scholarly journals Cortical and STN spectral changes during limb movements in PD patients with and without dystonia

2022 ◽  
Author(s):  
Arie Nakhmani ◽  
Joseph Olson ◽  
Zachary Irwin ◽  
Lloyd Edwards ◽  
Christopher Gonzalez ◽  
...  
Keyword(s):  
Wavelet Transforms ◽  
Spectral Power ◽  
Low Frequency ◽  
Alpha Power ◽  
Limb Movements ◽  
Contralateral Limb ◽  
Spectral Content ◽  
Contralateral Hand ◽  
Cardinal Symptoms ◽  
Cortical Field

Background: Dystonia is a prevalent yet under-studied motor feature of Parkinson disease (PD). Although considerable efforts have focused on brain oscillations related to the cardinal symptoms of PD, whether dystonia is associated with specific electrophysiological features is unclear. Objectives: To investigate subcortical and cortical field potentials at rest and during contralateral hand and foot movements in PD patients with versus without dystonia. Methods: We examined the prevalence and somatotopy of dystonia in PD patients undergoing deep brain stimulation (DBS) surgery. We recorded intracranial electrophysiology from sensorimotor cortex and directional DBS electrodes in subthalamic nucleus (STN), during both rest and voluntary contralateral limb movements. We used wavelet transforms and linear mixed models to characterize spectral content in patients with and without dystonia (n=25). Results: Dystonia was highly prevalent at enrollment (61%) and most common in the foot (78%). PD patients with dystonia display greater subthalamic theta and alpha power during movement (p < 0.05) but not at rest. Regardless of dystonia status, cortical recordings display prominent beta desynchronization (13-30 Hz) during movement, whereas STN signals show increases in spectral power at lower frequencies (4-20 Hz), with peaks at 6.0 +/- 3.3 and 4.2 +/- 2.9 Hz during hand and foot movements, respectively (p < 0.03). Conclusions: Whereas cortex was characterized by beta desynchronization during hand and foot movements similarly, STN showed limb-specific low frequency activity which was increased in PD patients with dystonia. These findings may help elucidate why PD-related dystonia is most common in the foot and help guide future closed-loop DBS devices.

scholarly journals In search of Universal Cortical Power Changes Linked to NMDA-Antagonist based Anesthetic Induced Reductions in Consciousness

2019 ◽  
Author(s):  
Andria Pelentritou ◽  
Levin Kuhlmann ◽  
John Cormack ◽  
Steven Mcguigan ◽  
Will Woods ◽  
...  
Keyword(s):  
Spectral Power ◽  
Low Frequency ◽  
Nmda Antagonist ◽  
Alpha Power ◽  
Source Imaging ◽  
Source Power ◽  
Gamma Range ◽  
Anesthetic Agents ◽  
Low Frequency Power ◽  
Frequency Power

