Abstract
The assessment of human visual functions is accomplished today with non-invasive psychophysical and electrophysiological methods, made available by recent computational advances which help the display of visual stimuli, the experimental programming, online data analysis, etc. In order to understand the mechanisms responsible for visual losses, still not well understood, human studies using modern psychophysical and electrophysiological techniques are needed, as well as studies in animal models in which direct access to the retina and higher centers is possible. The present project proposes the development of clinical testing protocols and/or new methodologies for the study of the visual system in humans and animals, in conditions of health and disease, with the objectives of understanding pathological mechanisms and of providing tools for early diagnosis and for follow up. The project will investigate the visual system through perceptual tests and psychophysical scaling methods; through pseudo-random electrophysiological responses; through visual functions such as color vision, contrast sensitivity, Vernier acuity, visual perimetry and others; through visual neuropsychology, involving memory and attention to visual stimuli. The performance in several of these tests will be evaluated under different conditions ambient illumination, to test the new illumination resources available in the market, based on LED technology. We will also evaluate the effects of direct current transcrianial stimulation in these functions with the objectives of understanding underlying neural mechanisms and of proposing clinical applications. The color vision experiments will be combined with the genetic determination of visual pigment types for each individual tested in humans and in monkeys, and these molecular techniques will be extended to several questions posed by the evolution of color vision in vertebrates. Pupillometry will be used to evaluate the functions of the recently discovered melanopsin pigment, which is responsible for the pupil light reflex, for circadian rhythms, and several other functions, such as seasonal depression. In animal models patch clamp experiments will be conducted aiming at the understanding of basic visual mechanisms and electro-retinography studies will be run to evaluate retinal mechanisms underlying visual perception and to test therapeutic drugs. The project involves basic and clinical research groups from various institutions: the Vision Lab from the Institute of Psychology at the University of São Paulo, (proponent), the Biological Science Center, the Tropical Medicine Nucleus and the Primate School, from the Federal University of Pará (Brazilian collaborators) and the University of Erlangen, in Germany, and the CNRS in France (overseas collaborators). The project proposes study and work missions among the different research groups with the objective of making available to both national groups the new methods of visual system investigation. (AU)
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