Showing papers on "Photopic vision published in 1974"

Influence of temperature on retinal ganglion cell response and e.r.g. of goldfish

Abstract: 1. Extracellular recordings were made from the colour and spatial coded ganglion cells in the isolated goldfish retina. 2. Electroretinograms (e.r.g.s) were obtained from unanaesthetized goldfish. 3. For both types of responses the amplitude and phase characteristics were determined at various temperatures by means of Gaussian noise modulated light. 4. The shape of these characteristics, depicted as Bode plots, is invariant with temperature. For the ganglion cell responses this holds from 7 to 19° C, whereas for the e.r.g.s invariance is found over the entire range of temperatures used (6-30° C). 5. To obtain overlapping Bode plots shifts along the frequency axis are needed that are in accordance with the Arrhenius relation. The Q10 of the e.r.g. is about 1·9 and of the spike response about 2·7. 6. These relatively low values of Q10 indicate that the dynamics of retinal signal transformations are dominated by diffusion controlled reactions. This implies that real transport delays can be neglected in retinal input—output relations. 7. To verify whether a relationship exists between temperature and spectral coding, as has been suggested on the basis of behavioural studies, photopic e.r.g. action spectra were recorded and the spectral coding of ganglion cells were determined as a function of temperature. 8. The results point to a temperature invariance of both the photopic e.r.g. action spectra and the colour coding of ganglion cell responses. 9. The general conclusion of this study is that `rules' found in the poikilothermic goldfish are not bound by temperature.

Hue discrimination in peripheral vision under conditions of dark and light adaptation

Abstract: Rod interference is a possible factor contributing to the elevation of chromatic threshold in peripheral vision. It was found that light adaptation lowered peripheral chromatic thresholds. This result was interpreted as being due to the lowering of rod sensitivity. It was also found that light in the photochromatic interval appeared blue, indicating that rods may add a blue component to peripheral color vision.

Psychovisual disturbances in glaucoma. A study of temporal and spatial summation.

Abstract: Spatial and temporal summations in the photopic and mesopic state of adaptation were studied in areas of relative visual field disturbance in patients with chronic simple glaucoma. Neither of these modalities of psychovisual testing was more disturbed than the differential threshold. Neither modality therefore offers promise of detecting earlier glaucomatous disturbances than profile perimetry.

Achromatopsia with amblyopia. I. A clinical and electroretinographical study of 39 cases.

Abstract: In three of the five achromats examined psychophysically, evidence of three plateaux was found at certain areas of the retina during the normally photopic phase of dark adaptation while the scotopic plateau was normal. These high intensity plateaux coincided fairly well with the photopic phase of our standard dark adaptation curve and the fourth plateau with its scotopic phase. This points to three photopic submodalities and to a normal scotopic mechanism in these achromats. However, the spectral sensitivities, both in the retinal periphery and in the fovea, were maximal between 500 nm and 510 nm for the three photopic plateaux and for the scotopic one and fitted satisfactorily with the 1951 CIE scotopic standard. The mechanisms underlying the appearance of the up to three fast, high-intensity plateaux in the achromats' dark adaptation curves do not fulfill normal requirements completely since they are photopic as to the kinetics of their recovery and scotopic as to their spectral luminous efficiency. The data from the subjects examined indicate three types of receptors with cone kinetics during dark adaptation but containing rhodopsin. The theoretical significance of the findings is discussed, especially why rhodopsin seems to regenerate faster in cones than in rods or in the test tube. Other cases were found, one only illustrated, with only one fast high-intensity plateau similar to those described in the literature.

Effect of luminance and contrast on processing large disparities

Abstract: Although reduced luminance impairs the discrimination of small disparity stimuli, large-disparity discrimination may improve. For example, crossed and uncrossed stimulus disparities of 4° that are not discriminated at photopic levels may be easily discriminated at mesopic levels near the color threshold. This improvement of stereo processing appears to be dependent upon an effective contrast reduction produced neurally, because a physical reduction of contrast without a change of background luminance may also improve large-disparity stereopsis.

Scotopic and Photopic Visual Capacities of an Arboreal Squirrel (Sciurus niger)

Abstract: Behavioral measurements of visual capacities were made on fox squirrels (Sciurus niger). Spectral sensitivity functions measured in the context of an increment-threshold task reveal

Effects of the cone-cell distribution on pattern-detection experiments.

