cones but whose rods and rod pathways to the brain were * Instituto Neurologico, Via Celoria 11, Milano. t Present address: Physiological Laboratory, University of Cambridge.12-2

show abstract

mentioning

confidence: 97%

Increment thresholds in a subject deficient in cone vision

Fuortes¹,

Gunkel²,

Rushton³

1961

The Journal of Physiology

View full text Add to dashboard Cite

show abstract

“…It has been claimed that achromats of this general type can exhibit a rudimentary form of dichromatic vision (Blackwell & Blackwell, 1961;Grutzner, 1964;Alpern et al 1971;Daw & Enoch, 1973). The crucial question that must be addressed is whether colour discrimination is possible for these achromats at illuminance levels where rod photoreceptors are known to be saturated (Aguilar & Stiles, 1954;Hess & Nordby, 1986 & Pointer, 1987).…”

Section: Colour Discriminationmentioning

confidence: 99%

“…This is very rare, with an incidence thought to be 1:106, and is a type of atypical achromatopsia with an X-linked form of inheritance (Spivey, 1965; Smith, Pokorny, Delleman, Cozijnsen, Houtman & Went, 1983). Although it was initially thought that only normal rods and normal short wavelength-absorbing (S) cones subserved the vision of these subjects and hence the term blue mono-cone monochromacy was adopted (Blackwell & Blackwell, 1961; Alpern, Lee & Spirey, 1965), later studies suggested that they also possessed anomalous foveal cones with an absorbance peak at 505 nm (i.e. rhodopsin cones; Pokorny, Smith & Swartley, 1970; Alpern, Lee, Maaseidvaag & Miller, 1971).…”

Section: Introductionmentioning

confidence: 99%

The photoreceptors in atypical achromatopsia.

Hess

Mullen

Sharpe

et al. 1989

The Journal of Physiology

View full text Add to dashboard Cite

SUMMARY1. The receptoral mechanisms underlying the vision of two atypical achromats of the complete variety were studied with standard psychophysical procedures.2. Under scotopic conditions the spectral sensitivity of each achromat was well described by the CIE (Commission Internationale de l'Eclairage) scotopic sensitivity function and the recovery of sensitivity after a retinal bleach showed characteristic duplex behaviour with the time constant of recovery of the slower phase matching that of normal rod vision for both foveal and peripheral stimulation.3. Their spectral sensitivity was measured under conditions of chromatic adaptation in order to reveal any residual middle or long wavelength cone activity. Only one photopic spectral response was found and this was adequately described by the spectral sensitivity function of Stiles' H3 mechanism of normal vision.4. Increment threshold measurements as a function of background intensity revealed a double-branched function in the fovea. The lower branch was found to have the spectral sensitivity of the rods; the upper branch that of Stiles' n3 mechanism. Stiles-Crawford measurements of directional sensitivity confirmed that the branch with the rhodopsin action spectrum had the directional sensitivity of rods and that the branch with the action spectrum of rI3 had the directional sensitivity of cones.5. These was no evidence for hue discrimination under photopic conditions. Regions of apparently normal performance on hue discrimination tests on more careful examination could be explained by luminosity judgements mediated by short wavelength-absorbing receptors.6. We reject the notion of there being rhodopsin-filled cones in the fovea of these subjects. The foveal and peripheral vision of each of these achromats can be adequately described in terms of the participation of only two types of receptor, namely normally functional rods under scotopic conditions and normally functioning short wavelength-absorbing cones under photopic conditions. They are therefore functional blue mono-cone monochromats, an explanation which was originally proposed by Blackwell & Blackwell (1957) over thirty years ago.

show abstract

“…Direct measurements of macaque cones by the suction-electrode technique (Schnapf, Nunn, Meister & Baylor, 1990) suggest little difference between cone types in their dynamic range. "Blue cone" monochromats offer psychophysical evidence against saturation of the short-wave cones: their acuity continues to improve in the photopic region and does not deteriorate at high luminance levels in the way that the acuity of rod monochromats does (Blackwell & Blackwell, 1961).…”

Section: The Nature Of the Saturation Of The Short-wave Systemmentioning

confidence: 99%

A reduction in stimulus duration can improve wavelength discriminations mediated by short-wave cones

1992

View full text Add to dashboard Cite

Virtually all visual discriminations become less accurate when either the luminance or the duration of the stimulus is reduced. An exception is found for wavelength discriminations near 460 nm, where an increase in either luminance or duration can cause the threshold to rise. For flashes of 100 msec or less, the critical variable is the total energy of the flash (i.e. the product of retinal illuminance and flash duration), and wavelength discrimination is optimal at an intermediate value; higher stimulus energy causes discrimination to deteriorate. To explain these findings we suppose that discrimination in this region of the spectrum is mediated by a channel that draws opposed signals from the short-wavelength cones and from some combination of the middle-and long-wavelength cones, and that high stimulus energies cause saturation of this channel.Colour

show abstract

Rod and cone receptor mechanisms in typical and atypical congenital achromatopsia

Cited by 127 publications

References 12 publications

Increment thresholds in a subject deficient in cone vision

Increment thresholds in a subject deficient in cone vision

The photoreceptors in atypical achromatopsia.

A reduction in stimulus duration can improve wavelength discriminations mediated by short-wave cones

Contact Info

Product

Resources

About