scholarly journals THE FLICKER RESPONSE CONTOUR FOR THE GECKO (ROD RETINA)

1939 ◽  
Vol 22 (5) ◽  
pp. 555-566 ◽  
Author(s):  
W. J. Crozier ◽  
Ernst Wolf
Keyword(s):  
Visual Performance ◽  
Histological Evidence ◽  
Rods And Cones ◽  
Flicker Response ◽  
Intensity Range ◽  
Probability Integral ◽  
Equivalent Conditions

The flicker response contour for the gecko Sphaerodactylus (retina with only rods) agrees in all essential respects (intensity range, shape) with that for the turtle Pseudemys (cone retina), as determined under equivalent conditions with the same apparatus. With experimentally determined correction for the expansion of the iris at the very lowest intensities, the F - log I contour for the gecko is a simple probability integral. Its maximum F is lower than that for other animals; this means simply a smaller number of available sensory elements. The quantitative parallelism in the magnitudes of the intensities at the inflection of F - log I and the shape constants for rod and cone animals show that assumptions from comparative histological evidence concerning the properties of rods and cones in relation to visual performance may be quite misleading.

scholarly journals REACTION TO VISUAL FLICKER IN THE NEWT TRITURUS

1940 ◽  
Vol 23 (6) ◽  
pp. 667-676 ◽  
Author(s):  
W. J. Crozier ◽  
Ernst Wolf
Keyword(s):  
Fresh Water ◽  
Response Curve ◽  
Integral Form ◽  
Quantitative Structure ◽  
Rods And Cones ◽  
Flicker Response ◽  
Probability Integral ◽  
Cone Curve ◽  
Critical Intensity

The flicker response curve for the newt Triturus viridescens (water phase) has much the same quantitative structure as that found with various fresh-water teleosts at the same temperature (21.5°). The variability of critical intensity and of critical flash frequency likewise follows the same rules. The cone portion of the F - log I curve is much more widely spread, however. This, and the rather low maximum to which the rod curve rises, produce a considerable overlapping of the two parts additively fused. In addition, and to an extent which differs in various individuals, there is apparent a slight departure from the probability integral form of the cone curve. Reasons are given for considering that this is possibly connected with the role of an additional (small) number of (perhaps temporary, or developmental) retinal elements in addition to the typical rods and cones.

scholarly journals THE FLICKER RESPONSE CONTOUR FOR PHRYNOSOMA (HORNED LIZARD; CONE RETINA)

1941 ◽  
Vol 24 (3) ◽  
pp. 317-324 ◽  
Author(s):  
W. J. Crozier ◽  
Ernst Wolf
Keyword(s):  
Intensity Level ◽  
Flash Intensity ◽  
Flicker Response ◽  
Normal Probability ◽  
Probability Integral

The lizard Phrynosoma, with purely cone retina, provides a simplex flicker response contour (log critical flash intensity as a function of flash frequency). It is well described as a normal probability integral (F - log I). The Phrynosoma curve differs markedly, in higher slope and in higher median intensity level, from that obtained under the same conditions for the turtle Pseudemys, also with entirely cone retina. Other comparisons having a bearing on the duplexity doctrine are discussed.

scholarly journals THE FLICKER RESPONSE FUNCTION FOR THE TURTLE PSEUDEMYS

1939 ◽  
Vol 22 (3) ◽  
pp. 311-340 ◽  
Author(s):  
W. J. Crozier ◽  
Ernst Wolf ◽  
Gertrud Zerrahn-Wolf
Keyword(s):  
Flash Intensity ◽  
Rods And Cones ◽  
Sensory Effects ◽  
Retinal Rods ◽  
Fixed Proportion ◽  
Order Of Magnitude ◽  
The Mean ◽  
Probability Integral ◽  
The Individual ◽  
Critical Intensity

