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Magnetoencephalography

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https://www.readbyqxmd.com/read/28723578/convolutional-neural-network-based-encoding-and-decoding-of-visual-object-recognition-in-space-and-time
#1
REVIEW
K Seeliger, M Fritsche, U Güçlü, S Schoenmakers, J-M Schoffelen, S E Bosch, M A J van Gerven
Representations learned by deep convolutional neural networks (CNNs) for object recognition are a widely investigated model of the processing hierarchy in the human visual system. Using functional magnetic resonance imaging, CNN representations of visual stimuli have previously been shown to correspond to processing stages in the ventral and dorsal streams of the visual system. Whether this correspondence between models and brain signals also holds for activity acquired at high temporal resolution has been explored less exhaustively...
July 16, 2017: NeuroImage
https://www.readbyqxmd.com/read/28719422/polarity-independent-effects-of-transcranial-direct-current-stimulation-over-the-bilateral-opercular-somatosensory-region-a-magnetoencephalography-study
#2
Kei Nakagawa, Soichiro Koyama, Koji Inui, Satoshi Tanaka, Ryusuke Kakigi, Norihiro Sadato
The opercular somatosensory region (OP) plays an indispensable role in pain perception. In the present study, we investigated the neurophysiological effects of transcranial direct current stimulation (tDCS) over the OP. Somatosensory-evoked magnetic fields following noxious intraepidermal electrical stimulation to the left index finger (pain-SEFs) were recorded before and after tDCS with a single-blind, sham-controlled, cross-over trial design. Three tDCS conditions of left anodal/right cathodal tDCS, left cathodal/right anodal tDCS (each, 2 mA, 12 min), and sham tDCS (2 mA, 15 s) were applied...
July 17, 2017: Neuroreport
https://www.readbyqxmd.com/read/28718763/a-theory-of-working-memory-without-consciousness-or-sustained-activity
#3
Darinka Trübutschek, Sébastien Marti, Andrés Ojeda, Jean-Rémi King, Yuanyuan Mi, Misha Tsodyks, Stanislas Dehaene
Working memory and conscious perception are thought to share similar brain mechanisms, yet recent reports of non-conscious working memory challenge this view. Combining visual masking with magnetoencephalography, we investigate the reality of non-conscious working memory and dissect its neural mechanisms. In a spatial delayed-response task, participants reported the location of a subjectively unseen target above chance-level after several seconds. Conscious perception and conscious working memory were characterized by similar signatures: a sustained desynchronization in the alpha/beta band over frontal cortex, and a decodable representation of target location in posterior sensors...
July 18, 2017: ELife
https://www.readbyqxmd.com/read/28716718/multivariate-pattern-analysis-of-meg-and-eeg-a-comparison-of-representational-structure-in-time-and-space
#4
Radoslaw Martin Cichy, Dimitrios Pantazis
Multivariate pattern analysis of magnetoencephalography (MEG) and electroencephalography (EEG) data can reveal the rapid neural dynamics underlying cognition. However, MEG and EEG have systematic differences in sampling neural activity. This poses the question to which degree such measurement differences consistently bias the results of multivariate analysis applied to MEG and EEG activation patterns. To investigate, we conducted a concurrent MEG/EEG study while participants viewed images of everyday objects...
July 14, 2017: NeuroImage
https://www.readbyqxmd.com/read/28716297/on-the-relative-merits-of-invasive-and-non-invasive-pre-surgical-brain-mapping-new-tools-in-ablative-epilepsy-surgery
#5
Andrew C Papanicolaou, Roozbeh Rezaie, Shalini Narayana, Asim F Choudhri, Abbas-Babajani-Feremi, Frederick A Boop, James W Wheless
Cortical Stimulation Mapping (CSM) and the Wada procedure have long been considered the gold standard for localizing motor and language-related cortical areas and for determining the language and memory-dominant hemisphere, respectively. In recent years, however, non-invasive methods such as magnetoencephalography (MEG), functional magnetic resonance imaging (fMRI), and transcranial magnetic stimulation (TMS) have emerged as promising alternatives to the aforementioned procedures, particularly in cases where the invasive localization of eloquent cortex has proven to be challenging...