B. AbstractBackground.Despite their intriguing nature, investigations of the neurophysiology of N-methyl-D-aspartate (NMDA)-antagonists Xenon (Xe) and nitrous oxide (N2O) are limited and have revealed inconsistent frequency-dependent alterations, in spectral power and functional connectivity. Discrepancies are likely due to using low resolution electroencephalography restricted to sensor level changes, concomitant anesthetic agent administration and dosage. Our intention was to describe the effects of equivalent stepwise levels of Xe and N2O administration on oscillatory source power using a crossover design, to explore universal mechanisms of NMDA-based anesthesia.Methods.22 healthy males participated in a study of simultaneous magnetoencephalography and electroencephalography recordings. In separate sessions, equivalent subanesthetic doses of gaseous anesthetic agents N2O and Xe (0.25, 0.50, 0.75 equi MAC-awake) and 1.30 MAC-awake Xe (for Loss of Responsiveness) were administered. Source power in various frequency bands was computed and statistically assessed relative to a conscious baseline.Results.Delta (l-4Hz) and theta (4-8Hz) band power was significantly increased at the highest Xe concentration (42%, 1.30 MAC-awake) relative to baseline for both magnetoencephalography and electroencephalography source power (p<0.005). A reduction in frontal alpha (8-13 Hz) power was observed upon N2O administration, and shown to be stronger than equivalent Xe dosage reductions (p=0.005). Higher frequency activity increases were observed in magnetoencephalographic but not encephalographic signals for N2O alone with occipital low gamma (30-49Hz) and widespread high gamma (51-99Hz) rise in source power.Conclusions.Magnetoencephalography source imaging revealed unequivocal and widespread power changes in dissociative anesthesia, which were divergent to source electroencephalography. Loss of Responsiveness anesthesia at 42% Xe (1.30 MAC-awake) demonstrated, similar to inductive agents, low frequency power increases in frontal delta and global theta. N2O sedation yielded a rise in high frequency power in the gamma range which was primarily occipital for lower gamma bandwidth (3049 Hz) and substantially decreased alpha power, particularly in frontal regions.Clinical trial number and Registry URLNot applicable.Prior PresentationsPelentritou Andria, Kuhlmann Levin; Lee Heonsoo; Cormack John; Mcguigan Steven; Woods Will; Sleigh Jamie; Lee UnCheol; Muthukumaraswamy Suresh; Liley David. Searching For Universal Cortical Power Changes Linked To Anesthetic Induced Reductions In Consciousness. The Science of Consciousness April 4th2018. Tucson, Arizona, USA.Summary StatementNot applicable.

FLUCTUATIONS AND INTERACTIONS BETWEEN BRAIN WAVES DURING DEEP AND SHALLOW ANESTHESIA

2012 ◽  
Vol 11 (01) ◽  
pp. 1240018 ◽  
Author(s):  
B. MUSIZZA ◽  
F. F. BAJROVIĆ ◽  
J. PETROVČIČ ◽  
A. STEFANOVSKA ◽  
S. RIBARIČ
Keyword(s):  
Slow Wave ◽  
Wavelet Transforms ◽  
Spectral Power ◽  
Low Frequency ◽  
Autism Spectrum ◽  
Brain Dynamics ◽  
Brain Waves ◽  
Coupling Strengths ◽  
Left And Right ◽  
Insight Into

Using gold plated electrodes, inserted into the rat's head above the dura of the left and right parietal cortex, we recorded EEG during deep and shallow anesthesia with either pentobarbital (PB) or ketamine-xylazine (KX). The fluctuations in time series were then analyzed using wavelet transforms and the spectral power was determined within 7 frequency intervals (slow wave 2, S2, 0.0067–0.0167 Hz; slow wave 1, S1, 0.02–0.19 Hz; δ, 0.2–3.9 Hz; θ, 4–7.9 Hz; α, 8–12.9 Hz; β, 13–24.9 Hz and γ, 25–34.9 Hz). In addition, the coupling strengths between individual oscillatory components during deep and shallow anesthesia were evaluated for both anesthetics. We show specific changes for both anesthetics indicating that during deep anesthesia PB reduces high and low frequency activity (0.2–35 Hz) and enhances coupling especially between δ, θ and α waves, while KX reduces low frequency activity (0.005 to 0.2 Hz) and enhances coupling between frequency waves α, β and γ. Our results, using two anesthetics known to block different ion channels, provide an insight into brain dynamics and could have wide implications in creating biomarkers for detecting various neurophysiological modifications, such as in Alzheimer and Parkinson's disease or Autism spectrum disorder, as well as in providing more realistic models of brain dynamics.