Abstract: At photopic luminance levels, the cone-cell variation of packing density across the retina provides a natural limit to the effective size of wide-field stimulus patterns. In some experiments, this eliminates the need for small test spots, which produce band-broadening effects in the spatial-frequency domain. Calculations of these effects are given, to aid in the design of such experiments.

A family with two siblings affected by Morquio syndrome (MPS IV). Electrophysiological and psychophysical findings in the visual system.

Abstract: Two siblings of normal intelligence, belonging to a nonconsanguineous marriage, had their conditions diagnosed as mucopolysaccharidosis (MPS) type IV—the so-called Morquio syndrome. Despite corneal cloudiness, no other ophthalmological abnormalities or complaints emerged, the visual acuity, fields, and color vision being normal. The electroretinogram, recorded during dark adaptation, pointed to slight photopic impairment, and its amplitudes were normal in the one and supernormal in the other case. The psychophysical dark adaptation also indicates some scotopic impairment. In view of the normal electrooculogram, the scotopic deficiency should be located in the inner retina. Conduction in the optic pathways and the information processing in the striate cortex examined by the visual evoked potential were normal. No ophthalmological and electrophysiological deficiencies have been found in other members of the family, including the carrier.

Form-specific colour after effects in scotopic illumination.

Abstract: THE retina of the human eye contains rod and cone receptors, and in very dim light the rods alone function (scotopic illumination) so that objects appear colourless At higher light levels, cones also function (photopic illumination) and colours are seen

Electro-Ophthalmology of a Family with X-chromosomal Recessive Nyctalopia and Myopia

Abstract: Sixteen patients of a family suffering from nyctalopia with myopia, X-chromosomal recessively inherited, were examined ophthalmoscopically and psychophysically. Of two other families with X-chromosomal recessive nyctalopia and myopia we examined four affected members. In all these patients we found an almost normal EOG, a lowered scotopic ERG and no oscillatory potentials. The photopic ERG appeared to be very specific, viz. the a-wave was deep and broad, the b-wave very small, often consisting of several peaks. On account of these data the disturbance has to be post-receptoral.

Multivariate vectorial analysis of the visual evoked response

Abstract: Principal component analysis of a set of V.E.R.s yields vectorial representations of the responses in a diagram of a reduced dimensionality. In a vectorial diagram the responses can be resolved into components, associated with the aspects of the stimulus modulation and the state of the visual system. The appearance of a scotopic and a photopic component is demonstrated. In another experiment small modulations of luminance and color evoked the responses. The distorting effect of a type of non-linearity of the visual system, that is latency variation of the responses and the components, is discussed and demonstrated.

Visual Acuity as a Function of Wavelength in Three Catarrhine Species

Abstract: The visual acuity criterion was used to determine the relative spectral luminous efficiency function at scotopic and photopic levels in the rhesus monkey, sooty mangabey, and olive baboon. The stimulus energy necessary to resolve gratings subtending 11.235 and 1.976 min of arc was determined at nine wavelengths. The coarser gratings had a visual acuity requirement of 0.089, which could be resolved at very dim luminance levels, while the finer gratings had an acuity requirement of 0.506, which could be resolved only at very high luminance levels. The relative luminous efficiency functions obtained with the coarse gratings were comparable for the three species except in the long wavelength region where the baboons were relatively less sensitive and the mangabeys relatively more sensitive than the rhesus. With the finer gratings, the major differences among species again were in the long wavelength region with the rhesus showing a pronounced relatively reduced sensitivity.

Spectral Sensitivity Function Determined by the Visually Evoked Cortical Potential in Several Classes of Colour Deficiency (Cone Monochromatism, Rod Monochromatism, Protanopia, Deuteranopia)

Abstract: The spectral sensitivity function was studied by measuring the sensory threshold and by recording the visually evoked cortical potential in normal and colour-defective subjects (rod monochromatism, cone monochromatism, protanopia, deuteranopia).In the rod monochromat, the loss of sensitivity at increasing background illumination was higher as compared to the normal observer. The spectral sensitivity in the dark adapted state and during light adaptation was the same and Cone Monochromatism corresponded closely to the CIE scotopic luminosity curve In two protanopes and one cone monochromat, the photopic sensitivity curve was greatly reduced at longer wavelengths as compared to the normal observer. In a deuteranope, the sensitivity to the wavelengths tested was close to the CIEphotopic luminosity curve

