Brief Communication HUMAN SCALP RECORDED SIGMA ACTIVITY IS MODULATED BY SLOW EEG OSCILLATIONS DURING DEEP SLEEP

Abstract

The EEG during deep sleep exhibits a distinct cortically generated slow oscillation of around and below 1 Hz which can be distinguished from other delta (0.5-3.5 Hz) activity. Intracranial studies showed that this slow oscillation triggers and groups cortical network firing. In the present study, we examined whether the phases of the slow oscillation during sleep stage 4 are correlated with the magnitude of sigma (12-16 Hz) and gamma (> 20 Hz) scalp activity. For this purpose, 10-min segments of uninterrupted stage 4 sleep EEG from 9 subjects were analyzed by applying wavelet techniques. We found that scalp recorded sigma, but not gamma, activity is modulated by the phases of the slow oscillation during deep sleep. Enhancement of sigma activity was observed to be triggered by the peak of the surface positive slow wave component, whereas reduction of sigma activity started around the peak of the negative component.

Human Gamma Oscillations during Slow Wave Sleep

“…In most of the cases, gamma oscillations were correlated with positive peaks of scalp slow waves, confirming previous animal data suggesting that gamma oscillations occur during the active component of the slow wave (‘UP’ state). This observation of enhanced gamma activities during surface-positive components of slow oscillations is also consistent with the grouping of spindle and beta activities reported for human scalp EEG [13], [14]. This depolarization phase is associated with increased cortical firing, which drives the generation of spindle, beta and gamma oscillations in thalamo-cortical feedback loops [3].…”

“…Nevertheless, although activities in the gamma-range have been observed at the scalp level during a variety of cognitive tasks [12], no evidences of a phasic expression of gamma activities during SWS in human macroscopic EEG recordings were reported so far. For example, Fell and colleagues [13] used the scalp EEG data during sleep and showed that sigma activity (12–16 Hz) is modulated by slow EEG oscillations. In another study, Molle and collaborators [14] found that grouping of spindles and beta oscillations are coincident with slow waves in human SWS.…”

Investigation of the modulation between EEG alpha waves and slow/fast delta waves in children in different depths of Desflurane anesthesia

“…9(c2)), results are not very good for f-indexes greater than 2.5 or less than 0.5 Hz. More precisely saying, an f-index, which is greater than 2.5 Hz, fails to give low standard deviation in light and deep anesthesia (stages 1,4,5), and an f-index which is less than 0.5 Hz, basically fails to yield a low standard deviation in deep and moderate anesthesia (stages 1 to 3). Fig.…”

“…The depolarizing phase, on the other hand, is found to be accompanied by a corticothalamic facilitation of neural firing. Fell et al, used the scalp EEG data during sleep and showed that sigma activity ( [12][13][14][15][16] Hz) is modulated by slow EEG oscillations [5]. However, they did not find a strong modulation between slow delta waves and gamma oscillations on scalp EEG recordings as Steriade et al, had shown in their neuronal level recordings.…”

“…L'interprétation du paramètre SOM * Corresponding author. LTSI, campus de Beaulieu, université de Rennes1, bâtiment 22, 5 e étage, 56 B. Molaee-Ardekani et al / IRBM 31 (2010) [55][56][57][58][59][60][61][62][63][64][65][66] indique que la bande Delta comporte trois sous-bandes principales correspondant approximativement aux intervalles [0,5], [0,7-1,7] et [2-4] Hz (activité très lente, lente et rapide). Néanmoins, les limites de ces bandes sont susceptibles de varier avec la profondeur d'anesthésie.…”