Plank, Tina and Frolo, Jozef and Brandl-Ruehle, Sabine and Renner, Agnes B. and Jaegle, Herbert and Greenlee, Mark W. (2017) fMRI with Central Vision Loss: Effects of Fixation Locus and Stimulus Type. OPTOMETRY AND VISION SCIENCE, 94 (3). pp. 297-310. ISSN 1040-5488, 1538-9235
Full text not available from this repository. (Request a copy)Abstract
Purpose In patients with central visual field scotomata, a large part of visual cortex is not adequately stimulated. Patients often use a new eccentric fixation area on intact peripheral retina (preferred retinal locusPRL) that functions as a pseudo-fovea. We used functional magnetic resonance imaging (fMRI) to examine whether stimulating this pseudo-fovea leads to increased activation or altered activation patterns in visual cortex in comparison to stimulating a comparable peripheral area in the opposite hemifield (OppPRL). Methods Nineteen patients with binocular central scotomata caused by hereditary retinal dystrophies and an age-matched control group were tested. The center of the visual field, PRL, and OppPRL were stimulated with flickering checkerboard stimuli and object pictures during fMRI measurement. Results Results show that stimulation with pictures of everyday objects led to overall larger BOLD (blood oxygen level dependent) responses in visual cortex compared to that evoked by stimulation with flickering checkerboards. Patients showed this enhancement as early as in V1. When the PRL was directly stimulated with object pictures, the central representation area in early visual cortex was coactivated in the patients but not in the controls. In higher visual areas beyond retinotopic cortex, BOLD responses to stimulation of the PRL with object pictures were significantly enhanced in comparison to stimulation of the OppPRL area. Highly stable eccentric fixation with the PRL was associated with a higher BOLD signal in visual cortex in patients, and this effect was most pronounced in the conditions with object picture stimulation. Conclusions The observed results suggest that naturalistic images are more likely to trigger top-down processes that regulate activation in early visual cortex in patients with central vision loss.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | HUMAN CEREBRAL-CORTEX; MACULAR DEGENERATION; VISUAL-CORTEX; STRIATE CORTEX; RETINAL LOCUS; FOVEAL LOSS; ADULT CAT; REORGANIZATION; PERCEPTION; SCOTOMAS; hereditary macular dystrophy; central visual field scotomata; visual impairment; visual cortex; functional magnetic resonance imaging |
| Subjects: | 100 Philosophy & psychology > 150 Psychology |
| Divisions: | Psychology and Pedagogy > Institut für Psychologie > Lehrstuhl für Psychologie I (Allgemeine Psychologie I und Methodenlehre) - Prof. Dr. Mark W. Greenlee |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 14 Dec 2018 13:00 |
| Last Modified: | 27 Feb 2019 11:59 |
| URI: | https://pred.uni-regensburg.de/id/eprint/277 |
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