Limits...
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 spectal powers and scores on principal components.Single-Hz log-transformed spectral powers (ln power) were averaged over frequency ranges roughly corresponding to delta (1–4 Hz), theta (5–8 Hz), alpha (9–12 Hz), and sigma activity (13–16 Hz). The 1st–4th principal component scores and ln powers were aligned relative to the 0-minute of onset of NREM sleep stage 1 (N1), stage 2 (N2), and stage 3 (N3), and then averaged on 3-min intervals prior and after this minute (i.e., minutes from −4 to −2, from −1 to +1, from +2 to +4, etc.). Wakefulness was (N1) and was not accounted (N2 and N3). Results of two-way ANOVAs with fixed factor “Three-min interval” and random factor “Participant” (n=14 for N3 and n=18 for N1 and N2).
© Copyright Policy - CC BY-NC-ND
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4608893&req=5

f0010: Time courses of spectal powers and scores on principal components.Single-Hz log-transformed spectral powers (ln power) were averaged over frequency ranges roughly corresponding to delta (1–4 Hz), theta (5–8 Hz), alpha (9–12 Hz), and sigma activity (13–16 Hz). The 1st–4th principal component scores and ln powers were aligned relative to the 0-minute of onset of NREM sleep stage 1 (N1), stage 2 (N2), and stage 3 (N3), and then averaged on 3-min intervals prior and after this minute (i.e., minutes from −4 to −2, from −1 to +1, from +2 to +4, etc.). Wakefulness was (N1) and was not accounted (N2 and N3). Results of two-way ANOVAs with fixed factor “Three-min interval” and random factor “Participant” (n=14 for N3 and n=18 for N1 and N2).

Mentions: One-way repeated-measure analyses of variance (rANOVAs) with within-subjects factor “Three-min interval” were performed for examining whether an EEG index ehibites statistically significant changes both prior to and after onset of a stage. The Bonferroni multiple comparison test was used in the post hoc analysis, i.e., for examining significance of differences between a value of an index for 0-minute of stage onset and the preceding and following values (Table 1). Additionally, 2-way ANOVAs were run on time courses of the EEG indexes (Fig. 2) with fixed factor “Interval”, i.e., either “Three-min interval” (Fig. 3B) or “One-min interval” (Fig. 4), and random factor “Participant” (Fig. 3A). Finally, two-way ANOVAs with two fixed factors were conducted on these time courses to test whether they are different for different experimental conditions, times of day, delays of stage onset, etc. The first fixed factors was “Three-min interval” and the second was, respectively, “Condition” (sleep deprived vs. slept), “Time of day” (12 clock times; Fig. 3A), “Stage onset delay” (minutes −12, −9, −6, −3, and 0), etc.


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 spectal powers and scores on principal components.Single-Hz log-transformed spectral powers (ln power) were averaged over frequency ranges roughly corresponding to delta (1–4 Hz), theta (5–8 Hz), alpha (9–12 Hz), and sigma activity (13–16 Hz). The 1st–4th principal component scores and ln powers were aligned relative to the 0-minute of onset of NREM sleep stage 1 (N1), stage 2 (N2), and stage 3 (N3), and then averaged on 3-min intervals prior and after this minute (i.e., minutes from −4 to −2, from −1 to +1, from +2 to +4, etc.). Wakefulness was (N1) and was not accounted (N2 and N3). Results of two-way ANOVAs with fixed factor “Three-min interval” and random factor “Participant” (n=14 for N3 and n=18 for N1 and N2).
© Copyright Policy - CC BY-NC-ND
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4608893&req=5

f0010: Time courses of spectal powers and scores on principal components.Single-Hz log-transformed spectral powers (ln power) were averaged over frequency ranges roughly corresponding to delta (1–4 Hz), theta (5–8 Hz), alpha (9–12 Hz), and sigma activity (13–16 Hz). The 1st–4th principal component scores and ln powers were aligned relative to the 0-minute of onset of NREM sleep stage 1 (N1), stage 2 (N2), and stage 3 (N3), and then averaged on 3-min intervals prior and after this minute (i.e., minutes from −4 to −2, from −1 to +1, from +2 to +4, etc.). Wakefulness was (N1) and was not accounted (N2 and N3). Results of two-way ANOVAs with fixed factor “Three-min interval” and random factor “Participant” (n=14 for N3 and n=18 for N1 and N2).
Mentions: One-way repeated-measure analyses of variance (rANOVAs) with within-subjects factor “Three-min interval” were performed for examining whether an EEG index ehibites statistically significant changes both prior to and after onset of a stage. The Bonferroni multiple comparison test was used in the post hoc analysis, i.e., for examining significance of differences between a value of an index for 0-minute of stage onset and the preceding and following values (Table 1). Additionally, 2-way ANOVAs were run on time courses of the EEG indexes (Fig. 2) with fixed factor “Interval”, i.e., either “Three-min interval” (Fig. 3B) or “One-min interval” (Fig. 4), and random factor “Participant” (Fig. 3A). Finally, two-way ANOVAs with two fixed factors were conducted on these time courses to test whether they are different for different experimental conditions, times of day, delays of stage onset, etc. The first fixed factors was “Three-min interval” and the second was, respectively, “Condition” (sleep deprived vs. slept), “Time of day” (12 clock times; Fig. 3A), “Stage onset delay” (minutes −12, −9, −6, −3, and 0), etc.

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.