1. At constant temperature, with a fixed proportion of light time in a flash cycle (namely, tL/tD = 1), the mean critical intensity for motor response to visual flicker by the turtle Pseudemys scripta follows a probability integral (log I) as a function of flash frequency F. The fit is close and satisfactory; certain quite minor but consistent deviations are adequately explained by features of the experiments. 2. The variation (σI) of critical I is directly proportional to the mean critical intensity (Im), over the entire explorable range. 3. These facts are consistent with the fact that the retina of this turtle is devoid of rods. It contains only cones, histologically, which, with their central representations, provide a single population of sensory effects. The properties of this population are compared with those of homologous populations deduced from corresponding measurements with other forms (various fishes; amphibian; man) which exhibit two such groups of sensory effects associated with the possession of retinal rods and cones. 4. Certain other formulations which have previously been applied to homologous data obtained with other organisms do not properly describe the Pseudemys measurements. 5. The use of a probability integral to describe the data of response to visual flicker for the dissection of the compound curves provided by animals possessing both rods and cones, is accordingly Justified. 6. Persisting differences among individuals of Pseudemys as regards the values of the critical flash intensity under various conditions of experimentation are of the same order of magnitude as are the transitory differences found in lots of other kinds of animals. 7. Determinations of mean critical flash frequency (Fm) at fixed levels of I lie slightly above determinations of Im at fixed values of I, as with other forms. The variation of critical flash frequency goes through a maximum as log I is increased; its height is lower than with certain other forms, in correlation with the low general slope of the F - log I curve (more properly, band). 8. These facts are consistent with the view that the dispersions of the individual critical intensities (and flash frequencies) are determined by organic variation rather than by "experimental error." 9. When the temperature is altered the F - log Im curve is shifted, with no change of Fmax. or of shape; the curve moves to lower intensities as the temperature is raised. 10. The reciprocal of the mean critical intensity, at fixed flash frequency, is a measure of excitability. With increase of temperature (12.5° to 36°) 1/Im for given F follows the Arrhenius equation, exhibiting a "break" at 29.5° (µ = 26,700, 12.5° to 29.5°; 12,400, 29.5° to 36°). This is explained by the necessary theory that, the number of elements of sensory effect required for the index response at fixed F being constant, the ease of their excitation is governed by temperature through its control of the velocity of an interrelated system of catalyzed processes common to all of the sensory elements concerned.

scholarly journals FLICKER RESPONSE CONTOURS FOR THE SPARROW, AND THE THEORY OF THE AVIAN PECTEN

1944 ◽  
Vol 27 (4) ◽  
pp. 315-324 ◽  
Author(s):  
W. J. Crozier ◽  
Ernst Wolf
Keyword(s):  
Zebra Finch ◽  
House Sparrow ◽  
Passer Domesticus ◽  
Rods And Cones ◽  
Flicker Response ◽  
Analytical Separation

The flicker contour for the house sparrow Passer domesticus is duplex, corresponding to the presence of both rods and cones in the retina. The presence of the pecten brings about changes in the "cone" part of the contour when the light-time in the flash cycle is varied. These changes are of the same sort as those we have already described for the visually simplex zebra finch, and for man provided with an artificial "pecten shadow." The changes are such as to greatly enhance flicker acuity for small dark-times (moving stripe technique). The form of the scotopic part of the duplex contour (also as in the case with man) gives no evidence that rod excitation is specifically influenced by the presence of the pecten. The changing integration of "rod" and "cone" effects as the light-time fraction is altered provides another means of testing the theory used for the analytical separation of the two components of the duplex flicker contour.

scholarly journals THE SIMPLEX FLICKER THRESHOLD CONTOUR FOR THE ZEBRA FINCH

1941 ◽  
Vol 24 (5) ◽  
pp. 625-633 ◽  
Author(s):  
W. J. Crozier ◽  
Ernst Wolf
Keyword(s):  
Zebra Finch ◽  
Visual Theory ◽  
Time Ratio ◽  
Flicker Response ◽  
Dark Time ◽  
Normal Probability ◽  
Probability Integral ◽  
Critical Intensity

The flicker response contour has been determined, with equality of light-dark time ratio, for the diurnal bird the Australian zebra finch. This bird has only cones in the retina. The curve of log critical intensity as a function of flash frequency is simplex, a normal probability integral. In this respect it is like that for other vertebrates not exhibiting visual duplexity. The parameters of the curve most closely approach those for the turtle Pseudemys (extrapolated to about the same temperature); it is not improbable that the approximation of these two curves would be less close for other values of the light-time fraction. Some points of interpretive visual theory are discussed in relation to the present measurements.

