Unmasking human visual perception with the magnetic coil and its relationship to hemispheric asymmetry.
Visual suppression by a magnetic coil (MC) pulse delivered over human calcarine cortex after a transient visual stimulus 80-100 ms earlier has been used to suppress the representation of a 'masking' visual stimulus and thus to unmask a 'target' visual stimulus given, e.g., 100 ms before the mask. The resulting target unmasking as a function of the interval between mask and MC pulse is approximately the inverse of the visual suppression curve. Arbitrary visual linear patterns can similarly be unmasked. At the long target-mask interval used, the site of masking is deduced to lie beyond calcarine cortex. In several right-handed subjects tested, powerful MC stimulation of the left (but not right) temporo-parieto-occipital cortex also led to (weaker) unmasking.
Amassian
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Department of Physiology, State University of New York Health Science Center, Brooklyn 11203.
Cracco
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Maccabee
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Cracco
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Rudell
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Eberle
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D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008280:Magnetics; D010470:Perceptual Masking / Q000502:physiology*; D010775:Photic Stimulation; D014793:Visual Cortex / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*