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Principal component analysis of the EEG spectrum can provide yes-or-no criteria for demarcation of boundaries between NREM sleep stages.

Putilov AA - Sleep Sci (2015)

Bottom Line: This was mostly a change from negative to positive score.Therefore, it might serve as yes-or-no criterion of stage 3 onset.Additionally, similarly rapid changes in sign of scores were exhibited by the 1st and 2nd principal components on the boundary of stages 2 and 1 and on the boundary between stage 1 and wakefulness, respectively.

View Article: PubMed Central - PubMed

Affiliation: Research Institute for Molecular Biology and Biophysics, Siberian Branch of the Russian Academy of Medical Sciences, Novosibirsk, Russia.

ABSTRACT
Human sleep begins in stage 1 and progresses into stages 2 and 3 of Non-Rapid-Eye-Movement (NREM) sleep. These stages were defined using several arbitrarily-defined thresholds for subdivision of albeit continuous process of sleep deepening. Since recent studies indicate that stage 3 (slow wave sleep) has unique vital functions, more accurate measurement of this stage duration and continuity might be required for both research and practical purposes. However, the true neurophysiological boundary between stages 2 and 3 remains unknown. In a search for non-arbitrary threshold criteria for distinguishing the boundaries between NREM sleep stages, scores on the principal components of the electroencephalographic (EEG) spectrum were analyzed in relation to stage onsets. Eighteen young men made 12-20-minute attempts to nap during 24-hour wakefulness. Single-minute intervals of the nap EEG records were assigned relative to the minute of onsets of polysomnographically determined stages 1, 2, and 3. The analysis of within-nap time courses of principal components scores revealed that, unlike any conventional spectral EEG index, score on the 4th principal component exhibited a rather rapid rise on the boundary between stages 2 and 3. This was mostly a change from negative to positive score. Therefore, it might serve as yes-or-no criterion of stage 3 onset. Additionally, similarly rapid changes in sign of scores were exhibited by the 1st and 2nd principal components on the boundary of stages 2 and 1 and on the boundary between stage 1 and wakefulness, respectively.

No MeSH data available.


Time courses of probability of stages 2 and 3. (A) Time courses of scores on the 1st and 2nd principal components (dotted and solid lines, respectively) relative to onsets of stages 1 (N1) and 2 (N2), and time courses of probability of stage 2 (circles and dashed lines) determined by assigning the 1st score to 0 when negative and to +1 when positive. For N1 (left and middle plots), mean values were taken from results of three-way ANOVAs with random factor “Participant” (n=11 vs. 18) and fixed factors “One-min interval” and “N2” (With or Without N2 initiated within the first 6 min of sleep). For N2 (right plots), results of two-way ANOVAs with random factor “Participant” (n=18) and fixed factor “One-min interval”. (B) Time courses of score on the 4th and 2nd principal components (dotted and solid lines) relative to onsets of stages 2 (N2) and 3 (N3), and time courses of probability of stage 3 (circles and dashed lines, respectively) determined by assigning the 4th score to 0 when negative and to +1 when positive. For N2 (left and middle plots), results of three-way ANOVAs with random factor “Participant” (n=14 vs. 18) and fixed factors “One-min interval” and “N3” (With or Without N3). For N3 (right plots), results of two-way ANOVAs with random factor “Participant” (n=14) and fixed factor “One-min interval”. See also the legend to Fig. 2.
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f0020: Time courses of probability of stages 2 and 3. (A) Time courses of scores on the 1st and 2nd principal components (dotted and solid lines, respectively) relative to onsets of stages 1 (N1) and 2 (N2), and time courses of probability of stage 2 (circles and dashed lines) determined by assigning the 1st score to 0 when negative and to +1 when positive. For N1 (left and middle plots), mean values were taken from results of three-way ANOVAs with random factor “Participant” (n=11 vs. 18) and fixed factors “One-min interval” and “N2” (With or Without N2 initiated within the first 6 min of sleep). For N2 (right plots), results of two-way ANOVAs with random factor “Participant” (n=18) and fixed factor “One-min interval”. (B) Time courses of score on the 4th and 2nd principal components (dotted and solid lines) relative to onsets of stages 2 (N2) and 3 (N3), and time courses of probability of stage 3 (circles and dashed lines, respectively) determined by assigning the 4th score to 0 when negative and to +1 when positive. For N2 (left and middle plots), results of three-way ANOVAs with random factor “Participant” (n=14 vs. 18) and fixed factors “One-min interval” and “N3” (With or Without N3). For N3 (right plots), results of two-way ANOVAs with random factor “Participant” (n=14) and fixed factor “One-min interval”. See also the legend to Fig. 2.

Mentions: In order to analyze and illustrate (Table 1, Figs. 2–3) steepness of changes in the EEG indexes during transitions from one stage to another, one-min values were further averaged on 3-min intervals (i.e., from minute −4 to −2, from −1 to +1, from +2 to +4, etc.). Additionally, all positive and negative one-min scores on a component (i.e., 1st or 4th) were transformed into +1 and 0, respectively, for illustrating time courses of probability of association of a stage (i.e., 2 or 3) with positive score on a component (Fig. 4).