Abnormalities of Alpha Activity in Frontocentral Region of the Brain as a Biomarker to Diagnose Adolescents With Bipolar Disorder

2019 ◽  
Vol 50 (5) ◽  
pp. 311-318 ◽  
Author(s):  
Ali Khaleghi ◽  
Mohammad Reza Mohammadi ◽  
Mahdi Moeini ◽  
Hadi Zarafshan ◽  
Mahbod Fadaei Fooladi
Keyword(s):  
Bipolar Disorder ◽  
Depressive Episode ◽  
Spectral Power ◽  
Low Frequency ◽  
Alpha Power ◽  
K Nearest Neighbors ◽  
Frequency Bands ◽  
Gamma Frequency ◽  
Alpha Oscillation ◽  
Depressive Episodes

Objectives. To investigate brain abnormalities in adolescents with new-onset bipolar disorder (BD) during acute hypomanic and depressive episodes using electroencephalogram (EEG) analysis and to derive a computer-based method for diagnosis of the disorder. Methods. EEG spectral power and entropy of 21 adolescents with BD (included 11 patients in the hypomanic episode and 10 patients in the depressive episode) and 18 healthy adolescents were compared. Moreover, using significant differences and K-nearest-neighbors (KNN) classifier, it was attempted to distinguish the BD adolescents from normal ones. Results. The BD adolescents had higher values of spectral power in all frequency bands, particularly in the frontocentral, mid-temporal, and right parietal regions. Also, spectral entropy had significantly increased in delta, alpha, and gamma frequency bands for BD. A high accuracy of 95.8% was achieved by all significant differences in the alpha band in discriminating adolescents with BD. The depressive state showed higher values of spectral power and entropy in low-frequency bands (delta and theta) compared to the hypomanic state. Conclusion. Based on BD symptoms, especially inattention, increased alpha power is a rational finding which is associated with thalamus dysfunction. Thus, it seems that EEG alpha oscillation is the main source of abnormality in BD. Furthermore, EEG slowing in the depressive episode is related to inhibition of electrical activity and reduced cognitive functions.

scholarly journals Low-Frequency Content of THz Emission from Two-Color Femtosecond Filament

Photonics ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 17
Author(s):  
Daniil E. Shipilo ◽  
Nikolay A. Panov ◽  
Irina A. Nikolaeva ◽  
Alexander A. Ushakov ◽  
Pavel A. Chizhov ◽  
...  
Keyword(s):  
Spectral Power ◽  
Low Frequency ◽  
Local Maximum ◽  
Spot Size ◽  
Quantitative Agreement ◽  
Angular Distributions ◽  
Spectral Content ◽  
Znte Crystal ◽  
Golay Cell ◽  
The One

We experimentally investigate the low-frequency (below 1 THz) spectral content of broadband terahertz (THz) emission from two-color femtosecond filament formed by the 2.7-mJ, 40-fs, 800+400-nm pulse focused into air. For incoherent detection, we screened the Golay cell by the bandpass filters and measured the THz angular distributions at the selected frequencies ν=0.5, 1, 2 and 3 THz. The measured distributions of THz fluence were integrated over the forward hemisphere taking into account the transmittance of the filters, thus providing the estimation of spectral power at the frequencies studied. The spectral power decreases monotonically with the frequency increasing from 0.5 to 3 THz, thus showing that the maximum of THz spectrum is attained at ν≤0.5 THz. The THz waveform measured by electro-optical sampling (EOS) based on ZnTe crystal and transformed into the spectral domain shows that there exists the local maximum of the THz spectral power at ν≈1 THz. This disagrees with monotonic decrease of THz spectral power obtained from the filter-based measurements. We have introduced the correction to the spectral power reconstructed from EOS measurements. This correction takes into account different focal spot size for different THz frequencies contained in the broadband electromagnetic pulse. The corrected EOS spectral power is in semi-quantitative agreement with the one measured by a set of filters.

scholarly journals EEG Measures of Value-Directed Strategic Processing in Older Adults With and Without Mild Cognitive Impairment

2020 ◽  
Vol 4 (Supplement_1) ◽  
pp. 292-293
Author(s):  
Lydia Nguyen ◽  
Shraddha Shende ◽  
Daniel Llano ◽  
Raksha Mudar
Keyword(s):  
Older Adults ◽  
Cognitive Impairment ◽  
Mild Cognitive Impairment ◽  
Cognitive Aging ◽  
Spectral Power ◽  
Group Differences ◽  
Cognitive Resources ◽  
Alpha Power ◽  
Strategic Processing ◽  
Unique Word

