Visual phenotype in Williams-Beuren syndrome challenges magnocellular theories explaining human neurodevelopmental visual cortical disorders
Miguel Castelo-Branco, … , Luis Pérez-Jurado, Eduardo Silva
Miguel Castelo-Branco, … , Luis Pérez-Jurado, Eduardo Silva
Published November 21, 2007
Citation Information: J Clin Invest. 2007;117(12):3720-3729. https://doi.org/10.1172/JCI32556.
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Research Article Ophthalmology

Visual phenotype in Williams-Beuren syndrome challenges magnocellular theories explaining human neurodevelopmental visual cortical disorders

Abstract

Williams-Beuren syndrome (WBS), a neurodevelopmental genetic disorder whose manifestations include visuospatial impairment, provides a unique model to link genetically determined loss of neural cell populations at different levels of the nervous system with neural circuits and visual behavior. Given that several of the genes deleted in WBS are also involved in eye development and the differentiation of retinal layers, we examined the retinal phenotype in WBS patients and its functional relation to global motion perception. We discovered a low-level visual phenotype characterized by decreased retinal thickness, abnormal optic disk concavity, and impaired visual responses in WBS patients compared with age-matched controls by using electrophysiology, confocal and coherence in vivo imaging with cellular resolution, and psychophysics. These mechanisms of impairment are related to the magnocellular pathway, which is involved in the detection of temporal changes in the visual scene. Low-level magnocellular performance did not predict high-level deficits in the integration of motion and 3D information at higher levels, thereby demonstrating independent mechanisms of dysfunction in WBS that will require remediation strategies different from those used in other visuospatial disorders. These findings challenge neurodevelopmental theories that explain cortical deficits based on low-level magnocellular impairment, such as regarding dyslexia.

Authors

Miguel Castelo-Branco, Mafalda Mendes, Ana Raquel Sebastião, Aldina Reis, Mário Soares, Jorge Saraiva, Rui Bernardes, Raquel Flores, Luis Pérez-Jurado, Eduardo Silva

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Figure 3

Analysis of RT and RNFL thickness across groups.

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Analysis of RT and RNFL thickness across groups. (A) Scheme of regions w...
(A) Scheme of regions where RT and RNFL were analyzed. Numbers code different regions. (B) Overall thickness reduction in all 9 regions (see A for respective local labels) explored in the central 20 degrees of the WBS retina in comparison with age-matched control subjects, as illustrated by percentile plots. Box boundaries correspond to upper and lower twenty-fifth percentiles, outer bars to the tenth percentiles, and middle bars to the median. In spite of the preserved morphology of the foveomacular pit, we observed a significant thickness reduction in WBS subjects when compared with age-matched controls (P < 0.0001 for all 9 regions, Mann-Whitney U test). (C) The ganglion cell RNFL thickness in the central part of the retina was less dissimilar between groups, differences only being significant in outer and nasal sectors. RNFL, ganglion cell RNFL.