scholarly journals Kurtosis and skewness of high-frequency brain signals are altered in paediatric epilepsy

2020 ◽  
Vol 2 (1) ◽  
Author(s):  
Jing Xiang ◽  
Ellen Maue ◽  
Yuyin Fan ◽  
Lei Qi ◽  
Francesco T Mangano ◽  
...  
Keyword(s):  
High Frequency ◽  
Intractable Epilepsy ◽  
Low Frequency ◽  
Brain Regions ◽  
Control Group ◽  
Frequency Bands ◽  
Non Invasive ◽  
Brain Signals ◽  
Paediatric Epilepsy ◽  
Virtual Electrode

Abstract Intracranial studies provide solid evidence that high-frequency brain signals are a new biomarker for epilepsy. Unfortunately, epileptic (pathological) high-frequency signals can be intermingled with physiological high-frequency signals making these signals difficult to differentiate. Recent success in non-invasive detection of high-frequency brain signals opens a new avenue for distinguishing pathological from physiological high-frequency signals. The objective of the present study is to characterize pathological and physiological high-frequency signals at source levels by using kurtosis and skewness analyses. Twenty-three children with medically intractable epilepsy and age-/gender-matched healthy controls were studied using magnetoencephalography. Magnetoencephalographic data in three frequency bands, which included 2–80 Hz (the conventional low-frequency signals), 80–250 Hz (ripples) and 250–600 Hz (fast ripples), were analysed. The kurtosis and skewness of virtual electrode signals in eight brain regions, which included left/right frontal, temporal, parietal and occipital cortices, were calculated and analysed. Differences between epilepsy and controls were quantitatively compared for each cerebral lobe in each frequency band in terms of kurtosis and skewness measurements. Virtual electrode signals from clinical epileptogenic zones and brain areas outside of the epileptogenic zones were also compared with kurtosis and skewness analyses. Compared to controls, patients with epilepsy showed significant elevation in kurtosis and skewness of virtual electrode signals. The spatial and frequency patterns of the kurtosis and skewness of virtual electrode signals among the eight cerebral lobes in three frequency bands were also significantly different from that of the controls (2–80 Hz, P < 0.001; 80–250 Hz, P < 0.00001; 250–600 Hz, P < 0.0001). Compared to signals from non-epileptogenic zones, virtual electrode signals from epileptogenic zones showed significantly altered kurtosis and skewness (P < 0.001). Compared to normative data from the control group, aberrant virtual electrode signals were, for each patient, more pronounced in the epileptogenic lobes than in other lobes(kurtosis analysis of virtual electrode signals in 250–600 Hz; odds ratio = 27.9; P < 0.0001). The kurtosis values of virtual electrode signals in 80–250 and 250–600 Hz showed the highest sensitivity (88.23%) and specificity (89.09%) for revealing epileptogenic lobe, respectively. The combination of virtual electrode and kurtosis/skewness measurements provides a new quantitative approach to distinguishing pathological from physiological high-frequency signals for paediatric epilepsy. Non-invasive identification of pathological high-frequency signals may provide novel important information to guide clinical invasive recordings and direct surgical treatment of epilepsy.

scholarly journals Differential Effects of Isoflurane on High-frequency and Low-frequency γ Oscillations in the Cerebral Cortex and Hippocampus in Freely Moving Rats

2011 ◽  
Vol 114 (3) ◽  
pp. 588-595 ◽  
Author(s):  
Anthony G. Hudetz ◽  
Jeannette A. Vizuete ◽  
Siveshigan Pillay
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Brain Regions ◽  
Loss Of Consciousness ◽  
Dependent Manner ◽  
General Anesthetics ◽  
Frequency Bands ◽  
Depth Electrodes ◽  
Righting Reflex ◽  
40 Hz

