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Magnetoencephalography

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https://www.readbyqxmd.com/read/29159037/reorganization-of-the-somatosensory-cortex-in-hemiplegic-cerebral-palsy-associated-with-impaired-sensory-tracts
#1
Christos Papadelis, Erin E Butler, Madelyn Rubenstein, Limin Sun, Lilla Zollei, Donna Nimec, Brian Snyder, Patricia Ellen Grant
Functional neuroimaging studies argue that sensory deficits in hemiplegic cerebral palsy (HCP) are related to deviant somatosensory processing in the ipsilesional primary somatosensory cortex (S1). A separate body of structural neuroimaging literature argues that these deficits are due to structural damage of the ascending sensory tracts (AST). The relationship between the functional and structural integrity of the somatosensory system and the sensory performance is largely unknown in HCP. To address this relationship, we combined findings from magnetoencephalography (MEG) and probabilistic diffusion tractography (PDT) in 10 children with HCP and 13 typically developing (TD) children...
2018: NeuroImage: Clinical
https://www.readbyqxmd.com/read/29157849/imaging-of-chronic-concussion
#2
REVIEW
Eliana Bonfante, Roy Riascos, Octavio Arevalo
Conventional imaging findings in patients with cerebral concussion and chronic traumatic encephalopathy are absent or subtle in the majority of cases. The most common abnormalities include cerebral volume loss, enlargement of the cavum of the septum pellucidum, cerebral microhemorrhages, and white matter signal abnormalities, all of which have poor sensitivity and specificity. Advanced imaging modalities, such as diffusion tensor imaging (DTI), blood oxygen level dependent functional MR Imaging (BOLD fMRI), MR spectroscopy, perfusion imaging, positron emission tomography (PET), single photon emission computed tomography (SPECT), and magnetoencephalography detect physiologic abnormalities in symptomatic patients and, although currently in the investigation phase, may become useful in the clinical arena...
February 2018: Neuroimaging Clinics of North America
https://www.readbyqxmd.com/read/29146728/source-estimation-of-epileptic-activity-using-eloreta-kurtosis-analysis
#3
Shunichiro Ikeda, Ryouhei Ishii, Leonides Canuet, Roberto D Pascual-Marqui
Exact low-resolution brain electromagnetic tomography (eLORETA) is a technique for three-dimensional representation of the distribution of sources of electrical activity in the brain. Kurtosis analysis allows for identification of spiky activity in the brain. To evaluate the reliability of eLORETA kurtosis analysis, the results of the analysis were compared with those of equivalent current dipole (ECD) and synthetic aperture magnetometry (SAM) kurtosis analysis of magnetoencephalography (MEG) data in a patient with epilepsy with elementary visual seizures in a 6-year follow-up...
November 16, 2017: BMJ Case Reports
https://www.readbyqxmd.com/read/29146464/language-control-mechanisms-differ-for-native-languages-neuromagnetic-evidence-from-trilingual-language-switching
#4
Suzanne C A Hut, Päivi Helenius, Alina Leminen, Jyrki P Mäkelä, Minna Lehtonen
How does the brain process and control languages that are learned at a different age, when proficiency in all these languages is high? Early acquired strong languages are likely to have higher baseline activation levels than later learned less-dominant languages. However, it is still largely unknown how the activation levels of these different languages are controlled, and how interference from an irrelevant language is prevented. In this magnetoencephalography (MEG) study on language switching during auditory perception, early Finnish-Swedish bilinguals (N=18) who mastered English with high proficiency after childhood were presented with spoken words in each of the three languages, while performing a simple semantic categorisation task...
November 13, 2017: Neuropsychologia
https://www.readbyqxmd.com/read/29138310/sparsity-enables-estimation-of-both-subcortical-and-cortical-activity-from-meg-and-eeg
#5
Pavitra Krishnaswamy, Gabriel Obregon-Henao, Jyrki Ahveninen, Sheraz Khan, Behtash Babadi, Juan Eugenio Iglesias, Matti S Hämäläinen, Patrick L Purdon
Subcortical structures play a critical role in brain function. However, options for assessing electrophysiological activity in these structures are limited. Electromagnetic fields generated by neuronal activity in subcortical structures can be recorded noninvasively, using magnetoencephalography (MEG) and electroencephalography (EEG). However, these subcortical signals are much weaker than those generated by cortical activity. In addition, we show here that it is difficult to resolve subcortical sources because distributed cortical activity can explain the MEG and EEG patterns generated by deep sources...