Incremental Threshold as Obtained by the Visually Evoked Cortical Potential (VECP)

Abstract: Measurements were made of the range of threshold (dl) in response to a blue (451 nm) and a green (550 nm) monochromatic test light during exposure to step-wise increased backgrounds of illumination Ph

Thresholds of the Oscillatory Potentials in Mice

Abstract: The spectral sensitivity curve of the b-wave and the oscillatory potentials reveals no photopic activity. This finding is confirmed by evaluation of the increment thresholds of the b-wave and the oscillatory potentials. Using coloured lights no Purkinje-shift was observed. The increment thresholds of the b-wave obey the Weber’s law.

A cat's form‐experienced but visual‐motor deprived eye lacks focal vision

Abstract: Cats were allowed to move about freely from birth to 18 months with one eye open; the other eye was open during daily 1-hr periods of binocular exposure in a holder, but was deprived of all visual-motor experience. Focal vision failed to develop in the deprived eye (DE): (1) the DE's guidance deficit was especially pronounced for targets in the central field and in the photopic light range (it was much smaller in the periphery and in the mesopic range); (2) conjugate eye control, required for binocular fixation of objects in focal viewing, was disrupted by strabismus (squint); and (3) focal vision's identification function was virtually absent in the DE—it showed only slight recognition of patterns learned by the experienced eye (EE) and little ability to learn to identify them itself.

Monochromatic ERGs in a Case of Progressive Cone Dystrophy

Abstract: A 32-year-old man with progressive cone dystrophy was subjected to ERG recording and psychophysical testing. Under mesopic conditions the scanning over 16 monochromatic flashes produced a series of b-waves in which the maximum response occurred at 500 nm, and no response in the range above 660 nm. The attenuation of the b-waves with increasing background illumination occurred more rapidly in the patient’s eye than normal. Under photopic conditions repeated time-locked scanning permitted the recording of a series of minimal bp-waves in which the maximum was at 540 nm and was 10 µV or less in amplitude. Psychophysical testing with the same 16 monochromatic flashes showed that a central island of the visual field, i.e. the island of residual pure cones, showed peak spectral sensitivity at 560 nm, but away from this island the peak was found to be shifted to near 500 nm with some eccentric fixation.

Rod Signals in Higher Color Mechanisms: The McCollough Color Aftereffect Observed in Scotopic Illumination

Abstract: The McCollough color aftereffect — a long-lasting color aftereffect specific to both line orientation and spatial frequency — was observed in scotopic illumination well below the rod-cone break. Two color adaptation procedures were used: (a) Adaptation to a photopic green vertical grating alternating with a magenta horizontal grating or to an orange vertical grating alternating with a blue horizontal grating; (b) Adaptation to vertical green and magenta gratings of different low apatial frequencies. After color adaptation, test patterns were viewed in scotopic illumination. The sftereffects observed were specific to both the orientation and spatial frequency of the test patterns. These results are consistent with physiological observations that rod signals feed into opponent color mechanisms.

Contribution of the Central and the Peripheral Part of the Retina to the VECP Under Photopic Conditions

Abstract: It is a moot point if the retinal periphery contributes substantially to the VECPs. Outside the central retinal area no reasonable cortical potentials can be obtained with localized stimuli. In the experiments described here, the total retina and the whole retinal periphery have been stimulated. Three kinds of responses were observed: a positive foveal potential, a negative para- and perifoveal one and some small peripheral potentials. As to the peaktimes of these various components inter-individual variations occur.

Peripheral visual response time to colored stimuli imaged on the horizontal meridian

Abstract: Two male observers were administered a binocular visual response time task to small (45 min arc), flashed, photopic stimuli at four dominant wavelengths (632 nm red; 583 nm yellow; 526 nm green; 464 nm blue) imaged across the horizontal retinal meridian. The stimuli were imaged at 10 deg arc intervals from 80 deg left to 90 deg right of fixation. Testing followed either prior light adaptation or prior dark adaptation. Results indicated that mean response time (RT) varies with stimulus color. RT is faster to yellow than to blue and green and slowest to red. In general, mean RT was found to increase from fovea to periphery for all four colors, with the curve for red stimuli exhibiting the most rapid positive acceleration with increasing angular eccentricity from the fovea. The shape of the RT distribution across the retina was also found to depend upon the state of light or dark adaptation. The findings are related to previous RT research and are discussed in terms of optimizing the color and position of colored displays on instrument panels.

