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ELEKTROENCEFALOGRAFSKA KOHERENCA MED VIDNIMI IN MOTORICNIMI PODROCJI MOŽGANSKE SKORJE PRI VIDNO-MOTORICNI NALOGI
Avtor: Simon Brežan, Vito Logar, Veronika Rutar
Mentor: prof. dr. Janez Zidar
IZHODIŠCE: Funkcijsko povezovanje ("binding") raznih podrocij možganov, ki je lahko npr. mehanizem zaznave dražljajev, morda poteka prek sinhronizirane oscilirajoce aktivnosti nevronov, ki se da dolociti z merjenjem elektroencefalografske koherence. Takšno povezovanje vidnih in motoricnih podrocij možganske skorje je lahko tudi osnova vidno-motoricne integracije, ki jo zahteva izvajanje motoricnih nalog, vodenih z vidom. Pri gibih ene roke se aktivira primarna motoricna možganska skorja predvsem v nasprotni polobli, premotoricna polja pa so aktivna v obeh. NAMEN: Osnovni cilj raziskave je bil vpeljati metodo merjenja elektroencefalografske koherence. Izbrali smo model vidno-motoricne naloge, ker je že dobro raziskan in je zato dobljene rezultate možno primerjati z drugimi ter tako preizkusiti veljavnost metode. Drugi cilj je bil primerjava sprememb koherence in mocnostnih spektrov nad levo in desno možgansko poloblo pri izvajanju vidno-motoricne naloge z desno ali z levo roko. HIPOTEZE: Predpostavili smo, da bo koherenca med vidnimi in motoricnimi podrocji možganske skorje vecja med izvajanjem vidno-motoricne naloge kot med kontrolnimi nalogami. Predpostavili smo tudi, da bo povecanje koherence pri izvajanju naloge z desnico vecje nad levo poloblo in obratno. METODE: Meritve smo izvedli na 6 desnicnih zdravih preiskovancih. Med elektroencefalografskim snemanjem so izvajali 4 naloge: vidno-motoricno nalogo z levo in desno roko (zahtevala je usklajeno delovanje vidnih in motoricnih polj), vidno, motoricno ter vidno in motoricno (hkrati neodvisno aktivni obe polji). Za izracun sprememb koherence in mocnostnih spektrov smo izdelali racunalniški program v programskem okolju Matlab. Rezultate smo statisticno obdelali z metodami dvosmerne variance, enosmerne variance ter s post hoc testi t s korekcijo po Bonferroniju. REZULTATI: Dokazali smo statisticno pomembno povecanje koherence (p < 0,05) pri vidno-motoricni nalogi glede na ostale naloge v frekvencnih pasovih alfa in beta 1. Spremembe koherence niso bile statisticno pomembno odvisne od tega, s katero roko so preiskovanci izvajali nalogo, in so se v obeh primerih simetricno zvecale v obeh poloblah. ZAKLJUCKI: V skladu s prejšnjimi raziskavami smo dokazali specificno povecanje koherence med vidnimi in motoricnimi polji pri izvajanju vidno-motoricne naloge in pokazali, da ni prepricljivih asimetrij pri izvajanju le-te z desno oz. levo roko. Slednje je možno razložiti, ce povecanje koherence odseva sodelovanje med sekundarnimi kompleksnejšimi vidnimi in motoricnimi podrocji možganske skorje.
[Abstract / English version]
ELEKTROENCEFALOGRAFSKA KOHERENCA MED VIDNIMI IN MOTORICNIMI PODROCJI MOŽGANSKE SKORJE PRI VIDNO-MOTORICNI NALOGI
Author: Simon Brežan, Vito Logar, Veronika Rutar
Mentor: prof. dr. Janez Zidar
BACKGROUND: The functional integration ("binding") of different brain areas, for example as a possible mechanism for stimulus perception, is perhaps mediated by the synchronizing oscillatory activity of neuronal populations, which can be determined by the electroencephalographic coherence analysis. Visuomotor integration in a visuomotor task requires functional cooperation between motor and visual cortical areas. Unilateral limb movements are based on the activation of contralateral primary motor cortex and the bilateral activation of premotor cortices. AIM: Our main aim was to introduce a new method of coherence analysis and to compare our results measured on a well-established model of the visuomotor task with other comparable studies, thereby assessing the validity of the method. Then we compared the changes in coherence and power spectra of the left and the right hemisphere of the brain while subjects performed the visuomotor task with the right and with the left hand. HYPOTHESES: We presumed that the coherence between visual and motor areas of the cortex would increase for the visuomotor task compared to the control tasks. We also hypothesized that increase in coherence and decrease in power spectrum while performing the task with the right hand would be greater in the left hemisphere and vice versa. METHODS: We tested 6 healthy, right-handed subjects and recorded their electroencephalogram while they performed 4 different tasks: visuomotor task with the right and the left hand (which required coordination between visual and motor brain areas), visual, motor and, visual and motor task (which required independent activation of visual and motor areas). For coherence and spectral analysis, a special computer programme was designed using Matlab software. The results were statistically analysed by a two-way analysis of variance, one-way analysis of variance and post hoc t-tests with Bonferroni correction. RESULTS: We demonstrated a statistically significant increase in coherence (p < 0.05) for the visuomotor task compared to other tasks in alpha and beta 1 frequency bands. There were no significant differences in coherence values depending on the hand used. The changes of coherence between both hemispheres were symmetrical. CONCLUSIONS: In accordance with previous studies, we demonstrated a specific increase of coherence for the visuomotor task and showed that there are no conclusive asymmetries when performing the task with the right or with the left hand. This could be explained in a way that the increase in coherence reflects cooperation between more complex visual and motor brain areas.