Removal of Ocular Artifacts From the REM Sleep EEG

Waterman, Dé; Woestenburg, Jaap C.; Elton, Martin; Hofman, W.F.; Kok, Albert

doi:10.1093/sleep/15.4.371

Cited by 15 publications

(7 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We only considered oscillations above 2 Hz, as eye movement potentials mainly extend over 0.3 and 2 Hz (Tan et al, 2001). Moreover, eye movement artifacts are usually restricted to frontal derivations (Waterman et al, 1992), but in our study increased slow frequency power in phasic REM was spread (at a trend level) over more posterior regions, arguing against a mere effect of ocular contamination. Finally, slow frequency activity showed increased synchronization as measured by GFS and WPLI.…”

Section: Discussioncontrasting

confidence: 48%

The paradox of Rapid Eye Movement sleep in the light of oscillatory activity and functional synchronization during phasic and tonic microstates

Simor

Wijk

Gombos

et al. 2018

Preprint

View full text Add to dashboard Cite

Rapid Eye Movement (REM) sleep is a peculiar neural state showing a combination of muscle atonia and intense cortical activity. REM sleep is usually considered as a unitary state in neuroscientific research; however, it is composed of two different microstates: phasic and tonic REM. These differ in awakening thresholds, sensory processing, and cortical oscillations. Nevertheless, studies examining cortical oscillations during REM microstates are scarce, and used low spatial sampling. Here, we analyzed the data of 18 healthy individuals assessed by high-density sleep EEG recordings. We systematically contrasted phasic and tonic REM periods in terms of topographical distribution, source localization, as well as local, global and long-range synchronization of frequency-specific cortical activity. Tonic periods showed relatively increased high alpha and beta power over frontocentral derivations. In addition, higher frequency components of beta power exhibited increased global synchronization during tonic compared to phasic states. In contrast, in phasic periods we found increased power and synchronization of low frequency oscillations coexisting with increased and synchronized gamma activity. Source localization revealed several multimodal, higher-order associative, as well as sensorimotor areas as potential sources of increased high alpha/beta power during tonic compared to phasic REM. Increased gamma power in phasic REM was attributed to medial prefrontal and right lateralized temporal areas associated with emotional processing. Our findings emphasize the heterogeneous nature of REM sleep, expressed in two microstates with remarkably different neural activity. Considering the microarchitecture of REM sleep may provide new insights into the mechanisms of REM sleep in health and disease.

show abstract

Section: Discussioncontrasting

confidence: 48%

The paradox of Rapid Eye Movement sleep in the light of oscillatory activity and functional synchronization during phasic and tonic microstates

Simor

Wijk

Gombos

et al. 2018

Preprint

View full text Add to dashboard Cite

show abstract

“…Because REM potentials are not manifested above 2 Hz (Tan et al ., ), spectral power values below this frequency range were excluded from the analyses; however, delta and theta power increases in phasic periods still might be related to the potentials generated by eye movements. The lack of delta and theta power increments in the posterior region supports this assumption, as ocular contamination is negligible in posterior leads (Waterman et al ., ). Increased spectral power in the high alpha and beta range during the tonic state as well as greater gamma activity during phasic periods was also reported in earlier scalp EEG (Abe et al ., ; Jouny et al ., ; Waterman et al ., ) and intracranial assessments (Gross and Gotman, ).…”

Section: Discussionmentioning

confidence: 97%

EEG spectral power in phasic and tonic REM sleep: different patterns in young adults and children

