scholarly journals Variations in Electrocortical Activity due to Surgical Incision in Anaesthetized Cardiac Patients: Electroencephalogram-Based Quantitative Analysis

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Manpreet Kaur ◽  
Neelam Rup Prakash ◽  
Parveen Kalra ◽  
Goverdhan Dutt Puri ◽  
Tanvir Samra ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Frequency Standard ◽  
Wavelet Domain ◽  
Surgical Incision ◽  
Mean Frequency ◽  
Electrocortical Activity ◽  
Time Frequency ◽  
Band Power ◽  
Delta Band ◽  
Approximation Coefficients

This study examines the alterations in scalp recorded cortical activity due to surgical incision in anaesthetized cardiac patients using electroencephalogram (EEG) patterns. The primary aim was to compare the changes in electrocortical activity after surgical incision. The secondary aim was to compare the changes in time, frequency, and wavelet domain parameters after loss of consciousness (LoC) and after intubation. Real-time EEG data were recorded from 19 patients undergoing cardiac surgery and signals were quantified with time, frequency, and wavelet domain parameters. An increase in hjorth activity, hjorth complexity, rms value, total band power, relative delta band power, standard deviation and maxima of approximation coefficients (a5), minima of detail coefficients (d5, d4, and d3) and decrease in hjorth mobility; approximate entropy; relative theta, alpha, and beta band power; specentropy; median, spectral edge, and mean frequency; mean of detail coefficients (d4); standard deviation of detail coefficients (d5, d4, and d3); maxima of detail coefficients (d5); and minima of approximation coefficients (a5) were observed during LoC. Decrease in hjorth activity; hjorth mobility; rms value; total band power; relative theta band power; median frequency; standard deviation of coefficients (a5, d5, d4, and d3); and maxima of coefficients (a5, d5, d4, and d3) and increase in hjorth complexity; mean of detail coefficients (d5); and minima of coefficients (a5, d5, d4, and d3) were observed after intubation. Significant decrease in hjorth activity; hjorth mobility; total band power; relative alpha band power; specentropy; median and mean frequency; standard deviation and maxima of detail coefficients (d5, d4, and d3) and increase in rms value; relative delta band power; mean of coefficients (a5 and d5); and minima of coefficients (d5, d4, and d3) were observed due to surgical incision. It can be concluded that different spectral and temporal parameters of EEG signals are highly sensitive to induction, intubation, and surgical incision which are potentially informative for measuring the depth of anaesthesia or efficacy of anaesthetic agents.

scholarly journals Sensor-Level Wavelet Analysis Reveals EEG Biomarkers of Perceptual Decision-Making

Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2461
Author(s):  
Alexander Kuc ◽  
Vadim V. Grubov ◽  
Vladimir A. Maksimenko ◽  
Natalia Shusharina ◽  
Alexander N. Pisarchik ◽  
...  
Keyword(s):  
Decision Making ◽  
Sensory Information ◽  
Stimulus Onset ◽  
Perceptual Process ◽  
Perceptual Decision Making ◽  
Beta Band ◽  
Perceptual Decision ◽  
Time Frequency ◽  
Band Power ◽  
Sensory Features

Perceptual decision-making requires transforming sensory information into decisions. An ambiguity of sensory input affects perceptual decisions inducing specific time-frequency patterns on EEG (electroencephalogram) signals. This paper uses a wavelet-based method to analyze how ambiguity affects EEG features during a perceptual decision-making task. We observe that parietal and temporal beta-band wavelet power monotonically increases throughout the perceptual process. Ambiguity induces high frontal beta-band power at 0.3–0.6 s post-stimulus onset. It may reflect the increasing reliance on the top-down mechanisms to facilitate accumulating decision-relevant sensory features. Finally, this study analyzes the perceptual process using mixed within-trial and within-subject design. First, we found significant percept-related changes in each subject and then test their significance at the group level. Thus, observed beta-band biomarkers are pronounced in single EEG trials and may serve as control commands for brain-computer interface (BCI).

scholarly journals ‘Awake delta’ and theta-rhythmic hippocampal network modes during intermittent locomotor behaviors in the rat

2019 ◽  
Author(s):  
Nathan W. Schultheiss ◽  
Maximillian Schlecht ◽  
Maanasa Jayachandran ◽  
Deborah R. Brooks ◽  
Jennifer L. McGlothan ◽  
...  
Keyword(s):  
Clustering Algorithms ◽  
Field Potential ◽  
Small Sample ◽  
Network Activity ◽  
Time Frequency ◽  
Theta Power ◽  
Frequency Decomposition ◽  
Speed Modulation ◽  
Delta Band ◽  
Locomotor Behaviors

