scholarly journals Link Prediction Investigation of Dynamic Information Flow in Epilepsy

2018 ◽  
Vol 2018 ◽  
pp. 1-13
Author(s):  
Yan He ◽  
Fan Yang ◽  
Yunli Yu ◽  
Celso Grebogi
Keyword(s):  
Link Prediction ◽  
Focal Epilepsy ◽  
Phase Locking ◽  
Brain Regions ◽  
Performance Comparison ◽  
Brain Disorder ◽  
Common Neighbor ◽  
Comparison Results ◽  
Ictal Activity ◽  
Phase Locking Value

As a brain disorder, epilepsy is characterized with abnormal hypersynchronous neural firings. It is known that seizures initiate and propagate in different brain regions. Long-term intracranial multichannel electroencephalography (EEG) reflects broadband ictal activity under seizure occurrence. Network-based techniques are efficient in discovering brain dynamics and offering finger-print features for specific individuals. In this study, we adopt link prediction for proposing a novel workflow aiming to quantify seizure dynamics and uncover pathological mechanisms of epilepsy. A dataset of EEG signals was enrolled that recorded from 8 patients with 3 different types of pharmocoresistant focal epilepsy. Weighted networks are obtained from phase locking value (PLV) in subband EEG oscillations. Common neighbor (CN), resource allocation (RA), Adamic-Adar (AA), and Sorenson algorithms are brought in for link prediction performance comparison. Results demonstrate that RA outperforms its rivals. Similarity, matrix was produced from the RA technique performing on EEG networks later. Nodes are gathered to form sequences by selecting the ones with the highest similarity. It is demonstrated that variations are in accordance with seizure attack in node sequences of gamma band EEG oscillations. What is more, variations in node sequences monitor the total seizure journey including its initiation and termination.

scholarly journals Phase-locking of resting-state brain networks with the gastric basal electrical rhythm

2020 ◽  
Author(s):  
Ann S. Choe ◽  
Bohao Tang ◽  
Kimberly R. Smith ◽  
Hamed Honari ◽  
Martin A. Lindquist ◽  
...  
Keyword(s):  
Resting State ◽  
Phase Locking ◽  
Statistical Significance ◽  
Null Distribution ◽  
Surrogate Data ◽  
Brain Regions ◽  
Vagal Afferents ◽  
Network Disruptions ◽  
Time Courses ◽  
Phase Locking Value

ABSTRACTA network of myenteric interstitial cells of Cajal in the corpus of the stomach serves as its “pacemaker”, continuously generating a ca. 0.05 Hz electrical slow wave, which is transmitted to the brain chiefly by vagal afferents. A recent study combining resting-state functional MRI (rsfMRI) with concurrent surface electrogastrography (EGG), with cutaneous electrodes placed on the epigastrium, found 12 brain regions with activity that was significantly phase-locked with this gastric basal electrical rhythm. Therefore, we asked whether fluctuations in brain resting state networks (RSNs), estimated using a spatial independent component analysis (ICA) approach, might be synchronized with the stomach. In the present study, in order to determine whether any RSNs are phase-locked with the gastric rhythm, an individual participant underwent 22 scanning sessions; in each, two 15-minute runs of concurrent EGG and rsfMRI data were acquired. EGG data from three sessions had weak gastric signals and were excluded; the other 19 sessions yielded a total of 9.5 hours of data. The rsfMRI data were analyzed using group ICA; RSN time courses were estimated using dual regression; for each run, the phase-locking value (PLV) was computed between each RSN and the gastric signal. To assess statistical significance, PLVs from all pairs of “mismatched” data (EGG and rsfMRI data acquired on different days) were used as surrogate data to generate a null distribution for each RSN. Of a total of 18 RSNs, three were found to be significantly phase-locked with the basal gastric rhythm, namely, a cerebellar network, a dorsal somatosensory-motor network, and a default mode network. Disruptions to the gut-brain axis, which sustains interoceptive feedback between the central nervous system and the viscera, are thought to be involved in various disorders; manifestation of the infra-slow rhythm of the stomach in brain rsfMRI data could be useful for studies in clinical populations.

