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Abstract

During motion stimuli cortical DC potentials were recorded over occipital, occipito-parietal and frontal cortical areas. The trials consisted of 3 sec lasting left and right moving stimuli patterns followed by 3 sec pause without motion. Subjects viewed (a) counterphase flicker of checkerboard and random dot patterns, (b) moving random dot patterns and (c) moving bars with different texture motion: no motion of the texture elements ('drift balance'), object and their texture elements moving in the same ('Fourier motion') or in opposite direction ('theta motion'). The averaged DC potentials of 8 subjects showed similar activation patterns. Over frontal cortical areas a short lasting positivation occurred 250-500 msec after motion onset. A triphasic potential occurred over occipital an occipitoparietal cortical areas: in most subjects a negativation (250-300 msec) was followed by a positivation with its maximum at 350-550 msec and a subsequent sustained negativity until the motion stopped. A direction specific activation over the left and right cortical hemispheres occurred during the viewing of object motion (condition c). These results indicate that cortical DC potentials can reflect neural processing of motion information.