P300 HEMISPHERIC AMPLITUDE ASYMMETRIES FROM A VISUAL ODDBALL TASK

The P3(00) event-related potential (ERP) was elicited in 80 normal, ri ght-handed male subjects using a simple visual discrimination task, wi th electroencephalographic (EEG) activity recorded at 19 electrodes. P 3 amplitude was larger over the right than over the left hemisphere el ectrode sites primarily at anteromedial locations (F3/4, C3/4) for tar get, novel, and standard stimuli. The N1, P2, and N2 components also d emonstrated hemispheric asymmetries. The strongest P3 hemispheric asym metries for all stimuli were observed at anterior locations, suggestin g a frontal right hemisphere localization for initial stimulus process ing, although target stimuli produced larger P3 amplitudes at parietal locations than did novel stimuli. The relationships of hemispheric as ymmetries to anatomical variables, background EEG activity, and neuroc ognitive factors are discussed.