Dissociation between contingent negative variation and Bereitschaftspotential in a patient with cerebellar efferent lesion.

Contingent negative variation (CNV) and Bereitschaftspotential (BP) were from the scalp in a patient with a discrete infarct in the mesial tegmentum of the midbrain involving the decussation of the superior cerebellar peduncle. Bereitschaftspotential in association with hand movements was completely absent while CNV was normally present at the frontocentral midline. This indicates that CNV is, as opposed to BP, generated without cerebro-cerebellar interactivation, suggesting different generating mechanisms.