Effect of Power and Phase Synchronization in Multi-Trial Speech Imagery

2018 ◽  
Vol 10 (4) ◽  
pp. 44-61 ◽  
Author(s):  
Sandhya Chengaiyan ◽  
Divya Balathayil ◽  
Kavitha Anandan ◽  
Christy Bobby Thomas
Keyword(s):  
Phase Synchronization ◽  
Brain Connectivity ◽  
Phase Locking ◽  
Brain Regions ◽  
Multiple Trials ◽  
Phase Locking Value ◽  
The Mind ◽  
Processing Techniques ◽  
Lock In ◽  
Time Frames

Speech imagery is one form of mental imagery which refers to the imagining of speaking a word to oneself silently in the mind without any articulation movement. In this work, electroencephalography (EEG) signals were acquired while speaking and during the imagining of speaking consonant-vowel-consonant (CVC) words in multiple trials of different time frames. Relative powers were computed for each EEG frequency band. It has been observed that relative power of alpha and theta bands was dominant. Phase Locking Value (PLV), a functional brain connectivity parameter has been estimated to understand the phase synchronicity between two brain regions. PLV results show that the left hemispheric frontal and temporal electrodes has maximum phase lock in alpha and theta band during speech and speech imagery process. The combination of brain connectivity estimators and signal processing techniques will thus be a reliable framework for understanding the nature of speech imagery signals captured through EEG.

Effect of Power and Phase Synchronization in Multi-Trial Speech Imagery

2020 ◽  
pp. 1654-1673
Author(s):  
Sandhya Chengaiyan ◽  
Divya Balathayil ◽  
Kavitha Anandan ◽  
Christy Bobby Thomas
Keyword(s):  
Phase Synchronization ◽  
Brain Connectivity ◽  
Phase Locking ◽  
Brain Regions ◽  
Multiple Trials ◽  
Phase Locking Value ◽  
The Mind ◽  
Processing Techniques ◽  
Lock In ◽  
Time Frames

Speech imagery is one form of mental imagery which refers to the imagining of speaking a word to oneself silently in the mind without any articulation movement. In this work, electroencephalography (EEG) signals were acquired while speaking and during the imagining of speaking consonant-vowel-consonant (CVC) words in multiple trials of different time frames. Relative powers were computed for each EEG frequency band. It has been observed that relative power of alpha and theta bands was dominant. Phase Locking Value (PLV), a functional brain connectivity parameter has been estimated to understand the phase synchronicity between two brain regions. PLV results show that the left hemispheric frontal and temporal electrodes has maximum phase lock in alpha and theta band during speech and speech imagery process. The combination of brain connectivity estimators and signal processing techniques will thus be a reliable framework for understanding the nature of speech imagery signals captured through EEG.

scholarly journals Magnetoencephalography-based identification of functional connectivity network disruption following mild traumatic brain injury

2016 ◽  
Vol 116 (4) ◽  
pp. 1840-1847 ◽  
Author(s):  
Ahmad Alhourani ◽  
Thomas A. Wozny ◽  
Deepa Krishnaswamy ◽  
Sudhir Pathak ◽  
Shawn A. Walls ◽  
...  
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Functional Connectivity ◽  
Mild Traumatic Brain Injury ◽  
Phase Locking ◽  
Brain Regions ◽  
Memory And Attention ◽  
Control Subjects ◽  
Cortical Regions ◽  
Phase Locking Value

Mild traumatic brain injury (mTBI) leads to long-term cognitive sequelae in a significant portion of patients. Disruption of normal neural communication across functional brain networks may explain the deficits in memory and attention observed after mTBI. In this study, we used magnetoencephalography (MEG) to examine functional connectivity during a resting state in a group of mTBI subjects ( n = 9) compared with age-matched control subjects ( n = 15). We adopted a data-driven, exploratory analysis in source space using phase locking value across different frequency bands. We observed a significant reduction in functional connectivity in band-specific networks in mTBI compared with control subjects. These networks spanned multiple cortical regions involved in the default mode network (DMN). The DMN is thought to subserve memory and attention during periods when an individual is not engaged in a specific task, and its disruption may lead to cognitive deficits after mTBI. We further applied graph theoretical analysis on the functional connectivity matrices. Our data suggest reduced local efficiency in different brain regions in mTBI patients. In conclusion, MEG can be a potential tool to investigate and detect network alterations in patients with mTBI. The value of MEG to reveal potential neurophysiological biomarkers for mTBI patients warrants further exploration.

