Search results for "magnetoencephalograph"

Context-dependent minimisation of prediction errors involves temporal-frontal activation

2020

According to the predictive coding model of perception, the brain constantly generates predictions of the upcoming sensory inputs. Perception is realised through a hierarchical generative model which aims at minimising the discrepancy between predictions and the incoming sensory inputs (i.e., prediction errors). Notably, prediction errors are weighted depending on precision of prior information. However, it remains unclear whether and how the brain monitors prior precision when minimising prediction errors in different contexts. The current study used magnetoencephalography (MEG) to address this question. We presented participants with repetition of two non-predicted probes embedded in cont…

Prior precision modulates the minimisation of prediction error in human auditory cortex

2018

AbstractThe predictive coding model of perception proposes that successful representation of the perceptual world depends upon cancelling out the discrepancy between prediction and sensory input (i.e., prediction error). Recent studies further suggest a distinction between prediction error associated with non-predicted stimuli of different prior precision (i.e., inverse variance). However, it is not fully understood how prediction error from different precision levels is minimised in the predictive process. The current research used magnetoencephalography (MEG) to examine whether prior precision modulates the cortical dynamics of the making of perceptual inferences. We presented participant…

Neural Mechanisms Underlying Human Auditory Evoked Responses Revealed By Human Neocortical Neurosolver

2022

Funding Information: This study was supported by National Institutes of Health (Grant Nos. NIBIB RO1 EB022889, NIMH RO1 MH106174). Publisher Copyright: © 2021, The Author(s). Auditory evoked fields (AEFs) are commonly studied, yet their underlying neural mechanisms remain poorly understood. Here, we used the biophysical modelling software Human Neocortical Neurosolver (HNN) whose foundation is a canonical neocortical circuit model to interpret the cell and network mechanisms contributing to macroscale AEFs elicited by a simple tone, measured with magnetoencephalography. We found that AEFs can be reproduced by activating the neocortical circuit through a layer specific sequence of feedforwar…

Studi numerici per la magnetoencefalografia

2012

Bio-electromagnetic Numerical Modeling for Health Diagnostics

Spatiotemporal Dynamics of the Processing of Spoken Inflected and Derived Words:A Combined EEG and MEG Study

2011

The spatiotemporal dynamics of the neural processing of spoken morphologically complex words are still an open issue. In the current study, we investigated the time course and neural sources of spoken inflected and derived words using simultaneously recorded electroencephalography (EEG) and magnetoencephalography (MEG) responses. Ten participants (native speakers) listened to inflected, derived, and monomorphemic Finnish words and judged their acceptability. EEG and MEG responses were time-locked to both the stimulus onset and the critical point (suffix onset for complex words, uniqueness point for monomorphemic words). The ERP results showed that inflected words elicited a larger left-late…

Musical sound processing in the human brain. Evidence from electric and magnetic recordings.

2001

Recently, our knowledge regarding the brain's ability to represent invariant features of musical information even during the performance of a simultaneous task (unrelated to the sounds) has accumulated rapidly. Recordings of the change-specific mismatch negativity component of event-related brain potentials have shown that temporally and spectrally complex sounds as well as their relations are automatically processed by human auditory cortex. Furthermore, recent magnetoencephalographic and positron emission topographic investigations indicate that this processing differs between phonetic and musical sounds within and between the cerebral hemispheres. These data thus suggest that despite the…

2021

Abstract Developmental dyslexia is a specific learning disorder with impairments in reading and spelling acquisition. Apart from literacy problems, dyslexics show inefficient speech encoding and deficient novel word learning, with underlying problems in phonological processing and learning. These problems have been suggested to be related to deficient specialization of the left hemisphere for language processing. To examine this possibility, we tracked with magnetoencephalography (MEG) the activation of the bilateral temporal cortices during formation of neural memory traces for new spoken word forms in 7–8-year-old children with high familial dyslexia risk and in controls. The at-risk chil…

2020

Learning to associate written letters with speech sounds is crucial for the initial phase of acquiring reading skills. However, little is known about the cortical reorganization for supporting letter-speech sound learning, particularly the brain dynamics during the learning of grapheme-phoneme associations. In the present study, we trained 30 Finnish participants (mean age: 24.33 years, SD: 3.50 years) to associate novel foreign letters with familiar Finnish speech sounds on two consecutive days (first day ​~ ​50 ​min; second day ​~ ​25 ​min), while neural activity was measured using magnetoencephalography (MEG). Two sets of audiovisual stimuli were used for the training in which the graphe…

Modulation in alpha band activity reflects syntax composition: an MEG study of minimal syntactic binding

2021

Successful sentence comprehension requires the binding, or composition, of multiple words into larger structures to establish meaning. Using magnetoencephalography (MEG), we investigated the neural mechanisms involved in binding of language at the level of syntax, in a task in which contributions from semantics were minimized. Participants were auditorily presented with minimal sentences that required binding (pronoun and pseudo-verb with the corresponding morphological inflection; "she grushes") and wordlists that did not require binding (two pseudo-verbs; "cugged grushes"). Relative to the no binding wordlist condition, we found that syntactic binding in a minimal sentence structure was a…