scholarly journals THEORY AND MEASUREMENT OF VISUAL MECHANISMS

1942 ◽  
Vol 25 (3) ◽  
pp. 369-379 ◽  
Author(s):  
W. J. Crozier ◽  
Ernst Wolf
Keyword(s):  
Integral Form ◽  
Statistical Nature ◽  
Lower Segment ◽  
Response Curves ◽  
Flicker Response ◽  
Sensory Effects ◽  
Normal Probability ◽  
Neural Integration ◽  
Probability Integral ◽  
Cone Curve

Flicker response curves (man) obtained with images formed entirely within the fovea are like those secured with lower animals having only one general class of retinal receptors. They are normal probability integrals (F vs. log Im), and the properties of their parameters agree with those for visually simplex animals and for the "cone" portions of contours exhibiting visual duplexity. By several different procedures, involving experimental modifications of the "cone" curve, the "rod" part of the typical human duplex curve can be obtained free from overlapping by the extrapolated "cone" curve. It then has the probability integral form which the lower segment does not directly exhibit when combined with "cone" effects. These results are discussed with reference to the statistical nature of the fundamental form of the flicker contour and to the interpretation of duplex curves produced by the neural integration of two independently modifiable groups of sensory effects.

scholarly journals THE FLICKER RESPONSE CONTOUR FOR THE FROG

1939 ◽  
Vol 23 (2) ◽  
pp. 229-237 ◽  
Author(s):  
W. J. Crozier ◽  
Ernst Wolf
Keyword(s):  
Small Group ◽  
Rana Pipiens ◽  
Direct Proportion ◽  
Low Intensity ◽  
Flicker Response ◽  
Sensory Effects ◽  
Probability Integral ◽  
Cone Curve ◽  
Homogeneous Data

The flicker response contour for the frog Rana pipiens exhibits the duplex character typical for most vertebrates. By comparison (under the same conditions of temperature, 21.5°, and light-time fraction, = 0.5), the low intensity section of the F - log I curve is the smallest thus far found. The cone portion of the curve is satisfactorily described by a probability integral. The rod part represents the addition of a small group of sensory effects upon the lower end of the cone curve, from which it can be analytically separated. The relation between the two groups of sensory effects permits certain tests of the rule according to which (in homogeneous data) Im and σ1I1 are in direct proportion.

scholarly journals Directional sensitivity of the retina: 75 years of Stiles–Crawford effect

2008 ◽  
Vol 275 (1653) ◽  
pp. 2777-2786 ◽  
Author(s):  
Gerald Westheimer
Keyword(s):  
Spatial Distribution ◽  
Fine Structure ◽  
Luminous Efficiency ◽  
Visual Performance ◽  
Directional Sensitivity ◽  
Optical Parameters ◽  
Rods And Cones ◽  
Open Questions ◽  
Ocular Aberrations ◽  
Membrane Anchoring

The reduction of the brightness when a light beam's entry into the eye is shifted from the centre to the edge of the pupil has from the outset been shown to be due to a change in luminous efficiency of radiation when it is incident obliquely on the retina. The phenomenon is most prominent in photopic vision and this has concentrated attention on the properties of retinal cones, where responsibility has yet to be assigned to factors such as differences in shape, fine structure and configuration, and membrane anchoring of photopigment molecules. Geometrical optics and waveguide formulations have been applied to the question of how light is guided in receptors, but details of their geometry and optical parameters even if they become available will make calculations complex and of only moderate generality. In practice, the diminution of oblique light helps visual performance by reducing deleterious influence of ocular aberrations and of glare caused by light scattering when the pupil is wide. Receptor orientation can come into play in ocular conditions due to mechanical disturbance and has been shown to have potentiality as a tool for clinical diagnosis. Currently, open questions include microanatomical and molecular differences between rods and cones, the coupling of the optical image of the eye with the transducing apparatus in the photoreceptors, possible phototropism and more convincing methods of estimating the actual spatial distribution of photon events as it affects visual resolution.

