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Brain Source Localization

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https://www.readbyqxmd.com/read/28816702/as-above-so-below-towards-understanding-inverse-models-in-bci
#1
Jussi T Lindgren
In Brain-Computer Interfaces (BCI), measurements of the users brain activity are classified into commands for the computer. With EEG-based BCIs, the origins of the classified phenomena are often considered to be spatially localized in the cortical volume and mixed in the EEG. Does the reconstruction of the source activities in the volume help in building more accurate BCIs? The answer remains inconclusive despite previous work. In this paper, we study the question by contrasting the physiology-driven source reconstruction with data-driven representations obtained by statistical machine learning...
August 17, 2017: Journal of Neural Engineering
https://www.readbyqxmd.com/read/28809667/nonlinear-dynamic-complexity-and-sources-of-resting-state-eeg-in-abstinent-heroin-addicts
#2
Qinglin Zhao, Hua Jiang, Bin Hu, Yonghui Li, Ning Zhong, Mi Li, Wenhua Lin, Quanying Liu
It has been reported that chronic heroin intake induces both structural and functional changes in human brain; however, few studies have investigated the carry-over adverse effects on brain after heroin withdrawal. In this paper, we examined the neurophysiological differences between the abstinent heroin addicts (AHAs) and healthy controls (HCs) using nonlinear dynamic analysis and source localization analysis in resting-state electroencephalogram (EEG) data; 5 min resting EEG data from 20 AHAs and twenty age-, education-, and gender-matched HCs were recorded using 64 electrodes...
July 2017: IEEE Transactions on Nanobioscience
https://www.readbyqxmd.com/read/28808190/cholesterol-crystal-embolization-following-plaque-rupture-a-systemic-disease-with-unusual-features
#3
Firas Ghanem, Deepthi Vodnala, Jagadeesh K Kalavakunta, Sridevi Durga, Noah Thormeier, Prem Subramaniyam, Scott Abela, George S Abela
Cholesterol crystal embolic (CCE) syndrome is often a clinically challenging condition that has a poor prognostic implication. It is a result of plaque rupture with release of cholesterol crystals into the circulation that embolize into various tissue organs. Plaque rupture seems to be triggered by an expanding necrotic core during cholesterol crystallization forming sharp tipped crystals that perforate and tear the fibrous cap. Embolizing cholesterol crystals then initiate both local and systemic inflammation that eventually lead to vascular fibrosis and obstruction causing symptoms that can mimic other vasculitic conditions...
January 19, 2017: Journal of Biomedical Research
https://www.readbyqxmd.com/read/28800118/deep-source-localization-with-magnetoencephalography-based-on-sensor-array-decomposition-and-beamforming
#4
Yegang Hu, Yicong Lin, Baoshan Yang, Guangrui Tang, Tao Liu, Yuping Wang, Jicong Zhang
In recent years, the source localization technique of magnetoencephalography (MEG) has played a prominent role in cognitive neuroscience and in the diagnosis and treatment of neurological and psychological disorders. However, locating deep brain activities such as in the mesial temporal structures, especially in preoperative evaluation of epilepsy patients, may be more challenging. In this work we have proposed a modified beamforming approach for finding deep sources. First, an iterative spatiotemporal signal decomposition was employed for reconstructing the sensor arrays, which could characterize the intrinsic discriminant features for interpreting sensor signals...
August 11, 2017: Sensors
https://www.readbyqxmd.com/read/28790884/the-effect-of-electroencephalogram-eeg-reference-choice-on-information-theoretic-measures-of-the-complexity-and-integration-of-eeg-signals
#5
Logan T Trujillo, Candice T Stanfield, Ruben D Vela
Converging evidence suggests that human cognition and behavior emerge from functional brain networks interacting on local and global scales. We investigated two information-theoretic measures of functional brain segregation and integration-interaction complexity C I (X), and integration I(X)-as applied to electroencephalographic (EEG) signals and how these measures are affected by choice of EEG reference. CI(X) is a statistical measure of the system entropy accounted for by interactions among its elements, whereas I(X) indexes the overall deviation from statistical independence of the individual elements of a system...
2017: Frontiers in Neuroscience
https://www.readbyqxmd.com/read/28783620/reducing-sensor-noise-in-meg-and-eeg-recordings-using-oversampled-temporal-projection
#6
Eric Larson, Samu Taulu
Here we review the theory of suppression of spatially uncorrelated, sensor-specific noise in electro- and magento-encephalography (EEG and MEG) arrays, and introduce a novel method for suppression. Our method requires only that the signals of interest are spatially oversampled by the sensor array, which is a reasonable assumption for many EEG and MEG systems. Our method is based on a leave-one-out procedure using overlapping temporal windows in a mathematical framework to project spatially uncorrelated noise in the temporal domain...
