P1 and Traveling Alpha Waves: Evidence for Evoked Oscillations

2007 ◽  
Vol 97 (2) ◽  
pp. 1311-1318 ◽  
Author(s):  
Wolfgang Klimesch ◽  
Simon Hanslmayr ◽  
Paul Sauseng ◽  
Walter R. Gruber ◽  
Michael Doppelmayr
Keyword(s):  
Time Window ◽  
Event Related Potential ◽  
Frequency Range ◽  
Alpha Wave ◽  
Alpha Frequency ◽  
Absolute Phase ◽  
The Brain ◽  
Phase Relationships ◽  
Traveling Speed ◽  
Alpha Waves

The hypothesis is tested whether the P1 of the event-related potential (ERP) component behaves like an evoked, traveling alpha wave. This hypothesis is based on different kinds of evidence showing, e.g., that—after undergoing phase reorganization—frequencies in the broad alpha range become synchronized (aligned) in absolute phase and contribute significantly to the generation of the P1. We investigated data from a Stroop task in which subjects had to respond only to the color and ignore the meaning of the presented words. Analyzing topographical phase relationships expressed in terms of traveling speed (with respect to Pz as trailing site) revealed that a systematic posterior to anterior traveling pattern appeared only in the broad time window of the P1-N1 complex and in the extended alpha frequency range. The obtained findings are consistent with the oscillatory ERP model and suggest that the P1 component may be considered a manifestation of an evoked, traveling alpha wave. We assume that the P1 reflects a top-down process in a sense that traveling alpha waves control or “gate” the direction of information processing in the brain.

scholarly journals Perceptual inference employs intrinsic alpha frequency to resolve perceptual ambiguity

2018 ◽  
Author(s):  
Lu Shen ◽  
Biao Han ◽  
Lihan Chen ◽  
Qi Chen
Keyword(s):  
Time Window ◽  
Inference Process ◽  
Perceptual Inference ◽  
Band Frequency ◽  
Sensory Inputs ◽  
Alpha Frequency ◽  
Neural Representations ◽  
Intracranial Recordings ◽  
Time Information ◽  
The Brain

AbstractThe brain uses its intrinsic dynamics to actively predict observed sensory inputs, especially under perceptual ambiguity. However, it remains unclear how this inference process is neurally implemented in biasing perception of ambiguous inputs towards the predicted percepts. Using electroencephalography and intracranial recordings, we first show that the alpha-band frequency defines a unified time window for perceptual grouping across both space and time: information segments, either spatially or temporally segregated, will be integrated if they fall within the same alpha cycle. Moreover, predictions employ this prior knowledge on intrinsic alpha frequency to shift perceptual inference towards the most possibly observed percepts. Multivariate decoding analysis showed that perceptual inference, based on variance in prestimulus alpha frequency (PAF), biases post-stimulus neural representations by inducing preactivation of the predicted percepts. fMRI results additionally showed that prestimulus activity and intrinsic organization status in the frontoparietal attentional network predict perceptual outcomes, probably by modulating occipitoparietal PAFs.

Feel Thine Own Self – Mood Congruency Evaluation of Emotional State Adjectives

2020 ◽  
pp. 1-17
Author(s):  
Szczepan J. Grzybowski ◽  
Miroslaw Wyczesany ◽  
Jan Kaiser
Keyword(s):  
Mood Induction ◽  
Semantic Analysis ◽  
Emotional State ◽  
Time Window ◽  
Event Related Potential ◽  
Negativity Bias ◽  
Positive Potential ◽  
Semantic Access ◽  
Current Mood ◽  
Component Time

Abstract. The goal of the study was to explore event-related potential (ERP) differences during the processing of emotional adjectives that were evaluated as congruent or incongruent with the current mood. We hypothesized that the first effects of congruence evaluation would be evidenced during the earliest stages of semantic analysis. Sixty mood adjectives were presented separately for 1,000 ms each during two sessions of mood induction. After each presentation, participants evaluated to what extent the word described their mood. The results pointed to incongruence marking of adjective’s meaning with current mood during early attention orientation and semantic access stages (the P150 component time window). This was followed by enhanced processing of congruent words at later stages. As a secondary goal the study also explored word valence effects and their relation to congruence evaluation. In this regard, no significant effects were observed on the ERPs; however, a negativity bias (enhanced responses to negative adjectives) was noted on the behavioral data (RTs), which could correspond to the small differences traced on the late positive potential.