Principal component analysis of the EEG spectrum can provide yes-or-no criteria for demarcation of boundaries between NREM sleep stages.

Putilov AA - Sleep Sci (2015)

Time courses of probability of stages 2 and 3. (A) Time courses of scores on the 1st and 2nd principal components (dotted and solid lines, respectively) relative to onsets of stages 1 (N1) and 2 (N2), and time courses of probability of stage 2 (circles and dashed lines) determined by assigning the 1st score to 0 when negative and to +1 when positive. For N1 (left and middle plots), mean values were taken from results of three-way ANOVAs with random factor “Participant” (n=11 vs. 18) and fixed factors “One-min interval” and “N2” (With or Without N2 initiated within the first 6 min of sleep). For N2 (right plots), results of two-way ANOVAs with random factor “Participant” (n=18) and fixed factor “One-min interval”. (B) Time courses of score on the 4th and 2nd principal components (dotted and solid lines) relative to onsets of stages 2 (N2) and 3 (N3), and time courses of probability of stage 3 (circles and dashed lines, respectively) determined by assigning the 4th score to 0 when negative and to +1 when positive. For N2 (left and middle plots), results of three-way ANOVAs with random factor “Participant” (n=14 vs. 18) and fixed factors “One-min interval” and “N3” (With or Without N3). For N3 (right plots), results of two-way ANOVAs with random factor “Participant” (n=14) and fixed factor “One-min interval”. See also the legend to Fig. 2.
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Related In: Results  -  Collection

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f0020: Time courses of probability of stages 2 and 3. (A) Time courses of scores on the 1st and 2nd principal components (dotted and solid lines, respectively) relative to onsets of stages 1 (N1) and 2 (N2), and time courses of probability of stage 2 (circles and dashed lines) determined by assigning the 1st score to 0 when negative and to +1 when positive. For N1 (left and middle plots), mean values were taken from results of three-way ANOVAs with random factor “Participant” (n=11 vs. 18) and fixed factors “One-min interval” and “N2” (With or Without N2 initiated within the first 6 min of sleep). For N2 (right plots), results of two-way ANOVAs with random factor “Participant” (n=18) and fixed factor “One-min interval”. (B) Time courses of score on the 4th and 2nd principal components (dotted and solid lines) relative to onsets of stages 2 (N2) and 3 (N3), and time courses of probability of stage 3 (circles and dashed lines, respectively) determined by assigning the 4th score to 0 when negative and to +1 when positive. For N2 (left and middle plots), results of three-way ANOVAs with random factor “Participant” (n=14 vs. 18) and fixed factors “One-min interval” and “N3” (With or Without N3). For N3 (right plots), results of two-way ANOVAs with random factor “Participant” (n=14) and fixed factor “One-min interval”. See also the legend to Fig. 2.
Mentions: In order to analyze and illustrate (Table 1, Figs. 2–3) steepness of changes in the EEG indexes during transitions from one stage to another, one-min values were further averaged on 3-min intervals (i.e., from minute −4 to −2, from −1 to +1, from +2 to +4, etc.). Additionally, all positive and negative one-min scores on a component (i.e., 1st or 4th) were transformed into +1 and 0, respectively, for illustrating time courses of probability of association of a stage (i.e., 2 or 3) with positive score on a component (Fig. 4).

Bottom Line: This was mostly a change from negative to positive score.Therefore, it might serve as yes-or-no criterion of stage 3 onset.Additionally, similarly rapid changes in sign of scores were exhibited by the 1st and 2nd principal components on the boundary of stages 2 and 1 and on the boundary between stage 1 and wakefulness, respectively.

View Article: PubMed Central - PubMed

Affiliation: Research Institute for Molecular Biology and Biophysics, Siberian Branch of the Russian Academy of Medical Sciences, Novosibirsk, Russia.

ABSTRACT
Human sleep begins in stage 1 and progresses into stages 2 and 3 of Non-Rapid-Eye-Movement (NREM) sleep. These stages were defined using several arbitrarily-defined thresholds for subdivision of albeit continuous process of sleep deepening. Since recent studies indicate that stage 3 (slow wave sleep) has unique vital functions, more accurate measurement of this stage duration and continuity might be required for both research and practical purposes. However, the true neurophysiological boundary between stages 2 and 3 remains unknown. In a search for non-arbitrary threshold criteria for distinguishing the boundaries between NREM sleep stages, scores on the principal components of the electroencephalographic (EEG) spectrum were analyzed in relation to stage onsets. Eighteen young men made 12-20-minute attempts to nap during 24-hour wakefulness. Single-minute intervals of the nap EEG records were assigned relative to the minute of onsets of polysomnographically determined stages 1, 2, and 3. The analysis of within-nap time courses of principal components scores revealed that, unlike any conventional spectral EEG index, score on the 4th principal component exhibited a rather rapid rise on the boundary between stages 2 and 3. This was mostly a change from negative to positive score. Therefore, it might serve as yes-or-no criterion of stage 3 onset. Additionally, similarly rapid changes in sign of scores were exhibited by the 1st and 2nd principal components on the boundary of stages 2 and 1 and on the boundary between stage 1 and wakefulness, respectively.

No MeSH data available.