November 14, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/29138088/comparing-multilayer-brain-networks-between-groups-introducing-graph-metrics-and-recommendations
#6
Kanad Mandke, Jil Meier, Matthew J Brookes, Reuben D O'Dea, Piet Van Mieghem, Cornelis J Stam, Arjan Hillebrand, Prejaas Tewarie
There is an increasing awareness of the advantages of multi-modal neuroimaging. Networks obtained from different modalities are usually treated in isolation, which is however contradictory to accumulating evidence that these networks show non-trivial interdependencies. Even networks obtained from a single modality, such as frequency-band specific functional networks measured from magnetoencephalography (MEG) are often treated independently. Here, we discuss how a multilayer network framework allows for integration of multiple networks into a single network description and how graph metrics can be applied to quantify multilayer network organisation for group comparison...
November 11, 2017: NeuroImage
https://www.readbyqxmd.com/read/29122721/a-common-periodic-representation-of-interaural-time-differences-in-mammalian-cortex
#7
Nelli H Salminen, Simon J Jones, Gestur B Christianson, Torsten Marquardt, David McAlpine
Binaural hearing, the ability to detect small differences in the timing and level of sounds at the two ears, underpins the ability to localize sound sources along the horizontal plane, and is important for decoding complex spatial listening environments into separate objects - a critical factor in 'cocktail-party listening'. For human listeners, the most important spatial cue is the interaural time difference (ITD). Despite many decades of neurophysiological investigations of ITD sensitivity in small mammals, and computational models aimed at accounting for human perception, a lack of concordance between these studies has hampered our understanding of how the human brain represents and processes ITDs...
November 6, 2017: NeuroImage
https://www.readbyqxmd.com/read/29122719/interocular-interaction-of-contrast-and-luminance-signals-in-human-primary-visual-cortex
#8
E Chadnova, A Reynaud, S Clavagnier, D H Baker, S Baillet, R F Hess
Interocular interaction in the visual system occurs under dichoptic conditions when contrast and luminance are imbalanced between the eyes. Human psychophysical investigations suggest that interocular interaction can be explained by a contrast normalization model. However, the neural processes that underlie such interactions are still unresolved. We set out to assess, for the first time, the proposed normalization model of interocular contrast interactions using magnetoencephalography (MEG) and to extend this model to incorporate interactions based on interocular luminance differences...
November 7, 2017: NeuroImage
https://www.readbyqxmd.com/read/29118962/epileptic-meg-spike-detection-using-statistical-features-and-genetic-programming-with-knn
#9
Turky N Alotaiby, Saud R Alrshoud, Saleh A Alshebeili, Majed H Alhumaid, Waleed M Alsabhan
Epilepsy is a neurological disorder that affects millions of people worldwide. Monitoring the brain activities and identifying the seizure source which starts with spike detection are important steps for epilepsy treatment. Magnetoencephalography (MEG) is an emerging epileptic diagnostic tool with high-density sensors; this makes manual analysis a challenging task due to the vast amount of MEG data. This paper explores the use of eight statistical features and genetic programing (GP) with the K-nearest neighbor (KNN) for interictal spike detection...
2017: Journal of Healthcare Engineering
https://www.readbyqxmd.com/read/29118198/a-fast-invariant-representation-for-human-action-in-the-visual-system
#10
Leyla Isik, Andrea Tacchetti, Tomaso A Poggio
Humans can effortlessly recognize others' actions in the presence of complex transformations, such as changes in viewpoint. Several studies have located the regions in the brain involved in invariant action recognition, however, the underlying neural computations remain poorly understood. We use magnetoencephalography (MEG) decoding and a dataset of well-controlled, naturalistic videos of five actions (run, walk, jump, eat, drink) performed by different actors at different viewpoints to study the computational steps used to recognize actions across complex transformations...
November 8, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/29111591/magnetoencephalographic-imaging-of-ictal-high-frequency-oscillations-80-200%C3%A2-hz-in-pharmacologically-resistant-focal-epilepsy
#11
Jayabal Velmurugan, Srikantan S Nagarajan, Narayanan Mariyappa, Shankar G Ravi, Kandavel Thennarasu, Ravindranadh C Mundlamuri, Kenchaiah Raghavendra, Rose Dawn Bharath, Jitender Saini, Arimappamagan Arivazhagan, Jamuna Rajan, Anita Mahadevan, Malla B Rao, Parthasarathy Satishchandra, Sanjib Sinha
OBJECTIVE: Specificity of ictal high-frequency oscillations (HFOs) in identifying epileptogenic abnormality is significant, compared to the spikes and interictal HFOs. The objectives of the study were to detect and to localize ictal HFOs by magnetoencephalography (MEG) for identifying the seizure onset zone (SOZ), evaluate the cortical excitability from preictal to ictal transition, and establish HFO concordance rates with other modalities and postsurgical resection. METHODS: Sixty-seven patients with drug-resistant epilepsy had at least 1 spontaneous seizure each during MEG acquisition, and analysis was carried out on 20 seizures from 20 patients...
