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"To explain all nature is too difficult a task for anyone man or even for anyone age. Tis much better to do a little with certainty, and leave the rest for others that come after you, than to explain all things ... " Sir Isaac Newton (1642-1727) This book describes and discusses some new aspects of col or vision in primates which have emerged from a series of experiments conducted over the past 8 years both on single ganglion cells in monkey retina and on the visually evoked cortical potential in man: corresponding psychophysical mechanisms of human perception will be considered as well. An attempt will be made to better understand the basic mechanisms of color vision using a more comprehensive approach which takes into account new mechanisms found in single cells and relates them to those found valid for the entire visual system. The processing of color signals was followed up from the retina to the visual cortex and to the percepq.tal centers, as far as the available techniques permitted.
List of contents
1 Introduction.- 1.1 Color Vision Theories. Historical Aspects.- 1.2 Electrophysiological Studies Related to Color Vision.- 2 Methods.- 2.1 Methods of Single Cell Recording in Rhesus Monkeys.- 2.2 Identification of Cone Inputs in Retinal Ganglion Cells.- 3 Types of Retinal Ganglion Cells and Their Distribution.- 3.1 Introductory Remarks.- 3.2 The Concept of Color-Opponency.- 3.3 The Various Types of Color-Opponent Cells.- 3.4 Variations in Color-Opponency.- 3.5 Spectrally Non-Opponent Ganglion Cells.- 3.6 Distribution of Classes of Ganglion Cells Across the Retina.- 3.7 A Simplified Classification Procedure.- 3.8 Résumé: Some Implications for the Understanding of the Visual System's Function.- 4 Special Properties of Blue-Sensitive Ganglion Cells.- 4.1 Some Recent Electrophysiological and Psychophysical Data on the Blue-Sensitive Cone System.- 4.2 Chromatic Adaptation and Spectral Sensitivity.- 4.3 Paradoxical Phenomena Occurring During Light and Dark Adaptation in Blue-Sensitive Ganglion Cells.- 4.4 A Model Describing the Interaction Between Cone Mechanisms in Blue-Sensitive, Color-Opponent Ganglion Cells.- 4.5 Résumé: What is Special About the Blue Cone Mechanism?.- 5 Temporal Properties of Color-Opponent Ganglion Cells..- Flicker-Stimulation; Testing the "Channel" Hypothesis.- 5.1 Critical Flicker Frequencies (CFF) in Tonic and Phasic Ganglion Cells.- 5.2 Influence of Stimulation Frequency on the Spectral Sensitivity Function: Loss of Color-Opponency at Higher Flicker Rates.- 5.3 The Basic Mechanism: Phase-Shift Between Center and Surround Responses.- 5.4 Latency of Center and Surround Responses.- 5.5 The Processing of Luminous and Chromatic Flicker.- 5.6 Stimulus Duration Changes the Action Spectrum.- 5.7 Résumé: Possible Implication of the TransitionBetween Antagonism and Synergism in Color-Opponent Ganglion Cells.- 6 The Spectral Properties of the Human Visual System as Revealed by Visually Evoked Cortical Potentials (VECP) and Psychophysical Investigations.- 6.1 Methods as Applied in Human Observers.- 6.2 Rods and Cones.- 6.3 Fundamental Cone Functions.- 6.4 Color-Opponency in the VECP and in Psychophysical Measurements.- 6.5 The Influence of Flicker Frequency on Spectral Sensitivity.- 6.6 Conclusion: To What Extent Can Visually Evoked Cortical Potentials Reveal the Function of Individual Receptor Mechanisms?.- Epilogue.- Summary.- References.
