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P50 Sensory Gating in Infants
Published on: December 26, 2013
Delta (0.5-1.5 Hz) and sigma (11.5-15.5 Hz) EEG power dynamics throughout quiet sleep in infants
P Y Ktonas1, I Fagioli, P Salzarulo
1Department of Electrical Engineering, University of Houston, Calhoun, TX 77204-4793, USA.
Insights
Infant sleep EEG shows distinct changes in delta and sigma brainwave power between 7-14 weeks and continuing into infancy. These patterns reveal evolving quiet sleep (QS) dynamics in developing brains.
Area of Science:
- Neuroscience
- Developmental Biology
- Sleep Science
Background:
- Quiet sleep (QS) is a crucial stage for infant brain development.
- Understanding the electroencephalogram (EEG) patterns during QS provides insights into neurodevelopmental trajectories.
- Temporal dynamics of EEG power spectra during QS in early infancy are not fully characterized.
Purpose of the Study:
- To investigate age-related changes in EEG power spectral density during quiet sleep in healthy infants.
- To analyze the temporal evolution of delta and sigma band power during the longest QS phase in different infant age groups.
Main Methods:
- Ninety-eight healthy infants were divided into three age groups: 2-6 weeks, 7-14 weeks, and 4-12 months.
- Overnight EEG recordings were obtained, and the longest quiet sleep (QS) phase between 8 p.m. and midnight was selected.
- EEG power spectral analysis was performed on the delta band (0.5-1.5 Hz) and sigma band (11.5-15.5 Hz) during the QS phase.
Main Results:
- Infants aged 2-6 weeks showed no significant changes in sigma band power, with delta band power increasing and then decreasing.
- Infants aged 7-14 weeks exhibited a progressive decrease in sigma band power and an initial increase in delta band power.
- Infants aged 4-12 months displayed a significant decrease in sigma band power after 15 minutes and progressive increases in delta band power, with delta changes preceding sigma changes.
Conclusions:
- A distinct temporal inhomogeneity pattern in EEG during quiet sleep emerges between 7-14 weeks of age.
- These evolving EEG patterns during quiet sleep continue from the fourth month of life onwards.
- The findings provide quantitative evidence of age-dependent maturation of sleep neurophysiology in infants.
Abstract:
Twenty-eight healthy infants, split into 3 groups according to age (group 1: 2-6 weeks, n = 10; group 2: 7-14 weeks, n = 10; and group 3: 4-12 months, n = 8), were recorded during the whole night. For each infant, the longest quiet sleep (QS) phase occurring between 8 p.m. and midnight was selected for EEG power spectral analysis. The power in the frequency band related to low-frequency delta waves (0.5-1.5 Hz, "delta band") and the power in the frequency band related to sigma spindles (11.5-15.5 Hz, "sigma band") were analyzed. Group 1 infants showed no significant modification of the power in the sigma band in the course of the QS phase; the power in the delta band showed a significant increase between the second and the third 5 min segment and a decrease thereafter. Group 2 infants showed a progressive reduction of the power in the sigma band, whereas the power in the delta band increased during the first 15 min. In group 3 infants, the sigma band power significantly decreased between the third and the fifth 5 min segment without further changes. The power in the delta band, on the contrary, increased progressively for the first 20 min and showed a second progressive increase beyond 35 min. For both group 2 and group 3 infants, it appeared that the change in delta power preceded the change in sigma power. The above results provide quantitative evidence that a well-defined temporal inhomogeneity pattern in the EEG of the QS phase may appear between 7 and 14 weeks of age and continues from the fourth month on.
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