July 31, 2017: IEEE Transactions on Bio-medical Engineering
https://www.readbyqxmd.com/read/28782872/the-role-of-vascular-resistance-in-bold-responses-to-progressive-hypercapnia
#7
James Duffin, Olivia Sobczyk, Adrian Crawley, Julien Poublanc, Lashmi Venkatraghavan, Kevin Sam, Alan Mutch, David Mikulis, Joseph Fisher
The ability of the cerebral vasculature to regulate vascular diameter, hence resistance and cerebral blood flow (CBF), in response to metabolic demands (neurovascular coupling), and perfusion pressure changes (autoregulation) may be assessed by measuring the CBF response to carbon dioxide (CO2 ). In healthy individuals, the CBF response to a ramp CO2 stimulus from hypocapnia to hypercapnia is assumed sigmoidal or linear. However, other response patterns commonly occur, especially in individuals with cerebrovascular disease, and these remain unexplained...
August 7, 2017: Human Brain Mapping
https://www.readbyqxmd.com/read/28782683/unidirectional-brain-to-muscle-connectivity-reveals-motor-cortex-control-of-leg-muscles-during-stereotyped-walking
#8
Fiorenzo Artoni, Chiara Fanciullacci, Federica Bertolucci, Alessandro Panarese, Scott Makeig, Silvestro Micera, Carmelo Chisari
In lower mammals, locomotion seems to be mainly regulated by subcortical and spinal networks. On the contrary, recent evidence suggests that in humans the motor cortex is also significantly engaged during complex locomotion tasks. However, a detailed understanding of cortical contribution to locomotion is still lacking especially during stereotyped activities. Here, we show that cortical motor areas finely control leg muscle activation during treadmill stereotyped walking. Using a novel technique based on a combination of Reliable Independent Component Analysis, source localization and effective connectivity, and by combining electroencephalographic (EEG) and electromyographic (EMG) recordings in able-bodied adults we were able to examine for the first time cortical activation patterns and cortico-muscular connectivity including information flow direction...
August 4, 2017: NeuroImage
https://www.readbyqxmd.com/read/28769776/affective-aspects-of-perceived-loss-of-control-and-potential-implications-for-brain-computer-interfaces
#9
Sebastian Grissmann, Thorsten O Zander, Josef Faller, Jonas Brönstrup, Augustin Kelava, Klaus Gramann, Peter Gerjets
Most brain-computer interfaces (BCIs) focus on detecting single aspects of user states (e.g., motor imagery) in the electroencephalogram (EEG) in order to use these aspects as control input for external systems. This communication can be effective, but unaccounted mental processes can interfere with signals used for classification and thereby introduce changes in the signal properties which could potentially impede BCI classification performance. To improve BCI performance, we propose deploying an approach that potentially allows to describe different mental states that could influence BCI performance...
2017: Frontiers in Human Neuroscience
https://www.readbyqxmd.com/read/28755756/brain-extracellular-space-the-final-frontier-of%C3%A2-neuroscience
#10
REVIEW
Charles Nicholson, Sabina Hrabětová
Brain extracellular space is the narrow microenvironment that surrounds every cell of the central nervous system. It contains a solution that closely resembles cerebrospinal fluid with the addition of extracellular matrix molecules. The space provides a reservoir for ions essential to the electrical activity of neurons and forms an intercellular chemical communication channel. Attempts to reveal the size and structure of the extracellular space using electron microscopy have had limited success; however, a biophysical approach based on diffusion of selected probe molecules has proved useful...
July 26, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28743861/multimodal-fingerprints-of-resting-state-networks-as-assessed-by-simultaneous-trimodal-mr-pet-eeg-imaging
#11
N J Shah, J Arrubla, R Rajkumar, E Farrher, J Mauler, E Rota Kops, L Tellmann, J Scheins, F Boers, J Dammers, P Sripad, C Lerche, K J Langen, H Herzog, I Neuner
Simultaneous MR-PET-EEG (magnetic resonance imaging - positron emission tomography - electroencephalography), a new tool for the investigation of neuronal networks in the human brain, is presented here for the first time. It enables the assessment of molecular metabolic information with high spatial and temporal resolution in a given brain simultaneously. Here, we characterize the brain's default mode network (DMN) in healthy male subjects using multimodal fingerprinting by quantifying energy metabolism via 2- [(18)F]fluoro-2-desoxy-D-glucose PET (FDG-PET), the inhibition - excitation balance of neuronal activation via magnetic resonance spectroscopy (MRS), its functional connectivity via fMRI and its electrophysiological signature via EEG...