November 7, 2017: Epilepsia
https://www.readbyqxmd.com/read/29107610/altered-resting-state-functional-connectivity-in-patients-with-obsessive-compulsive-disorder-a-magnetoencephalography-study
#12
Min Jung Koh, Jaeho Seol, Jee In Kang, Bong-Soo Kim, Kee Namkoong, Jin Woo Chang, Se Joo Kim
Aberrant cortical-striatal-thalamic-cortical circuits have been implicated in the pathophysiology of obsessive-compulsive disorder (OCD). However, the neurobiological basis of OCD remains unclear. We compared patterns of functional connectivity in patients with OCD and in healthy controls using resting-state magnetoencephalography (MEG). Participants comprised 24 patients with OCD (21 men, 3 women) and 22 age- and sex-matched healthy controls (19 men, 3 women). Resting-state measurements were obtained over a 6-min period using a 152-channel whole-head MEG system...
October 28, 2017: International Journal of Psychophysiology
https://www.readbyqxmd.com/read/29106374/the-rate-of-transient-beta-frequency-events-predicts-behavior-across-tasks-and-species
#13
Hyeyoung Shin, Robert Law, Shawn Tsutsui, Christopher I Moore, Stephanie R Jones
Beta oscillations (15-29Hz) are among the most prominent signatures of brain activity. Beta power is predictive of healthy and abnormal behaviors, including perception, attention and motor action. In non-averaged signals, beta can emerge as transient high-power 'events'. As such, functionally relevant differences in averaged power across time and trials can reflect changes in event number, power, duration, and/or frequency span. We show that functionally relevant differences in averaged beta power in primary somatosensory neocortex reflect a difference in the number of high-power beta events per trial, i...
November 6, 2017: ELife
https://www.readbyqxmd.com/read/29103032/alterations-of-effective-connectivity-patterns-in-mild-cognitive-impairment-an-meg-study
#14
Carlos Gómez, Celia Juan-Cruz, Jesús Poza, Saúl J Ruiz-Gómez, Javier Gomez-Pilar, Pablo Núñez, María García, Alberto Fernández, Roberto Hornero
Neuroimaging techniques have demonstrated over the years their ability to characterize the brain abnormalities associated with different neurodegenerative diseases. Among all these techniques, magnetoencephalography (MEG) stands out by its high temporal resolution and noninvasiveness. The aim of the present study is to explore the coupling patterns of resting-state MEG activity in subjects with mild cognitive impairment (MCI). To achieve this goal, five minutes of spontaneous MEG activity were acquired with a 148-channel whole-head magnetometer from 18 MCI patients and 26 healthy controls...
October 30, 2017: Journal of Alzheimer's Disease: JAD
https://www.readbyqxmd.com/read/29102813/spontaneous-brain-oscillations-as-neural-fingerprints-of-working-memory-capacities-a-resting-state-meg-study
#15
Victor Oswald, Younes Zerouali, Aubrée Boulet-Craig, Maja Krajinovic, Caroline Laverdière, Daniel Sinnett, Pierre Jolicoeur, Sarah Lippé, Karim Jerbi, Philippe Robaey
Short-term storage and mental information manipulation capacities in the human brain are key to healthy cognition. These brain processes collectively known as working memory (WM) are associated with modulations of rhythmic brain activity across multiple brain areas and frequencies. Yet, it is not clear whether - and, if so, how-intrinsic resting-state neuronal oscillations are related to individual WM capacities, as measured by standard neuropsychological tests. We addressed this question by probing the correlation between resting-state brain activity, recorded with magnetoencephalography (MEG), and verbal and visuo-spatial WM indices obtained from the standardized Wechsler Adult Intelligence Scale (WAIS-IV) and the Wechsler Memory Scale (WMS-IV)...
