Scalp topographic distribution of beta and gamma ratios during sleep

Research output: Contribution to journalArticle

Abstract

The present study analyzes the topographic distribution of two newly introduced measures related to the beta and gamma EEG bands during REM sleep. For this purpose, power spectra of three EEG channels (F4, C4, and O2, all referred to A1) were obtained by means of the fast Fourier transform, and the power of the bands ranging from 0.75-4.50 Hz (delta) and 12.50-15.00 (sigma) was calculated for the whole period of analysis (7 h) in 10 healthy subjects. Also, two additional time series - the ratio between beta and gamma2 and between gamma1 and gamma2 - were calculated (beta and gamma ratios). The difference between the mean group values of the delta and sigma bands power, and of the beta and gamma ratios, during the different sleep stages, over the three different scalp locations recorded was evaluated by means of the nonparametric Friedman ANOVA. During non-REM slow-wave sleep, the delta band showed the highest values over the central and frontal regions, followed by those observed over the occipital lead. During sleep stage 2, the sigma band showed the highest values over the central regions, followed by those observed over the occipital areas and, lastly, those from the frontal lead. During REM sleep, the beta ratio showed its highest values over the central field, which were significantly higher that those obtained from both the frontal and the occipital regions. The gamma ratio showed a statistically nonsignificant tendency to show a similar topographic distribution pattern. Sleep can be considered a complex phenomenon with a differential involvement of multiple cortical and subcortical structures. The analysis of high-frequency EEG bands and of our beta and gamma ratios represent an additional important element to include in the study of sleep.

Original languageEnglish
Pages (from-to)107-113
Number of pages7
JournalJournal of Psychophysiology
Volume16
Issue number2
DOIs
Publication statusPublished - 2002

Keywords

  • Beta band
  • EEG power spectrum
  • Fast Fourier transform
  • Gamma band
  • High-frequency EEG bands
  • REM sleep
  • Sleep

ASJC Scopus subject areas

  • Neuroscience(all)
  • Neuropsychology and Physiological Psychology

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