A Novel Method for Reducing the Effect of Tonic Muscle Activity on the Gamma Band of the Scalp EEG

Nottage, Judith; Morrison, Paul; Williams, Steven; ffytche, Dominic H.

doi:10.1007/s10548-012-0255-9

Cited by 25 publications

(30 citation statements)

References 28 publications

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“…In contrary, applying automatic artefact rejection has the disadvantage that it reduces or modifies the raw data. To improve artefact rejection in future studies, it is recommendable to apply a novel approach proposed by Nottage et al [25] to remove tonic muscle artefacts.…”

Section: Eeg Methodologymentioning

confidence: 99%

Altered Frequency Distribution in the Electroencephalogram is Correlated to the Analgesic Effect of Remifentanil

Graversen

Malver

Kurita

et al. 2014

Basic Clin Pharma Tox

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Opioids alter resting state brain oscillations by multiple and complex factors, which are still to be elucidated. To increase our knowledge, multi-channel electroencephalography (EEG) was subjected to multivariate pattern analysis (MVPA), to identify the most descriptive frequency bands and scalp locations altered by remifentanil in healthy volunteers. Sixty-two channels of resting EEG followed by independent measures of pain scores to heat and bone pain were recorded in 21 healthy males before and during remifentanil infusion in a placebo-controlled, double-blind crossover study. EEG frequency distributions were extracted by a continuous wavelet transform and normalized into delta, theta, alpha, beta and gamma bands. Alterations relative to pre-treatment responses were calculated for all channels and used as input to the MVPA. Compared to placebo, remifentanil increased the delta band and decreased the theta and alpha band oscillations as a mean over all channels (all p ≤ 0.007). The most discriminative channels in these frequency bands were F1 in delta (83.33%, p = 0.0023) and theta bands (95.24%, p < 0.0001), and C6 in the alpha band (80.95%, p = 0.0054). These alterations were correlated to individual changes in heat pain in the delta (p = 0.045), theta (p = 0.038) and alpha (p = 0.039) bands and to bone pain in the alpha band (p = 0.0092). Hence, MVPA of multi-channel EEG was able to identify frequency bands and corresponding channels most sensitive to altered brain activity during remifentanil treatment. As the EEG alterations were correlated to the analgesic effect, the approach may prove to be a novel methodology for monitoring individual efficacy to opioids.Remifentanil is a selective l-receptor opioid agonist with short onset and duration of action [1,2]. This provides a remarkable titratability, which has proved useful for balanced anaesthesia and analgosedation as well as scientific research in experimental and clinical settings [3]. For scientific research on the underlying mechanisms of action of remifentanil, electroencephalography (EEG) provides information about the time course of electrical activity in the brain. This has been investigated in several previous studies, and the results indicate a relationship between EEG changes and the potency of remifentanil [4,5]. However, although the results of these studies have shed light on many of the underlying mechanisms of remifentanil, data are conflicting and the linkage between altered brain activity and the analgesic effect of remifentanil still remains unclear.Elucidation of the association between pain stimulation/measurement and altered EEG characteristics is therefore warranted. This could be accomplished in a placebo-controlled, crossover study in healthy volunteers treated with low-dose remifentanil, which enables comparison of EEG alterations during remifentanil treatment in comparison with alterations during placebo therapy. In such a low-dose set-up, the healthy volunteer would still be conscious and able to rate pain sensations...

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Section: Eeg Methodologymentioning

confidence: 99%

Altered Frequency Distribution in the Electroencephalogram is Correlated to the Analgesic Effect of Remifentanil

Graversen

Malver

Kurita

et al. 2014

Basic Clin Pharma Tox

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“…Firstly the signal must have the same phase across electrodes, and secondly the power line component must not contain other signals as well as the power line noise, or removal of this component will alter the underlying electroencephalogram. In practice these conditions may not be met, and therefore noise cancellation has recently been proposed as an alternative method for addressing the power line noise artefact [33,34]. One or more electrodes are used to record the power line noise simultaneously with the electroencephalogram, and this signal is transformed so as to replicate the power line signal at each electrode.…”

Section: Extracting Neural High-frequency Oscillations From Human Scamentioning

confidence: 99%

“…An alternative approach is to fit a mathematical model to individual muscle spikes and subtract these from the signal [34]. The muscle spikes are modelled using a Gabor function, which consists of a sine wave multiplied by a Gaussian function.…”