July 25, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28739163/strategies-for-statistical-thresholding-of-source-localization-maps-in-magnetoencephalography-and-estimating-source-extent
#12
Kostiantyn Maksymenko, Bernard Giusiano, Nicolas Roehri, Christian-G Bénar, Jean-Michel Badier
BACKGROUND: Magnetoencephalography allows defining non-invasively the spatio-temporal activation of brain networks thanks to source localization algorithms. A major difficulty of MNE and beamforming methods, two classically used techniques, is the definition of proper thresholds that allow deciding the extent of activated cortex. NEW METHOD: We investigated two strategies for computing a threshold, taking into account the difficult multiple comparison issue. The strategies were based either on parametric statistics (Bonferroni, FDR correction) or on empirical estimates (local FDR and a custom measure based on the survival function)...
July 21, 2017: Journal of Neuroscience Methods
https://www.readbyqxmd.com/read/28735921/frontal-dysfunction-in-patients-with-restless-legs-syndrome-performing-a-visual-oddball-task-an-event-related-potential-source-imaging-study
#13
Kwang Su Cha, Jeong Woo Choi, Ki-Young Jung, Kyung Hwan Kim
Restless legs syndrome (RLS) is a sensorimotor neurological disorder that is accompanied by the compelling urge to move one's legs, and unpleasant, disturbing sensations in the legs. Several neuropsychological studies have shown that RLS is associated with deficits in cognitive functions, such as attention, working memory, and frontal executive function, presumably due to abnormal frontal activities. However, the mechanism underlying the cognitive deficits in RLS patients is mostly unknown. To investigate the cortical origin of cognitive dysfunction in RLS, we analyzed the P2 and P3 event-related potential (ERP) components evoked by a visual oddball task using distributed cortical source localization via low-resolution brain electromagnetic tomography (LORETA) algorithm...
August 2017: Sleep Medicine
https://www.readbyqxmd.com/read/28735011/assessment-and-elimination-of-the-effects-of-head-movement-on-meg-resting-state-measures-of-oscillatory-brain-activity
#14
Eirini Messaritaki, Loes Koelewijn, Diana C Dima, Gemma M Williams, Gavin Perry, Krish D Singh
Magnetoencephalography (MEG) is increasingly being used to study brain function because of its excellent temporal resolution and its direct association with brain activity at the neuronal level. One possible cause of error in the analysis of MEG data comes from the fact that participants, even MEG-experienced ones, move their head in the MEG system. Head movement can cause source localization errors during the analysis of MEG data, which can result in the appearance of source variability that does not reflect brain activity...
July 20, 2017: NeuroImage
https://www.readbyqxmd.com/read/28734112/fused-multivariate-empirical-mode-decomposition-memd-and-inverse-solution-method-for-eeg-source-localization
#15
Pegah Khosropanah, Abdul Rahman Ramli, Kheng Seang Lim, Mohammad Hamiruce Marhaban, Anvarjon Ahmedov
EEG source localization is determining possible cortical sources of brain activities with scalp EEG. Generally, every step of the data processing sequence affects the accuracy of EEG source localization. In this paper, we introduce a fused multivariate empirical mode decomposing (MEMD) and inverse solution algorithm with an embedded unsupervised eye blink remover in order to localize the epileptogenic zone accurately. For this purpose, we constructed realistic forward models using MRI and boundary element method (BEM) for each patient to obtain results that are more realistic...
July 22, 2017: Biomedizinische Technik. Biomedical Engineering
https://www.readbyqxmd.com/read/28725180/endothelial-nitric-oxide-synthase-is-present-in-dendritic-spines-of-neurons-in-primary-cultures
#16
Ariel Caviedes, Manuel Varas-Godoy, Carlos Lafourcade, Soledad Sandoval, Javiera Bravo-Alegria, Thilo Kaehne, Angela Massmann, Jorge P Figueroa, Francisco Nualart, Ursula Wyneken
Nitric oxide exerts important regulatory functions in various brain processes. Its synthesis in neurons has been most commonly ascribed to the neuronal nitric oxide synthase (nNOS) isoform. However, the endothelial isoform (eNOS), which is significantly associated with caveolae in different cell types, has been implicated in synaptic plasticity and is enriched in the dendrites of CA1 hippocampal neurons. Using high resolution microscopy and co-distribution analysis of eNOS with synaptic and raft proteins, we now show for the first time in primary cortical and hippocampal neuronal cultures, virtually devoid of endothelial cells, that eNOS is present in neurons and is localized in dendritic spines...
