[Evoked potentials in the human visual cortex when observing whole figures and their elements].
Evoked potentials changes were analyzed in 32 subjects in a task of observing whole and disintegrated images. In the occipital and parietal regions, reactions to a disintegrated image appeared early (within the period of P1 development), and their characteristics were determined by the magnitude of the response to the whole image. In the occipital cortex, a low-amplitude P1 (the 1st group of subjects) increased in response to image disintegration, whereas in cases of a high P1 amplitude (the 2nd group), the tendency to its reduction was observed. In the parietal regions, the effects were distinct only in the 1st group of subjects and different in the right and left hemispheres: in the left hemisphere, the P1 amplitude increased when simpler elements appeared in the image, in the right hemisphere, a change in the spatial disposition of details was more significant. In the inferior temporal cortex, the amplitude of the later wave N1 decreased in response to disintegration, the effect being significant only in the 2nd group of subjects. The appearance of simpler elements in the image resulted in a P3 wave increase in both groups. The results point to topographic and temporal specificity of the reactions of the visual cortex to image disintegration and suggest the existence of various strategies of the visual image analysis at the early stages.
Slavutskaia
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AV
Mikhaĭlova
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ES
D000328:Adult; D004569:Electroencephalography; D005074:Evoked Potentials, Visual; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008297:Male; D010364:Pattern Recognition, Visual; D011603:Psychophysiology; D014793:Visual Cortex / Q000502:physiology*; D055815:Young Adult