Effects of the SNAP25 on Integration Ability of Brain Functions in Children With ADHD

2020 ◽  
pp. 108705472096456
Author(s):  
Yue Yang ◽  
Gang Peng ◽  
Hongwu Zeng ◽  
Diangang Fang ◽  
Linlin Zhang ◽  
...  
Keyword(s):  
Time Window ◽  
Precentral Gyrus ◽  
Children With Adhd ◽  
Brain Functions ◽  
Lingual Gyrus ◽  
Window Method ◽  
Central Gyrus ◽  
The Right ◽  
The Brain ◽  
Insight Into

Objective: The present study aimed to examine the effects of SNAP25 on the integration ability of intrinsic brain functions in children with ADHD, and whether the integration ability was associated with working memory (WM). Methods: A sliding time window method was used to calculate the spatial and temporal concordance among five rs-fMRI regional indices in 55 children with ADHD and 20 healthy controls. Results: The SNAP25 exhibited significant interaction effects with ADHD diagnosis on the voxel-wise concordance in the right posterior central gyrus, fusiform gyrus and lingual gyrus. Specifically, for children with ADHD, G-carriers showed increased voxel-wise concordance in comparison to TT homozygotes in the right precentral gyrus, superior frontal gyrus, postcentral gyrus, and middle frontal gyrus. The voxel-wise concordance was also found to be related to WM. Conclusion: Our findings provided a new insight into the neural mechanisms of the brain function of ADHD children.

An Electrophysiological Measure of Temporal Resolution in Normal Subjects Using Frequency Modulated Signals

2002 ◽  
Vol 11 (1) ◽  
pp. 42-49
Author(s):  
Devin L. McCaslin ◽  
Lawrence L. Feth ◽  
Gary P. Jacobson ◽  
Pamela J. Mishler
Keyword(s):  
Temporal Resolution ◽  
Mismatch Negativity ◽  
Normal Subjects ◽  
Single Step ◽  
Event Related Potential ◽  
Frequency Range ◽  
Temporal Properties ◽  
Step Duration ◽  
The Mean ◽  
Modulated Signals

This investigation was conducted to determine whether an exogenous event-related potential called the mismatch negativity (MMN) would change systematically in response to frequency-modulated signals with varying temporal properties. Both N1 and P2 waveforms were recorded for 50-ms frequency-modulated signals from normal hearing listeners. The standard stimuli for this investigation were continuous sweep tones with center frequencies of 1000 Hz that traversed a frequency range of 200 Hz in a single step. The rare stimuli were signals that traversed the same frequency range in two, four, six, or eight discrete steps. Results suggest that for the 10 participants, 1) the mean MMN peak-to-peak amplitude and mean area decreased significantly with decreases in step duration, 2) MMN area amplitude was the best indicator of psychophysical performance for the two magnitude measures, and 3) MMN onsets and peak latencies did not show either a significant increase or decrease in latency as step duration decreased.

scholarly journals Analyzing EEG of Quasi-Brain-Death Based on Dynamic Sample Entropy Measures

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Li Ni ◽  
Jianting Cao ◽  
Rubin Wang
Keyword(s):  
Brain Death ◽  
Real Time ◽  
Time Window ◽  
Approximate Entropy ◽  
Sample Entropy ◽  
Well Performance ◽  
Entropy Measures ◽  
Brain Death Determination ◽  
Death Determination ◽  
The Brain

To give a more definite criterion using electroencephalograph (EEG) approach on brain death determination is vital for both reducing the risks and preventing medical misdiagnosis. This paper presents several novel adaptive computable entropy methods based on approximate entropy (ApEn) and sample entropy (SampEn) to monitor the varying symptoms of patients and to determine the brain death. The proposed method is a dynamic extension of the standard ApEn and SampEn by introducing a shifted time window. The main advantages of the developed dynamic approximate entropy (DApEn) and dynamic sample entropy (DSampEn) are for real-time computation and practical use. Results from the analysis of 35 patients (63 recordings) show that the proposed methods can illustrate effectiveness and well performance in evaluating the brain consciousness states.

