Sireteanu R, 2006, "Visual misperceptions and cortical binocularity loss" Perception 35 ECVP Abstract Supplement
Visual misperceptions and cortical binocularity loss
Visual misperceptions reported by humans with developmental impairments in binocular vision were investigated with a combination of psychophysical, computational, and brain-imaging techniques. In psychophysical experiments, the spatial distortions and temporal uncertainties were characterised in a large number of subjects with impaired binocular vision (strabismic and/or anisometropic amblyopes, strabismics with alternating fixation). The resulting descriptions were visualised with automated computer simulations. In a further series of experiments, the monocular activation and the residual binocular brain activity of these subjects were investigated by functional magnetic resonance imaging (fMRI). Most amblyopic subjects showed significant spatial distortions of the visual percept of their amblyopic eyes. In about half of the amblyopic subjects, these misperceptions were temporally stable. The remaining subjects experienced temporal instabilities either in addition or in the absence of spatial distortions. Subjects experiencing subjective distortions also showed impaired cortical activation at higher cortical levels on the ventral visual pathway, especially in the lateral occipital complex (LOC). Subjects with impaired stereopsis showed significantly reduced interocular transfer of adaptation, as assessed with an fMRI adaptation paradigm. These results point to a cortical involvement, affecting mainly the higher extrastriate cortical levels, in subjects with compromised binocularity.
[Supported by Deutsche Forschungsgemeinschaft SI/17-1,2,3.]
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