October 3, 2017: Cortex; a Journal Devoted to the Study of the Nervous System and Behavior
https://www.readbyqxmd.com/read/29102808/causal-cortical-dynamics-of-a-predictive-enhancement-of-speech-intelligibility
#16
Giovanni M Di Liberto, Edmund C Lalor, Rebecca E Millman
Speech perception may be underpinned by a hierarchical cortical system, which attempts to match "external" incoming sensory inputs with "internal" top-down predictions. Prior knowledge modulates internal predictions of an upcoming stimulus and exerts its effects in temporal and inferior frontal cortex. Here, we used source-space magnetoencephalography (MEG) to study the spatiotemporal dynamics underpinning the integration of prior knowledge in the speech processing network. Prior knowledge was manipulated to i) increase the perceived intelligibility of speech sentences, and ii) dissociate the perceptual effects of changes in speech intelligibility from acoustical differences in speech stimuli...
November 2, 2017: NeuroImage
https://www.readbyqxmd.com/read/29101022/lsd-modulates-effective-connectivity-and-neural-adaptation-mechanisms-in-an-auditory-oddball-paradigm
#17
REVIEW
Christopher Timmermann, Meg J Spriggs, Mendel Kaelen, Robert Leech, David J Nutt, Rosalyn J Moran, Robin L Carhart-Harris, Suresh D Muthukumaraswamy
Under the predictive coding framework, perceptual learning and inference are dependent on the interaction between top-down predictions and bottom-up sensory signals both between and within regions in a network. However, how such feedback and feedforward connections are modulated in the state induced by lysergic acid diethylamide (LSD) is poorly understood. In this study, an auditory oddball paradigm was presented to healthy participants (16 males, 4 female) under LSD and placebo, and brain activity was recorded using magnetoencephalography (MEG)...
October 31, 2017: Neuropharmacology
https://www.readbyqxmd.com/read/29095816/concurrent-temporal-channels-for-auditory-processing-oscillatory-neural-entrainment-reveals-segregation-of-function-at-different-scales
#18
Xiangbin Teng, Xing Tian, Jess Rowland, David Poeppel
Natural sounds convey perceptually relevant information over multiple timescales, and the necessary extraction of multi-timescale information requires the auditory system to work over distinct ranges. The simplest hypothesis suggests that temporal modulations are encoded in an equivalent manner within a reasonable intermediate range. We show that the human auditory system selectively and preferentially tracks acoustic dynamics concurrently at 2 timescales corresponding to the neurophysiological theta band (4-7 Hz) and gamma band ranges (31-45 Hz) but, contrary to expectation, not at the timescale corresponding to alpha (8-12 Hz), which has also been found to be related to auditory perception...
November 2017: PLoS Biology
https://www.readbyqxmd.com/read/29079768/non-invasive-detection-of-language-related-prefrontal-high-gamma-band-activity-with-beamforming-meg
#19
Hiroaki Hashimoto, Yuka Hasegawa, Toshihiko Araki, Hisato Sugata, Takufumi Yanagisawa, Shiro Yorifuji, Masayuki Hirata
High gamma band (>50 Hz) activity is a key oscillatory phenomenon of brain activation. However, there has not been a non-invasive method established to detect language-related high gamma band activity. We used a 160-channel whole-head magnetoencephalography (MEG) system equipped with superconducting quantum interference device (SQUID) gradiometers to non-invasively investigate neuromagnetic activities during silent reading and verb generation tasks in 15 healthy participants. Individual data were divided into alpha (8-13 Hz), beta (13-25 Hz), low gamma (25-50 Hz), and high gamma (50-100 Hz) bands and analysed with the beamformer method...
October 27, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29078281/multimodal-mapping-of-the-brain-s-functional-connectivity-and-the-adult-outcome-of-attention-deficit-hyperactivity-disorder
#20
Gustavo Sudre, Eszter Szekely, Wendy Sharp, Steven Kasparek, Philip Shaw
We have a limited understanding of why many children with attention deficit hyperactivity disorder do not outgrow the disorder by adulthood. Around 20-30% retain the full syndrome as young adults, and about 50% show partial, rather than complete, remission. Here, to delineate the neurobiology of this variable outcome, we ask if the persistence of childhood symptoms into adulthood impacts on the brain's functional connectivity. We studied 205 participants followed clinically since childhood. In early adulthood, participants underwent magnetoencephalography (MEG) to measure neuronal activity directly and functional MRI (fMRI) to measure hemodynamic activity during a task-free period (the "resting state")...
October 31, 2017: Proceedings of the National Academy of Sciences of the United States of America
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