Subsequent projects

Prof. Dr. Mark Greenlee

University of Regensburg

Prof. Dr. Stuart Anstis

University of California, San Diego
Department of Psychology

Compensation and adaptation for loss of central vision

Patients with the hereditary form of macular dystrophy (Stargardt's disease, cone-rod dystrophy) develop central scotomata (blind spots) in the central visual field with diameters of 10 degrees or more. Many of the patients are not consciously aware of their scotoma, suggesting the phenomenon of perceptual filling-in. Filling-in refers to the perceptual process by which the brain attempts to complete information that is no longer transmitted to the corresponding cortical projection zones. In our cooperative project we investigate this filling-in process using psychophysical and functional magnetic resonance imaging (fMRI) methodologies. During the first project period we investigated patients' ability to detect the orientation of a square-wave grating presented together with a grey disk. The disk was located either completely within the scotoma region or it extended beyond the scotoma rim. We further conducted fMRI to determine how visual cortex responded to conditions where filling-in occurred and when it did not occur. The results point to neural activation in visual cortex that is correlated with the filling-in phenomenon. In the second project period we plan to investigate the orientation selectivity of this induced activation. We present patients with three different orientations (10°, 70°, 130°) during fMRI. The resulting activations are subjected to a support-vector machine algorithm to determine the regions of interest that carry information about stimulus orientation. In this way we can determine at which level in the visual pathway the filling-in process leads to compensatory (orientation-specific) activations in scotomatous projection zones. Our results should lead to a better understanding of the processes underlying filling-in in patients with central retinal lesions. As such they could be used to guide the rehabilitation of patients with central scotoma owing to macular dystrophy.

Primary project: Compensation and adaptation for loss of central vision

Final Report

Patients with macular dystrophy often report that they are unaware of their central scotoma, suggesting the presence of perceptual filling-in. We used functional magnetic resonance imaging to determine possible neural correlates of perceptual filling-in in patients with retinal dystrophy and central scotoma in both eyes. Data from n = 10 patients (7 Stargardt disease, 1, cone-rod dystrophy, 2 age-related macular degeneration; scotoma diameter 10-20°) and of 10 normally sighted controls were analyzed. Fixation behavior and perimetry were measured with a Nidek microperimeter. In a series of three experiments participants viewed large (30°) square-wave gratings with a low spatial frequency, gratings with a vertical orientation (Exp. 1 and Exp. 2) or with one of three orientations (10°, 70°, 130°: Exp. 3). The gratings were either a) continuous, or b) were interrupted by a central grey disk. The disk was either set to be slightly larger than the scotoma (detectable on 75% of trials) or slightly smaller (detectable on 25% of trials). To control for attention in Exp. 3, participants responded with a button press every time the same orientation of the grating was presented twice in a row (i.e., one-back task). Results indicate that patients exhibit fMRI signal increases in retinotopic visual cortex and these signals were higher during filling-in, and that the correct classification rate, (i.e. identification of the grating orientation based on the pattern of brain activity) in the foveal projection zone is above chance levels. Ongoing support vector machine analysis suggests higher classification rates in the foveal projection zone during filling-in conditions (Goldhacker et al., in preparation).  These findings suggest that filling-in of the central scotoma is accompanied by fMRI signal increases in the foveal projection zone in patients with macular dystrophy. Such signal increases could reflect top-down processes that inform cortical neurons about stimulus context.


Anstis, S., & Greenlee, M. W. (2014). Contour erasure and filling-in: New observations. I-Perception, 5(2), 79–86.

Goldhacker M,  Rosengarth K, Brandl-Ruhle S, Plank T., Anstis S., Greenlee MW. Neural correlates of perceptual filling-in in patients with macular distrophy (in preparation).

Conference abstracts:

Greenlee MW, Anstis S., Rosengarth K, Goldhacker M, Brandl-Ruhle S, Plank T. Neural correlates of perceptual filling-in: fMRI evidence in the foveal projection zone of patients with central scotoma. Abstract of paper to be presented at Annual Meeting of the Vision Sciences Society (VSS), May 11 – 16, 2012 in Naples, FL, USA.

Goldhacker, M., Rosengarth, K., Anstis, S., Wirth, A. M., Plank, T., & Greenlee, M. W. (2013, January). FMRI evidence for perceptual filling-in in patients with macular dystrophy. In PERCEPTION (Vol. 42, pp. 72-73). 207.

Greenlee, M. W.,  Goldhacker, M., Rosengarth, K., Anstis, S., Plank, T. (2013, November) fMRI correlates of perceptual filling-in in patients with central scotoma due to macular dystrophy. Society for Neuroscience. San Diego, CA, USA.


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