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Magnetoencephalography

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https://www.readbyqxmd.com/read/28198413/pre-encoding-gamma-band-activity-during-auditory-working-memory
#1
Jochen Kaiser, Maria Rieder, Cornelius Abel, Benjamin Peters, Christoph Bledowski
Previous magnetoencephalography (MEG) studies have revealed gamma-band activity at sensors over parietal and fronto-temporal cortex during the delay phase of auditory spatial and non-spatial match-to-sample tasks, respectively. While this activity was interpreted as reflecting the memory maintenance of sound features, we noted that task-related activation differences might have been present already prior to the onset of the sample stimulus. The present study focused on the interval between a visual cue indicating which sound feature was to be memorized (lateralization or pitch) and sample sound presentation to test for task-related activation differences preceding stimulus encoding...
February 15, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28195524/the-sources-of-sequential-modulations-of-control-processes-in-arithmetic-strategies-a-magnetoencephalography-study
#2
Thomas Hinault, Jean-Michel Badier, Sylvain Baillet, Patrick Lemaire
In a wide variety of cognitive domains, performance is determined by the selection and execution of cognitive strategies to solve problems. We used magnetoencephalography to identify the brain regions involved and specify the time course of dynamic modulations of executive control processes during strategy execution. Participants performed a computational estimation task in which they were instructed to execute a poorer or better strategy to estimate results of two-digit multiplication problems. When participants were asked to execute the poorer strategy, two distinct sets of brain activations were identified, depending on whether the poorer strategy (engaging the left inferior frontal junction) or the better strategy (engaging ACC) had been executed on the immediately preceding items...
February 14, 2017: Journal of Cognitive Neuroscience
https://www.readbyqxmd.com/read/28195522/source-localization-of-brain-states-associated-with-canonical-neuroimaging-postures
#3
Michael Lifshitz, Robert T Thibault, Raquel R Roth, Amir Raz
Cognitive neuroscientists rarely consider the influence that body position exerts on brain activity; yet, postural variation holds important implications for the acquisition and interpretation of neuroimaging data. Whereas participants in most behavioral and EEG experiments sit upright, many prominent brain imaging techniques (e.g., fMRI) require participants to lie supine. Here we demonstrate that physical comportment profoundly alters baseline brain activity as measured by magnetoencephalography (MEG)-an imaging modality that permits multipostural acquisition...
February 14, 2017: Journal of Cognitive Neuroscience
https://www.readbyqxmd.com/read/28194558/structural-imaging-of-mild-traumatic-brain-injury-may-not-be-enough-overview-of-functional-and-metabolic-imaging-of-mild-traumatic-brain-injury
#4
REVIEW
Samuel S Shin, James W Bales, C Edward Dixon, Misun Hwang
A majority of patients with traumatic brain injury (TBI) present as mild injury with no findings on conventional clinical imaging methods. Due to this difficulty of imaging assessment on mild TBI patients, there has been much emphasis on the development of diffusion imaging modalities such as diffusion tensor imaging (DTI). However, basic science research in TBI shows that many of the functional and metabolic abnormalities in TBI may be present even in the absence of structural damage. Moreover, structural damage may be present at a microscopic and molecular level that is not detectable by structural imaging modality...
February 13, 2017: Brain Imaging and Behavior
https://www.readbyqxmd.com/read/28194133/current-and-emerging-potential-of-magnetoencephalography-in-the-detection-and-localization-of-high-frequency-oscillations-in-epilepsy
#5
REVIEW
Eleonora Tamilia, Joseph R Madsen, Patricia Ellen Grant, Phillip L Pearl, Christos Papadelis
Up to one-third of patients with epilepsy are medically intractable and need resective surgery. To be successful, epilepsy surgery requires a comprehensive preoperative evaluation to define the epileptogenic zone (EZ), the brain area that should be resected to achieve seizure freedom. Due to lack of tools and methods that measure the EZ directly, this area is defined indirectly based on concordant data from a multitude of presurgical non-invasive tests and intracranial recordings. However, the results of these tests are often insufficiently concordant or inconclusive...
