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Multimodal investigation of fMRI and fNIRS derived breath hold BOLD signals with an expanded balloon model

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dc.contributor Ph.D. Program in Biomedical Engineering.
dc.contributor.advisor Akın, Ata.
dc.contributor.advisor Öztürk, Cengizhan.
dc.contributor.author Emir, Uzay Emrah.
dc.date.accessioned 2023-03-16T13:17:29Z
dc.date.available 2023-03-16T13:17:29Z
dc.date.issued 2008.
dc.identifier.other BM 2008 E45 PhD
dc.identifier.uri http://digitalarchive.boun.edu.tr/handle/123456789/19146
dc.description.abstract Multimodal investigation of blood oxygenation level-dependent (BOLD) signal, using both functional near infrared spectroscopy (fNIRS) and functional magnetic resonance imaging (fMRI), may give further insight to the underlying physiological principles and the detailed transient dynamics of the vascular response. Utilizing a breath hold task (BHT), we measured deoxy-hemoglobin (HbR) and oxy-hemoglobin (HbO) changes via fNIRS and blood oxygen level dependent (BOLD) changes by fMRI. Measurements were taken in four volunteers asynchronously and carefully aligned for comparative analysis. In order to describe the main stimulus in BHT, partial pressure of carbon dioxide (PaCO2) parameter was integrated into the balloon model as the driving function of cerebral blood ow (CBF) which led to the development of an expanded balloon model (EBM). During BHT, the increase in HbR was observed later than the BOLD peak and coincided temporally with its post stimulus undershoot. Further investigation of these transients with PaCO2 integrated balloon model suggests that post stimulus undershoot measured by fMRI is dominated by slow return of cerebral blood volume (CBV). This was con rmed by fNIRS measurements. In addition, BOLD signal decreased with the increase of the initial level of PaCO2 derived from EBM, indicating an e ect of basal CBF level on the BOLD signal. In conclusion, a multimodal approach with an appropriate biophysical model gave a comprehensive description of the hemodynamic response during BHT.|Keywords: Functional near-infrared spectroscopy, Functional magnetic resonance imaging, BOLD signal, Partial pressure of CO2, Balloon model, Post stimulus undershoot.
dc.format.extent 30cm.
dc.publisher Thesis (Ph.D.)-Bogazici University. Institute of Biomedical Engineering, 2008.
dc.relation Includes appendices.
dc.relation Includes appendices.
dc.subject.lcsh Magnetic resonance imaging.
dc.subject.lcsh Near infrared spectroscopy.
dc.subject.lcsh Carbon dioxide.
dc.title Multimodal investigation of fMRI and fNIRS derived breath hold BOLD signals with an expanded balloon model
dc.format.pages xiv, 84 leaves;


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