Mapping of Scalp Potential Fields Elicited by Cortical Generators: The Use of Dynamic Random Dot Stereograms

The mammalian visual system offers a unique possibility to study electrophysiologically cortical neuronal mechanisms without interference by subcortical activity. Since the input of the two eyes remains separated up to the level of the visual cortex, evoked potential components generated exclusively by cortical structures may be investigated when dynamic random dot stereo-grams (RDS; Julesz 1960, 1971) are presented binocularly. The perception of such stereograms depends on the fusion of two, nonidentical, horizontally disparate, monocular inputs in the visual cortex. Under monocular viewing conditions a given RDS stimulus cannot be perceived stereoscopically (see below and data in Fig. 1C).

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