Date of Degree
MS (Master of Science)
There are lots of dynamic process exist co-currently and spontaneously when the neurons in the brain are activated by the external stimulation, like cerebral blood flow (CBF) change, oxygen extraction change. The study of the dynamic relationship among these physiological variables, which describe the brain activity through different aspects, can help people understand the brain function when it gets excited and researchers can interpret the physiological meaning of these parameters better. The most common functional magnetic resonance imaging techniques are BOLD and ASL fMRI, in this research, the correlation between these two methods has been studied through a simultaneous data acquisition strategy. Assessing such correlation between BOLD fMRI measures and CBF offers a link of these two to the underlying of the spontaneous brain activities.
In the study, an ASL pulse sequence PICORE has been used to perform the fMRI experiment on 7 health subjects. A rapid median nerve electrical stimulation paradigm has been used to detect the activation of the brain from seven normal health right-handed human subjects. Three ROIs (SMA, S1, M1) have been selected and the data were analyzed to investigate the correlation between CBF value and BOLD signal change during brain activities. We found the CBF value rises for 5 - 6 ml/min/100g for fixed ROI and 11 - 12 ml/min/100g for non-fixed ROI and the BOLD signal change was around 0.8% for both situations. Our results shows for a fixed size ROI of each individual subject, no significant difference has been found for CBF value difference and the BOLD signal change between different runs and neither did the ratio of these two parameters (p > 0.05). When studied the activation area size for each run, we found significant difference for both CBF value difference and BOLD signal change (p < < 0.05) but no significant difference for the ratio of those two (p > 0.05). The dynamic relationship between CBF value difference and BOLD contrast signal change has been shown to be stable for a fixed ROI study. The amount of neurons being activated (activation size) for these two approaches has a habituation and decreased between runs, but the relationship between them remains typically the same since the ratio has no significant difference.
vii, 44 pages
Includes bibliographical references (pages 42-44).
Copyright 2014 Huijing Yang