Amplitude difference between pattern-evoked potentials after left and right hemifield stimulation in normal subjects.

The amplitude of visual evoked potentials (VEPs) to pattern hemifield stimulation was measured in 14 normal right-handed subjects. The paired t test was used to determine if the values differed between right and left hemifield stimulation. The amplitude of transient VEPs from a midoccipital electrode and a lateral occipital electrode ipsilateral to the hemifield stimulated was significantly greater with right hemifield stimulation. This result is compatible with neuroanatomic asymmetries of human striate cortex. Amplitude distribution over the scalp was markedly different between transient and steady-state VEPs that probably reflect activities of different populations of cortical neurons.