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 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).

Colour Vision Deficiencies XII

Colour Vision Deficiencies XII PDF

Author: B. Drum

Publisher: Springer Science & Business Media

Published: 2012-12-06

Total Pages: 545

ISBN-13: 9401105073

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From the 98 presentations of the XIIth Symposium on Colour Vision Deficiencies, 61 were selected after peer review and revision by the authors. In addition to these contributions this volume contains a cumulative index to all authors in the IRGCVD proceedings since the first one in 1968, including the present volume. The contents include contributions on basic questions of anatomical and electrophysiological organisation of the neural pathways underlying colour vision; and on ways in which disturbances of these pathways can produce acquired colour vision deficiencies. Further contributions deal with genetics and congenital red--green colour deficiencies and colour vision testing. The resulting publication contains much of interest to basic vision scientists as well as to specialists in colour vision deficiencies.

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.

Night Vision

Night Vision PDF

Author: R. F. Hess

Publisher: Cambridge University Press

Published: 1990-09-27

Total Pages: 566

ISBN-13: 9780521327367

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This detailed 1990 book describes the light and dark adaptation of receptoral and post-receptoral mechanisms from a number of perspectives. The authors emphasise the importance of the study of achromatopsia, a rare congenital condition in which the visual mechanisms that mediate day vision are absent whilst those that mediate night vision remain intact.

Colour Vision Deficiencies VII

Colour Vision Deficiencies VII PDF

Author: G. Verriest

Publisher: Springer Science & Business Media

Published: 2012-12-06

Total Pages: 409

ISBN-13: 9400965516

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Proceedings of the Seventh Symposium of the International Research Group on Colour Vision Deficiencies Held at Centre Medical Universitaire, Geneva, Switzerland, 23-25 June, 1983

Physiology of Photoreceptor Organs

Physiology of Photoreceptor Organs PDF

Author: Michelangelo G.F. Fuortes

Publisher: Springer Science & Business Media

Published: 2012-12-06

Total Pages: 784

ISBN-13: 3642653405

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This volume is a collection of essays which attempts to summarize the recent progress in the field of photoreceptor and retinal physiology. Reflecting the way in which research is organized, each author reports on the studies performed with the techniques with which he is most familiar: morpholo gical, chemical or physiological. The first chapters describe the structure of visual cells and the histological architecture of the retina. Next comes a summary of the laws governing photochemical reactions and a report on the biochemistry of photopigments. Four articles cover the optical properties of invertebrate eyes and the electrophysiology and the interactions of their photoreceptors. These are followed by a discussion of the properties of vertebrate eyes, including chapters on optics, on the electrical responses of rods and cones and on the functional organization of the retina. The final chapter provides an extensive review of retinal biochemistry and metabolism. Even though the experimental approach differs, all studies are directed toward the solution of two basic problems: transduction in the photoreceptors and orga nization (often called "information processing") in the retina. The central problem of photoreceptor cells is to determine how light produces a response. We know that illumination evokes electrical changes and we have recently learned a great deal about the features of these changes. The evidence indicates however that elaborate processes must be interposed between the ab sorption of photons by the pigment and the production of electric currents through the membrane. These intermediary cvents remain to be unraveled.

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