Cortical rhythms as markers of neural processing

Hannu Laaksonen

Cortical rhythms as markers of neural processing

Julkaisun otsikon käännös: Aivokuoren rytmit hermostollisen käsittelyn merkkinä

Hannu Laaksonen

Tutkimustuotos: Doctoral Thesis › Collection of Articles

Abstrakti

Magnetoenkefalografia (MEG) on erinomainen työkalu aivojen toiminnan tutkimiseen pään ulkopuolelta. Se mahdollistaa aivosignaalien mittauksen millisekunttien aikatarkkuudella ja hyvällä paikkatarkkuudella. Perinteisesti tehtäväsidonnaista aivotoimintaa on tutkittu tehtävään tai ärsykkeeseen vaihelukittuneilla herätevasteilla. Aivot tuottavat myös spontaaneja rytmejä, joiden on havaittu vaihtelevan tehtävän aikana tai ärsykkeen seurauksena. Tämä väitöskirja keskittyy aivokuoren rytmiseen toimintaan, sen tutkimiseen tarvittavien menetelmien kehittämiseen ja rytmien ja herätevasteiden välisen yhteyden tarkasteluun. Vaikka anturitason MEG-signaalia voidaan käyttää menestyksekkäästi herätevasteiden ja rytmien tutkimiseen, niiden perusteellinen tarkastelu vaatii myös tietoa aktiivisten aivoalueiden paikoista. Tätä varten väitöskirjassa käytettiin Dynamic Imaging of Coherent Sources (DICS) -menetelmää, jonka avulla on mahdollista tutkia sekä rytmisen toiminnan tehon muokkautumista eri aivoalueilla että toiminnallista kytkeytyvyyttä aivoalueiden välillä. Väitöskirjassa kehitettiin tehtäväsidonnainen versio DICS:stä (event-related DICS, erDICS) rytmisen toiminnan mallintamisen avuksi. Menetelmän käyttökelpoisuutta testattiin simuloidun ja oikean MEG-datan avulla. Uutta menetelmää sovellettiin herätevasteiden ja rytmisen toiminnan vertailuun useita aivoalueita aktivoivassa kokeessa, jossa koehenkilöt nimesivät kuvia. Loppupäätelmänä oli, että nämä kaksi aivokuoren aktivaation mittaria ovat pitkälti eriävät ja molempia tarvitaan aivojen toiminnan kokonaisuuden hahmottamiseksi. Toisessa kokeessa, jossa tutkittiin sanalistojen ns. priming-vaikutusta (virittäminen), erDICS:ia käytettiin toiminnallisen kytkeytyvyyden tutkimiseen. Menetelmä paljasti erilaiset aivoverkot äänneasun ja merkityksen virittämisessä.

Julkaisun otsikon käännös	Aivokuoren rytmit hermostollisen käsittelyn merkkinä
Alkuperäiskieli	Englanti
Pätevyys	Tohtorintutkinto
Myöntävä instituutio	Aalto-yliopisto
Valvoja/neuvonantaja	Koskelainen, Ari, Vastuuprofessori Salmelin, Riitta, Ohjaaja
Kustantaja	Aalto University
Painoksen ISBN	978-952-60-4786-7
Sähköinen ISBN	978-952-60-4787-4
Tila	Julkaistu - 2012
OKM-julkaisutyyppi	G5 Artikkeliväitöskirja

Tutkimusalat

magnetoenkefalografia
MEG
rytmit
funktionaalinen kytkeytyvyys

Pääsy asiakirjaan

http://urn.fi/URN:ISBN:978-952-60-4787-4

Siteeraa tätä

@phdthesis{6a5dd8f2157a4fc1a9c132d2da8e6173,

title = "Cortical rhythms as markers of neural processing",

abstract = "Magnetoencephalography (MEG) is an excellent tool for noninvasive investigation of neuronal activity from outside of the head. It provides millisecond temporal accuracy and good spatial resolution. The classical measure of task-related brain activity is the evoked response that is phase-locked to task or stimulus. But the brain also exhibits spontaneous oscillations, or rhythmic activity, that has been observed to be modulated during task or in response to stimuli. This Thesis mainly focuses on investigations of cortical brain rhythms, developing methods for analyzing them and probing their relationship with evoked responses. While the sensor level MEG signal can be used successfully for studying evoked responses and cortical rhythmic activity, a proper evaluation of the data requires localization of the active brain areas. For this purpose, a beamforming technique called Dynamic Imaging of Coherent Sources (DICS) was used and modified in this Thesis. With DICS, it is possible to examine both power level modulations of rhythmic activity and functional connectivity between different brain regions conveyed by rhythmic activity. In this Thesis, an event-related version of a beamformer method DICS was implemented to assist the modeling of rhythmic activity. The feasibility of this new method, erDICS, was shown with simulations and real MEG data. The method was further applied to compare evoked responses and rhythmic activity in a high-level cognitive task of picture naming, with the conclusion that the two measures of cortical processes are largely detached and that both measures are needed for an accurate portrayal of brain activity. With another data set from a word priming study, erDICS was used to investigate connections between the left superior temporal cortex and other cortical regions. The method revealed different brain networks for phonological and semantic priming.",

