Equipotential maps of pattern-evoked potentials in man

Pattern-evoked cortical potentials for half field stimuli were recorded from 16 electrodes on the scalp, and equipotential maps were constructed. For right and left half field stimuli, the maximal values of the maps were found over the hemisphere ipsilateral to the visual half field stimulated. For lower half field binocular stimuli, the maxima were more anterior than for monocular stimuli (for upper field stimuli, inverted location differences were found). In hemianoptic patients, the maxima were obtained over the impaired hemisphere regardless which part of the visual field was stimulated. The maxima of pattern-evoked ERG fields on the face were found around the stimulated eye.