scholarly journals Phase-locking of resting-state brain networks with the gastric basal electrical rhythm

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0244756
Author(s):  
Ann S. Choe ◽  
Bohao Tang ◽  
Kimberly R. Smith ◽  
Hamed Honari ◽  
Martin A. Lindquist ◽  
...  
Keyword(s):  
Resting State ◽  
Phase Locking ◽  
Statistical Significance ◽  
Null Distribution ◽  
Surrogate Data ◽  
Brain Regions ◽  
Vagal Afferents ◽  
Network Disruptions ◽  
Time Courses ◽  
Phase Locking Value

A network of myenteric interstitial cells of Cajal in the corpus of the stomach serves as its “pacemaker”, continuously generating a ca 0.05 Hz electrical slow wave, which is transmitted to the brain chiefly by vagal afferents. A recent study combining resting-state functional MRI (rsfMRI) with concurrent surface electrogastrography (EGG), with cutaneous electrodes placed on the epigastrium, found 12 brain regions with activity that was significantly phase-locked with this gastric basal electrical rhythm. Therefore, we asked whether fluctuations in brain resting state networks (RSNs), estimated using a spatial independent component analysis (ICA) approach, might be synchronized with the stomach. In the present study, in order to determine whether any RSNs are phase-locked with the gastric rhythm, an individual participant underwent 22 scanning sessions; in each, two 15-minute runs of concurrent EGG and rsfMRI data were acquired. EGG data from three sessions had weak gastric signals and were excluded; the other 19 sessions yielded a total of 9.5 hours of data. The rsfMRI data were analyzed using group ICA; RSN time courses were estimated; for each run, the phase-locking value (PLV) was computed between each RSN and the gastric signal. To assess statistical significance, PLVs from all pairs of “mismatched” data (EGG and rsfMRI data acquired on different days) were used as surrogate data to generate a null distribution for each RSN. Of a total of 18 RSNs, three were found to be significantly phase-locked with the basal gastric rhythm, namely, a cerebellar network, a dorsal somatosensory-motor network, and a default mode network. Disruptions to the gut-brain axis, which sustains interoceptive feedback between the central nervous system and the viscera, are thought to be involved in various disorders; manifestation of the infra-slow rhythm of the stomach in brain rsfMRI data could be useful for studies in clinical populations.

scholarly journals Electroencephalogram Source Imaging and Brain Network Based Natural Grasps Decoding

2021 ◽  
Vol 15 ◽  
Author(s):  
Baoguo Xu ◽  
Leying Deng ◽  
Dalin Zhang ◽  
Muhui Xue ◽  
Huijun Li ◽  
...  
Keyword(s):  
Parietal Lobe ◽  
Phase Locking ◽  
Brain Network ◽  
Internal Communication ◽  
Peak Performance ◽  
Source Imaging ◽  
Planning Stage ◽  
Grand Average ◽  
Reach And Grasp ◽  
Phase Locking Value

Studying the decoding process of complex grasping movement is of great significance to the field of motor rehabilitation. This study aims to decode five natural reach-and-grasp types using sources of movement-related cortical potential (MRCP) and investigate their difference in cortical signal characteristics and network structures. Electroencephalogram signals were gathered from 40 channels of eight healthy subjects. In an audio cue-based experiment, subjects were instructed to keep no-movement condition or perform five natural reach-and-grasp movements: palmar, pinch, push, twist and plug. We projected MRCP into source space and used average source amplitudes in 24 regions of interest as classification features. Besides, functional connectivity was calculated using phase locking value. Six-class classification results showed that a similar grand average peak performance of 49.35% can be achieved using source features, with only two-thirds of the number of channel features. Besides, source imaging maps and brain networks presented different patterns between each condition. Grasping pattern analysis indicated that the modules in the execution stage focus more on internal communication than in the planning stage. The former stage was related to the parietal lobe, whereas the latter was associated with the frontal lobe. This study demonstrates the superiority and effectiveness of source imaging technology and reveals the spread mechanism and network structure of five natural reach-and-grasp movements. We believe that our work will contribute to the understanding of the generation mechanism of grasping movement and promote a natural and intuitive control of brain–computer interface.

