Decomposing N2 NOGO wave of event-related potentials into independent components.

Inconsistencies in previous attempts to localize the N2 wave in the GO/NOGO task led to the present investigation. The inconsistencies were probably because of heterogeneity of psychological operations involved in GO/NOGO tasks. We applied the independent component analysis to a collection of individual event-related potentials in response to GO and NOGO cues in the two stimulus visual GO/NOGO task. The selected six independent components with different topographies and time courses constituted 87% of the artifact-free signal variance. Three of them were loaded into the frontally distributed N2 wave. According to standardized low-resolution electromagnetic tomography these three independent components were generated in the supplementary motor cortex, left angular gyrus and anterior cingulate cortex.