2017: Frontiers in Neurology
https://www.readbyqxmd.com/read/28179479/impaired-auditory-to-motor-entrainment-in-parkinson-s-disease
#6
Erik S Te Woerd, Robert Oostenveld, Floris Pieter De Lange, Peter Praamstra
Several electrophysiological studies suggest that PD patients have a reduced tendency to entrain to regular environmental patterns. Here we investigate whether this reduced entrainment concerns a generalized deficit or is confined to movement-related activity, leaving sensory entrainment intact. Magnetoencephalography (MEG) was recorded during a rhythmic auditory target detection task in 14 PD patients and 14 control subjects. Participants were instructed to press a button when hearing a target tone amidst an isochronous sequence of standard tones...
February 8, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28175518/206%C3%A2-spikes-slowing-and-functional-connectivity-multimodal-magnetoencephalography-in-epilepsy-surgery
#7
Dario J Englot, John David Rolston, Doris D Wang, Heidi E Kirsch, Srikantan S Nagarajan, Edward F Chang
No abstract text is available yet for this article.
August 1, 2016: Neurosurgery
https://www.readbyqxmd.com/read/28174530/an-event-related-field-study-of-rapid-grammatical-plasticity-in-adult-second-language-learners
#8
Ainhoa Bastarrika, Douglas J Davidson
The present study used magnetoencephalography (MEG) to investigate how Spanish adult learners of Basque respond to morphosyntactic violations after a short period of training on a small fragment of Basque grammar. Participants (n = 17) were exposed to violation and control phrases in three phases (pretest, training, generalization-test). In each phase participants listened to short Basque phrases and they judged whether they were correct or incorrect. During the pre-test and generalization-test, participants did not receive any feedback...
2017: Frontiers in Human Neuroscience
https://www.readbyqxmd.com/read/28169349/dynamic-hub-load-predicts-cognitive-decline-after-resective-neurosurgery
#9
Ellen W S Carbo, Arjan Hillebrand, Edwin van Dellen, Prejaas Tewarie, Philip C de Witt Hamer, Johannes C Baayen, Martin Klein, Jeroen J G Geurts, Jaap C Reijneveld, Cornelis J Stam, Linda Douw
Resective neurosurgery carries the risk of postoperative cognitive deterioration. The concept of 'hub (over)load', caused by (over)use of the most important brain regions, has been theoretically postulated in relation to symptomatology and neurological disease course, but lacks experimental confirmation. We investigated functional hub load and postsurgical cognitive deterioration in patients undergoing lesion resection. Patients (n = 28) underwent resting-state magnetoencephalography and neuropsychological assessments preoperatively and 1-year after lesion resection...
February 7, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28169281/gating-of-memory-encoding-of-time-delayed-cross-frequency-meg-networks-revealed-by-graph-filtration-based-on-persistent-homology
#10
Jarang Hahm, Hyekyoung Lee, Hyojin Park, Eunjoo Kang, Yu Kyeong Kim, Chun Kee Chung, Hyejin Kang, Dong Soo Lee
To explain gating of memory encoding, magnetoencephalography (MEG) was analyzed over multi-regional network of negative correlations between alpha band power during cue (cue-alpha) and gamma band power during item presentation (item-gamma) in Remember (R) and No-remember (NR) condition. Persistent homology with graph filtration on alpha-gamma correlation disclosed topological invariants to explain memory gating. Instruction compliance (R-hits minus NR-hits) was significantly related to negative coupling between the left superior occipital (cue-alpha) and the left dorsolateral superior frontal gyri (item-gamma) on permutation test, where the coupling was stronger in R than NR...
February 7, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28164736/strength-of-20-hz-rebound-and-motor-recovery-after-stroke
#11
Eeva Parkkonen, Kristina Laaksonen, Harri Piitulainen, Johanna Pekkola, Lauri Parkkonen, Turgut Tatlisumak, Nina Forss
BACKGROUND: Stroke is a major cause of disability worldwide, and effective rehabilitation is crucial to regain skills for independent living. Recently, novel therapeutic approaches manipulating the excitatory-inhibitory balance of the motor cortex have been introduced to boost recovery after stroke. However, stroke-induced neurophysiological changes of the motor cortex may vary despite of similar clinical symptoms. Therefore, better understanding of excitability changes after stroke is essential when developing and targeting novel therapeutic approaches...
