Joel Pokorny - US grants

We propose to study normal color vision, and the nature of defects in color which occur in individuals with stationary hereditary color defects ahd those which occur in various retinal and choroidal disease states. We shall use psychophysical techniques to measure the color defects and relate these defects to normal color vision and to the various disease states. We shall use retinal densitometry to study cone visual pigment kinetics in color defective observers and will evaluate the feasibility of studying cone visual pigments kinetics in patients with acquired macular disorders. In addition to empirical studies, we develop models of normal and abnormal color vision. Our theoretical approach is based in the question: To what extent can established biological or physical phenomena explain the data of color vision: This approach is one which allows us to examine the plausibility of various hypotheses which are not subject to direct experimental evaluation.

Much of what we learn about human sensory processing comes from experiments that use the approach known as psychophysics, in which carefully quantified stimulus parameters are used to obtain highly reproducible, quantifiable responses. Such tests can include, for example, threshold measurements in which a subject responds by telling whether or not a particular stimulus is perceived. Much of what we learn about how the cells of the brain process information comes from animal experiments, in which quantified stimuli produce recordable neural activity that can be measured in a variety of ways. Recently it has become clear that both approaches can be used on some of the same sensory issues. This conference has the specific intent of bringing together vision researchers using both approaches, to address recent successes in relating physiological and psychophysical results from primate and human work, and to stimulate new interdisciplinary and cooperative research in vision among the international community. The publication from the conference will likely have impact on sensory scientists in general, in addition to its value to visual neuroscience and psychology.

This proposal is directed toward the study of normal color vision, and to the assessment of the color defects which occur in individuals with stationary, hereditary color defects and those which occur in various retinal and choroidal disease states. Psychophysical methods will be used to study heterochromatic sensitivity, color matching, and spectral sensitivity of the cone mechanisms. These studies are designed to reveal the nature of the retinal cone mosaic, including the numbers and types of photoreceptors in observers with normal and abnormal color vision. Psychophysical and electroretinographic techniques will allow basic studies of the short wavelength sensitive (SWS) cone mechanism in color normal individuals and in patients with retinal disease. Studies of temporal modulation sensitivity using heterochromatic modulation photometry will be performed with the aim of separating the effects of radiance, chromaticity and temporal frequency. Retinal densitometry will be used to study cone visual pigment kinetics in color normal and color defective observers and will evaluate the feasibility of studying cone visual pigment kinetics in patients with acquired macular disorders. The development and evaluation of protocols for testing patients with eye disease will be continued. The aim is to develop easily-performed and rapid tests which give specific information concerning visual function in eye disease. In addition to empirical studies, models of normal and abnormal color vision will continue to be developed. The theoretical approach is based in the question: to what extent can established biological or physical phenomena explain the data of color vision? This approach is one which allows us to examine the plausibility of various hypotheses which are not subject to direct experimental evaluation.

DESCRIPTION (provided by applicant): This application is directed toward the study of visual mechanisms in observers with normal vision, observers with congenital color vision defects, and observers with acquired visual defects secondary to various disease states. The studies are designed to reveal the biological processes that limit human visual performance. The proposed research is organized into 6 projects: Project 1 concerns the mechanisms limiting the human observer's sensitivity at low light levels. Project 2 looks at the function of the two major processing streams between eye and brain, and how the parvocellular (PC) and magnocellular (MC) pathways are involved in achromatic discriminations. Measures will be taken for a variety of spatial tasks in normal observers, and PC and MC function will be measured in color defective observers and in patients with ophthalmic disease. Project 3 involves delineating the postreceptoral pathways for rod signals and rod-cone interactions. The proposed experiments examine the role of the rod system in daylight vision. Project 4 addresses the function of a newly discovered retinal ganglion cell type with the properties of an S-cone off cell. Experiments are designed to assess psychophysically the function of this new cell type. Project 5 describes continuing collaborative neurobiological studies of retinal function that allow the opportunity to compare retinal and psychophysical responses to the similar or identical light stimuli. Project 6 involves the development and evaluation of new clinical tests of visual function that may improve the functional diagnosis of congenital color vision defects and help differentiate patients with eye disease. The goal is to translate difficult and time-consuming psychophysical experiments into rapid and easily performed clinical tests. In addition to empirical studies, models of normal and abnormal vision will continue to be developed. The theoretical approach is based on the question: to what extent can established biological or physical phenomena explain the data of color vision? This approach is one which allows us to examine the plausibility of various hypotheses that are not subject to direct experimental evaluation.