Scotopic Vision
Mostrando 1-12 de 16 artigos, teses e dissertações.
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1. Visual acuity and retinal function in patients with Bardet-Biedl syndrome
OBJECTIVE: Bardet-Biedl syndrome is a genetic, multisystem disorder that causes severe visual impairment. This condition is characterized by retinal dystrophy, obesity, digit anomalies, renal disease, and hypogonadism. The purpose of this study was to analyze visual acuity and full-field electroretinogram findings in patients with the Bardet-Biedl syndrome p
Clinics. Publicado em: 2012
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2. Estudo computacional sobre a influência de sinapses elétricas entre bastonetes na faixa dinâmica escotópica da retina de vertebrados / A computational study on the influence of rod coupling by electrical synapses on the scotopic dynamic range of the vertebrate retina.
Recentes estudos sugerem a existência de sinapses elétricas mediadas por junções gap entre fotorreceptores na retina de vertebrados. Neste trabalho, descrevemos um modelo computacional dos circuitos primário e secundário mediados pelos bastonetes da retina de vertebrados. O modelo é composto pelas seguintes populações de células: bastonetes, cones,
Publicado em: 2008
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3. Dim-Light Sensitivity of Cells in the Awake Cat's Lateral Geniculate and Medial Interlaminar Nuclei: A Correlation With Behavior
Contrast thresholds of cells in the dorsal lateral geniculate (LGNd) and medial interlaminar (MIN) nuclei of awake cats were measured for scotopic and mesopic vision with drifting sine gratings (1/8, 2, and 4 cycles/deg [cpd]; 4-Hz temporal frequency). Thresholds for mean firing rate (F0) and temporally modulated responses (F1) were derived with receiver-ope
American Physiological Society.
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4. Symptomatic abnormalities of dark adaptation in patients with age-related Bruch's membrane change.
Some patients with age-related changes at the level of Bruch's membrane and good visual acuity report poor vision in dim light, fading vision in bright light, and a central scotoma noticeable in the dark. Ophthalmic examination, scotopic thresholds, and dark adaptation kinetics were recorded in 12 eyes of 12 patients with such symptoms. All had macular druse
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5. Contrast Sensitivity of Cats and Humans in Scotopic and Mesopic Conditions
Human contrast sensitivity in low scotopic conditions is regulated according to the deVries–Rose law. Previous cat behavioral data, as well as cat and mice electrophysiological data, have not confirmed this relationship. To resolve this discrepancy at the behavioral level, we compared sensitivity in dim light for cats and humans in parallel experiments usi
American Physiological Society.
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6. The photoreceptors in atypical achromatopsia.
1. 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
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7. Spatial and temporal limits of vision in the achromat.
Threshold detection for sine-wave grating stimuli of varying spatial and temporal frequency was used to investigate the nature of spatial and temporal post-receptoral sensitivity in the typical, complete achromat. Threshold spatial and temporal sensitivities under low photopic conditions show no evidence of cone function. The abrupt fall-off in sensitivity i
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8. The photocurrent, noise and spectral sensitivity of rods of the monkey Macaca fascicularis.
Visual transduction in rods of the cynomolgus monkey, Macaca fascicularis, was studied by recording membrane current from single outer segments projecting from small pieces of retina. Light flashes evoked transient outward-going photocurrents with saturating amplitudes of up to 34 pA. A flash causing twenty to fifty photoisomerizations gave a response of hal
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9. Rod and cone activity in patients with dominantly inherited retinitis pigmentosa: comparisons between psychophysical and electroretinographic measurements.
Extended electroretinographic (ERG) testing has been carried out in a series of patients with retinitis pigmentosa, dominantly inherited. In 36 of 57 cases only cone b waves were evoked. In 20 of these, psychophysical tests showed only cones mediated vision (Massof class I), while in 16 statis scotopic perimetry demonstrated residual rod function (class II).
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10. Structures of the Visual Chromophores and Related Pigments: A Conformational Basis of Visual Excitation
A detailed conformational analysis of the known crystal structures of vitamin A, carotenoid, and xanthenoid derivatives has been made. These studies suggest that the visual chromophore 11-cis retinal and its isomers may each occur in several different conformational states, which would be expected to have different lightabsorbing characteristics. The presenc
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11. Spatial and temporal properties of human rod vision in the achromat.
The spatial and temporal properties of rod vision were measured for stimuli at and above the detection threshold in an achromat whose spectral sensitivity, dark adaptation, spatial and temporal thresholds and Stiles-Crawford effect suggest the presence of only a normally functioning rod system. The properties of rod and cone vision were compared at illuminan
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12. The temporal properties of rod vision.
1. Profiles which represent rod thresholds for flickering fields seen against backgrounds of various intensity have shapes which depend on flicker frequency. Low frequency profiles rise smoothly as background intensity is increased. High frequency profiles are only affected by bright backgrounds, which cause them to rise steeply. Intermediate frequency profi