Search results for "NCEP"
showing 10 items of 3866 documents
Audiovisual processing of Chinese characters elicits suppression and congruency effects in MEG
2019
Learning to associate written letters/characters with speech sounds is crucial for reading acquisition. Most previous studies have focused on audiovisual integration in alphabetic languages. Less is known about logographic languages such as Chinese characters, which map onto mostly syllable-based morphemes in the spoken language. Here we investigated how long-term exposure to native language affects the underlying neural mechanisms of audiovisual integration in a logographic language using magnetoencephalography (MEG). MEG sensor and source data from 12 adult native Chinese speakers and a control group of 13 adult Finnish speakers were analyzed for audiovisual suppression (bimodal responses…
More comprehensive proprioceptive stimulation of the hand amplifies its cortical processing
2021
Corticokinematic coherence (CKC) quantifies the phase coupling between limb kinematics and cortical neurophysiological signals reflecting proprioceptive feedback to the primary sensorimotor (SM1) cortex. We studied whether the CKC strength or cortical source location differs between proprioceptive stimulation (i.e., actuator-evoked movements) of right-hand digits (index, middle, ring, and little). Twenty-one volunteers participated in magnetoencephalography measurements during which three conditions were tested: 1) simultaneous stimulation of all four fingers at the same frequency, 2) stimulation of each finger separately at the same frequency, and 3) simultaneous stimulation of the fingers…
Neural generators of the frequency-following response elicited to stimuli of low and high frequency: A magnetoencephalographic (MEG) study.
2021
The frequency-following response (FFR) to periodic complex sounds has gained recent interest in auditory cognitive neuroscience as it captures with great fidelity the tracking accuracy of the periodic sound features in the ascending auditory system. Seminal studies suggested the FFR as a correlate of subcortical sound encoding, yet recent studies aiming to locate its sources challenged this assumption, demonstrating that FFR receives some contribution from the auditory cortex. Based on frequency-specific phase-locking capabilities along the auditory hierarchy, we hypothesized that FFRs to higher frequencies would receive less cortical contribution than those to lower frequencies, hence supp…
Compensated transfer entropy as a tool for reliably estimating information transfer in physiological time series
2013
We present a framework for the estimation of transfer entropy (TE) under the conditions typical of physiological system analysis, featuring short multivariate time series and the presence of instantaneous causality (IC). The framework is based on recognizing that TE can be interpreted as the difference between two conditional entropy (CE) terms, and builds on an efficient CE estimator that compensates for the bias occurring for high dimensional conditioning vectors and follows a sequential embedding procedure whereby the conditioning vectors are formed progressively according to a criterion for CE minimization. The issue of IC is faced accounting for zero-lag interactions according to two a…
Beta-band MEG signal power changes in older adults after physical exercise program with and without additional cognitive training
2023
Physical exercise has been considered to be an efficient mean of preserving cognitive function and it influences both the structural and functional characteristics of the brain. It has especially been shown to increase brain plasticity, the capacity to re-structure brain properties in response to interaction, such as cognitive practice. Studies have also examined the potential additive effect of cognitive training on the documented benefit of physical exercise, commonly, however, not at the neural level. We monitored, using magnetoencephalography (MEG), the brain processes associated with executive functions in older individuals who participated in a 12-month randomized controlled trial inc…
Analysis of Somatosensory Cortical Responses to Different Electrotactile Stimulations as a Method Towards an Objective Definition of Artificial Senso…
2022
Sensory feedback is a critical component in many human-machine interfaces (e.g., bionic limbs) to provide missing sensations. Specifically, electrotactile stimulation is a popular feedback modality able to evoke configurable sensations by modulating pulse amplitude, duration, and frequency of the applied stimuli. However, these sensations coded by electrotactile parameters are thus far predominantly determined by subjective user reports, which leads to heterogeneous and unstable feedback delivery. Thus, a more objective understanding of the impact that different stimulation parameters induce in the brain, is needed. Analysis of cortical responses to electrotactile afference might be an effe…
Gating Patterns to Proprioceptive Stimulation in Various Cortical Areas : An MEG Study in Children and Adults using Spatial ICA
2020
Proprioceptive paired-stimulus paradigm was used for 30 children (10–17 years) and 21 adult (25–45 years) volunteers in magnetoencephalography (MEG). Their right index finger was moved twice with 500-ms interval every 4 ± 25 s (repeated 100 times) using a pneumatic-movement actuator. Spatial-independent component analysis (ICA) was applied to identify stimulus-related components from MEG cortical responses. Clustering was used to identify spatiotemporally consistent components across subjects. We found a consistent primary response in the primary somatosensory (SI) cortex with similar gating ratios of 0.72 and 0.69 for the children and adults, respectively. Secondary responses with similar …
Effects of physical activity on neural markers of attention in children
2016
Huoli passiivisen elämäntavan vaikutuksista oppimisen edellytyksiin on kasvanut, kun lasten fyysinen aktiivisuus on vähentynyt. Useat tutkimukset tukevat fyysisen aktiivisuuden suojaavaa vaikutusta erilaisiin kognitiivisiin toimintoihin. Tarkkaavaisuuden kohdistaminen relevantteihin ärsykkeisiin näyttää olevan merkittävä osa oppimista, minkä vuoksi mielenkiinto on kohdistettu nykytutkimuksessa tarkkaavaisuuden mekanismeihin. Alfa-oskillaatioiden inhibitorinen rooli tarkkaavaisuudessa on saanut vahvistusta spatiaalista tarkkaavaisuutta selvittäneistä tutkimuksista. Alfa-oskillaatioiden on havaittu lateralisoituvan siten, että alfa-aktiivisuus laskee näköärsykettä prosessoivalla aivokuorella …
Dynamics of morphological processing in pre-school children with and without familial risk for dyslexia
2020
Difficulties in phonological processing and speech perception are associated with developmental dyslexia, but there is considerable diversity across people with developmental dyslexia (e.g., dyslexics with and without phonological difficulties). Phonological and morphological awareness are both known to play an important role in reading acquisition. Problems in morpho-phonological information processing could arguably be associated with developmental dyslexia, especially for Finnish, which is a rich morphologically language. We used MEG to study the connection between morpho-phonology in the Finnish language and familial risk for developmental dyslexia. We measured event-related fields (ERF…
Somatosensory evoked fields after exercise induced pain
2017
The amount of research utilizing magnetoencephalography (MEG) has increased within the last few decades because of the development and better availability of equipment. With MEG, different areas of brain functionality can be studied in a variety of tasks and pathologies. Somatosensory evoked fields (SEF) are magnetic fields generated by tens of thousands of neurons firing in the primary somatosensory cortex. The purpose of this master’s thesis is to study the modulation of SEFs after exercise induced pain. The study was carried out in Jyväskylä Centre for Interdisciplinary Brain Research (CIBR). The study subjects (N=18, male 10, female 8) were healthy and suitable for MEG measurements. Dat…