Search results for "kuori"
showing 10 items of 105 documents
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…
Identification of proprioceptive thalamocortical tracts in children: comparison of fMRI, MEG, and manual seeding of probabilistic tractography
2022
Publisher Copyright: © The Author(s) 2022. Published by Oxford University Press. Studying white matter connections with tractography is a promising approach to understand the development of different brain processes, such as proprioception. An emerging method is to use functional brain imaging to select the cortical seed points for tractography, which is considered to improve the functional relevance and validity of the studied connections. However, it is unknown whether different functional seeding methods affect the spatial and microstructural properties of the given white matter connection. Here, we compared functional magnetic resonance imaging, magnetoencephalography, and manual seedin…
Deviance detection in sound frequency in simple and complex sounds in urethane-anesthetized rats
2019
Mismatch negativity (MMN), which is an electrophysiological response demonstrated in humans and animals, reflects memory-based deviance detection in a series of sounds. However, only a few studies on rodents have used control conditions that were sufficient in eliminating confounding factors that could also explain differential responses to deviant sounds. Furthermore, it is unclear if change detection occurs similarly for sinusoidal and complex sounds. In this study, we investigated frequency change detection in urethane-anesthetized rats by recording local-field potentials from the dura above the auditory cortex. We studied change detection in sinusoidal and complex sounds in a series of …
Short-interval intracortical inhibition is not affected by varying visual feedback in an isometric task in biceps brachii muscle
2013
Short-interval intracortical inhibition (SICI) of the primary motor cortex (M1) appears to play a significant role in skill acquisition. Consequently, it is of interest to find out which factors cause modulation of SICI. Purpose: To establish if visual feedback and force requirements influence SICI. Methods: SICI was assessed from 10 healthy adults (5 males and 5 females aged between 21 and 35 years) in three submaximal isometric elbow flexion torque levels (5%, 20% and 40% of maximal voluntary contraction [MVC]) and with two tasks differing in terms of visual feedback. Single-pulse and paired-pulse motor evoked potentials (MEPs), supramaximal M-wave and background surface electromyogram (s…
Transkraniaalinen magneettistimulaatiotutkimus kätisyydestä
2013
Transkraniaalisen magneettistimulaation (TMS) avulla voidaan tutkia kivuttomasti ja noninvasiivisesti aivokuoren ja kortikospinaalisten ratojen toimintaa. Kohdistamalla stimulaatio primaariselle motoriselle aivokuorelle (M1) aiheutetaan lihasvaste (MEP) kehon vastakkaisella puolella. Kätisyyden vaikutuksesta kortikospinaalisten ratojen toimintaan on esitetty ristiriitaista tietoa. Tämän tutkielman tarkoituksena oli selvittää käden dominanssin vaikutusta MEP:hin oikea- ja vasenkätisillä. Lisäksi kätisyyksien välisiä eroavaisuuksia tarkasteltiin käsien vertailevien toiminnallisten testien avulla. Tutkimukseen osallistui 23 tervettä vapaaehtoista henkilöä (22–56-vuotta), joista 14 oli oikeakät…
Proprioceptive response strength in the primary sensorimotor cortex is invariant to the range of finger movement
2023
Available online 13 February 2023 Proprioception is the sense of body position and movement that relies on afference from the proprioceptors in muscles and joints. Proprioceptive responses in the primary sensorimotor (SM1) cortex can be elicited by stim- ulating the proprioceptors using evoked (passive) limb movements. In magnetoencephalography (MEG), propri- oceptive processing can be quantified by recording the movement evoked fields (MEFs) and movement-induced beta power modulations or by computing corticokinematic coherence (CKC) between the limb kinematics and cortical activity. We examined whether cortical proprioceptive processing quantified with MEF peak strength, relative beta supp…
Corticokinematic coherence is stronger to regular than irregular proprioceptive stimulation of the hand
2021
Funding Information: This study was supported by the Academy of Finland “Brain changes across the life-span” profiling funding to University of Jyva€skyla€. H. Piitulainen was supported by Academy of Finland (Grants 296240, 326988, 307250, and 327288) and Jane and Aatos Erkko Foundation. Publisher Copyright: © 2021 the American Physiological Society. Proprioceptive afference can be investigated using corticokinematic coherence (CKC), which indicates coupling between limb kinematics and cortical activity. CKC has been quantified using proprioceptive stimulation (movement actuators) with fixed interstimulus interval (ISI). However, it is unclear how regularity of the stimulus sequence (jitter…
CMC is more than a measure of corticospinal tract integrity in acute stroke patients
2021
In healthy subjects, motor cortex activity and electromyographic (EMG) signals from contracting contralateral muscle show coherence in the beta (15-30 Hz) range. Corticomuscular coherence (CMC) is considered a sign of functional coupling between muscle and brain. Based on prior studies, CMC is altered in stroke, but functional significance of this finding has remained unclear. Here, we examined CMC in acute stroke patients and correlated the results with clinical outcome measures and corticospinal tract (CST) integrity estimated with diffusion tensor imaging (DTI). During isometric contraction of the extensor carpi radialis muscle, EMG and magnetoencephalographic oscillatory signals were re…
Entrainment and its perturbation in the auditory cortex of the rat : phase and frequency modulations
2010
Tutkimuksen tavoitteena oli luoda oskillatorista tahdistamista rotan kuuloaivokuorella sekä valikoivasti häiritä sitä. Tahdistamista ei ole juuri lainkaan tutkittu aiemmin, joten tutkimuksessa yritettiin löytää uutta tietoa käyttäen ainutlaatuista kokeellista asetelmaa. Viisitoista rottaa nukutettiin uretaanilla ja niiltä mitattiin paikallisia kenttäpotentiaaleja (local field potentials,LFPs) kovakalvon päälle sijoitetun solun ulkopuolisen mikroelektrodin avulla. Neljässä pääkokeessa luotiin 2,5 Hz tahdistamista yhdeksän ärsykkeen äänijonoilla, missä tahdistamisäänen taajuus oli 4000 Hz ja häiritsevän äänen taajuus oli 4500 Hz. Häirintä oli aina kahdeksannessa äänessä, jonka vaihetta ja/tai…
Modulation of plasticity of the soleus area of the motor cortex using paired associative stimulation
2015
Paired associative stimulation (PAS) repeatedly combines single somatosensory nerve stimuli with single transcranial magnetic stimuli to induce bidirectional changes in the excitability of the cortical projections to the target muscle. PAS and motor training have been shown to share common neural mechanisms, suggesting that PAS tests functionally relevant neuronal circuits. While PAS has been used extensively to target the hand area of the motor cortex, few studies have targeted the leg area of the motor cortex. The optimal interstimulus inter- val (ISI) to induce plasticity in the cortical projections to lower limbs is still not well established. Thus, the first purpose of this thesis was …