The Functional Examination of the Human Photopic Visual System with the Aid of Psychophysical Flicker Thresholds and ERG Flicker Responses

Abstract: This paper deals with the use of flicker fusion thresholds, as plotted by De Lange, and averaged flicker ERG recorded with conventional clinical equipment. Different methods are developed to quantify the morphological changes of the ERG responses and express them in empirical attenuation curves. The objective and subjective results are discussed in point of view of the De Lange model.

Coupled Electrophysiological and Colour Fluorographic Studies as a Part of the Anatomical Diagnosis of Retinopathies

Abstract: The main procedures involved in the electrophysiological investigation of the visual tract are (Alfieri et al., 1970): 1. the electroretinogram (ERG) which demonstrates the activity of the photoreceptors and bipolar cells; this examination conducted in monochromatic light (Sole, 1965) makes it possible to study individually the photopic system in red stimulation (ERG-r) and the scotopic system in blue stimulation (ERG-b); 2. the visual evoked response (VER) which, in our point of view, essentially reflects the permeability of the visual pathways from the ‘optic nerve’ link to the ‘visual cortex’. Such an examination carried out in monochromatic light (Plane, 1969 and Rigal, 1970) allows an individual study of the conduction systems: the macular ones (central cones) in red stimulation (VER-r) on the one hand, and the extramacular ones (peripheral cones and rods) in blue stimulation (VER-b) on the other hand.

Monochromatic ergs in a case of progressive cone dystrophy.

Abstract: A 32-year-old man with progressive cone dystrophy was subjected to ERG recording and psychophysical testing. Under mesopic conditions the scanning over 16 mono­ chromatic flashes produced a series of b-waves in which the maximum response occurred at 500 nm, and no response in the range above 660 urn. The attenuation of the b-waves with increasing background illumination occurred more rapidly in the patient's eye than normal. Under photopic conditions repeated time-locked scanning permitted the recording of a series of minimal bp-waves in which the maximum was at 540 nm and was 10 fLY or less in amplitude. Psychophysical testing with the same 16 monochromatic flashes showed that a central island of the visual field, i.e. the island of residual pure cones, showed peak spectral sensitivity at 560 urn, but away from this island the peak was found to be shifted to near 500 urn with some eccentric fixation. The clinical entity of progressive cone dystrophy (degeneration) has recently been established, predicated on the fact that there exist progressive and general­ ized dystrophic changes in the cone system as contrasted to a normal rod system. The electroretinogram (ERG) is of importance not only to the clinical diagnosis, but also to the analysis of normally remaining rod function and declining cone function. There are several reports (BABEL & STANGOS, 1973; BERSON et aI., 1968; GOODMAN et aI., 1963; KELSEY & ARDEN, 1972; KRILL & DEUTMAN, 1972; SLOAN & BROWN, 1962) on detailed findings of the ERG in the disease. However, as pointed out by BERSON (1968), in many cases the cone responses are too small for quantitative studies at different wavelengths. We had an opportunity to study the disorder in a typical case. The patient exhibited considerable photopic response to monochromatic flashes that were balanced on a quantum basis. The same stimulating system was also used for psychophysical testing. The purpose of this report is to present the spectral response of the patient's eye under mesopic and photopic conditions, and the spectral sensitivity in several portions of degenerating retina.

Electroretinography of Cone Dysfunction with Monochromatic Light

Abstract: The possibility of showing electrophysiologically the involvement of the photopic system is demonstrated from the results obtained from dynamic ERG using coloured filters, mainly with Wratten red-orange (WK 26) or red (WK 92) filters, by means of flickering, by means of O.P., and also using static ERG with high intensity white stimuli in the presence of a background light to saturate the rod ERG.

Cone Dystrophy with Dominant Inheritance Part I: Clinical Case Histories

Abstract: Nine patients with acquired cone dystrophy inherited as an autosomal dominant trait are reported in a family pedigree spanning four generations. Preliminary color vision testing included the usual AO H-R-R and Ishihara pseudoisochromatic plates. In addition, dark adaptometry and electroretinography was performed. ERGs with flicker fusion determinatives confirmed the functional photopic defect. Fluorescein angiography was performed in selected cases.