2017: Frontiers in Cellular Neuroscience
https://www.readbyqxmd.com/read/28716282/serum-amyloid-p-component-a-novel-potential-player-in-vessel-degeneration-in-cadasil
#17
Akihito Nagatoshi, Mitsuharu Ueda, Akihiko Ueda, Masayoshi Tasaki, Yasuteru Inoue, Yihong Ma, Teruaki Masuda, Mayumi Mizukami, Sayaka Matsumoto, Takayuki Kosaka, Takayuki Kawano, Takaaki Ito, Yukio Ando
In cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), granular osmiophilic material (GOM) may play some roles in inducing cerebrovascular events. To elucidate the pathogenesis of CADASIL, we used laser microdissection and liquid chromatography-tandem mass spectrometry to analyze cerebrovascular lesions of patients with CADASIL for GOM. The analyses detected serum amyloid P component (SAP), annexin A2, and periostin as the proteins with the largest increase in the samples, which also demonstrated NOTCH3...
August 15, 2017: Journal of the Neurological Sciences
https://www.readbyqxmd.com/read/28714589/meg-biomarker-of-alzheimer-s-disease-absence-of-a-prefrontal-generator-during-auditory-sensory-gating
#18
Sanja Josef Golubic, Cheryl J Aine, Julia M Stephen, John C Adair, Janice E Knoefel, Selma Supek
Magnetoencephalography (MEG), a direct measure of neuronal activity, is an underexplored tool in the search for biomarkers of Alzheimer's disease (AD). In this study, we used MEG source estimates of auditory gating generators, nonlinear correlations with neuropsychological results, and multivariate analyses to examine the sensitivity and specificity of gating topology modulation to detect AD. Our results demonstrated the use of MEG localization of a medial prefrontal (mPFC) gating generator as a discrete (binary) detector of AD at the individual level and resulted in recategorizing the participant categories in (1) controls with mPFC generator localized in response to both the standard and deviant tones; (2) a possible preclinical stage of AD participants (a lower functioning group of controls) in which mPFC activation was localized to the deviant tone only; and (3) symptomatic AD in which mPFC activation was not localized to either the deviant or standard tones...
July 17, 2017: Human Brain Mapping
https://www.readbyqxmd.com/read/28701933/network-efficiency-and-posterior-alpha-patterns-are-markers-of-recovery-from-general-anesthesia-a-high-density-electroencephalography-study-in-healthy-volunteers
#19
Stefanie Blain-Moraes, Vijay Tarnal, Giancarlo Vanini, Tarik Bel-Behar, Ellen Janke, Paul Picton, Goodarz Golmirzaie, Ben J A Palanca, Michael S Avidan, Max B Kelz, George A Mashour
Recent studies have investigated local oscillations, long-range connectivity, and global network patterns to identify neural changes associated with anesthetic-induced unconsciousness. These studies typically employ anesthetic protocols that either just cross the threshold of unconsciousness, or induce deep unconsciousness for a brief period of time-neither of which models general anesthesia for major surgery. To study neural patterns of unconsciousness and recovery in a clinically-relevant context, we used a realistic anesthetic regimen to induce and maintain unconsciousness in eight healthy participants for 3 h...
2017: Frontiers in Human Neuroscience
https://www.readbyqxmd.com/read/28677252/impairment-in-predictive-processes-during-auditory-mismatch-negativity-in-scz-evidence-from-event-related-fields
#20
Andreas Sauer, Maor Zeev-Wolf, Tineke Grent-'t-Jong, Marc Recasens, Catherine Wacongne, Michael Wibral, Saskia Helbling, Abraham Peled, Alexander Grinshpoon, Wolf Singer, Abraham Goldstein, Peter J Uhlhaas
Patients with schizophrenia (ScZ) show pronounced dysfunctions in auditory perception but the underlying mechanisms as well as the localization of the deficit remain unclear. To examine these questions, the current study examined whether alterations in the neuromagnetic mismatch negativity (MMNm) in ScZ-patients could involve an impairment in sensory predictions in local sensory and higher auditory areas. Using a whole-head MEG-approach, we investigated the MMNm as well as P300m and N100m amplitudes during a hierarchical auditory novelty paradigm in 16 medicated ScZ-patients and 16 controls...
July 5, 2017: Human Brain Mapping
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