Showing papers in "Vision Research in 1968"

TL;DR: In this paper, three major neural components of the mammalian ERG have been demonstrated, including the late RP (receptor potential), b-wave, and d.c. component, plus the c-wave from the pigment epithelium.

TL;DR: The small size and number of cones in frog retinas probably makes the total relative contribution of cone pigment molecules too small for successful spectroscopic studies in extracts.

TL;DR: General equations are developed to describe the pigment kinetics in a wide range of conditions, and the regeneration rate depends upon the amount of 11- cis retinal immediately available, and during a prolonged bleach this is largely exhausted.

TL;DR: From the values 40,600 cm 2 and 30,000 cm 2 respectively for the molar extinctions (e max ) of A 1 and A 2 pigments it follows that the quantum efficiency γ (in hydroxylamine at 25°C) is about the same—23—for all visual pigments.

TL;DR: The results suggest that it is possible to determine refractive error by observing the changes in two components of the evoked cortical potential when a stimulus pattern is viewed through a series of lenses.

TL;DR: The liminal contrast sensitivity measured as a function of the exposure duration of the stimulus and as afunction of the velocity of the horizontally moving vertical sine-wave gratings showed some temporal characteristics in the spatial response.

TL;DR: A diver-operated instrument is described that allows the spectral contrast between a grey target and its water background to be measured and shows that in Mediterranean waters those visual pigments with a λmax corresponding to the wavelength of maximum light transmission through the water are best suited for detecting large very dark or very bright objects.

TL;DR: Results indicate that perceived orientation of oblique lines is closer to the horizontal or vertical than is geometrical slant, the difference being of the order of 5 °, and what type of information is actually used in the visual system to arrive at “orientation” is investigated.

TL;DR: In this paper, contrast thresholds of the goldfish eye were determined by the method of constant stimuli using a yes-no conditioned cardiac-response and computerized probit analysis was used to treat the data.

TL;DR: A previously described neural unit, for the description of brightness distributions produced by luminance patterns, was improved to combine both types of inhibition, including the Mach-type and Hering-type.

TL;DR: Several lines of evidence indicate that the VER provides a valid objective index of foveal function and excellent agreement between the VER and subjective thresholds in studies of the area-intensity relation, Stiles-Crawford effect and spectral sensitivity.

TL;DR: The summing properties of ganglion cells in the cat's retina have been examined, using as stimuli two stationary, flashing spots of light both positioned within the center regions of the cells' receptive fields and found to be non-linear in both cases.

TL;DR: It is concluded, that neither acetylcholine nor noradrenaline are the main and only transmitters of retinal excitation or inhibition.

TL;DR: The area-luminance relation was investigated in a study of simultaneously recorded electroretinograms and evoked potentials and the results were interpreted in terms of the additivity of response and the distribution of retinal elements.

TL;DR: Visual acuity and ERG critical flicker frequency of 4 diurnal and 2 nocturnal primate species were related to the morphologic organization of photoreceptors and the retina, and similarities in acuity were associated with the convergence of receptors on ganglion cells, whereas visual learning capacity was associated with differences in visual projection and association areas in the brain.

TL;DR: Electrophysiological studies support the hypothesis that all or most of the Optic Nerve fibres supplying Lateral Geniculate Nucleus (LGN) bifurcate to supply Anterior Colliculus (AC) and three similar groups of fibres are activated in ON by stimulating either in AC or in LGN.

TL;DR: Recordings in the cat lateral geniculate nucleus under conditions of visual stimulation corresponding to those which in the human observer would lead to masking and metacontrast produced results at the unit level which are parallel to the perceptual masking effects obtained in man.

TL;DR: Electrical pulses of 1 msec duration passed radially through the isolated carp retina evoke electrical responses in the S-cells (horizontal cells), which were always positive (depolarization) and were evoked by a sclera-positive direction of the stimulating current.

TL;DR: Stroboscopic movement perception of random-dot stereograms differs from the perception of classical stimuli both quantitatively and qualitatively, provided that the former stimuli are presented such that in addition to the elimination of all monocular form cues allmonocular movement cues are removed.

TL;DR: Cue reports taken in conjunction with measures of accuracy indicate that two-pulse manipulations produce complex perceptual changes which cannot always be related to temporal resolution.

TL;DR: The results indicate that the human visual system contains different velocity-sensitive mechanisms, each of which is most responsive to a specific range of contour velocities.

TL;DR: The half-lives for the thermal decay of several of the intermediates formed in the bleaching of rhodopsin have been studied in the retina of the albino rat using the fast photo voltages produced by the action of light on these intermediates.

TL;DR: Responses of single cells in the macaque lateral geniculate nucleus were recorded through extracellular micropipettes and a decrease in responses to excitatory stimuli was predominant, implying removal of corticofugal excitation.

TL;DR: Gaze displacements and fixations were recorded by a vectorial method in normal subjects during the free search of a simple (P1) and a complex (P2) visual pattern.

TL;DR: The data from color-blindSs suggested that each type of dichromat possesses only one of the three possible classes of opponent-color cells which can be constructed using two of three possible receptor systems.

TL;DR: These findings give a basis for understanding why visual functions are so completely dominated by rods under dark adapted conditions, and by cones after light adaptation, a problem at the heart of the duplicity theory.

TL;DR: Steady-state scalp potentials were evoked by stimulating the eye with monochromatic light whose intensity was sinusoidally modulated at frequencies between 4 c/s and 33 c/S, and the characteristics of the responses suggested that different mechanisms are important near the α frequency and around 16c/s.

TL;DR: The linear relation between decimal acuity and log luminance, well established for the fovea, is also found for parafoveal areas of the retina, and changes in retinal organization and their effects on the density of functional receptor units probably contribute to the observed regional differences.

TL;DR: The analysis of scotopic thresholds finally reached shows that, within a certain range, the scotopy sensitivity is proportional to the fraction of light absorbed, which suggests the dominance of photochemical processes over nervous ones in setting the sensitivity level.

TL;DR: The A λ max of protonated Schiff bases derived from retinal, a visual pigment chromophore, experience large bathochromic shifts in a non-polar solvent, and the absorptive properties of rhodopsins can be explained in terms of these observations.