Artificial scotoma-induced perceptual distortions are orientation dependent and short lived.
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.
Tailby
Chris
C
Department of Optometry and Vision Sciences, The University of Melbourne, Parkville, 3052, Australia.
Metha
Andrew
A
D006801:Humans; D009949:Orientation; D010469:Perceptual Distortion; D010775:Photic Stimulation / Q000379:methods*; D012607:Scotoma / Q000209:etiology* / Q000523:psychology*; D013997:Time Factors