scholarly journals THEORY AND MEASUREMENT OF VISUAL MECHANISMS

1943 ◽  
Vol 27 (2) ◽  
pp. 119-138 ◽  
Author(s):  
W. J. Crozier ◽  
Ernst Wolf
Keyword(s):  
White Light ◽  
Wave Length ◽  
Visual Performance ◽  
Mean Intensity ◽  
Flicker Response ◽  
Intensity Threshold ◽  
Neural Integration ◽  
Full Participation ◽  
Image Area ◽  
The Mean

Flicker response contours (F vs. log Im) for a square image subtending 0.602° on a side, located in the fovea, are simplex probability integrals for a "white" and for four (five) spectral regions filtered from this white, and with different light-time fractions in the flash cycle. The subjective phenomena (the appearance of the field, the intensity threshold for color, and others) at the fusion points along these contours parallel in a variety of ways those obtained on duplex flicker contours resulting from the use of larger or eccentrically placed flickered images. These phenomena therefore cannot be held to indicate involvements of "rod" excitation. The scatter of the index of variation of I1 is such as to demonstrate the full participation of all the potentially excitable neural units at all levels of flash frequency, for each kind of light. The magnitude of this scatter, a measure of neural integration in visual performance, is a function of the number of these units (with Fmax. nearly constant); the two quantities vary together when wave-length composition of light is altered. The properties of the contours for a white light and for the spectral regions filtered from it show that, for the image within the fovea, different numbers of units are excitable in flicker recognition according to the wave-length band used, and different mean frequencies of elements of effect under fixed conditions. The changes in the mean intensity for activation of these units as a function of the light-time fraction in the flash cycle are correlated with the numbers of these units; when this is corrected for, it is pointed out that despite the differences in shape of F vs. log I it cannot be concluded that the mechanism of excitation differs for different wave-lengths. It is indicated that "white" must be regarded as a synthesis, not a mere summation, of effects due to different spectral regions. Certain differences are pointed to as between foveal and more peripheral regions tested, and as between observers differing in the degree of the "yellow spot effect," with regard to the relative effects of wave-length and of image area. A general consequence is the outlining of conditions required for the precise comparison of excitabilities as a function of wave-length in the multivariate visual system.

scholarly journals THE FLICKER RESPONSE CONTOURS FOR GENETICALLY RELATED FISHES. II

1939 ◽  
Vol 22 (4) ◽  
pp. 463-485 ◽  
Author(s):  
W. J. Crozier ◽  
Ernst Wolf
Keyword(s):  
F1 Hybrids ◽  
Genetic Constitution ◽  
Rational Analysis ◽  
Organic System ◽  
Rods And Cones ◽  
Flicker Response ◽  
Physical Organization ◽  
Biological Performance ◽  
Intermediate Value ◽  
Invariant Properties

The flicker response contour has been determined for several species and types of the teleosts Xiphophorus (X.) and Platypoecilius (P.) under the same conditions. The curve (F vs. log Im) is the same for representatives of each generic type, but is different for the two genera. Its duplex nature is analyzable in each instance by application of the probability integral equation to the rod and cone constituent parts. The parameters of this function provide rational measures of invariant properties of the curves, which have specific values according to the genetic constitution of the animal. The F1 hybrids (H'') of X. montezuma x P. variatus show dominance of the X. properties with respect to cone Fmax. and σ' log I, but an intermediate value of the abscissa of inflection (τ'). The rod segment shows dominance of σ' log I from P., but an intermediate value of Fmax. and of τ'. The composite flicker curve involves the operation of two distinct assemblages of excitable elements, differing quantitatively but not qualitatively in physicochemical organization, probably only secondarily related to the histological differentiation of rods and cones because almost certainly of central nervous locus, but following different rules in hereditary determination, and therefore necessarily different in physical organization. The interpretation of the diverse behavior of the three parameters of the probability summation is discussed, particularly in relation to the physical significance of these parameters as revealed by their quantitative relations to temperature, retinal area, and light time fraction in the flash cycle, and to their interrelations in producing the decline of rod effects at higher intensities. It is stressed that in general the properties of the parameters of a chosen interpretive analytical function must be shown experimentally to possess the physical properties implied by the equation selected before the equation can be regarded as describing those invariant properties of the organic system concerned upon which alone can deduction of the nature of the system proceed. The importance of genetic procedures in furthering demonstration that the biological performance considered in any particular case exhibits constitutionally invariant features provides a potentially powerful instrument in such rational analysis.

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