The Rod After-effect in S-potentials from Cat Retina

The Rod After-effect in S-potentials from Cat Retina PDF

Author: Roy Herbert Steinberg

Publisher:

Published: 1969

Total Pages: 24

ISBN-13:

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The relation of the rod after-effect to percentage rhodopsin bleached was studied in S-potentials from cat retina. At threshold, flashes which produced the rod after-effect bleached only very small quantities of rhodopsin; and at a fixed flash duration, the duration of the after-effect increased as a function of log intensity. The after-effect's threshold occurred at about the intensity which saturated the maintained voltage. With flash intensity fixed (6.5 log td. scotopic) and flash duration increased (0.5 to 64.0 sec) the duration of the after-effect was a linear function of exposure time. The duration continued to increase after an exposure of 16 sec, even though at least 99 per cent of the rhodopsin had been bleached. It is concluded that the after-effect originates from something which accumulates after the maintained voltage in rod pathways reaches a ceiling. The accumulation can continue at a fixed rate irrespective of the bleaching rate. (Author).

Rod-cone Interaction in S-potentials from Cat Retina

Rod-cone Interaction in S-potentials from Cat Retina PDF

Author: Roy Herbert Steinberg

Publisher:

Published: 1969

Total Pages: 28

ISBN-13:

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Rod-cone interaction in cat S-potentials was studied by analyzing the effect of wavelength and intensity upon the form of dark-adapted responses. Flashes of white light and relatively monochromatic flashes produced responses that seemed to originate from the excitation of both receptor types. The rod response changed as a function of intensity, peaking at approx. 2.5 log above threshold and increasing in duration at approx. 3.0 log above threshold. The cone response seemed in some way to add to the changing rod response. V-Log I curves showed that the rod responses reached a ceiling (initial peak voltage) at approx. 3.5 log above threshold while the maintained voltage leveled off at a lower intensity. Both ceilings were obscured by the apparent addition of the cone contribution. Cone and rod responses to brief orange and blue lights of moderate intensity, separated in time, added together across a complete range of intervals. (Author).

Rod and Cone Contributions to S-potentials from Cat Retina

Rod and Cone Contributions to S-potentials from Cat Retina PDF

Author: Roy Herbert Steinberg

Publisher:

Published: 1969

Total Pages: 24

ISBN-13:

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The problem of whether the rods contribute to S-potentials was studied in the intact eye of the cat. S-potentials from luminosity units (L-units) were evoked by small spots of relatively monochromatic light in dark- and light-adapted retinae. The spectral sensitivity curve for dark-adapted S-potentials had its maximum at 500 nm, and the form of dark-adapted responses also suggested that rods were excited. The spectral sensitivity curve for light-adapted S-potentials had its maximum at 560 nm, and response latencies even at threshold were much faster than in dark adaptation. Individual S-potentials exhibited Purkinje shifts. It is concluded that rhodopsin rods contribute to S-potentials (L-type) in the cat and that cones contribute to the same responses. (Author).

The Rod After-effect in S-potentials from Cat Retina

The Rod After-effect in S-potentials from Cat Retina PDF

Author: Roy H. Steinberg

Publisher:

Published: 1969

Total Pages: 18

ISBN-13:

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The relation of the rod after-effect to percentage rhodopsin bleached was studied in S-potentials from cat retina. At threshold, flashes which produced the rod after-effect bleached only very small quantities of rhodopsin; and at a fixed flash duration, the duration of the after-effect increased as a function of log intensity. The after-effect's threshold occurred at about the intensity which saturated the maintained voltage. With flash intensity fixed (6.5 log td. scotopic) and flash duration increased (0.5 to 64.0 sec) the duration of the after-effect was a linear function of exposure time. The duration continued to increase after an exposure of 16 sec, even though at least 99 per cent of the rhodopsin had been bleached. It is concluded that the after-effect originates from something which accumulates after the maintained voltage in rod pathways reaches a ceiling. The accumulation can continue at a fixed rate irrespective of the bleaching rate. (Author).