Abstract Value-directed strategic processing is important for daily functioning. It allows selective processing of important information and inhibition of irrelevant information. This ability is relatively preserved in normal cognitive aging, but it is unclear if mild cognitive impairment (MCI) affects strategic processing and its underlying neurophysiological mechanisms. The current study examined behavioral and EEG spectral power differences between 16 cognitively normal older adults (CNOA; mean age: 74.5 ± 4.0 years) and 16 individuals with MCI (mean age: 77.1 ± 4.3 years) linked to a value-directed strategic processing task. The task used five unique word lists where words were assigned high- or low-value based on letter case and were presented sequentially while EEG was recorded. Participants were instructed to recall as many words as possible after each list to maximize their score. Results revealed no group differences in recall of low-value words, but individuals with MCI recalled significantly fewer high-value words and total number of words relative to CNOA. Group differences were observed in theta and alpha bands for low-value words, with greater synchronized theta power for CNOA than MCI and greater desynchronized alpha power for MCI than CNOA. Collectively, these findings demonstrate that more effortful neural processing of low-value words in the MCI group, relative to the CNOA group, allowed them to match their behavioral performance to the CNOA group. Individuals with MCI appear to utilize more cognitive resources to inhibit low-value information and might show memory-related benefits if taught strategies to focus on high-value information processing.

scholarly journals Comparing different wavelet transforms on removing electrocardiogram baseline wanders and special trends

2020 ◽  
Vol 20 (S11) ◽  
Author(s):  
Chao-Chen Chen ◽  
Fuchiang Rich Tsui
Keyword(s):  
Wavelet Transforms ◽  
Low Frequency ◽  
Clinical Decision Support Systems ◽  
Clinical Decision ◽  
Temporal Position ◽  
Important Indicator ◽  
Real Time Processing ◽  
Step Functions ◽  
Baseline Wander ◽  
Ecg Data

Abstract Background Electrocardiogram (ECG) signal, an important indicator for heart problems, is commonly corrupted by a low-frequency baseline wander (BW) artifact, which may cause interpretation difficulty or inaccurate analysis. Unlike current state-of-the-art approach using band-pass filters, wavelet transforms can accurately capture both time and frequency information of a signal. However, extant literature is limited in applying wavelet transforms (WTs) for baseline wander removal. In this study, we aimed to evaluate 5 wavelet families with a total of 14 wavelets for removing ECG baseline wanders from a semi-synthetic dataset. Methods We created a semi-synthetic ECG dataset based on a public QT Database on Physionet repository with ECG data from 105 patients. The semi-synthetic ECG dataset comprised ECG excerpts from the QT database superimposed with artificial baseline wanders. We extracted one ECG excerpt from each of 105 patients, and the ECG excerpt comprised 14 s of randomly selected ECG data. Twelve baseline wanders were manually generated, including sinusoidal waves, spikes and step functions. We implemented and evaluated 14 commonly used wavelets up to 12 WT levels. The evaluation metric was mean-square-error (MSE) between the original ECG excerpt and the processed signal with artificial BW removed. Results Among the 14 wavelets, Daubechies-3 wavelet and Symlets-3 wavelet with 7 levels of WT had best performance, MSE = 0.0044. The average MSEs for sinusoidal waves, step, and spike functions were 0.0271, 0.0304, 0.0199 respectively. For artificial baseline wanders with spikes or step functions, wavelet transforms in general had lower performance in removing the BW; however, WTs accurately located the temporal position of an impulse edge. Conclusions We found wavelet transforms in general accurately removed various baseline wanders. Daubechies-3 and Symlets-3 wavelets performed best. The study could facilitate future real-time processing of streaming ECG signals for clinical decision support systems.