Background Cortical γ oscillations are thought to play a role in conscious cognitive functions. Suppression of 40-Hz γ activity was implicated in the loss of consciousness during general anesthesia. However, several experimental studies found that γ oscillations were preserved in anesthesia. The authors investigated the concentration-dependent effect of isoflurane on spontaneous γ oscillations in two frequency bands and three distinct brain regions in the rat. Methods Adult Sprague-Dawley rats were chronically implanted with epidural and coaxial depth electrodes to record cortical field potentials in frontal cortex, visual cortex, and hippocampus in waking and at steady-state isoflurane concentrations of 0.4, 0.8, and 1.2%. The γ power was calculated for the frequency bands 30-50 and 70-140 Hz. Temporal variation and interregional synchrony of γ activity were analyzed using wavelet transform. Loss of consciousness was indexed by the loss of righting reflex. Results Rats lost their righting reflex at 0.8 ± 0.1% isoflurane. High-frequency γ power was decreased by isoflurane in a concentration-dependent manner (P < 0.001, 50% decrease at 0.8% isoflurane) in all brain regions. Low-frequency γ power was unaffected by isoflurane. The duration and interregional synchrony of high-frequency γ bursts was also reduced (P l < 0.001, 40% decrease at 0.8% isoflurane). Conclusions Distinction between high- and low-frequency γ bands is important when evaluating the effect of general anesthetics on brain electrical activity. Spontaneous 40-Hz γ power does not indicate the state of consciousness. The attenuation and interregional desynchronization of high-frequency γ oscillations appear to correlate with the loss of consciousness.

scholarly journals Bispectrum-based Cross-frequency Functional Connectivity: A Study of Alzheimer's Disease

2021 ◽  
Author(s):  
Dominik Klepl ◽  
Fei He ◽  
Min Wu ◽  
Daniel J Blackburn ◽  
Ptolemaios G Sarrigiannis
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Functional Connectivity ◽  
High Frequency ◽  
Neurodegenerative Disorder ◽  
Low Frequency ◽  
Brain Regions ◽  
Frequency Bands ◽  
Frequency Coupling ◽  
Eeg Recordings

Alzheimer's disease (AD) is a neurodegenerative disorder known to affect functional connectivity (FC) across many brain regions. Linear FC measures have been applied to study the differences in AD by splitting neurophysiological signals such as electroencephalography (EEG) recordings into discrete frequency bands and analysing them in isolation from each other. We address this limitation by quantifying cross-frequency FC in addition to the traditional within-band approach. Cross-bispectrum, a higher-order spectral analysis approach, is used to measure the nonlinear FC and is compared with the cross-spectrum, which only measures the linear FC within bands. This work reports the first use of cross-bispectrum to reconstruct a cross-frequency FC network where each frequency band is treated as a layer in a multilayer network with both inter- and intra-layer edges. An increase of within-band FC in AD is observed in low-frequency bands using both methods. Bispectrum also detects multiple cross-frequency differences, mainly increased FC in AD in delta-theta coupling. An increased importance of low-frequency coupling and decreased importance of high-frequency coupling is observed in AD. Integration properties of AD networks are more vulnerable than HC, while the segregation property is maintained in AD. Moreover, the segregation property of γ is less vulnerable in AD, suggesting the shift of importance from high-frequency activity towards low-frequency components. The results highlight the importance of studying nonlinearity and including cross-frequency FC in characterising AD. Moreover, the results demonstrate the advantages and limitations of using bispectrum to reconstruct FC networks.

scholarly journals Spectral fingerprints or spectral tilt? Evidence for distinct oscillatory signatures of memory formation

2018 ◽  
Author(s):  
Marie-Christin Fellner ◽  
Stephanie Gollwitzer ◽  
Stefan Rampp ◽  
Gernot Kreiselmeyr ◽  
Daniel Bush ◽  
...  
Keyword(s):  
Power Spectrum ◽  
High Frequency ◽  
Low Frequency ◽  
Brain Regions ◽  
Memory Formation ◽  
Memory Encoding ◽  
Frequency Bands ◽  
Theta Power ◽  
Gamma Power ◽  
Frequency Power