keywords = "magnetoencephalography, MEG, rhythms, oscillations, evoked response, functional connectivity, magnetoenkefalografia, MEG, rytmit, funktionaalinen kytkeytyvyys, magnetoencephalography, MEG, rhythms, oscillations, evoked response, functional connectivity",

author = "Hannu Laaksonen",

year = "2012",

language = "English",

isbn = "978-952-60-4786-7",

series = "Aalto University publication series DOCTORAL DISSERTATIONS",

publisher = "Aalto University",

number = "119",

address = "Finland",

school = "Aalto University",

}

TY - BOOK

T1 - Cortical rhythms as markers of neural processing

AU - Laaksonen, Hannu

PY - 2012

Y1 - 2012

N2 - Magnetoencephalography (MEG) is an excellent tool for noninvasive investigation of neuronal activity from outside of the head. It provides millisecond temporal accuracy and good spatial resolution. The classical measure of task-related brain activity is the evoked response that is phase-locked to task or stimulus. But the brain also exhibits spontaneous oscillations, or rhythmic activity, that has been observed to be modulated during task or in response to stimuli. This Thesis mainly focuses on investigations of cortical brain rhythms, developing methods for analyzing them and probing their relationship with evoked responses. While the sensor level MEG signal can be used successfully for studying evoked responses and cortical rhythmic activity, a proper evaluation of the data requires localization of the active brain areas. For this purpose, a beamforming technique called Dynamic Imaging of Coherent Sources (DICS) was used and modified in this Thesis. With DICS, it is possible to examine both power level modulations of rhythmic activity and functional connectivity between different brain regions conveyed by rhythmic activity. In this Thesis, an event-related version of a beamformer method DICS was implemented to assist the modeling of rhythmic activity. The feasibility of this new method, erDICS, was shown with simulations and real MEG data. The method was further applied to compare evoked responses and rhythmic activity in a high-level cognitive task of picture naming, with the conclusion that the two measures of cortical processes are largely detached and that both measures are needed for an accurate portrayal of brain activity. With another data set from a word priming study, erDICS was used to investigate connections between the left superior temporal cortex and other cortical regions. The method revealed different brain networks for phonological and semantic priming.

AB - Magnetoencephalography (MEG) is an excellent tool for noninvasive investigation of neuronal activity from outside of the head. It provides millisecond temporal accuracy and good spatial resolution. The classical measure of task-related brain activity is the evoked response that is phase-locked to task or stimulus. But the brain also exhibits spontaneous oscillations, or rhythmic activity, that has been observed to be modulated during task or in response to stimuli. This Thesis mainly focuses on investigations of cortical brain rhythms, developing methods for analyzing them and probing their relationship with evoked responses. While the sensor level MEG signal can be used successfully for studying evoked responses and cortical rhythmic activity, a proper evaluation of the data requires localization of the active brain areas. For this purpose, a beamforming technique called Dynamic Imaging of Coherent Sources (DICS) was used and modified in this Thesis. With DICS, it is possible to examine both power level modulations of rhythmic activity and functional connectivity between different brain regions conveyed by rhythmic activity. In this Thesis, an event-related version of a beamformer method DICS was implemented to assist the modeling of rhythmic activity. The feasibility of this new method, erDICS, was shown with simulations and real MEG data. The method was further applied to compare evoked responses and rhythmic activity in a high-level cognitive task of picture naming, with the conclusion that the two measures of cortical processes are largely detached and that both measures are needed for an accurate portrayal of brain activity. With another data set from a word priming study, erDICS was used to investigate connections between the left superior temporal cortex and other cortical regions. The method revealed different brain networks for phonological and semantic priming.

KW - magnetoencephalography

KW - MEG

KW - rhythms

KW - oscillations

KW - evoked response

KW - functional connectivity

KW - magnetoenkefalografia

KW - MEG

KW - rytmit

KW - funktionaalinen kytkeytyvyys

KW - magnetoencephalography

KW - MEG

KW - rhythms

KW - oscillations

KW - evoked response

KW - functional connectivity

M3 - Doctoral Thesis

SN - 978-952-60-4786-7

T3 - Aalto University publication series DOCTORAL DISSERTATIONS

PB - Aalto University

ER -

Cortical rhythms as markers of neural processing

Abstrakti

Tutkimusalat

Pääsy asiakirjaan

Sormenjälki

Siteeraa tätä