Characteristics of heart rate variability in patients with acute coronary syndrome without ST segment elevation in comparison with clinical and biochemical parameters

2021 ◽  
Vol 29 (3) ◽  
pp. 369-378
Author(s):  
Aleksej A. Nizov ◽  
Aleksej I. Girivenko ◽  
Mihail M. Lapkin ◽  
Aleksej V. Borozdin ◽  
Yana A. Belenikina ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Acute Coronary Syndrome ◽  
Creatine Phosphokinase ◽  
Spectral Power ◽  
Low Frequency ◽  
Heart Rhythm ◽  
St Segment Elevation ◽  
Coronary Syndrome ◽  
St Segment

BACKGROUND: The search for rational methods of primary, secondary, and tertiary prevention of coronary heart disease. To date, there are several publications on heart rate variability in ischemic heart disease. AIM: To study the state of the regulatory systems in the organism of patients with acute coronary syndrome without ST segment elevation based on the heart rhythm, and their relationship with the clinical, biochemical and instrumental parameters of the disease. MATERIALS AND METHODS: The open comparative study included 76 patients (62 men, 14 women) of mean age, 61.0 0.9 years, who were admitted to the Emergency Cardiology Department diagnosed of acute coronary syndrome without ST segment elevation. On admission, cardiointervalometry was performed using Varicard 2.51 apparatus, and a number of clinical and biochemical parameters were evaluated RESULTS: Multiple correlations of parameters of heart rate variability and clinical, biochemical and instrumental parameters were observed. From this, a cluster analysis of cardiointervalometry was performed, thereby stratifying patients into five clusters. Two extreme variants of dysregulation of the heart rhythm correlated with instrumental and laboratory parameters. A marked increase in the activity of the subcortical nerve centers (maximal increase of the spectral power in the very low frequency range with the underlying reduction of SDNN) in cluster 1 was associated with reduction of the left ventricular ejection fraction: cluster 147.0 [40.0; 49.0], cluster 260.0 [58.0; 64.0], cluster 360.0 [52.5; 64.5] % (the data are presented in the form of median and interquartile range; Me [Q25; Q75], p 0,05). Cluster 5 showed significant reduction in SDNN (monotonous rhythm), combined with increased level of creatine phosphokinase (CPC): cluster 5446,0 [186.0; 782.0], cluster 4141.0 [98.0; 204.0] IU/l; Me [Q25; Q75], p 0.05) and MВ-fraction of creatine phosphokinase; cluster 532.0 [15.0; 45.0], 4 cluster 412.0 [9.0; 18.0] IU/l; Me [Q25; Q75], p 0.05). CONCLUSIONS: In patients with acute coronary syndrome without ST segment elevation, cluster analysis of parameters of heart rate variability identified different peculiarities of regulation of the heart rhythm. Pronounced strain of the regulatory systems of the body was found to be associated with signs of severe pathology: the predominance of VLF (spectral power of the curve enveloping a dynamic range of cardiointervals in the very low frequency range) in spectral analysis with an underlying reduced SDNN is characteristic of patients with a reduced ejection fraction, and a monotonous rhythm is characteristic of patients with an increased level of creatine phosphokinase and MB-fraction of creatine phosphokinase.

COMPARATIVE ANALYSIS OF SPECTRA OF THE 2000-YEAR NORTHERN HEMISPHERE AVERAGE SURFACE AIR TEMPERATURE RECONSTRUCTIONS

2021 ◽  
pp. 5-13
Author(s):  
N. M. DATSENKO ◽  
◽  
D. M. SONECHKIN ◽  
B. YANG ◽  
J.-J. LIU ◽  
...  
Keyword(s):  
High Resolution ◽  
Northern Hemisphere ◽  
Air Temperature ◽  
Wavelet Transforms ◽  
Spectral Composition ◽  
Low Frequency ◽  
Surface Air Temperature ◽  
Temporal Variations ◽  
Continuous Wavelet Transforms ◽  
Stable Estimation

The spectral composition of temporal variations in the Northern Hemisphere mean surface air temperature is estimated and compared in 2000-year paleoclimatic reconstructions. Continuous wavelet transforms of these reconstructions are used for the stable estimation of energy spectra. It is found that low-frequency parts of the spectra (the periods of temperature variations of more than 100 years) based on such high-resolution paleoclimatic indicators as tree rings, corals, etc., are similar to the spectrum of white noise, that is never observed in nature. This seems unrealistic. The famous reconstruction called “Hockey Stick” is among such unrealistic reconstructions. Reconstructions based not only on high-resolution but also on low-resolution indicators seem to be more realistic, since the low-frequency parts of their spectra have the pattern of red noise. They include the “Boomerang” reconstruction showing that some warm periods close to the present-day one were observed in the past.