AbstractDecreases in low frequency power (2-30 Hz) alongside high frequency power increases (>40 Hz) have been demonstrated to predict successful memory formation. Parsimoniously this change in the frequency spectrum can be explained by one factor, a change in the tilt of the power spectrum (from steep to flat) indicating engaged brain regions. A competing view is that the change in the power spectrum contains several distinct brain oscillatory fingerprints, each serving different computations. Here, we contrast these two theories in a parallel MEG-intracranial EEG study where healthy participants and epilepsy patients, respectively, studied either familiar verbal material, or unfamiliar faces. We investigated whether modulations in specific frequency bands can be dissociated in time, space and by experimental manipulation. Both, MEG and iEEG data, show that decreases in alpha/beta power specifically predicted the encoding of words, but not faces, whereas increases in gamma power and decreases in theta power predicted memory formation irrespective of material. Critically, these different oscillatory signatures of memory encoding were evident in different brain regions. Moreover, high frequency gamma power increases occurred significantly earlier compared to low frequency theta power decreases. These results speak against a “spectral tilt” and demonstrate that brain oscillations in different frequency bands serve different functions for memory encoding.

scholarly journals Magnetic Temporal Interference for Noninvasive Focal Brain Stimulation

2022 ◽  
Author(s):  
Adam Khalifa ◽  
Seyed Mahdi Abrishami ◽  
Mohsen Zaeimbashi ◽  
Alexander D. Tang ◽  
Brian Coughlin ◽  
...  
Keyword(s):  
Electric Fields ◽  
Brain Stimulation ◽  
High Frequency ◽  
Low Frequency ◽  
Brain Regions ◽  
Strong Increase ◽  
Non Invasive ◽  
Frequency Magnetic Field ◽  
Fos Expression ◽  
The Brain

Non-invasive stimulation of deep brain regions has been a major goal for neuroscience and neuromodulation in the past three decades. Transcranial magnetic stimulation (TMS), for instance, cannot target deep regions in the brain without activating the overlying tissues and has a poor spatial resolution. In this manuscript, we propose a new concept that relies on the temporal interference of two high-frequency magnetic fields generated by two electromagnetic solenoids. To illustrate the concept, custom solenoids were fabricated and optimized to generate temporal interfering electric fields for rodent brain stimulation. C-Fos expression was used to track neuronal activation. C-Fos expression was not present in regions impacted by only one high-frequency magnetic field indicating ineffective recruitment of neural activity in non-target regions. In contrast, regions impacted by two fields that interfere to create a low-frequency envelope display a strong increase in c-Fos expression. Therefore, this magnetic temporal interference solenoid-based system provides a framework to perform further stimulation studies that would investigate the advantages it could bring over conventional TMS systems.

scholarly journals Effect of Acupuncture on Heart Rate Variability: A Systematic Review

2014 ◽  
Vol 2014 ◽  
pp. 1-19 ◽  
Author(s):  
Joanne W. Y. Chung ◽  
Vincent C. M. Yan ◽  
Hongwei Zhang
Keyword(s):  
Systematic Review ◽  
Heart Rate ◽  
Heart Rate Variability ◽  
High Frequency ◽  
Healthy Subjects ◽  
Keyword Search ◽  
Data Extraction ◽  
Meta Analysis ◽  
Low Frequency ◽  
Control Group