Rod-cone Interaction in S-potentials from Cat Retina

Rod-cone Interaction in S-potentials from Cat Retina PDF

Author: Roy H. Steinberg

Publisher:

Published: 1969

Total Pages: 23

ISBN-13:

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Rod-cone interaction in cat S-potentials was studied by analyzing the effect of wavelength and intensity upon the form of dark-adapted responses. Flashes of white light and relatively monochromatic flashes produced responses that seemed to originate from the excitation of both receptor types. The rod response changed as a function of intensity, peaking at approx. 2.5 log above threshold and increasing in duration at approx. 3.0 log above threshold. The cone response seemed in some way to add to the changing rod response. V-Log I curves showed that the rod responses reached a ceiling (initial peak voltage) at approx. 3.5 log above threshold while the maintained voltage leveled off at a lower intensity. Both ceilings were obscured by the apparent addition of the cone contribution. Cone and rod responses to brief orange and blue lights of moderate intensity, separated in time, added together across a complete range of intervals. (Author).

Rod and Cone Contributions to S-potentials from Cat Retina

Rod and Cone Contributions to S-potentials from Cat Retina PDF

Author: Roy H. Steinberg

Publisher:

Published: 1969

Total Pages: 19

ISBN-13:

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The problem of whether the rods contribute to S-potentials was studied in the intact eye of the cat. S-potentials from luminosity units (L-units) were evoked by small spots of relatively monochromatic light in dark- and light-adapted retinae. The spectral sensitivity curve for dark-adapted S-potentials had its maximum at 500 nm, and the form of dark-adapted responses also suggested that rods were excited. The spectral sensitivity curve for light-adapted S-potentials had its maximum at 560 nm, and response latencies even at threshold were much faster than in dark adaptation. Individual S-potentials exhibited Purkinje shifts. It is concluded that rhodopsin rods contribute to S-potentials (L-type) in the cat and that cones contribute to the same responses. (Author).

The Retina A Model for Cell Biology Studies Part_2

The Retina A Model for Cell Biology Studies Part_2 PDF

Author: Ruben Adler

Publisher: Elsevier

Published: 2012-12-02

Total Pages: 363

ISBN-13: 0323154190

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The Retina: A Model for Cell Biology Studies, Part II, is the second of a two-part series that details developments in the study of retinal cell biology. The book begins with a review of the current evidence for the role of putative neurotransmitters at particular synapses in the retina. It then discusses pre- and postsynaptic regulatory mechanisms; the interactions of neurotransmitter-neuromodulatory systems; and cellular effects of putative neurotransmitters and neuromodulators. This is followed by an introduction to vision psychophysics, showing its application in studying the functioning of cells in the retina. The remaining chapters discuss how the retinal pigment epithelium cell might be used as a model for studying biological problems of current interest; extracellular matrix molecules; concepts and controversies regarding the biology of endothelial cells, the key elements in the phenomenon of intraocular neovascularization; the use of genetic mutations and genetic mosaics for the study of the retina; and the retina as a regenerating organ.

Neural Principles in Vision

Neural Principles in Vision PDF

Author: F. Zettler

Publisher: Springer Science & Business Media

Published: 2012-12-06

Total Pages: 438

ISBN-13: 3642664326

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Scientific investigation of the retina began with extensive studies of its anatomical structure. The selective staining of neurons achieved by the Golgi method has led to a comprehensive picture of the architecture of the tissue in terms of its individ ual elements. Cajal, in particular, used this tech nique to reveal the fundamentals of retinal struc ture. In the studies that followed, selective stain ing method continued to be decisive in the analysis of neuroanatomy, and in recent years these techniques have been complemented by electron microscopy. The complexity of retinal structure that has been revealed demands a functional explanation, and elec trophysiology attempts to provide it. But functional analysis, like anatomy, must ultimately be based on the single cell. It is only by using dyes to mark the recording site that one can identify the cells involved. When this succeeds, as it has recently, one can actually fit functional events into the ana tomical framework. With these advances, our strate gies and tactics toward an understanding of the structure and function of the retina have moved in to a new phase.

From Pigments to Perception

From Pigments to Perception PDF

Author: Arne Valberg

Publisher: Springer Science & Business Media

Published: 2012-12-06

Total Pages: 475

ISBN-13: 1461537185

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Proceedings of a NATO ARW on Advances in Understanding Visual Processes: Convergence of Neurophysiological and Psychological Evidence, held in Roros, Norway, August 6-10, 1990

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