[Clinical applications of late negative evoked potentials--contingent negative variation (CNV)]

Contingent negative variation /CNV/ is a slow negative potential described first in 1964 by Walter et al. It is a correlate of cerebral activity in the frontal lobes connected with expectation of stimulus and frontal cortex preparation for the stimulus to come. CNV develops in the time between the warning signal /S1/ and the commanding signal /S2/. CNV contains two main components connected directly with brain function: the first one, so called early component, is connected with the process of orientation or warning /it is called also orientation wave/, the second one /late component/ is connected with the preparation for movement /expectation wave or preparatory wave/. The clinical application of CNV is for the evaluation of the correlation of potential changes with changes in cognitive functions occurring in various diseases. Numerous studies reported recently have confirmed the applicability of CNV on the diagnosis of dementia, Parkinson's disease, epilepsy, schizophrenia, anxiety states, chronic pains, including migraine.