Aim.To summarize all relevant trials and critically evaluate the effect of acupuncture on heart rate variability (HRV).Method.This was a systematic review with meta-analysis. Keyword search was conducted in 7 databases for randomized controlled trials (RCTs). Data extraction and risk of bias were done.Results.Fourteen included studies showed a decreasing effect of acupuncture on low frequency (LF) and low frequency to high frequency ratio (LF/HF ratio) of HRV for nonhealthy subjects and on normalized low frequency (LF norm) for healthy subjects. The overall effect was in favour of the sham/control group for high frequency (HF) in nonhealthy subjects and for normalized high frequency (HF norm) in healthy subjects. Significant decreasing effect on HF and LF/HF ratio of HRV when acupuncture was performed on ST36 among healthy subjects and PC6 among both healthy and nonhealthy subjects, respectively.Discussion.This study partially supports the possible effect of acupuncture in modulating the LF of HRV in both healthy and nonhealthy subjects, while previous review reported that acupuncture did not have any convincing effect on HRV in healthy subjects. More published work is needed in this area to determine if HRV can be an indicator of the therapeutic effect of acupuncture.

Electroacupuncture at Zusanli Rescues the Enteric Neuronal Loss in the Stomach of Diabetic Rats

2012 ◽  
Vol 18 (1) ◽  
pp. 5-14 ◽  
Author(s):  
Min Hu ◽  
Fan Du ◽  
Shi Liu
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Neuronal Loss ◽  
Diabetic Rats ◽  
Enteric Neurons ◽  
Control Group ◽  
Sprague Dawley ◽  
Long Duration ◽  
Sprague Dawley Rats ◽  
Zusanli Acupoint

The purpose of this study was to investigate the effects of electroacupuncture at Zusanli acupoint on the enteric neuropathy in diabetic rats. Sprague–Dawley rats were divided into different groups depending on the total electroacupuncture span and frequency. The expression of nitric oxide synthase (nNOS), choline acetyltransferase (CHAT), protein gene product 9.5 (PGP9.5), and doublecortin was significantly decreased in the diabetic group compared with the control group. Long-term electroacupuncture at Zusanli with either high frequency or low frequency could increase the expression levels of nNOS, CHAT, PGP9.5, and doublecortin, and the increase was greater in the high-frequency group. But no obvious changes were seen in the short-term electroacupuncture groups. These results suggest that electroacupuncture at Zusanli can restore the deficiency of enteric neurons in diabetes partly but a comparative long duration of stimuli (6 weeks) is required. The increase of doublecortin may be involved in this positive process.

scholarly journals Low Frequency Oscillations drive EEG's complexity changes during wakefulness and sleep

2021 ◽  
Author(s):  
Joaquin Gonzalez ◽  
Diego M. Mateos ◽  
Matias Cavelli ◽  
Alejandra Mondino ◽  
Claudia Pascovich ◽  
...  
Keyword(s):  
Slow Wave Sleep ◽  
Low Frequency ◽  
Neuronal Population ◽  
Complexity Measures ◽  
Low Frequencies ◽  
New Approach ◽  
Frequency Bands ◽  
Cortical Oscillations ◽  
Brain Signals ◽  
Low Frequency Oscillations

Recently, the sleep-wake states have been analysed using novel complexity measures, complementing the classical analysis of EEGs by frequency bands. This new approach consistently shows a decrease in EEG's complexity during slow-wave sleep, yet it is unclear how cortical oscillations shape these complexity variations. In this work, we analyse how the frequency content of brain signals affects the complexity estimates in freely moving rats. We find that the low-frequency spectrum - including the Delta, Theta, and Sigma frequency bands - drives the complexity changes during the sleep-wake states. This happens because low-frequency oscillations emerge from neuronal population patterns, as we show by recovering the complexity variations during the sleep-wake cycle from micro, meso, and macroscopic recordings. Moreover, we find that the lower frequencies reveal synchronisation patterns across the neocortex, such as a sensory-motor decoupling that happens during REM sleep. Overall, our works shows that EEG's low frequencies are critical in shaping the sleep-wake states' complexity across cortical scales.

