Multiple equivalent current dipole source localization of visual event-related potentials during oddball paradigm with motor response

Event-related potentials (ERPs) during a visual oddball paradigm with butto n-pressing responses were recorded in 12 right-handed subjects from 32 scal p electrodes. The single equivalent current dipole (ECD) of the target C1 ( weak occipito-parietal negativity from 30-80ms) was consistently located at the primary visual cortex. From the 4-ECD localization of the target P1/N1 (temporally coincident frontal positivity and occipito-temporal negativity ), it was suggested that this complex reflected activities from distributed sources along both dorsal occipito-parietal and ventral occipito-temporal areas. The stable multiple ECD solutions for the target P3b were chosen as those including the left primary motor and/or sensorimotor dipole and satis fying goodness-of-fit (GOF) of more than 98% and confidence limit (CL) of l ess than 1mm. The obtained frontal dipoles were discussed in terms of visua l working memory and sustained attention in reference to the previous PET, fMRI and MEG studies. The distributed multiple ECDs may suggest that P3 sho uld be interpreted as being the embodiment of the cortico-limbic-thalamic n etwork which involves Halgren and Marinkovic's emotional and behavioral mod el and Mesulam's attentional circuit.