Investigation of Neurovascular Coupling with Multimodal Imaging System: a fNIRS-EEG Study
Keles, Hasan Onur
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Technological advances in functional neuroimaging contributed to understanding of the neurovascular coupling in humans over the years, however, the temporal and spatial relationship between large-scale neural oscillations and hemodynamic changes is still not completely understood during the different states and different disease states of the human cortex. It is also still unclear that what type of large-scale neural oscillations that mostly drive to the hemodynamic signal. There has been a need for novel tools and methods in neuroimaging to study neurovascular coupling. This thesis focused on the development of simultaneous Functional Near-Infrared Spectroscopy and Electroencephalography system (simultaneous fNIRS+EEG) that can be used for the investigation of neurovascular coupling over the whole head. The simultaneous fNIRS+EEG system is then applied to the resting state studies in healthy adult subjects. The results of these resting state experiments are presented. Our finding shows that the EEG signals at various frequencies tend to drive hemoglobin concentration changes with a typical time delay during the resting states. As side studies, the simultaneous fNIRS+EEG is applied to the cognitive task and artifact experiments to evaluate the suitability of the developed system. The results of these task and artifacts experiments are also presented. Our goal was to characterize the basic phenomena through practical, noninvasive methods in order to facilitate the study of diseases known to affect neurovascular coupling, such as traumatic brain injury.