Spindle frequencies in sleep EEG show U‐shape within first four NREM sleep episodes

Himanen, Sari-Leena; Virkkala, Jussi; Huhtala, Heini; Hasan, Joel

doi:10.1046/j.1365-2869.2002.00273.x

Cited by 75 publications

(74 citation statements)

References 28 publications

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“…Several reports have indicated changes in spindle frequency according to the natural sleep depth and/or the neural mechanism. 7,19 In one report on isoflurane anesthesia, bicoherence peak frequency in the spindle band seemed to decrease as isoflurane concentration increased. 8 The observed decreases in bicoherence peak frequencies in sevoflurane anesthesia are compatible with these reports.…”

Section: Discussionmentioning

confidence: 99%

“…6 These electrophysiologic oscillations driven from thalamocortical neurons are modulated by sleep depth. 7 That is, RE and TC neurons participate in the 7-to 14-Hz spindling ␣ rhythm of early sleep and the slower rhythms of deeper sleep, with different firing patterns. Because sleep regulation is thus closely re-lated to the thalamocortical network, examination of anesthesia-dependent changes in the bicoherence spectrum is important.…”

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confidence: 99%

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Anesthesia Depth–dependent Features of Electroencephalographic Bicoherence Spectrum during Sevoflurane Anesthesia

2008

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Background: Growth pattern in the electroencephalographic bicoherence spectrum has recently been found to relate to anesthetic depth, and bicoherence analysis can reflect behavior of the thalamocortical reverberating network. Because the thalamocortical network is known to represent a key factor in sleep by anesthesia, systematic and qualitative bicoherence studies of different anesthetic depths is necessary throughout all pairs of frequencies.Methods: Sixteen patients were anesthetized using sevoflurane (1, 2, or 3%) combined with remifentanil (0.4 g ⅐ kg ؊1 ⅐ min ؊1). Raw electroencephalographic signals were collected, and bicoherence was estimated in all pairs of frequencies, between 0.5 and 40 Hz at 0.5-Hz intervals.Results: Sevoflurane (1%) caused two main peaks, spindle frequencies (11.0 ؎ 1.2 Hz, 44.7 ؎ 12.3% [bicoherence growth]) and ␦-frequencies (5.4 ؎ 0.5 Hz, 33.0 ؎ 8.4%), in the diagonal line of biphasic bicoherence plots. High concentrations of sevoflurane (2% and 3%) shifted these peaks to 9.8 ؎ 1.1 Hz, 46.2 ؎ 12.7%; 8.7 ؎ 1.3 Hz, 37.2 ؎ 13.7% and 4.9 ؎ 0.5 Hz, 44.6 ؎ 7.0%; 4.3 ؎ 0.8 Hz, 45.2 ؎ 10.6%, respectively. Sevoflurane caused a third bicoherence peak to appear in another heterogeneous pair frequency (pair of ␣ basal frequency and its double frequency), outside the diagonal line, which also inherited the behavior of ␣ bicoherence peaks at different anesthetic depths.Conclusions: Sevoflurane anesthesia caused bicoherence peaks in ␣ and ␦-areas and also formed secondary third peaks. Deeper sevoflurane anesthesia shifted all bicoherence peaks to lower frequencies and caused increased bicoherence growth in the ␦-area. The obtained features are consistent with characteristics of the thalamocortical reverberating network and suggest the importance of bicoherence analysis for the thalamic system. BICOHERENCE analysis, a power-independent bispectral analysis, has been developed to detect cross-frequency phase coupling, as a method to examine nonlinear regulation of brain electrical activities. Although a theoretical link between neural network physiology and phase coupling had not been fully established, 1 a certain reverberating system can contribute to high bicoherence values. Bicoherence is a signal-processing technique capable of tracking changes in any reentry system, investigating phase relations between two input signals (f 1 , f 2 ) by introducing an output signal (f 1 ϩ f 2 ), and by quantifying the quadratic phase coupling between these signals. 2 In nonlinear modulation such as seen in a certain reverberating system, the output signal from the reverberating circuit is expected to reenter into the system as the input signal and cause self-modulated characteristics, namely the components of intermodulation products (a signal component produced by multiplication of input signal components). Because this results in quadratic phase coupling between input signal components, bicoherence is expected to grow in these frequency components. A reverberating source such as seen in the thalamocortical ...

