scholarly journals Visualization of Phase-Amplitude Coupling Using Rhythmic High-Frequency Activity

2020 ◽  
Author(s):  
Hiroaki Hashimoto ◽  
Hui Ming Khoo ◽  
Takufumi Yanagisawa ◽  
Naoki Tani ◽  
Satoru Oshino ◽  
...  
Keyword(s):  
High Frequency ◽  
Focal Epilepsy ◽  
Low Frequency ◽  
Θ Rhythm ◽  
Human Epilepsy ◽  
High Frequency Activity ◽  
Phase Amplitude ◽  
Intracranial Electrode ◽  
Intracranial Electrodes ◽  
Frequency Phase

AbstractObjectiveHigh-frequency activities (HFAs) and phase-amplitude coupling (PAC) are gaining attention as key neurophysiological biomarkers for studying human epilepsy. We aimed to clarify and visualize how HFAs are modulated by the phase of low-frequency bands during seizures.MethodsWe used intracranial electrodes to record seizures of symptomatic focal epilepsy (15 seizures in seven patients). Ripples (80–250 Hz), as representative of HFAs, were evaluated along with PAC. The synchronization index (SI), representing PAC, was used to analyze the coupling between the amplitude of ripples and the phase of lower frequencies. We created a video in which the intracranial electrode contacts were represented by circles that were scaled linearly to the power changes of ripple.ResultsThe main low frequency band modulating ictal-ripple activities was the θ band (4–8 Hz), and after completion of ictal-ripple burst, δ (1–4 Hz)-ripple PAC occurred. The video showed that fluctuation of the diameter of these circles indicated the rhythmic changes during significant high values of θ-ripple PAC.ConclusionsWe inferred that ripple activities occurring during seizure evolution were modulated by θ rhythm. In addition, we concluded that rhythmic circles’ fluctuation presented in the video represents the PAC phenomenon. Our video is thus a useful tool for understanding how ripple activity is modulated by the low-frequency phase in relation with PAC.

scholarly journals Frequency band coupling with high-frequency activities during seizures shifts from θ band in tonic phase to δ band in clonic phase

2021 ◽  
Author(s):  
Hiroaki Hashimoto ◽  
Hui Ming Khoo ◽  
Takufumi Yanagisawa ◽  
Naoki Tani ◽  
Satoru Oshino ◽  
...  
Keyword(s):  
Frequency Band ◽  
High Frequency ◽  
Roc Analysis ◽  
Focal Epilepsy ◽  
Low Frequency ◽  
University Hospital ◽  
Electrode Placement ◽  
Phase Amplitude ◽  
Intracranial Electrode ◽  
Tonic Phase

Objective: To clarify variations in the relationship between high-frequency activities (HFAs) and low frequency bands from the tonic to the clonic phase in focal to bilateral tonic-clonic seizures (FBTCS), using phase-amplitude coupling. Methods: This retrospective study enrolled six patients with drug-resistant focal epilepsy who underwent intracranial electrode placement for presurgical invasive electroencephalography at Osaka University Hospital (July 2018–July 2019). We used intracranial electrodes to record seizures in focal epilepsy (11 FBTCS). The magnitude of synchronization index (SIm) and receiver operating characteristic (ROC) analysis were used to analyze the coupling between HFA amplitude (80–250 Hz) and lower frequencies phase. Results: The θ (4–8 Hz)-HFA SIm peaked in the tonic phase, whereas the δ (2–4 Hz)-HFA SIm peaked in the clonic phase. ROC analysis indicated that the δ-HFA SIm discriminated well the clonic from the tonic phase. Conclusions: The main low–frequency band modulating the HFA shifted from the θ band in the tonic phase to the δ band in the clonic phase. Significance: In FBTCS, low-frequency band coupling with HFA amplitude varies temporally. Especially, the δ band is specific to the clonic phase. These results suggest dynamically neurophysiological changes in the thalamus or basal ganglia throughout FBTCS.

scholarly journals A statistical framework to assess cross-frequency coupling while accounting for confounding analysis effects

