[Contingent negative variation and late components of evoked potentials during sleep in man].

The aim of this research was to study brain information processing during waking, deep slow sleep (stage IV) and paradoxical sleep (stage V) in humans, by using as a clue endogenous components of the sensory evoked potential, the emitted potential and the contingent negative variation (CNV). Eight subjects underwent three kinds of mixed auditory stimulus couples: (a) SI-SII: 2 identical clicks (50 msec, 5000 Hz); (b) SI-SIII: SIII (50 msec, 500 Hz) different from SI, was during waking, the target stimulus; (c) SI followed by an omitted click. During sleeping, the situation was used without motor response. The contingent negative variation was clearly observed during waking and paradoxical sleep as the evoked potential whose morphology during deep slow sleep was similar to K complexes. The emitted potential was obtained in four subjects out of seven during paradoxical sleep. These results suggest that during wakefulness, the discrimination of an unconditional stimulus involves a conditioning establishment revealed by the CNV and the emitted potential. The fact that the emitted potential and CNV were unavailable during stage IV is an argument in favor of the hypothesis that the conditioning effects disappear during deep slow sleep. The occurrence of CNV and emitted potential during the paradoxical stage of sleep, suggests that a conditioning established during waking can appear during this stage of sleep.