Topographical analysis of homotopic interhemispheric "relay" asymmetries in visual evoked potentials

Brown and colleagues (1994) found that most evoked potential studies provid e evidence of faster interhemispheric relay from the right to the left hemi sphere, as determined from N160 latencies derived from parietal and occipit al electrode sites. The experiment reported here was designed to complement those findings by 1) analyzing more electrode sites (several frontal, temp oral, and central sites in addition to the previously investigated sites) a nd more waveform (P1 and P2 waves); 3) introducing analysis of amplitude da ta; 4) carrying out site-specific and experiment-wise inference tests of pu tative interhemispheric relay asymmetry. We found that all of the conclusio ns of Brown and colleagues, regarding latency effects, could be extended to the ensemble of electrode sites and waveforms. However, amplitude effects were significantly compatible with stronger (though slower) relay from the left to the right hemisphere.