Mind–body interactive qigong improves physical and mental aspects of quality of life in inpatients with stroke: A randomized control study

2019 ◽  
Vol 18 (8) ◽  
pp. 658-666 ◽  
Author(s):  
Ching-Hsiang Chen ◽  
Kuo-Sheng Hung ◽  
Yu-Chu Chung ◽  
Mei-Ling Yeh
Keyword(s):  
Quality Of Life ◽  
Heart Rate ◽  
Heart Rate Variability ◽  
High Frequency ◽  
Standard Care ◽  
Low Frequency ◽  
Control Group ◽  
Subacute Stroke ◽  
Interactive Exercise

Background: Stroke, a medical condition that causes physical disability and mental health problems, impacts negatively on quality of life. Post-stroke rehabilitation is critical to restoring quality of life in these patients. Objectives: This study was designed to evaluate the effect of a mind–body interactive qigong intervention on the physical and mental aspects of quality of life, considering bio-physiological and mental covariates in subacute stroke inpatients. Methods: A randomized controlled trial with repeated measures design was used. A total of 68 participants were recruited from the medical and rehabilitation wards at a teaching hospital in northern Taiwan and then randomly assigned either to the Chan-Chuang qigong group, which received standard care plus a 10-day mind–body interactive exercise program, or to the control group, which received standard care only. Data were collected using the National Institutes of Health Stroke Scale, Hospital Anxiety and Depression Scale, Short Form-12, stroke-related neurologic deficit, muscular strength, heart rate variability and fatigue at three time points: pre-intervention, halfway through the intervention (day 5) and on the final day of the intervention (day 10). Results: The results of the mixed-effect model analysis showed that the qigong group had a significantly higher quality of life score at day 10 ( p<0.05) than the control group. Among the covariates, neurologic deficit ( p=0.04), muscle strength ( p=0.04), low frequency to high frequency ratio ( p=0.02) and anxiety ( p=0.04) were significantly associated with changes in quality of life. Conversely, heart rate, heart rate variability (standard deviation of normal-to-normal intervals, low frequency and high frequency), fatigue and depression were not significantly associated with change in quality of life ( p >0.05). Conclusions: This study supports the potential benefits of a 10-day mind–body interactive exercise (Chan-Chuang qigong) program for subacute stroke inpatients and provides information that may be useful in planning adjunctive rehabilitative care for stroke inpatients.

Is there a relationship between premature hair greying and hearing impairment?

2015 ◽  
Vol 129 (11) ◽  
pp. 1097-1100 ◽  
Author(s):  
I Ozbay ◽  
C Kahraman ◽  
C Kucur ◽  
N D Namdar ◽  
F Oghan
Keyword(s):  
Bone Mineral Density ◽  
Hearing Loss ◽  
Hearing Impairment ◽  
Bone Mineral ◽  
High Frequency ◽  
Low Frequency ◽  
Control Group ◽  
Mineral Density ◽  
Low Bone Mineral Density ◽  
High Frequency Audiometry

AbstractObjective:There is evidence for a strong correlation between low bone mineral density and hearing loss. Furthermore, premature hair greying has been associated with low bone mineral density. Hence, this study aimed to investigate, for the first time, the relationship between premature hair greying and hearing impairment.Methods:Fifty patients with premature hair greying (20 women and 30 men), aged under 40 years (mean, 30.1 ± 4.9 years), who had onset of hair greying in their twenties, were recruited, along with 45 age- and sex-matched healthy control subjects (17 women and 28 men; mean age, 28.7 ± 5.1 years). Each participant was tested with low frequency audiometry at 0.125 to 2 kHz, high frequency audiometry at 4 to 8 kHz, and extended high frequency audiometry at 9 to 20 kHz.Results:Hearing thresholds were similar at all frequencies from 0.25 to 4 kHz (p > 0.05); however, significant hearing loss was observed at all frequencies from 8 to 20 kHz in the premature hair greying group compared with the control group (p < 0.05).Conclusion:Patients with premature hair greying had hearing impairment at extended high frequencies. Premature hair greying may be an important risk factor for hearing loss.

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