The Influence of Hand Movements on Cortical Negative DC Potentials

In contrast to the numerous studies investigating changes of slow negative DC potentials before movement onset, caused by either the so-called Bereitschaftspotential (BP) preceding only self-paced movements (Kornhuber and Deecke, 1965) or by the contingent negative variation (CNV) in a conditioned, forewarned reaction task (Walter, 1964), very few studies have examined the relationship between slow negative DC potentials and different motor task conditions. Only recently has research interest in slow negative DC potentials shifted from the registration of events preceding the movement to the registration of events during the movement (Cooper, McCallum, and Cornthwaite, 1989; Lang et al. 1988a, 1988b). This is because, as Lang et al. (1989) pointed out in a study comparing simple and complex sequential movement tasks, performance-related DC shifts are more useful for separating motor tasks than is the preceding BP.