Search results for "magnetoencephalograph"

Building blocks of fetal cognition: emotion and language

2010

Magnetoencephalography (MEG) can be effectively used to record fetal and neonatal cognitive abilities/functions by recording completely non-invasively the magnetic fields produced by the active neurons in the brain. During the last trimester and the first months of life, the cognitive capabilities related to emotion recognition and language acquisition develop rapidly. Latest research shows that already the newborn has advanced abilities related to processing emotional information and speech sounds. These abilities form the basis of the child's development towards mastering social tasks and native language. The possibilities of using fetal or neonatal MEG in studying these important abiliti…

Prior Precision Modulates the Minimization of Auditory Prediction Error

2019

International audience; The predictive coding model of perception proposes that successful representation of the perceptual world depends upon canceling out the discrepancy between prediction and sensory input (i.e., prediction error). Recent studies further suggest a distinction to be made between prediction error triggered by non-predicted stimuli of different prior precision (i.e., inverse variance). However, it is not fully understood how prediction error with different precision levels is minimized in the predictive process. Here, we conducted a magnetoencephalography (MEG) experiment which orthogonally manipulated prime-probe relation (for contextual precision) and stimulus repetition…

Coherence between brain activation and speech envelope at word and sentence levels showed age-related differences in low frequency bands

2021

Abstract Speech perception is dynamic and shows changes across development. In parallel, functional differences in brain development over time have been well documented and these differences may interact with changes in speech perception during infancy and childhood. Further, there is evidence that the two hemispheres contribute unequally to speech segmentation at the sentence and phonemic levels. To disentangle those contributions, we studied the cortical tracking of various sized units of speech that are crucial for spoken language processing in children (4.7–9.3 years old, N = 34) and adults (N = 19). We measured participants’ magnetoencephalogram (MEG) responses to syllables, words, and…

Prefix Stripping Re-Re-Revisited: MEG Investigations of Morphological Decomposition and Recomposition

2019

We revisit a long-standing question in the psycholinguistic and neurolinguistic literature on comprehending morphologically complex words: are prefixes and suffixes processed using the same cognitive mechanisms? Recent work using Magnetoencephalography (MEG) to uncover the dynamic temporal and spatial responses evoked by visually presented complex suffixed single words provide us with a comprehensive picture of morphological processing in the brain, from early, form-based decomposition, through lexical access, grammatically constrained recomposition, and semantic interpretation. In the present study, we find that MEG responses to prefixed words reveal interesting early differences in the la…

A Meshfree Solver for the MEG Forward Problem

2015

Noninvasive estimation of brain activity via magnetoencephalography (MEG) involves an inverse problem whose solution requires an accurate and fast forward solver. To this end, we propose the Method of Fundamental Solutions (MFS) as a meshfree alternative to the Boundary Element Method (BEM). The solution of the MEG forward problem is obtained, via the Method of Particular Solutions (MPS), by numerically solving a boundary value problem for the electric scalar potential, derived from the quasi-stationary approximation of Maxwell’s equations. The magnetic field is then computed by the Biot-Savart law. Numerical experiments have been carried out in a realistic single-shell head geometry. The p…

2020

Abstract Efficient neuronal communication between brain regions through oscillatory synchronization at certain frequencies is necessary for cognition. Such synchronized networks are transient and dynamic, established on the timescale of milliseconds in order to support ongoing cognitive operations. However, few studies characterizing dynamic electrophysiological brain networks have simultaneously accounted for temporal non-stationarity, spectral structure, and spatial properties. Here, we propose an analysis framework for characterizing the large-scale phase-coupling network dynamics during task performance using magnetoencephalography (MEG). We exploit the high spatiotemporal resolution of…

The neural basis of sublexical speech and corresponding nonspeech processing: a combined EEG-MEG study.

2014

Abstract We addressed the neural organization of speech versus nonspeech sound processing by investigating preattentive cortical auditory processing of changes in five features of a consonant–vowel syllable (consonant, vowel, sound duration, frequency, and intensity) and their acoustically matched nonspeech counterparts in a simultaneous EEG–MEG recording of mismatch negativity (MMN/MMNm). Overall, speech–sound processing was enhanced compared to nonspeech sound processing. This effect was strongest for changes which affect word meaning (consonant, vowel, and vowel duration) in the left and for the vowel identity change in the right hemisphere also. Furthermore, in the right hemisphere, spe…

Exploring Frequency-Dependent Brain Networks from Ongoing EEG Using Spatial ICA During Music Listening

2020

Recently, exploring brain activity based on functional networks during naturalistic stimuli especially music and video represents an attractive challenge because of the low signal-to-noise ratio in collected brain data. Although most efforts focusing on exploring the listening brain have been made through functional magnetic resonance imaging (fMRI), sensor-level electro- or magnetoencephalography (EEG/MEG) technique, little is known about how neural rhythms are involved in the brain network activity under naturalistic stimuli. This study exploited cortical oscillations through analysis of ongoing EEG and musical feature during freely listening to music. We used a data-driven method that co…

Neuroimaging and electrophysiology meet invasive neurostimulation for causal interrogations and modulations of brain states.

2020

Deep brain stimulation (DBS) has developed over the last twenty years into a highly effective evidenced-based treatment option for neuropsychiatric disorders. Moreover, it has become a fascinating tool to provide illustrative insights into the functioning of brain networks. New anatomical and pathophysiological models of DBS action have accelerated our understanding of neurological and psychiatric disorders and brain functioning. The description of the brain networks arose through the unique ability to illustrate long-range interactions between interconnected brain regions as derived from state-of-the-art neuroimaging (structural, diffusion, and functional MRI) and the opportunity to record…

EEG and MEG primers for tracking DBS network effects

2020

Deep brain stimulation (DBS) is an effective treatment method for a range of neurological and psychiatric disorders. It involves implantation of stimulating electrodes in a precisely guided fashion into subcortical structures and, at a later stage, chronic stimulation of these structures with an implantable pulse generator. While the DBS surgery makes it possible to both record brain activity and stimulate parts of the brain that are difficult to reach with non-invasive techniques, electroencephalography (EEG) and magnetoencephalography (MEG) provide complementary information from other brain areas, which can be used to characterize brain networks targeted through DBS. This requires, howeve…