Section: Extracting Neural High-frequency Oscillations From Human Scamentioning

confidence: 99%

“…It is important that any method for reducing the EMG artefact is able to do so whilst preserving the neural gamma signal. The mathematical modelling method was able to effectively correct the gamma signal associated with a self-paced motor task [34], as can be seen in figure 5. The baseline gamma signal is substantially reduced, revealing a significant 65- to 85-Hz gamma activation over left motor/somatosensory areas.…”

Section: Extracting Neural High-frequency Oscillations From Human Scamentioning

confidence: 99%

“…Before EMG reduction, this gamma peak was not significant. See Nottage et al [34] for further details. …”

Section: Extracting Neural High-frequency Oscillations From Human Scamentioning

confidence: 99%

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State-of-the-Art Analysis of High-Frequency (Gamma Range) Electroencephalography in Humans

Nottage

Horder

2015

Neuropsychobiology

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Gamma oscillations (>30 Hz) in the brain are involved in attention, perception and memory. They are altered in various pathological states, as well as by neuropharmaceuticals, so that they are of interest in drug and clinical investigations. However, when the human electroencephalogram is recorded on the scalp, this neural high-frequency signal is buried under a range of other electrical signals such that, without careful handling, recordings of the high-frequency electroencephalogram cannot be considered reliable. The artefacts of concern originate from: power line noise, saccade-associated contraction of the extra-ocular muscles, activity of muscles in the scalp, face and neck, screen refresh artefacts and activity of the muscles associated with blinking. Recent progress in dealing with these artefacts is described, including either noise cancellation or phased noise template subtraction for power line noise, regression or independent component analysis for correcting extra-ocular muscle activity and mathematical modelling for reducing scalp, face and neck muscle activity. If the artefacts are properly addressed, the neural gamma signal can be uncovered.

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Delta-9-tetrahydrocannabinol, neural oscillations above 20 Hz and induced acute psychosis

et al. 2014

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RationaleAn acute challenge with delta-9-tetrahydrocannabinol (THC) can induce psychotic symptoms including delusions. High electroencephalography (EEG) frequencies, above 20 Hz, have previously been implicated in psychosis and schizophrenia.ObjectivesThe objective of this study is to determine the effect of intravenous THC compared to placebo on high-frequency EEG.MethodsA double-blind cross-over study design was used. In the resting state, the high-beta to low-gamma magnitude (21–45 Hz) was investigated (n = 13 pairs + 4 THC only). Also, the event-related synchronisation (ERS) of motor-associated high gamma was studied using a self-paced button press task (n = 15).ResultsIn the resting state, there was a significant condition × frequency interaction (p = 0.00017), consisting of a shift towards higher frequencies under THC conditions (reduced high beta [21–27 Hz] and increased low gamma [27–45 Hz]). There was also a condition × frequency × location interaction (p = 0.006), such that the reduction in 21–27-Hz magnitude tended to be more prominent in anterior regions, whilst posterior areas tended to show greater 27–45-Hz increases. This effect was correlated with positive symptoms, as assessed on the Positive and Negative Syndrome Scale (PANSS) (r = 0.429, p = 0.042). In the motor task, there was a main effect of THC to increase 65–130-Hz ERS (p = 0.035) over contra-lateral sensorimotor areas, which was driven by increased magnitude in the higher, 85–130-Hz band (p = 0.02) and not the 65–85-Hz band.ConclusionsThe THC-induced shift to faster gamma oscillations may represent an over-activation of the cortex, possibly related to saliency misattribution in the delusional state.Electronic supplementary materialThe online version of this article (doi:10.1007/s00213-014-3684-1) contains supplementary material, which is available to authorized users.

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A Novel Method for Reducing the Effect of Tonic Muscle Activity on the Gamma Band of the Scalp EEG

Cited by 25 publications

References 28 publications

Altered Frequency Distribution in the Electroencephalogram is Correlated to the Analgesic Effect of Remifentanil

Altered Frequency Distribution in the Electroencephalogram is Correlated to the Analgesic Effect of Remifentanil

State-of-the-Art Analysis of High-Frequency (Gamma Range) Electroencephalography in Humans

Delta-9-tetrahydrocannabinol, neural oscillations above 20 Hz and induced acute psychosis

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