July 3, 2017: Epilepsy Research
https://www.readbyqxmd.com/read/28714589/meg-biomarker-of-alzheimer-s-disease-absence-of-a-prefrontal-generator-during-auditory-sensory-gating
#6
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/28714584/oscillations-during-observations-dynamic-oscillatory-networks-serving-visuospatial-attention
#7
Alex I Wiesman, Elizabeth Heinrichs-Graham, Amy L Proskovec, Timothy J McDermott, Tony W Wilson
The dynamic allocation of neural resources to discrete features within a visual scene enables us to react quickly and accurately to salient environmental circumstances. A network of bilateral cortical regions is known to subserve such visuospatial attention functions; however the oscillatory and functional connectivity dynamics of information coding within this network are not fully understood. Particularly, the coding of information within prototypical attention-network hubs and the subsecond functional connections formed between these hubs have not been adequately characterized...
July 17, 2017: Human Brain Mapping
https://www.readbyqxmd.com/read/28713260/automated-detection-of-epileptic-biomarkers-in-resting-state-interictal-meg-data
#8
Miguel C Soriano, Guiomar Niso, Jillian Clements, Silvia Ortín, Sira Carrasco, María Gudín, Claudio R Mirasso, Ernesto Pereda
Certain differences between brain networks of healthy and epilectic subjects have been reported even during the interictal activity, in which no epileptic seizures occur. Here, magnetoencephalography (MEG) data recorded in the resting state is used to discriminate between healthy subjects and patients with either idiopathic generalized epilepsy or frontal focal epilepsy. Signal features extracted from interictal periods without any epileptiform activity are used to train a machine learning algorithm to draw a diagnosis...
2017: Frontiers in Neuroinformatics
https://www.readbyqxmd.com/read/28711663/cognitive-workload-across-the-spectrum-of-cognitive-impairments-a-systematic-review-of-physiological-measures
#9
REVIEW
Maud Ranchet, John C Morgan, Abiodun E Akinwuntan, Hannes Devos
Our objective was to identify the physiological measures that are sensitive to assessing cognitive workload across the spectrum of cognitive impairments. Three database searches were conducted: PubMed, PsychINFO, and Web of Science. Studies from the last decade that used physiological measures of cognitive workload in older adults (mean age >65 years-old) were reviewed. The cognitive workload of healthy older individuals was compared with the cognitive workload of younger adults, patients with mild cognitive impairment (MCI), and patients with Alzheimer's diseases (AD)...
July 12, 2017: Neuroscience and Biobehavioral Reviews
https://www.readbyqxmd.com/read/28702351/activation-of-dominant-hemisphere-association-cortex-during-naming-as-a-function-of-cognitive-performance-in-mild-traumatic-brain-injury-insights-into-mechanisms-of-lexical-access
#10
Mihai Popescu, John D Hughes, Elena-Anda Popescu, Judy Mikola, Warren Merrifield, Maria DeGraba, Gerard Riedy, Thomas J DeGraba
Patients with a history of mild traumatic brain injury (mTBI) and objective cognitive deficits frequently experience word finding difficulties in normal conversation. We sought to improve our understanding of this phenomenon by determining if the scores on standardized cognitive testing are correlated with measures of brain activity evoked in a word retrieval task (confrontational picture naming). The study participants (n = 57) were military service members with a history of mTBI. The General Memory Index (GMI) determined after administration of the Rivermead Behavioral Memory Test, Third Edition, was used to assign subjects to three groups: low cognitive performance (Group 1: GMI ≤ 87, n = 18), intermediate cognitive performance (Group 2: 88 ≤ GMI ≤ 99, n = 18), and high cognitive performance (Group 3: GMI ≥ 100, n = 21)...