Intrinsic and Scattering Attenuations in the Crust of the Racha Region, Georgia

2019 ◽  
Vol 14 (02) ◽  
pp. 2050006
Author(s):  
Ia Shengelia ◽  
Nato Jorjiashvili ◽  
Tea Godoladze ◽  
Zurab Javakhishvili ◽  
Nino Tumanova
Keyword(s):  
Time Window ◽  
Frequency Range ◽  
Quality Factors ◽  
Lapse Time ◽  
Intrinsic Attenuation ◽  
Total Attenuation ◽  
Relative Contribution ◽  
Normalization Methods ◽  
Coda Normalization ◽  
Back Scattering

Three hundred and thirty-five local earthquakes were processed and the attenuation properties of the crust in the Racha region were investigated using the records of seven seismic stations. We have estimated the quality factors of coda waves ([Formula: see text]) and the direct [Formula: see text] waves ([Formula: see text]) by the single back scattering model and the coda normalization methods, respectively. The Wennerberg’s method has been used to estimate relative contribution of intrinsic ([Formula: see text]) and scattering ([Formula: see text]) attenuations in the total attenuation. We have found that [Formula: see text] and [Formula: see text] parameters are frequency-dependent in the frequency range of 1.5–24[Formula: see text]Hz. [Formula: see text] values increase both with respect to lapse time window from 20[Formula: see text]s to 60[Formula: see text]s and frequency. [Formula: see text] and [Formula: see text] parameters are nearly similar for all frequency bands, but are smaller than [Formula: see text]. The obtained results show that the intrinsic attenuation has more significant effect than scattering attenuation in the total attenuation. The increase of [Formula: see text] with lapse time shows that the lithosphere becomes more homogeneous with depth.

scholarly journals Quantitative EEG evaluation in patients with acute encephalopathy

2013 ◽  
Vol 71 (12) ◽  
pp. 937-942 ◽  
Author(s):  
Aline Souza Marques da Silva Braga ◽  
Bruno Della Ripa Rodrigues Assis ◽  
Jamil Thiago Rosa Ribeiro ◽  
Patricia Maria Sales Polla ◽  
Breno Jose Hulle Pereira ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Spectral Power ◽  
Quantitative Eeg ◽  
Acute Encephalopathy ◽  
Frequency Range ◽  
Alpha Frequency ◽  
Outcome Group ◽  
Spectral Peaks ◽  
Group A ◽  
Group B

Objective To investigate the use of quantitative EEG (qEEG) in patients with acute encephalopathies (AEs) and EEG background abnormalities. Method Patients were divided into favorable outcome (group A, 43 patients) and an unfavorable outcome (group B, 5 patients). EEGLAB software was used for the qEEG analysis. A graphic of the spectral power from all channels was generated for each participant. Statistical comparisons between the groups were performed. Results In group A, spectral analysis revealed spectral peaks (theta and alpha frequency bands) in 84% (38/45) of the patients. In group B, a spectral peak in the delta frequency range was detected in one patient. The remainder of the patients in both groups did not present spectral peaks. Statistical analysis showed lower frequencies recorded from the posterior electrodes in group B patients. Conclusion qEEG may be useful in the evaluations of patients with AEs by assisting with the prognostic determination.

scholarly journals Baicalein, Baicalin, and Wogonin: Protective Effects against Ischemia-Induced Neurodegeneration in the Brain and Retina

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Li Pan ◽  
Kin-Sang Cho ◽  
Irvin Yi ◽  
Chi-Ho To ◽  
Dong Feng Chen ◽  
...  
Keyword(s):  
Time Window ◽  
Therapeutic Potential ◽  
Vascular Dysfunction ◽  
Pathological Condition ◽  
Vascular Occlusion ◽  
Protective Effects ◽  
Scutellaria Baicalensis Georgi ◽  
Retinal Vascular Occlusion ◽  
Low Cytotoxicity ◽  
The Brain