January 1, 2017: Neurorehabilitation and Neural Repair
https://www.readbyqxmd.com/read/28158201/children-show-right-lateralized-effects-of-spoken-word-form-learning
#12
Anni Nora, Leena Karvonen, Hanna Renvall, Tiina Parviainen, Jeong-Young Kim, Elisabet Service, Riitta Salmelin
It is commonly thought that phonological learning is different in young children compared to adults, possibly due to the speech processing system not yet having reached full native-language specialization. However, the neurocognitive mechanisms of phonological learning in children are poorly understood. We employed magnetoencephalography (MEG) to track cortical correlates of incidental learning of meaningless word forms over two days as 6-8-year-olds overtly repeated them. Native (Finnish) pseudowords were compared with words of foreign sound structure (Korean) to investigate whether the cortical learning effects would be more dependent on previous proficiency in the language rather than maturational factors...
2017: PloS One
https://www.readbyqxmd.com/read/28155864/aberrant-neuronal-dynamics-during-working-memory-operations-in-the-aging-hiv-infected-brain
#13
Tony W Wilson, Amy L Proskovec, Elizabeth Heinrichs-Graham, Jennifer O'Neill, Kevin R Robertson, Howard S Fox, Susan Swindells
Impairments in working memory are among the most prevalent features of HIV-associated neurocognitive disorders (HAND), yet their origins are unknown, with some studies arguing that encoding operations are disturbed and others supporting deficits in memory maintenance. The current investigation directly addresses this issue by using a dynamic mapping approach to identify when and where processing in working memory circuits degrades. HIV-infected older adults and a demographically-matched group of uninfected controls performed a verbal working memory task during magnetoencephalography (MEG)...
February 3, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28149919/comparison-of-group-level-source-localized-activity-for-simultaneous-functional-near-infrared-spectroscopy-magnetoencephalography-and-simultaneous-fnirs-fmri-during-parametric-median-nerve-stimulation
#14
Theodore Huppert, Jeff Barker, Benjamin Schmidt, Shawn Walls, Avniel Ghuman
Functional near-infrared spectroscopy (fNIRS) is a noninvasive neuroimaging technique, which uses light to measure changes in cerebral blood oxygenation through sensors placed on the surface of the scalp. We recorded concurrent fNIRS with magnetoencephalography (MEG) and functional magnetic resonance imaging (fMRI) in order to investigate the group-level correspondence of these measures with source-localized fNIRS estimates. Healthy participants took part in both a concurrent fNIRS-MEG and fNIRS-fMRI neuroimaging session during two somatosensory stimulation tasks, a blocked design median nerve localizer and parametric pulsed-pair median nerve stimulation using interpulse intervals from 100 to 500 ms...
January 2017: Neurophotonics
https://www.readbyqxmd.com/read/28141836/effects-of-visual-speech-on-early-auditory-evoked-fields-from-the-viewpoint-of-individual-variance
#15
Izumi Yahata, Tetsuaki Kawase, Akitake Kanno, Hiroshi Hidaka, Shuichi Sakamoto, Nobukazu Nakasato, Ryuta Kawashima, Yukio Katori
The effects of visual speech (the moving image of the speaker's face uttering speech sound) on early auditory evoked fields (AEFs) were examined using a helmet-shaped magnetoencephalography system in 12 healthy volunteers (9 males, mean age 35.5 years). AEFs (N100m) in response to the monosyllabic sound /be/ were recorded and analyzed under three different visual stimulus conditions, the moving image of the same speaker's face uttering /be/ (congruent visual stimuli) or uttering /ge/ (incongruent visual stimuli), and visual noise (still image processed from speaker's face using a strong Gaussian filter: control condition)...
2017: PloS One
https://www.readbyqxmd.com/read/28131892/using-generative-models-to-make-probabilistic-statements-about-hippocampal-engagement-in-meg
#16
Sofie S Meyer, Holly Rossiter, Matthew J Brookes, Mark W Woolrich, Sven Bestmann, Gareth R Barnes
Magnetoencephalography (MEG) enables non-invasive real time characterization of brain activity. However, convincing demonstrations of signal contributions from deeper sources such as the hippocampus remain controversial and are made difficult by its depth, structural complexity and proximity to neocortex. Here, we demonstrate a method for quantifying hippocampal engagement probabilistically using simulated hippocampal activity and realistic anatomical and electromagnetic source modelling. We construct two generative models, one which supports neuronal current flow on the cortical surface, and one which supports it on both the cortical and hippocampal surfaces...