2017: NeuroImage: Clinical
https://www.readbyqxmd.com/read/28702344/directional-information-flow-in-patients-with-alzheimer-s-disease-a-source-space-resting-state-meg-study
#11
M M A Engels, M Yu, C J Stam, A A Gouw, W M van der Flier, Ph Scheltens, E C W van Straaten, A Hillebrand
In a recent magnetoencephalography (MEG) study, we found posterior-to-anterior information flow over the cortex in higher frequency bands in healthy subjects, with a reversed pattern in the theta band. A disruption of information flow may underlie clinical symptoms in Alzheimer's disease (AD). In AD, highly connected regions (hubs) in posterior areas are mostly disrupted. We therefore hypothesized that in AD the information flow from these hub regions would be disturbed. We used resting-state MEG recordings from 27 early-onset AD patients and 26 healthy controls...
2017: NeuroImage: Clinical
https://www.readbyqxmd.com/read/28701945/magnetoencephalography-in-preoperative-epileptic-foci-localization-enlightenment-from-cognitive-studies
#12
REVIEW
Qian Wang, Pengfei Teng, Guoming Luan
Over 30% epileptic patients are refractory to medication, who are amenable to neurosurgical treatment. Non-invasive brain imaging technologies including video-electroencephalogram (EEG), magnetic resonance imaging (MRI), and magnetoencephalography (MEG) are widely used in presurgical assessment of epileptic patients. This review mainly discussed the current development of clinical MEG imaging as a diagnose approach, and its correlations with the golden standard intracranial electroencephalogram (iEEG). More importantly, this review discussed the possible applications of functional networks in preoperative epileptic foci localization in future studies...
2017: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/28698376/frequency-specific-directed-interactions-in-the-human-brain-network-for-language
#13
Jan-Mathijs Schoffelen, Annika Hultén, Nietzsche Lam, André F Marquand, Julia Uddén, Peter Hagoort
The brain's remarkable capacity for language requires bidirectional interactions between functionally specialized brain regions. We used magnetoencephalography to investigate interregional interactions in the brain network for language while 102 participants were reading sentences. Using Granger causality analysis, we identified inferior frontal cortex and anterior temporal regions to receive widespread input and middle temporal regions to send widespread output. This fits well with the notion that these regions play a central role in language processing...
July 11, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28694855/the-effects-of-sweet-bitter-salty-and-sour-stimuli-on-alpha-rhythm-a-meg-study
#14
Athanasia Kotini, Photios Anninos, Triandafillos Gemousakakis, Adam Adamopoulos
OBJECTIVE: the possible diff erences in processing gustatory stimuli in healthy subjects was investigated by magnetoencephalography (meg). MATHERIAL AND METHOD: meg recordings were evaluated for 10 healthy volunteers (3 men within the age range 20-46 years, 7 women within the age range 10-28 years), with four diff erent gustatory stimuli: sweet, bi" er, sour and salty. Fast fourier transform was performed on meg epochs recorded for the above conditions and the eff ect of each kind of stimuli on alpha rhythm was examined...
September 2016: Mædica
https://www.readbyqxmd.com/read/28694336/magnified-neural-envelope-coding-predicts-deficits-in-speech-perception-in-noise
#15
Rebecca E Millman, Sven L Mattys, André D Gouws, Garreth Prendergast
Verbal communication in noisy backgrounds is challenging. Understanding speech in background noise that fluctuates in intensity over time is particularly difficult for hearing-impaired listeners with a sensorineural hearing loss (SNHL). The reduction in fast-acting cochlear compression associated with SNHL exaggerates the perceived fluctuations in intensity in amplitude-modulated sounds. SNHL-induced changes in the coding of amplitude-modulated sounds may have a detrimental effect on the ability of SNHL listeners to understand speech in the presence of modulated background noise...
