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Vis Neurosci. 2004 Jan-Feb;21(1):79-87.

Artificial scotoma-induced perceptual distortions are orientation dependent and short lived.

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Department of Optometry and Vision Sciences, The University of Melbourne, Parkville, 3052, Australia.


Conditioning human observers with an "artificial scotoma"-a small retinal area deprived of patterned stimulation within a larger area of dynamically textured noise-results in contractions and expansions of perceived space that are thought to reflect receptive-field changes among cells in the primary visual cortex (Kapadia et al., 1994). Here we show that one-dimensional counter-phase flickering grating patterns are also potent stimuli for producing artificial scotomata capable of altering three-element bisection ability analogous to those results reported earlier. Moreover, we found that the magnitude of the induced spatial distortions depends critically on the relative orientations of peri-scotomatous and test-stimulus spatial contrast. In addition, the perceptual distortions are found to be relatively short lived, decaying within 660 ms. The results support the hypothesis that artificial scotoma-induced perceptual distortions are generated by dynamic alteration of connection efficacy within a network linking cortical areas of similar orientation specificity, consistent with established anatomical and physiological results.

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