AbstractDelta-frequency network activity is commonly associated with sleep or behavioral disengagement accompanied by a dearth of cortical spiking, but delta in awake behaving animals is not well understood. We show that hippocampal (HC) synchronization in the delta frequency band (1-4 Hz) is related to animals’ locomotor behavior using a detailed analysis of simultaneous head- and body-tracking data. In contrast to running-speed modulation of the theta rhythm (6-10 Hz, a critical mechanism in navigation models), we observed that strong delta synchronization occurred when animals were stationary or moving slowly and while theta and fast gamma (55-120 Hz) were weak. We next combined time-frequency decomposition of the local field potential with hierarchical clustering algorithms to categorize momentary estimations of the power spectral density (PSD) into putative modes of HC activity. Delta and theta power measures from these modes were notably orthogonal, and theta and delta coherences between HC recording sites were monotonically related to theta-delta ratios across modes. Next, we focused on bouts of precisely-defined running and stationary behavior. Extraction of delta and theta power density estimates for each instance of these bout types confirmed the orthogonality between frequency bands seen across modes. We found that delta-band and theta-band coherence within HC, and in a small sample, between HC and medial prefrontal cortex (mPFC), mirrored delta and theta components of the PSD. Delta-band synchronization often developed rapidly when animals paused briefly between runs, as well as appearing throughout longer stationary bouts. Taken together, our findings suggest that delta-dominated network modes (and corresponding mPFC-HC couplings) represent functionally-distinct circuit dynamics that are temporally and behaviorally interspersed amongst theta-dominated modes during navigation. As such these modes of mPFC-HC circuit dynamics could play a fundamental role in coordinating encoding and retrieval mechanisms or decision-making processes at a timescale that segments event sequences within behavioral episodes.

scholarly journals Rhetorical Discourse Analysis of State of the Nation Address of Select Philippine Presidents

2016 ◽  
Vol 25 (1) ◽  
Author(s):  
Lilibeth A. Calonge ◽  
Ismael N. Talili
Keyword(s):  
Discourse Analysis ◽  
Standard Deviation ◽  
Public Discourse ◽  
Public Speaking ◽  
Frequency Standard ◽  
The Philippines ◽  
Weighted Mean ◽  
Rhetorical Device ◽  
Rhetorical Devices ◽  
Rhetorical Discourse

The art of public speaking has been one of the commonly feared tasks for some people because they are not prepared and equipped with knowledge in rhetoric. The study was conducted to analyze the State of the Nation Address (SONA) delivered by the three presidents of the Philippines. Speech videos and speech manuscripts were analyzed using validated rubrics. A survey was also conducted to gather information on students’ perception on the study of rhetoric. Frequency, standard deviation, and weighted mean were used to analyze the rhetorical devices and canons of rhetoric employed in the speeches. It was found out that metaphor is a common rhetorical device used by the Presidents. The results show that the canons of rhetoric: invention, arrangement, style, memory and delivery were utilized in the speeches. Majority of the students of Rhetoric and Public Discourse, self-reported (or agreed) that the rhetorical discourse analysis of the SONA is beneficial to them as Rhetoric and Public Discourse students. The study concludes that the Presidents used the rhetorical elements and techniques to convince and influence the audience. It is recommended that the presidents (or their speech writers) should consider optimum use of the rhetorical elements and techniques to evoke the desired response from the audience.

scholarly journals Low-Frequency Oscillations Are a Biomarker of Injury and Recovery After Stroke

Stroke ◽  
2020 ◽  
Vol 51 (5) ◽  
pp. 1442-1450 ◽  
Author(s):  
Jessica M. Cassidy ◽  
Anirudh Wodeyar ◽  
Jennifer Wu ◽  
Kiranjot Kaur ◽  
Ashley K. Masuda ◽  
...  
Keyword(s):  
Primary Motor Cortex ◽  
Low Frequency ◽  
Inpatient Rehabilitation ◽  
Motor Recovery ◽  
Rehabilitation Facility ◽  
Low Frequency Oscillations ◽  
Band Power ◽  
Interhemispheric Coherence ◽  
Delta Band ◽  
Inpatient Rehabilitation Facility