January 25, 2017: NeuroImage
https://www.readbyqxmd.com/read/28131890/a-new-generation-of-magnetoencephalography-room-temperature-measurements-using-optically-pumped-magnetometers
#17
Elena Boto, Sofie S Meyer, Vishal Shah, Orang Alem, Svenja Knappe, Peter Kruger, T Mark Fromhold, Mark Lim, Paul M Glover, Peter G Morris, Richard Bowtell, Gareth R Barnes, Matthew J Brookes
Advances in the field of quantum sensing mean that magnetic field sensors, operating at room temperature, are now able to achieve sensitivity similar to that of cryogenically cooled devices (SQUIDs). This means that room temperature magnetoencephalography (MEG), with a greatly increased flexibility of sensor placement can now be considered. Further, these new sensors can be placed directly on the scalp surface giving, theoretically, a large increase in the magnitude of the measured signal. Here, we present recordings made using a single optically-pumped magnetometer (OPM) in combination with a 3D-printed head-cast designed to accurately locate and orient the sensor relative to brain anatomy...
January 25, 2017: NeuroImage
https://www.readbyqxmd.com/read/28125984/the-youth-mental-health-risk-and-resilience-study-your-study
#18
Peter J Uhlhaas, Ruchika Gajwani, Joachim Gross, Andrew I Gumley, Stephen M Lawrie, Matthias Schwannauer
BACKGROUND: The transition from adolescence to adulthood is associated with the emergence of psychosis and other mental health problems, highlighting the importance of this developmental period for the understanding of developing psychopathology and individual differences in risk and resilience. The Youth Mental Health Risk and Resilience Study (YouR-Study) aims to identify neurobiological mechanisms and predictors of psychosis-risk with a state-of-the-art neuroimaging approach (Magnetoencephalography, Magnetic Resonance Spectroscopy, Magnetic Resonance Imaging) in combination with core psychological processes, such as affect regulation and attachment, that have been implicated in the development and maintenance of severe mental health problems...
January 26, 2017: BMC Psychiatry
https://www.readbyqxmd.com/read/28116447/localized-n20-component-of-somatosensory-evoked-magnetic-fields-in-frontoparietal-brain-tumor-patients-using-noise-normalized-approaches
#19
Nor Safira Elaina, Aamir Saeed Malik, Wafaa Khazaal Shams, Nasreen Badruddin, Jafri Malin Abdullah, Mohammad Faruque Reza
PURPOSE: To localize sensorimotor cortical activation in 10 patients with frontoparietal tumors using quantitative magnetoencephalography (MEG) with noise-normalized approaches. MATERIAL AND METHODS: Somatosensory evoked magnetic fields (SEFs) were elicited in 10 patients with somatosensory tumors and in 10 control participants using electrical stimulation of the median nerve via the right and left wrists. We localized the N20m component of the SEFs using dynamic statistical parametric mapping (dSPM) and standardized low-resolution brain electromagnetic tomography (sLORETA) combined with 3D magnetic resonance imaging (MRI)...
January 23, 2017: Clinical Neuroradiology
https://www.readbyqxmd.com/read/28113256/the-power-of-connecting-dots-advanced-techniques-to-evaluate-brain-functional-connectivity-in-humans
#20
Fabio Babiloni, James C Gee
Brain functional connectivity estimation allows to depict patterns of cerebral activity not understandable otherwise with the standard brain imaging techniques such as functional magnetic resonance imaging (fMRI) as well as electro or magnetoencephalography (hr-EEG, MEG). This special issue of TBME reports a range of methodological innovations toward the estimation of functional connectivity from brain activity data, with emphasis on neuroelectric and hemodynamic imaging modalities. Functional connectivity methodologies enable "connecting of the dots" derived from brain activity observations over multiple distributed sites, as depicted by such fMRI and hr-EEG/MEG devices...
October 26, 2016: IEEE Transactions on Bio-medical Engineering
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