Article

Dynamics of EEG background activity level within quiet sleep in successive cycles in infants

University of Santiago, Chile, CiudadSantiago, Santiago Metropolitan, Chile
Electroencephalography and Clinical Neurophysiology 02/1995; 94(1):6-11. DOI: 10.1016/0013-4694(94)00227-C
Source: PubMed

ABSTRACT

We investigated in infants the emergence of the trends of the EEG synchronization throughout quiet sleep (QS) as a function of the QS rank. The night sleep of 3 groups with 6 subjects each (aged respectively 9-18 weeks, 21-47 weeks, and 16-45 years) was recorded. A parameter value reflecting the degree of synchronization of the EEG background activity for successive epochs was computed by automatic analysis. For each QS phase 3 indicators of the dynamics of the time course of the EEG parameter activity were determined: the range (difference between the EEG parameter value at the beginning of the QS episode and that at the trough), the trough latency (after QS onset), and the rate of synchronization (range/trough latency). The range and the trough latency increased with age, whereas the rate of synchronization decreased. The range and the rate of synchronization decreased in the successive cycles, whereas the trough latency increased. These results provide further support for the hypothesis of the early emergence of the process S mechanisms and suggest that the framework of the 2-process model could account also for the development of both the EEG background activity dynamics and the sleep-wake organization.

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    • "Epochs of stage 2, 3 and 4 were used to compute power spectra. For roS analysis, EEG power in the 0.4 to 4.4 Hz band for each 30-s epoch was averaged every minute and smoothed using two successive averages over a 5 point window (Fagioli et al., 1995, 2001). The time course of the smoothed spectral values was plotted against sleep stages. "
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    ABSTRACT: Twenty-four hour sleep patterns were measured in six healthy male volunteers during a 90-minute short sleep-wake (SW 30:60) cycle protocol for 48 hours. Sleep pressure estimates (amount of Slow Wave Sleep [SWS], SWA, and Rate of Synchronization [RoS: the rate of SWA build-up at the beginning of the NREM period]) were compared with the 24-hour patterns of body temperature (Tb24) and sleep propensity. A moderate sleep debt was incurred over the 48 hour study as indicated by decreased levels of 24 hour sleep. On day 1, ultradian patterns of REM and SWS sleep were prominent; on day 2, more prominent were circadian patterns of REM sleep, SWS, Sleep Latency, TST and Tb24. Also on Day 2, biphasic patterns of SWA and RoS were expressed, with peaks occurring during the falling and rising limbs of Tb24. The biphasic peaks in SWA and RoS may be associated with phase-specific interactions of the circadian pacemaker with the sleep homeostat during conditions of moderate sleep pressure. Further research is needed to replicate the finding and to identify biological factors that may underlie the twelve hour pattern in SWA.
    Full-text · Article · Dec 2009 · Archives italiennes de biologie
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    • "The time course of the smoothed spectral values were plotted against sleep stages that were manually scored according to Rechtschaffen and Kales' [11] criteria. For the NREM sleep period of each NREM-REM cycle, RoS was de®ned as the ratio of the difference between initial (®rst min of stage 2) and maximum delta power to the latency from the beginning of the stage 2 episode to the time of maximum delta power [1] [6]. BS nights were de®ned by the occurrence of two nocturnal sleep episodes containing at least three consecutive NREM-REM cycles each separated by a waking period starting before 02:00 h and lasting more than 104 min. "
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    ABSTRACT: Dynamics of electroencephalographic (EEG) slow wave activity (0.5-4.5 Hz) and body temperature, as estimates, respectively, of the process S and process C, regulating sleep and waking alternate occurrence, were measured during monophasic and biphasic sleep patterns that occurred spontaneously in a 35-year-old woman who lived for 105 days in a winter-type photoperiod (10-14 h light-dark). In monophasic nights, rate of EEG synchronization showed a decreasing trend across the first three non-rapid eye movement (NREM) periods. In biphasic nights, rate of EEG synchronization increased during the third NREM period which precedes the nocturnal awakening. Temperature cycle was not different between biphasic and monophasic nights. Those results confirm that EEG dynamics reflects homeostatic sleep regulatory mechanism, and suggest that the period of prolonged wakefulness in the middle of biphasic night is pre-programmed.
    Full-text · Article · Mar 2001 · Neuroscience Letters
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    • "Another explanation , not necessarily conflicting with the previous one, could take into account a maturational factor, the increase with age of the synaptic connections in the cerebral cortex (Feinberg et al., 1977), which could lead to an increase in slow wave activity. The increase with age of the trough latency parallels the increase of the duration of the QS phase, independently of age and rank of the cycle (as shown in infants by Fagioli et al., 1990; see also Peirano et al., 1993). Given that the increase with age of the trough latency outweighs that of the EEG parameter range, it follows that the rate of synchronization shows a decreasing trend with age. "
    [Show abstract] [Hide abstract]
    ABSTRACT: We investigated in infants the emergence of the trends of the EEG synchronization throughout quiet sleep (QS) as a function of the QS rank. The night sleep of 3 groups with 6 subjects each (aged respectively 9-18 weeks, 21-47 weeks, and 16-45 years) was recorded. A parameter value reflecting the degree of synchronization of the EEG background activity for successive epochs was computed by automatic analysis. For each QS phase 3 indicators of the dynamics of the time course of the EEG parameter activity were determined: the range (difference between the EEG parameter value at the beginning of the QS episode and that at the trough), the trough latency (after QS onset), and the rate of synchronization (range/trough latency). The range and the trough latency increased with age, whereas the rate of synchronization decreased. The range and the rate of synchronization decreased in the successive cycles, whereas the trough latency increased. These results provide further support for the hypothesis of the early emergence of the process S mechanisms and suggest that the framework of the 2-process model could account also for the development of both the EEG background activity dynamics and the sleep-wake organization.
    Full-text · Article · Feb 1995 · Electroencephalography and Clinical Neurophysiology
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