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Jessica K Nadalin ◽  
Louis-Emmanuel Martinet ◽  
Ethan B Blackwood ◽  
Meng-Chen Lo ◽  
Alik S Widge ◽  
...  
Keyword(s):  
High Frequency ◽  
Statistical Power ◽  
Brain Activity ◽  
Low Frequency ◽  
Modeling Framework ◽  
Frequency Coupling ◽  
Phase Amplitude ◽  
Cross Frequency Coupling ◽  
Frequency Phase

Cross frequency coupling (CFC) is emerging as a fundamental feature of brain activity, correlated with brain function and dysfunction. Many different types of CFC have been identified through application of numerous data analysis methods, each developed to characterize a specific CFC type. Choosing an inappropriate method weakens statistical power and introduces opportunities for confounding effects. To address this, we propose a statistical modeling framework to estimate high frequency amplitude as a function of both the low frequency amplitude and low frequency phase; the result is a measure of phase-amplitude coupling that accounts for changes in the low frequency amplitude. We show in simulations that the proposed method successfully detects CFC between the low frequency phase or amplitude and the high frequency amplitude, and outperforms an existing method in biologically-motivated examples. Applying the method to in vivo data, we illustrate examples of CFC during a seizure and in response to electrical stimuli.

scholarly journals Phase-amplitude coupling supports phase coding in human ECoG

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Andrew J Watrous ◽  
Lorena Deuker ◽  
Juergen Fell ◽  
Nikolai Axmacher
Keyword(s):  
Human Brain ◽  
High Frequency ◽  
Low Frequency ◽  
Phase Coding ◽  
Neural Representations ◽  
Simultaneous Acquisition ◽  
Categorical Information ◽  
High Frequency Activity ◽  
Phase Amplitude ◽  
Intracranial Recordings

Prior studies have shown that high-frequency activity (HFA) is modulated by the phase of low-frequency activity. This phenomenon of phase-amplitude coupling (PAC) is often interpreted as reflecting phase coding of neural representations, although evidence for this link is still lacking in humans. Here, we show that PAC indeed supports phase-dependent stimulus representations for categories. Six patients with medication-resistant epilepsy viewed images of faces, tools, houses, and scenes during simultaneous acquisition of intracranial recordings. Analyzing 167 electrodes, we observed PAC at 43% of electrodes. Further inspection of PAC revealed that category specific HFA modulations occurred at different phases and frequencies of the underlying low-frequency rhythm, permitting decoding of categorical information using the phase at which HFA events occurred. These results provide evidence for categorical phase-coded neural representations and are the first to show that PAC coincides with phase-dependent coding in the human brain.

scholarly journals High-frequency neural activity predicts word parsing in ambiguous speech streams

2016 ◽  
Vol 116 (6) ◽  
pp. 2497-2512 ◽  
Author(s):  
Anne Kösem ◽  
Anahita Basirat ◽  
Leila Azizi ◽  
Virginie van Wassenhove
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Acoustic Properties ◽  
Neural Oscillations ◽  
Speech Comprehension ◽  
Top Down ◽  
Linguistic Representations ◽  
High Frequency Activity ◽  
Speech Percept ◽  
The Brain

During speech listening, the brain parses a continuous acoustic stream of information into computational units (e.g., syllables or words) necessary for speech comprehension. Recent neuroscientific hypotheses have proposed that neural oscillations contribute to speech parsing, but whether they do so on the basis of acoustic cues (bottom-up acoustic parsing) or as a function of available linguistic representations (top-down linguistic parsing) is unknown. In this magnetoencephalography study, we contrasted acoustic and linguistic parsing using bistable speech sequences. While listening to the speech sequences, participants were asked to maintain one of the two possible speech percepts through volitional control. We predicted that the tracking of speech dynamics by neural oscillations would not only follow the acoustic properties but also shift in time according to the participant's conscious speech percept. Our results show that the latency of high-frequency activity (specifically, beta and gamma bands) varied as a function of the perceptual report. In contrast, the phase of low-frequency oscillations was not strongly affected by top-down control. Whereas changes in low-frequency neural oscillations were compatible with the encoding of prelexical segmentation cues, high-frequency activity specifically informed on an individual's conscious speech percept.

