Vertex sharp waves and heart action during the onset of sleep

doi:10.1016/0013-4694(71)90078-2

Electroencephalography and Clinical Neurophysiology

Volume 31, Issue 6, December 1971, Pages 614-617

https://doi.org/10.1016/0013-4694(71)90078-2 Get rights and content

Abstract

Vertex responses evoked by rhythmic auditory stimulation (1 click/sec) and vertex sharp waves or K complexes occurring without external stimulation were studied in the transition from wakefulness to sleep (stages B₂-C) in eleven young adults.

Rhythmic auditory stimulation sporadically evoked one or more large vertex responses with a prominent negative peak identical to the component N₂ of the summated vertex response. Vertex sharp waves and K complexes appeared without external stimulation in a quite similar way. They exhibited a clear relation to the heart action, appearing most frequently 250 and 650 msec after the onset of the P wave in the ECG.

The results prove that, in the transition from wakefulness to sleep, there are epochs of enhanced cortical responsiveness during which interoceptor stimulation also may evoke large vertex responses.

Zusammenfassung

An elf erwachsenen Versuchspersonen wurden im Übergang vom Wachen zum Schlafen (Stadium B₂-C) akustisch ausgelöste Vertexpotentiale (1 Click/sec) und spontan auftretende Vertexpotentiale (“vertex sharp waves”, K Komplexe) untersucht.

Rhythmische akustische Reizung löste sporadish einzelne oder mehrere grosse Vertexpotentiale aus, deren negativer Gipfel der Komponente N₂ des summierten Reaktionspotentials entsprach. Spontane Vertexpotentiale traten ohne äussere Reizung in ganz ähnlicher Weise auf. Sie standen in deutlicher Beziehung zur Herztätigkeit, da sie gehäuft 250 msec and 650 msec nach Beginn der P-Zacke im EKG vorkamen.

Die vorliegenden Ergebnisse zeigen, dass es im Übergang vom Wachen zum Schlafen Phasen gesteigerter corticaler Erregbarkeit gibt, im Verlaufe derer auch die Reizung von Interozeptoren grosse Vertexpotentiale auslösen kann.