Inspiratory resistance delays the reporting of symptoms with central hypovolemia: association with cerebral blood flow

2007 ◽  
Vol 293 (1) ◽  
pp. R243-R250 ◽  
Author(s):  
Caroline A. Rickards ◽  
Kathy L. Ryan ◽  
William H. Cooke ◽  
Keith G. Lurie ◽  
Victor A. Convertino
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Cerebral Blood Flow Velocity ◽  
Lower Body Negative Pressure ◽  
Spectral Power ◽  
Human Subjects ◽  
Low Frequency ◽  
Cardiovascular Collapse ◽  
Absolute Level ◽  
Inspiratory Resistance

We tested the hypothesis that breathing through an inspiratory threshold device (ITD) during progressive central hypovolemia would protect cerebral perfusion and attenuate the reporting of presyncopal symptoms. Eight human subjects were exposed to lower-body negative pressure (LBNP) until the presence of symptoms while breathing through either an active ITD (−7 cmH2O impedance) or a sham ITD (0 cmH2O). Cerebral blood flow velocity (CBFV) was measured continuously via transcranial Doppler and analyzed in both time and frequency domains. Subjects were asked to report any subjective presyncopal symptoms (e.g., dizziness, nausea) at the conclusion of each LBNP exposure. Symptoms were coincident with physiological evidence of cardiovascular collapse (e.g., hypotension, bradycardia). Breathing on the active ITD increased LBNP tolerance time (mean ± SE) from 2,014 ± 106 s to 2,259 ± 138 s ( P = 0.006). We compared CBFV responses at the time of symptoms during the sham ITD trial with those at the same absolute time during the active ITD trial (when there were no symptoms). While there was no difference in mean CBFV at these time points (sham, 44 ± 4 cm/s vs. active, 47 ± 4; P = 0.587), total oscillations (sum of high- and low-frequency spectral power) of CBFV were higher ( P = 0.004) with the active ITD (45.6 ± 10.2 cm/s2) than the sham ITD (22.1 ± 5.4 cm/s2). We conclude that greater oscillations around the same absolute level of mean CBFV are induced by inspiratory resistance and may contribute to the delay in symptoms and cardiovascular collapse that accompany progressive central hypovolemia.

scholarly journals Natural variability and anthropogenic effects in a Central Mediterranean core

2012 ◽  
Vol 8 (2) ◽  
pp. 831-839 ◽  
Author(s):  
S. Alessio ◽  
G. Vivaldo ◽  
C. Taricco ◽  
M. Ghil
Keyword(s):  
Isotopic Ratio ◽  
Forecast Error ◽  
Singular Spectrum Analysis ◽  
Low Frequency ◽  
Natural Variability ◽  
Central Mediterranean ◽  
Spectral Content ◽  
Frequency Components ◽  
Oxygen Isotopic ◽  
Complete Series

Abstract. We evaluate the contribution of natural variability to the modern decrease in foraminiferal δ18O by relying on a 2200-yr-long, high-resolution record of oxygen isotopic ratio from a Central Mediterranean sediment core. Pre-industrial values are used to train and test two sets of algorithms that are able to forecast the natural variability in δ18O over the last 150 yr. These algorithms are based on autoregressive models and neural networks, respectively; they are applied separately to each of the δ18O series' significant variability components, rather than to the complete series. The separate components are extracted by singular-spectrum analysis and have narrow-band spectral content, which reduces the forecast error. By comparing the sum of the predicted low-frequency components to its actual values during the Industrial Era, we deduce that the natural contribution to these components of the modern δ18O variation decreased gradually, until it reached roughly 40%, as early as the end of the 1970s.

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