scholarly journals Brain oscillations and connectivity in autism spectrum disorders (ASD): new approaches to methodology, measurement and modelling

2016 ◽  
Author(s):  
K. Kessler ◽  
R. A. Seymour ◽  
G. Rippon
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Autism Spectrum ◽  
List Type ◽  
Brain Oscillations ◽  
New Techniques ◽  
Low Frequencies ◽  
High Frequency Activity ◽  
Recent Classification ◽  
The Brain

AbstractAlthough atypical social behaviour remains a key characterisation of ASD, the presence of sensory and perceptual abnormalities has been given a more central role in recent classification changes. An understanding of the origins of such aberrations could thus prove a fruitful focus for ASD research. Early neurocognitive models of ASD suggested that the study of high frequency activity in the brain as a measure of cortical connectivity might provide the key to understanding the neural correlates of sensory and perceptual deviations in ASD. As our review shows, the findings from subsequent research have been inconsistent, with a lack of agreement about the nature of any high frequency disturbances in ASD brains. Based on the application of new techniques using more sophisticated measures of brain synchronisation, direction of information flow, and invoking the coupling between high and low frequency bands, we propose a framework which could reconcile apparently conflicting findings in this area and would be consistent both with emerging neurocognitive models of autism and with the heterogeneity of the condition.HighlightsSensory and perceptual aberrations are becoming a core feature of the ASD symptom prolife.Brain oscillations and functional connectivity are consistently affected in ASD.Relationships (coupling) between high and low frequencies are also deficient.Novel framework proposes the ASD brain is marked by local dysregulation and reduced top-down connectivityThe ASD brain’s ability to predict stimuli and events in the environment may be affectedThis may underlie perceptual sensitives and cascade into social processing deficits in ASD

scholarly journals Spatiotemporal Patterns of High-Frequency Activity (80-170 Hz) in Long-term Intracranial EEG

Neurology ◽  
2020 ◽  
pp. 10.1212/WNL.0000000000011408
Author(s):  
Zhuying Chen ◽  
David B. Grayden ◽  
Anthony N. Burkitt ◽  
Udaya Seneviratne ◽  
Wendyl J. D'Souza ◽  
...  
Keyword(s):  
Circadian Rhythms ◽  
High Frequency ◽  
Focal Epilepsy ◽  
High Amplitude ◽  
Oscillatory Behavior ◽  
Patient Specific ◽  
Intracranial Eeg ◽  
Large Variability ◽  
High Frequency Activity

Objective:To determine the utility of high-frequency activity (HFA) and epileptiform spikes as biomarkers for epilepsy, we examined the variability in their rates and locations using long-term ambulatory intracranial EEG (iEEG) recordings.Methods:This study used continuous iEEG recordings obtained over an average of 1.4 years from 15 patients with drug-resistant focal epilepsy. HFA was defined as 80-170 Hz events with amplitudes clearly larger than the background, which was automatically detected using a custom algorithm. The automatically detected HFA was compared with visually annotated high-frequency oscillations (HFOs). The variations of HFA rates were compared with spikes and seizures on patient-specific and electrode-specific bases.Results:HFA included manually annotated HFOs and high-amplitude events occurring in the 80-170 Hz range without observable oscillatory behavior. HFA and spike rates had high amounts of intra- and inter-patient variability. Rates of HFA and spikes had large variability after electrode implantation in most of the patients. Locations of HFA and/or spikes varied up to weeks in more than one-third of the patients. Both HFA and spike rates showed strong circadian rhythms in all patients and some also showed multiday cycles. Furthermore, the circadian patterns of HFA and spike rates had patient-specific correlations with seizures, which tended to vary across electrodes.Conclusions:Analysis of HFA and epileptiform spikes should consider post-implantation variability. HFA and epileptiform spikes, like seizures, show circadian rhythms. However, the circadian profiles can vary spatially within patients and their correlations to seizures are patient-specific.