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Prior work hints at a possible coordination between central features and autonomic activity. For example, auditory-evoked K-complexes were associated with increased heart rate (de Zambotti et al., 2016) and have been shown to appear frequently 250 and 650 ms after the onset of the P wave in the electrocardiogram (ECG) (Fruhistorfer, Partanen, & Lumio, 1971). Furthermore, the QRS complex of ECG has been shown to modulate sleep spindle phases (Lechinger, Heib, Gruber, Schabus, & Klimesch, 2015).
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The main negativity of K-complexes are characterized by frontal dominance as showed by Ujszászi and Halász (1988) [67] and Bastien and Campbell (1992) [68]. The first studies of K-complexes showed that they are elicitable by several modalities of sensory stimuli [65,69,72–75] but most easily by acoustic stimuli, and are accompanied by autonomic discharges identical to those seen for arousals [76–83]. Laurino et al. [75] have shown that different modalities of sensory evoked potentials act as traveling cortico-cortical excitations.
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K-complex, a reactive EEG graphoelement of NREM sleep: An old chap in a new garment
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This review summarises data gathered on the KC phenomenon over the past 70 yr. The following issues are discussed: definitions, morphology and topography of KC, the regular participation in NREM sleep, elicitability features of evoked KC, autonomic and motor concomitants, relationship of KC with information processing during NREM sleep, relationship of KC and deltas of NREM sleep, and relationship of KC with sleep cyclicity. KC is a complex multifunctional phenomenon of the sleeping brain involved in information processing and defence against the arousal effect of sensory stimuli. To put the old chap in a new garment, the relationship of KC with synchronisation-type and desynchronisation-type micro-arousals, and the ‘cyclic alternating pattern’, will be discussed, with an emphasis on the sleep-protecting role of KC and synchronisation-type answers in sleep regulation executed by phasic events. Lastly, the role of KC providing gating functions in idiopathic generalized epilepsies and other, different, sleep disorders are characterised. A ‘theoretical epilogue’ is appended to show some system theoretical and regulational aspects.
Evoked potentials as a tool for the investigation of human sleep
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This review summarizes studies of evoked potentials (EPs) applied to the investigation of human sleep and of sleep disorders. The first part is devoted to studies dealing with the nature, mechanisms and extent of information processing during sleep. EP studies suggest that the brain's ability to detect salient stimuli persists during even the deepest sleep stages, while discrimination of the stimulus' intrinsic significance and/or semantic content may persist only in stage II and paradoxical sleep (PS). Deviance detection in non-rapid eye movement (NREM) sleep is reflected by amplitude recovery of K-complexes elicited by stimulations that differ from the background. The evoked K-complex appears to be formed by two functionally different modules. The first may be related to the discrimination of relevant information. The second appears more sensitive to stimulus salience than to its intrinsic significance. In PS, the EP signs of stimulus discrimination are similar to those observed during waking. Thus, if the possibilities of information processing are fairly similar during stage II and PS, their respective neural mechanisms are not the same, as judged by their electrophysiological counterparts.
The second part of the paper reviews clinical application of EPs to the study of sleep/wake disorders. While early potentials are of little use for diagnosis of sleep disorders, the cognitive P300 may help to quantify cognitive slowing and pathological sleepiness. However, intersubject variability restrains the use of these techniques in individual patients. A promising approach is the utilization of late responses to the study of sleep inertia with the use of “forced awakening” recording paradigms.
Electrophysiological evidence suggesting that sensory stimuli of unknown origin induce spontaneous K-complexes
1996, Electroencephalography and Clinical Neurophysiology
The present study was performed to determine whether or not spontaneous K-complexes are induced by sensory stimuli. In the first part of the present study, sound stimuli were prescribed during sleep in 7 healthy, young, adult subjects. EEG segments in stage 2 sleep were averaged separately according to the presence or absence of an evoked K-complex appearing after each stimulus. The sound stimulus induced N100 and P200 components in averaged EEGs regardless of K-complex appearance. The appearance of N100 and P200 components was considered to be an indicator of the presence of sensory stimuli. In the second part of the present study, EEG segments in stage 2 sleep containing an evoked K-complex or spontaneous K-complex were separately averaged with respect to the peak of N300, one of the main components constituting the K-complex. Small negative and positive components were found just before the main components of spontaneous K-complexes in averaged EEGs. These two components were judged to correspond to N100 and P200 components induced by the sound stimulus, as they appeared just before the main components of the spontaneous K-complex with almost the same lag time between the two components, or between each of the two components and the main components of K-complex, as in the case of N100 and P200 appearing just before the evoked K-complex. The present findings suggest that the spontaneous K-complex is not a spontaneous phenomenon, but that it is induced by sensory stimuli, probably of extracerebral origin.
Arousals without awakening-Dynamic aspect of sleep
1993, Physiology and Behavior
K complex as an elementary form of arousal was investigated by evoked K complexes. The components building up evoked K complexes and topographical sleep-level differences and influence of the kind of cognitive elaboration were analysed. Evidences are presented supporting that K complex represents a cascade of events originating from sources of different topography and probably by a different kind of elaboration activated in a certain order requested by the nature and context of the eliciting stimuli. The power spectra of evoked arousals—including K complexes—were investigated. The poststimulus spectral pattern is characterized by a short initial power elevation and a following reduction of all frequency bands except a simultaneous but prolonged (5–20 s) and strong (50%) power reduction at the 13–14 Hz sigma spindle band. This phenomenon seems to be a common feature in different stages of slow wave sleep. This stimulus-related microstate could serve as a transitory stand-by state ready to reach higher arousal rapidly while maintaining the continuity of sleep; hence, the inhibition of spindle activity could provide a phasically improved thalamocortical sensory inflow after environmental stimuli. A microstructural scheme of arousals without awakening has been delineated.

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Laboratory noteVertex sharp waves and heart action during the onset of sleepVertexpotentiale und herztätigkeit

Abstract

Zusammenfassung

Electroenceph. clin. Neurophysiol.

Electroenceph. clin. Neurophysiol.

Electroenceph. clin. Neurophysiol.

Electroenceph. clin. Neurophysiol.

Electroenceph. clin. Neurophysiol.

Electroenceph. clin. Neurophysiol.

Electroenceph. clin. Neurophysiol.

Electroenceph. clin. Neurophysiol.

Die Insuffizienz des Vigilitätstonus

Influence du cycle cardiaque sur l'excitabilité réflexe médullaire chez l'homme

C.R. Soc. Biol. (Paris)

Laboratory note
Vertex sharp waves and heart action during the onset of sleepVertexpotentiale und herztätigkeit