| Summary: | 碩士 === 國立臺灣大學 === 電機工程學研究所 === 90 === Functional magnetic resonance imaging (fMRI) is of a powerful tool in detecting the functional responses in the brains of the anesthetized animals. After the brain mapping for the result of fMRI, one can have the further understanding about the mechanism of the somatosensory and the pain in the brain. The purpose of this thesis is to develop an animal fMRI procedure to obtain a stable and high SNR fMRI data in NTU 3T MRI imager.
The best parameters of MRI for the study of fMRI of rats are set to find the influence of the parameters of electrical stimulation on BOLD signals. By stimulating the hindpaw or the tail of two kinds of rats anethesized by two drugs with different intensities and frequencies, experiments were designed in many domains to observe response signals and areas of fMRI and find the correlations between neural activities and fMRI, so that we have a further understanding of the brain of animals.
The results show that there is BOLD signal change, from 1% to 3%, in the contrallateral somatosensory cortex after increasing the intensity of electrical stimulation. There is also response in the ACC. The stimulation of peripheral nervous system induces the activation of the contrallateral somatosensory cortex. The activations were found in somatosensory Ⅰ、somatosensory Ⅱ、thalamus and ACC. The stronger the intensity of electrical stimulation, the higher the fMRI signal is. The fMRI signal once increased and then decreased if the frequency of electrical stimulation was raised. There were similar results in the two situations below: the experiments with different kinds of rat and with different regions of the same rat. In the experiment of stimulation with different kinds of anaesthetic, the results showed that the fMRI signal change was not obvious using pentobarbital. Future work includes the research of correlation between the intracortical recordings of physiological electrical signal and the fMRI signal.
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