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

Anesthesia Depth–dependent Features of Electroencephalographic Bicoherence Spectrum during Sevoflurane Anesthesia

2008

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“…Also slow spindles were found within sequences. This might be explained by including spindles from all sleep stages into our study, as sleep spindles are slower in deep sleep than in sleep stage 2 [11,17,33].…”

Section: Discussionmentioning

confidence: 99%

Occurrence of Periodic Sleep Spindles within and across Non-REM Sleep Episodes

et al. 2003

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Sleep spindles have been reported to occur both as single events and periodically in sequences. However, there is no systematic description about the occurrence of spindles in sequences in relation to time of night. The aim of the present study was to examine the temporal occurrence of periodic sleep spindles during the night. Sleep spindles of 19 healthy subjects were selected visually. A minimum of three consecutive spindles was required to form a spindle sequence. A 5-second upper time interval limit was applied as the longest duration between spindles belonging to a spindle sequence. The number of spindles and time occupied by spindle sequences increased from the first to the fourth non-REM (NREM) sleep episode. Within NREM sleep episodes, the number of spindles and spindle sequences dominated at the beginning. In the first two NREM sleep episodes with high slow-wave activity (SWA), there were few spindle sequences and they decreased with increasing SWA. In the third and fourth NREM sleep episode with less SWA, there were more spindle sequences and they were more evenly distributed. It is possible that in the first NREM sleep episodes, hyperpolarization of the thalamocortical cells deepens so rapidly that the NREM sleep level, where spindle sequences arise, is passed and spindle sequences are not formed. Spindle sequences could be regarded as markers of the evolution of the NREM sleep process and their lack or excess in relation to time of night and NREM sleep episode can hopefully be used to indicate changes in brain mechanisms behind NREM sleep.

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“…OALib Journal (1) Besides the low-frequency delta wave, the thalamocortical spindles of higher frequency also often occur during the slow wave sleep [4]. Recently, it has been demonstrated in both humans and animals that the thalamocortical spindles may be increased by the remaining weak cholinergic system then.…”

Section: The Supporting Evidencementioning

confidence: 99%

The Cholinergic-Regulated Thalamocortical Imagining as Mind Differentiated in Two Phases of Sleep: A View from the Guangdong People

Cai¹

2017

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Recently, many achievements on neural sciences have been made by the people in television, such as the adipose cause of male hypothalamic aging, and so on. In this article, it is reported that, on June 17 this year in evening in television, the people in Guangdong attending the Opening Ceremony of BRICS Games there suggested that the cholinergic-regulated thalamocortical activation would result in the cortical imagining in mind in sleep. In slow wave sleep, due to the inhibition of thalamic intralaminar nuclei, it would cause the thalamocortical spindle and random free imagining in mind away from the environment by the remaining weak cholinergic activity. In rapid eye movement sleep, due to the activation of the nonspecific thalamic intralaminar nuclei, it would cause the desynchronized dream with conscious attention and imagination in mind by the saliently active cholinergic system. It is thus simply demonstrated the secret of mind in sleep that many people are interested in, which is perspective in application to hypnosis and psychoanalysis.

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Spindle frequencies in sleep EEG show U‐shape within first four NREM sleep episodes

Cited by 75 publications

References 28 publications

Anesthesia Depth–dependent Features of Electroencephalographic Bicoherence Spectrum during Sevoflurane Anesthesia

Anesthesia Depth–dependent Features of Electroencephalographic Bicoherence Spectrum during Sevoflurane Anesthesia

Occurrence of Periodic Sleep Spindles within and across Non-REM Sleep Episodes

The Cholinergic-Regulated Thalamocortical Imagining as Mind Differentiated in Two Phases of Sleep: A View from the Guangdong People

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