Simor

Gombos

Szakadát

et al. 2016

Journal of Sleep Research

View full text Add to dashboard Cite

SUMMARYRapid eye movement sleep is composed of phasic and tonic periods, two distinguishable microstates in terms of arousal thresholds and sensory processing. Background electroencephalogram oscillations are also different between periods with (phasic state) and periods without (tonic state) eye movements. In Study 1, previous findings analysing electroencephalogram spectral power in phasic and tonic rapid eye movement sleep were replicated, and analyses extended to the high gamma range (52-90 Hz). In Study 2, phasic and tonic spectral power differences within a group of 4-8-year-old children were examined. Based on the polysomnographic data of 20 young adults, the phasic state yielded increased delta and theta power in anterior sites, as well as generally decreased high alpha and beta power in comparison to the tonic state. Moreover, phasic periods exhibited greater spectral power in the lower and the higher gamma band. Interestingly, children (n = 18) exhibited a different pattern, showing increased activity in the low alpha range during phasic periods. Moreover, during phasic in contrast to tonic rapid eye movement sleep, increased low and high gamma and enhanced low gamma band power emerged in anterior and posterior regions, respectively. The current findings show that spectral activity within the high gamma range substantially contributes to the differences between phasic and tonic rapid eye movement sleep, especially in adults. Moreover, the current data underscore the heterogeneity of rapid eye movement sleep, and point to marked differences between young adults and children regarding phasic/tonic electroencephalogram spectral power. These results suggest that the differentiation between phasic and tonic rapid eye movement periods undergoes maturation.

show abstract

“…For example, ocular artifact removal may have attenuated changes in delta power that might otherwise be present. 51 As we wanted to optimize electroencephalogram data for connectivity analyses, we did not employ the same artifact-removal strategies (e.g., ICA, visual inspection) as the spectral analyses, because these may interfere with phase synchronization data. 27,28 Thus, spectral and connectivity data results emerged from different data processing steps.…”

Section: Discussionmentioning

confidence: 99%

Neurophysiologic Correlates of Ketamine Sedation and Anesthesia

et al. 2017

View full text Add to dashboard Cite

Background Previous studies have demonstrated inconsistent neurophysiologic effects of ketamine, although discrepant findings might relate to differences in doses studied, brain regions analyzed, coadministration of other anesthetic medications, and resolution of the electroencephalograph. The objective of this study was to characterize the dose-dependent effects of ketamine on cortical oscillations and functional connectivity. Methods Ten healthy human volunteers were recruited for study participation. The data were recorded using a 128-channel electroencephalograph during baseline consciousness, subanesthetic dosing (0.5 mg/kg over 40 min), anesthetic dosing (1.5 mg/kg bolus), and recovery. No other sedative or anesthetic medications were administered. Spectrograms, topomaps, and functional connectivity (weighted and directed phase lag index) were computed and analyzed. Results Frontal theta bandwidth power increased most dramatically during ketamine anesthesia (mean power ± SD, 4.25 ± 1.90 dB) compared to the baseline (0.64 ± 0.28 dB), subanesthetic (0.60 ± 0.30 dB), and recovery (0.68 ± 0.41 dB) states; P < 0.001. Gamma power also increased during ketamine anesthesia. Weighted phase lag index demonstrated theta phase locking within anterior regions (0.2349 ± 0.1170, P < 0.001) and between anterior and posterior regions (0.2159 ± 0.1538, P < 0.01) during ketamine anesthesia. Alpha power gradually decreased with subanesthetic ketamine, and anterior-to-posterior directed connectivity was maximally reduced (0.0282 ± 0.0772) during ketamine anesthesia compared to all other states (P < 0.05). Conclusions Ketamine anesthesia correlates most clearly with distinct changes in the theta bandwidth, including increased power and functional connectivity. Anterior-to-posterior connectivity in the alpha bandwidth becomes maximally depressed with anesthetic ketamine administration, suggesting a dose-dependent effect.

show abstract

Removal of Ocular Artifacts From the REM Sleep EEG

Cited by 15 publications

References 0 publications

The paradox of Rapid Eye Movement sleep in the light of oscillatory activity and functional synchronization during phasic and tonic microstates

The paradox of Rapid Eye Movement sleep in the light of oscillatory activity and functional synchronization during phasic and tonic microstates

EEG spectral power in phasic and tonic REM sleep: different patterns in young adults and children

Neurophysiologic Correlates of Ketamine Sedation and Anesthesia

Contact Info

Product

Resources

About