Functional dissociation of the early and late portions of human K‐complexes

We analyzed K-complexes (KCs) evoked during sleep stage II by the subject's own name and by other names. KCs were composed either of four consecutive waves (full KCs, N2-P3-N3-P4) or of the two first components only (N2–P3). The amplitude of the late phase of KCs (N3–P4) was identical to all stimuli; conversely, own names enhanced selectively the N2–P3 waves, whether they were or not part of a full KC. Two independent phenomena appear to coexist during a full KC, one being connected to the physical characteristics of the stimulus (N3–P4) and the other to its intrinsic significance. This latter may appear either within a full KC or in isolation, and in this case it is reminiscent of the N200-P300 complex observed in wakefulness.