Background and Purpose— Low-frequency oscillations reflect brain injury but also contribute to normal behaviors. We examined hypotheses relating electroencephalography measures, including low-frequency oscillations, to injury and motor recovery poststroke. Methods— Patients with stroke completed structural neuroimaging, a resting-state electroencephalography recording and clinical testing. A subset admitted to an inpatient rehabilitation facility also underwent serial electroencephalography recordings. The relationship that electroencephalography measures (power and coherence with leads overlying ipsilesional primary motor cortex [iM1]) had with injury and motor status was assessed, focusing on delta (1–3 Hz) and high-beta (20–30 Hz) bands. Results— Across all patients (n=62), larger infarct volume was related to higher delta band power in bilateral hemispheres and to higher delta band coherence between iM1 and bilateral regions. In chronic stroke, higher delta power bilaterally correlated with better motor status. In subacute stroke, higher delta coherence between iM1 and bilateral areas correlated with poorer motor status. These coherence findings were confirmed in serial recordings from 18 patients in an inpatient rehabilitation facility. Here, interhemispheric coherence between leads overlying iM1 and contralesional M1 was elevated at inpatient rehabilitation facility admission compared with healthy controls (n=22), declining to control levels over time. Decreases in interhemispheric coherence between iM1 and contralesional M1 correlated with better motor recovery. Conclusions— Delta band coherence with iM1 related to greater injury and poorer motor status subacutely, while delta band power related to greater injury and better motor status chronically. Low-frequency oscillations reflect both injury and recovery after stroke and may be useful biomarkers in stroke recovery and rehabilitation.

Study on Aerospace Layering Time Synchronization Architecture and Time Synchronization Algorithm

2012 ◽  
Vol 546-547 ◽  
pp. 1614-1619
Author(s):  
Fei Jiang Huang ◽  
Xiao Chun Lu ◽  
Jun Yang ◽  
Qing Xiao Shan ◽  
Yong Bin Zhou
Keyword(s):  
Time Synchronization ◽  
Rapid Development ◽  
Frequency Standard ◽  
High Accuracy ◽  
Time Frequency ◽  
Aerospace Application ◽  
Visual Model ◽  
Application Systems ◽  
Synchronization Algorithm ◽  
Time And Frequency Standard

The rapid development of various kinds of aerospace application systems requires the appropriate high-accuracy time and frequency standard. This problem can be effectively solved by establishing suitable time and frequency standard in aerospace. Based on the establishment of aerospace satellite visual model, the simulation of satellite visual time on 3-layer constellation structure, including GEO satellite, IGSO satellites and MEO satellites, has been conducted. The visual features of this constellation have been gained. Combining with the major influencing factors of satellite clock correction error, aerospace time synchronization architecture on the basis of layering has been proposed. The time synchronization algorithm in line with this architecture has been researched. The results show that aerospace time frequency standard established based on this layering time synchronization architecture can meet the demand on high-accuracy time frequency of future aerospace application systems.

GLONASS on-board time/frequency standard-architecture and operation

2002 ◽  
Author(s):  
P.P. Bogdanov ◽  
Y.G. Gouzhva ◽  
A.G. Gevorkyan ◽  
A.B. Bassevich ◽  
A.E. Tyulyakov
Keyword(s):  
Frequency Standard ◽  
Time Frequency

Alternation of EEG Characteristics During Transcutaneous Acupoint Electrical Stimulation–Induced Sedation

2020 ◽  
pp. 155005942097630
Author(s):  
Fei Yan ◽  
Dawei Song ◽  
Zhen Dong ◽  
Yun Zhang ◽  
Haidong Wang ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Sedative Effect ◽  
Permutation Entropy ◽  
Functional Connections ◽  
Band Power ◽  
Delta Band ◽  
Significant Difference ◽  
Sedative Effects ◽  
The Difference ◽  
Global Strength

Recent studies have shown that applying acupuncture during general anesthesia can reduce the dosage of anesthetics. Hence, it is speculated that acupuncture may have a sedative effect. However, existing studies employed acupuncture in combination with anesthetics, which makes determine acupuncture’s role in producing sedation difficult. In this work, we investigated the sedative effect of acupuncture by using transcutaneous acupoint electrical stimulation (TAES) at bilateral Zusanli (ST36), Shenmen (HT7) and Sanyinjiao (SP6). Using a cross-over design, 2 separate sessions, that are, the resting and TAES sessions, were conducted for each subject. The sedative effect was quantified by using the bispectral index (BIS). The difference in brain activities between resting and TAES sessions was investigated by analyzing the simultaneously recorded EEG signals. Our results showed that a statistically significant difference in BIS values existed between resting and TAES sessions, which suggested that TAES alone was capable of inducing observable sedation. Using power spectrum analysis, we showed that TAES-induced sedation was accompanied by a reduction in alpha band power and an increment in delta band power. Permutation entropy was lower during the TAES session, which suggested that TAES reduced the complexity of the EEG signal. Moreover, a significant reduction in the global strength of brain functional connections was observed during TAES. These findings suggest that TAES alone can induce observable sedative effects, and this sedation effect is accompanied by changes in brain activities that have shown to be correlated with consciousness.

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