An optometrist with training in the clinical specialty of low vision seeks to acquire the psychophysical research skills to independently investigate spatial vision and neural plasticity in the human visual system. Recent physiological evidence reveals that cells in the adult visual cortex exhibit remarkably rapid plasticity after a retinal lesion or artificial scotoma.
The aim of the proposed laboratory research is to assess the perceptual changes induced by artificial scotomas and, then, by real retinal scotomas through psychophysical examination of alterations in receptive fields (RF) at retinal locations adjacent to the scotoma. Ricco's Area will be measured by determining the contrast thresholds for small, dark, squares on a field of uniform illumination. It is hypothesized that alterations in RF size due to the artificial scotomas should be reflected in changes in Ricco's Area. Contrast sensitivity functions (CSF) will be measured using Gabor patch gratings. A change in the shape of the CSF implies that a shift in the most sensitive RF has occurred. A shift in the position of the CSF implies expansion of the RF. Spatial localization will be studied by aligning foveal and peripheral fixation lines. Threshold elevation will provide further evidence for RF expansion while offset bias will reflect alterations in receptive field topography. It is expected that dichoptic stimulus presentation will help to localize the anatomical site of the RF alterations. The first phase of this project will consist of four components: 1) The psychophysical research described above, conducted under the direct guidance of a highly experienced sponsor, 2) Participation in physiological research in neural plasticity, 3) Participation in research using the Scanning Laser Ophthalmoscope (SLO), and 4) Coursework in selected areas. In the second phase, the candidate will proceed to independently continue the proposed psychophysical research. It is hoped that the results of this study, and of future studies on patients suffering from retinal disease, will provide further knowledge about neural plasticity that can be applied to improving the rehabilitation of individuals suffering from impaired vision as a result of pathological scotomas.
| Reich, L N; Bedell, H E (2000) Relative legibility and confusions of letter acuity targets in the peripheral and central retina. Optom Vis Sci 77:270-5 |
| Reich, L N; Levi, D M; Frishman, L J (2000) Dynamic random noise shrinks the twinkling aftereffect induced by artificial scotomas. Vision Res 40:805-16 |
| Reich, L N (1995) Field of view and equivalent viewing power of near-vision telescopes. Optom Vis Sci 72:411-6 |
