休息狀態網路（Resting state networks）為一種利用休息狀態磁振造影（rsfMRI）來量測神經元活動所引發之血氧濃度變化（BOLD）的訊號，而默認模式網路（DMN）為所有的休息狀態網路中被證實，當於高認知功能需求時會減少活化，且常用於查證神經功能失調。最近也有一些研究顯示大腦功能的活躍性與代謝物濃度相關，如：Glutamate、Glutamine及GABA。面回訊氫原子核磁振頻譜影像(PSPSI)是一種快速磁場磁振頻譜成像（MRSI）的掃描方法，之前我們的結果已經能夠重現分佈在大腦內側壁中的代謝物，而大腦矢狀面附近的內側壁可以覆蓋主要DMN大腦區域。本論文中，試著結合休息狀態磁振造影和磁振頻譜成像兩種掃描的結果，並使用面回訊氫原子核磁振頻譜影像比較默認模式網路和非默認模式網路中五種神經化學物質的代謝物濃度（NAA、mI、Cre、cho、Glx）分佈情形。實驗結果成功的將休息狀態磁振造影和磁振頻譜成像結合並發現代謝物NAA、Cre、Glx在默認模式網路和非默認模式網路有明顯的差異。

Resting state networks which relate to the alterations of coherent intrinsic neuronal activity based on blood oxygen level-dependent (BOLD) fluctuations can be observed in the resting state functional magnetic resonance imaging (rsfMRI). Among all resting state networks, default mode network (DMN) has been shown to exhibit reduced activation in the presence of high cognitive demand and has been used to investigate the neuronal dysfunctions. Recently, there are several studies showing that functional activity can be related to the baseline metabolic levels, such as glutamate, glutamine and GABA. Based on our previous results, proton echo planar spectroscopy imaging (PEPSI), as a fast magnetic resonance spectroscopic imaging (MRSI) method, is able to acquire the distribution of brain metabolites with acceptable reproducibility in the medial wall. As brain regions in DMN can be covered mostly by a sagittal plane near the medial wall. In this study, we try to combine rsfMRI and MRSI and use PEPSI to investigate the baseline level of 5 kinds of neurochemical metabolites (NAA Cre Cho mI Glx) in DMN regions and non DMN regions in normal subjects. The results successfully combine rsfMRI and MRSI, showed that there are significant differences metabolites in NAA, Cre and Glx in DMN region and non-DMN region.

[1] B. Biswal, F. Z. Yetkin, V. M. Haughton, and J. S. Hyde, "Functional connectivity in the motor cortex of resting human brain using echo-planar MRI," Magn Reson Med, vol. 34, pp. 537-41, Oct 1995.
[2] R. E. Harris, P. C. Sundgren, A. D. Craig, E. Kirshenbaum, A. Sen, V. Napadow, et al., "Elevated insular glutamate in fibromyalgia is associated with experimental pain," Arthritis Rheum, vol. 60, pp. 3146-52, Oct 2009.
[3] G. Northoff, M. Walter, R. F. Schulte, J. Beck, U. Dydak, A. Henning, et al., "GABA concentrations in the human anterior cingulate cortex predict negative BOLD responses in fMRI," Nat Neurosci, vol. 10, pp. 1515-7, Dec 2007.
[4] M. D. Greicius, G. Srivastava, A. L. Reiss, and V. Menon, "Default-mode network activity distinguishes Alzheimer's disease from healthy aging: evidence from functional MRI," Proc Natl Acad Sci U S A, vol. 101, pp. 4637-42, Mar 30 2004.
[5] D. M. Niddam, S. Y. Tsai, C. L. Lu, C. W. Ko, and J. C. Hsieh, "Reduced hippocampal glutamate-glutamine levels in irritable bowel syndrome: preliminary findings using magnetic resonance spectroscopy," Am J Gastroenterol, vol. 106, pp. 1503-11, Aug 2011.
[6] S. Y. Tsai, R. Otazo, S. Posse, Y. R. Lin, H. W. Chung, L. L. Wald, et al., "Accelerated proton echo planar spectroscopic imaging (PEPSI) using GRAPPA with a 32-channel phased-array coil," Magn Reson Med, vol. 59, pp. 989-98, May 2008.
[7] R. Hurd, N. Sailasuta, R. Srinivasan, D. B. Vigneron, D. Pelletier, and S. J. Nelson, "Measurement of brain glutamate using TE-averaged PRESS at 3T," Magn Reson Med, vol. 51, pp. 435-40, Mar 2004.
[8] V. D. Calhoun, T. Adali, G. D. Pearlson, and J. J. Pekar, "A method for making group inferences from functional MRI data using independent component analysis," Hum Brain Mapp, vol. 14, pp. 140-51, Nov 2001.
[9] H. L and Z. HR, "Astrocytic control of glutamatergic activity: astrocytes
as stars of the show," Trends Neurosci, pp. 735-43, 2004.
[10] L. Sang, W. Qin, Y. Liu, W. Han, Y. Zhang, T. Jiang, et al., "Resting-state functional connectivity of the vermal and hemispheric subregions of the cerebellum with both the cerebral cortical networks and subcortical structures," Neuroimage, vol. 61, pp. 1213-25, Jul 16 2012.