Ischemia is a common pathological condition present in many neurodegenerative diseases, including ischemic stroke, retinal vascular occlusion, diabetic retinopathy, and glaucoma, threatening the sight and lives of millions of people globally. Ischemia can trigger excessive oxidative stress, inflammation, and vascular dysfunction, leading to the disruption of tissue homeostasis and, ultimately, cell death. Current therapies are very limited and have a narrow time window for effective treatment. Thus, there is an urgent need to develop more effective therapeutic options for ischemia-induced neural injuries. With emerging reports on the pharmacological properties of natural flavonoids, these compounds present potent antioxidative, anti-inflammatory, and antiapoptotic agents for the treatment of ischemic insults. Three major active flavonoids, baicalein, baicalin, and wogonin, have been extracted from Scutellaria baicalensis Georgi (S. baicalensis); all of which are reported to have low cytotoxicity. They have been demonstrated to exert promising pharmacological capabilities in preventing cell and tissue damage. This review focuses on the therapeutic potentials of these flavonoids against ischemia-induced neurotoxicity and damage in the brain and retina. The bioactivity and bioavailability of baicalein, baicalin, and wogonin are also discussed. It is with hope that the therapeutic potential of these flavonoids can be utilized and developed as natural treatments for ischemia-induced injuries of the central nervous system (CNS).

scholarly journals Comparative Analysis of Methods for Estimation of Undirected Coupling from Time Series of Intracranial Eegs of Cortex of Rats-Genetic Models of Absence Epilepsy

2017 ◽  
Vol 12 (2) ◽  
pp. 317-326
Author(s):  
А.А. Грищенко ◽  
A.A. Grishchenko
Keyword(s):  
Time Window ◽  
Surrogate Data ◽  
Epileptic Activity ◽  
Absence Epilepsy ◽  
Information Function ◽  
Brain Areas ◽  
To Receive ◽  
Intracranial Recordings ◽  
The Brain ◽  
Mutual Information Function

Studying coupling between brain areas from its electromagnetic activity is one of the key approaches in epilepsy research now, since epileptic activity has been considered to be a result of pathological synchronization in the brain. Often, research is conducted on animal models, because this allows to perform intracranial measurement, and to get rid of interference caused by the skull and to receive signals from deeper regions of the brain such as thalamus or hippocampus. In this study, the intracranial recordings from the frontal and parietal areas of cortex are investigated with a nonlinear correlation coefficient and a mutual information function in a sliding time window. The coupling estimates obtained were subjected for statistical analysis for significance using surrogate data. The dynamics of connectivity between the frontal cortex and the parietal cortex was shown to vary from seizure to seizure and from animal to animal. Therefore, estimates of the significant change in connectivity associated with initiation of the absense seizure, found previously based on averaging over a large number of animals and a large number of seizures for an each animal, can be a result of contribution of a relatively small number of seizures (less than a half of considered), for which the changes are significant.

scholarly journals Are all code-switches processed the same? Examining semantic v. language unexpectancy

2020 ◽  
Author(s):  
Jorge Valdés Kroff ◽  
Patricia Roman ◽  
Paola E. Dussias
Keyword(s):  
Semantic Processing ◽  
Time Window ◽  
Time Windows ◽  
Target Population ◽  
Code Switching ◽  
Event Related Potential ◽  
N400 Effect ◽  
Online Processing ◽  
Sentence Level ◽  
Main Effect

Prior studies using the event-related potential (ERP) technique show that integrating sentential code-switches in online processing lead to a broadly distributed late positivity component while processing semantically unexpected continuations instead lead to the emergence of an N400 effect. While the N400 is generally assumed to index lexico-semantic processing, the LPC has two different interpretations. One account suggests that it reflects the processing of an improbable or unexpected event while an alternative account proposes sentence-level reanalysis. To investigate the relative costs of semantic to language-based unexpectancies (i.e., code-switches), the current study tests 24 Spanish-English bilinguals in an ERP reading study. Semantically constrained Spanish frames either varied in their semantic expectancy (high vs low expectancy) and/or their language continuation (same language vs code-switch) while participants’ electrophysiological responses were recorded. The Spanish-to-English switch direction provides a more naturalistic test for integration costs to code-switching as it better approximates the code-switching practices of the target population. Analyses across three time windows show a main effect for semantic expectancy in the N400 time window and a main effect for code-switching in the LPC time window. Additional analyses based on the self-reported code-switching experience of the participants suggested an early positivity linked to less experience with code-switching. The results suggest that not all code-switches lead to similar integration costs and that prior experience with code-switching is an important additional factor that modulates online processing.

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