Neuronavigation and fluoroscopy-assisted subdural strip electrode positioning: a simple method to increase intraoperative accuracy of strip localization in epilepsy surgery

2009 ◽  
Vol 110 (2) ◽  
pp. 327-331 ◽  
Author(s):  
Loránd Erõss ◽  
Attila G. Bagó ◽  
László Entz ◽  
Dániel Fabó ◽  
Péter Halász ◽  
...  
Keyword(s):  
Focal Epilepsy ◽  
Imaging Techniques ◽  
Electrode Placement ◽  
Epileptogenic Zone ◽  
Simple Method ◽  
Strip Electrode ◽  
Area Of Interest ◽  
Electrode Positioning ◽  
Intracranial Electrode ◽  
Intracranial Electrodes

For localization of the epileptogenic zone in cases of focal epilepsy, detailed clinical investigations, imaging studies, and electrophysiological methods are used. If the noninvasive presurgical evaluation provides insufficient data, intracranial electrodes are necessary. Computed tomography and MR imaging techniques are the gold standard for localization of the postoperative position of the implanted intracranial electrode contacts. If the electrode strips are inserted through a bur hole, however, the exact localization of the electrode contacts on the patient's brain remains uncertain for the surgeon during insertion. Therefore, the authors developed a simple method to visualize the electrodes during the procedure. In this method they combine neuronavigation and intraoperative fluoroscopy for parallel visualization of the cortex, electrodes, and the navigation probe. The target region is searched with neuronavigation, a bur hole is made over the optimal entry point, and using real-time fluoroscopy the strip electrode is slid to the tip of the navigation probe, which was kept over the area of interest. At the authors' institution 26 strips in 8 patients have been inserted with this technique, and none of the strips had to be repositioned. There were no complications with this procedure and the prolongation of surgery time is acceptable. Compared to previously published electrode placement methods, this one enhances the accuracy of electrode placement at occipital, parietal, frontal, or interhemispheric regions as well. Intraoperative visualization of the electrodes with fluoroscopy combined with neuronavigation during positioning through a bur hole gives the neurosurgeon the ability to control the real position of the electrode over the gyri during the procedure.

Opuntia Ficus Indica Increases Heart-Rate Variability in High-Level Athletes

2008 ◽  
Vol 18 (2) ◽  
pp. 169-178 ◽  
Author(s):  
Laurent Schmitt ◽  
Jean-Pierre Fouillot ◽  
Gérard Nicolet ◽  
Alain Midol
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
High Frequency ◽  
Low Frequency ◽  
Physiological Effects ◽  
Opuntia Ficus Indica ◽  
Diet Supplement ◽  
High Frequency Activity ◽  
High Level

Opuntia ficus indica (OFI) has many physiological effects, but a relationship between OFI and heart-rate variability (HRV) has never been established. The aim of this study was to describe the effects of a diet supplement of OFI on HRV in athletes. The first day, heart rate (HR) was measured at rest in supine (SU) and standing (ST) positions to analyze HRV in 10 athletes, followed by a randomized assignment to an OFI (5) or placebo (5) group. The next day, the athletes repeated the HRV test. One month later the crossover protocol was applied. In OFI, the high-frequency-activity HFSU (1,773 ± 2,927 vs. 5,856 ± 8,326 ms2, p < .05), HFST (295 ± 313 vs. 560 ± 515 ms2, p < .05), and low-frequency LFSU (1,621 ± 1,795 vs. 6,029 ± 9,007 ms2, p < .01) increased. HRSU (66 ± 13 vs. 57 ± 11 beats/min, p < .01) and HRST (87 ± 11 vs. 76 ± 9 beats/min, p < .01) decreased. A diet supplement of OFI increases HF and LF activities and decreases HR.

scholarly journals Low-frequency phase measurement with high-frequency squeezing

2012 ◽  
Vol 20 (16) ◽  
pp. 18173 ◽  
Author(s):  
Zehui Zhai ◽  
Jiangrui Gao
Keyword(s):  
High Frequency ◽  
Phase Measurement ◽  
Low Frequency ◽  
Frequency Phase
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