July 10, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28692453/neuromagnetic-evaluation-of-a-communication-support-system-for-hearing-impaired-patients
#16
Kei Nakagawa, Shinichiro Nakaishi, Takeshi Imura, Yumi Kawahara, Akira Hashizume, Kaoru Kurisu, Louis Yuge
Hearing-impaired patients often encounter obstacles in communication. Not all of them wear hearing aids, citing issues with usage difficulty and discomfort in wearing. To overcome these difficulties, a new endeavor was started to improve sound intelligibility from the speaker's side. The present study objectively evaluated an intelligible-hearing (IH) loudspeaker by means of magnetoencephalography. Magnetic counterparts of mismatch negativity (MMNm) to pronunciation ('mi' and 'ni') were recorded and compared when they were transmitted from the IH loudspeaker and from a normal-hearing loudspeaker...
August 16, 2017: Neuroreport
https://www.readbyqxmd.com/read/28666056/high-frequency-oscillations-the-state-of-clinical-research
#17
REVIEW
Birgit Frauscher, Fabrice Bartolomei, Katsuhiro Kobayashi, Jan Cimbalnik, Maryse A van 't Klooster, Stefan Rampp, Hiroshi Otsubo, Yvonne Höller, Joyce Y Wu, Eishi Asano, Jerome Engel, Philippe Kahane, Julia Jacobs, Jean Gotman
Modern electroencephalographic (EEG) technology contributed to the appreciation that the EEG signal outside the classical Berger frequency band contains important information. In epilepsy, research of the past decade focused particularly on interictal high-frequency oscillations (HFOs) > 80 Hz. The first large application of HFOs was in the context of epilepsy surgery. This is now followed by other applications such as assessment of epilepsy severity and monitoring of antiepileptic therapy. This article reviews the evidence on the clinical use of HFOs in epilepsy with an emphasis on the latest developments...
June 30, 2017: Epilepsia
https://www.readbyqxmd.com/read/28665820/magnetoencephalographic-recordings-in-infants-using-a-standard-sized-array-technical-adequacy-and-diagnostic-yield
#18
Sumiya Shibata, John C Mosher, Prakash Kotagal, Ajay Gupta, Andreas V Alexopoulos, Richard C Burgess
PURPOSE: Although a few magnetoencephalography (MEG) systems have been built specifically for infants (<2 years), most children are routinely examined using MEG systems designed primarily to accommodate adult subjects. The practicality of the adult MEG device has not been systematically reviewed in infants with epilepsy. The aim of this study is to investigate whether infant epilepsy patients, whose heads are small relative to the sensor helmet, can have clinically successful MEG recordings using the conventional adult-size MEG device...
June 29, 2017: Journal of Clinical Neurophysiology: Official Publication of the American Electroencephalographic Society
https://www.readbyqxmd.com/read/28662463/meg-language-lateralization-in-partial-epilepsy-using-dspm-of-auditory-event-related-fields
#19
Manoj Raghavan, Zhimin Li, Chad Carlson, Christopher T Anderson, Jeffrey Stout, David S Sabsevitz, Sara J Swanson, Jeffrey R Binder
OBJECTIVE: Methods employed to determine hemispheric language dominance using magnetoencephalography (MEG) have differed significantly across studies in the choice of language-task, the nature of the physiological response studied, recording hardware, and source modeling methods. Our goal was to determine whether an analysis based on distributed source modeling can replicate the results of prior studies that have used dipole-modeling of event-related fields (ERFs) generated by an auditory word-recognition task to determine language dominance in patients with epilepsy...
June 26, 2017: Epilepsy & Behavior: E&B
https://www.readbyqxmd.com/read/28659780/estimation-of-human-workload-from-the-auditory-steady-state-response-recorded-via-a-wearable-electroencephalography-system-during-walking
#20
Yusuke Yokota, Shingo Tanaka, Akihiro Miyamoto, Yasushi Naruse
Workload in the human brain can be a useful marker of internal brain state. However, due to technical limitations, previous workload studies have been unable to record brain activity via conventional electroencephalography (EEG) and magnetoencephalography (MEG) devices in mobile participants. In this study, we used a wearable EEG system to estimate workload while participants walked in a naturalistic environment. Specifically, we used the auditory steady-state response (ASSR) which is an oscillatory brain activity evoked by repetitive auditory stimuli, as an estimation index of workload...
2017: Frontiers in Human Neuroscience
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