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A key aspect of higher cortical function is the ability to selectively withhold or suppress action where appropriate. To examine the time course of executive control we used dense-sensor EEG recording techniques to study event-related electrical potentials (ERPs) during a visual 'go/no-go' task. We show that during both go and no-go trials there is a positive deflection in the ERP, which develops over posterior parietal sensors approximately 350 ms (P300) after the onset of a conditional visual stimulus, but is selectively suppressed during no-go trials. We also show that this modulation of the parietal P300 is preceded by a negative deflection in the ERP recorded over frontal cortex (N2), which is apparent only for no-go trials. We suggest that this signal provides an electrophysiological marker in man for the decision to withhold the execution of a motor response.
Jackson et al. (Mon,) studied this question.