Reward-Associated Gamma Oscillations in Ventral Striatum Are Regionally Differentiated and Modulate Local Firing Activity

2010 ◽  
Vol 103 (3) ◽  
pp. 1658-1672 ◽  
Author(s):  
Tobias Kalenscher ◽  
Carien S. Lansink ◽  
Jan V. Lankelma ◽  
Cyriel M. A. Pennartz
Keyword(s):  
Ventral Striatum ◽  
Phase Locking ◽  
Gamma Oscillations ◽  
Brain Regions ◽  
Reward Processing ◽  
Temporal Organization ◽  
Gamma Activity ◽  
Neural Ensembles ◽  
Gamma Range ◽  
Gamma Power

Oscillations of local field potentials (LFPs) in the gamma range are found in many brain regions and are supposed to support the temporal organization of cognitive, perceptual, and motor functions. Even though gamma oscillations have also been observed in ventral striatum, one of the brain's most important structures for motivated behavior and reward processing, their specific function during ongoing behavior is unknown. Using a movable tetrode array, we recorded LFPs and activity of neural ensembles in the ventral striatum of rats performing a reward-collection task. Rats were running along a triangle track and in each round collected one of three different types of rewards. The gamma power of LFPs on subsets of tetrodes was modulated by reward-site visits, discriminated between reward types, between baitedness of reward locations and was different before versus after arrival at a reward site. Many single units in ventral striatum phase-locked their discharge pattern to the gamma oscillations of the LFPs. Phase-locking occurred more often in reward-related than in reward-unrelated neurons and LFPs. A substantial number of simultaneously recorded LFPs correlated poorly with each other in terms of gamma rhythmicity, indicating that the expression of gamma activity was heterogeneous and regionally differentiated. The orchestration of LFPs and single-unit activity by way of gamma rhythmicity sheds light on the functional architecture of the ventral striatum and the temporal coordination of ventral striatal activity for modulating downstream areas and regulating synaptic plasticity.

Image Quality Assessment of Four Different Computed Radiography Systems for NDT Applications

2013 ◽  
Author(s):  
Angela Peterzol ◽  
Bruno Bader ◽  
Julien Banchet ◽  
Claire Caperaa ◽  
Vivian Didier
Keyword(s):  
Image Quality ◽  
Image Quality Assessment ◽  
Computed Radiography ◽  
Conventional Radiography ◽  
Performance Comparison ◽  
Source Image ◽  
Imaging Plate ◽  
Performance Limits ◽  
Joint Project ◽  
Comparison Results

Computed radiography (CR) is a digital radiographic technique, which uses very similar equipment to conventional radiography except that in place of a film to create the latent image, an imaging plate (IP) made of a photostimulable phosphor is used [1]. CR systems are commonly used in medical applications since they have proven reliability over more than two decades. Conversely, the NDT community has discussed the efficacy of film replacement by CR for more than 15 years. Though some standards were introduced in 2005 (ASTM E 2033, CEN EN 14784-2) and others are on the way (PR ISO 17636-2), CR is actually not included within the French RCCM, while the technique is commonly used in US for nuclear applications according to ASME (Section V, article 2). Since 2006, AREVA has been evaluating the performance of CR in comparison to conventional RT in the framework of EN 14784 for the digital part and the RCCM for the conventional part. The objective was to build a technical justification report to eventually support introduction of CR into the RCCM. In 2009 the subject gave rise to collaboration between AREVA NP – NETEC and EDF-CEIDRE, for a joint project to establish performance limits of CR towards EN 14784 specifications and RCCM image quality indicator (IQI) requirements [2]. In this paper, we present performance comparison results of four different CR systems. The measurements were conducted in 2012 and they demonstrate the current state of achievable image quality in CR. The performance has been evaluated for steel with a thickness range of 20÷60 mm using an Iridium 192 gamma source. Image quality has been assessed in terms of EN 462 and ASTM (E 747, E 1742) IQI. The results have been scored considering the PR ISO 17636-2, RCCM 2007, and ASME V-2010. This also permitted comparison among the different standard requirements.

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