Majeed Waqas, Magnuson Matthew, Keilholz Shella D
Georgia Institute of Technology and Emory University, Biomedical Engineering, Atlanta, Georgia, USA.
J Magn Reson Imaging. 2009 Aug;30(2):384-93. doi: 10.1002/jmri.21848.
To examine spatiotemporal dynamics of low frequency fluctuations in rat cortex.
Gradient-echo echo-planar imaging images were acquired from anesthetized rats (repetition time = 100 ms). Power spectral analysis was performed to detect different frequency peaks. Functional connectivity maps were obtained for the frequency peaks of interest. The images in the filtered time-series were displayed as a movie to study spatiotemporal patterns in the data for frequency bands of interest.
High temporal and spectral resolution allowed separation of primary components of physiological noise and visualization of spectral details. Two low frequency peaks with distinct characteristics were observed. Selective visualization of the second low frequency peak revealed waves of activity that typically began in the secondary somatosensory cortex and propagated to the primary motor cortex.
To date, analysis of these fluctuations has focused on the detection of functional networks assuming steady state conditions. These results suggest that detailed examination of the spatiotemporal dynamics of the low frequency fluctuations may provide more insight into brain function, and add a new perspective to the analysis of resting state fMRI data.
研究大鼠皮质低频波动的时空动态。
从麻醉大鼠获取梯度回波平面成像图像（重复时间 = 100毫秒）。进行功率谱分析以检测不同频率峰值。获取感兴趣频率峰值的功能连接图。将滤波后时间序列中的图像显示为电影，以研究感兴趣频段数据中的时空模式。
高时间和光谱分辨率允许分离生理噪声的主要成分并可视化光谱细节。观察到两个具有不同特征的低频峰值。对第二个低频峰值的选择性可视化显示出活动波，这些活动波通常起始于次级体感皮层并传播至初级运动皮层。
迄今为止，对这些波动的分析主要集中在假设稳态条件下功能网络的检测上。这些结果表明，对低频波动的时空动态进行详细检查可能会为脑功能提供更多见解，并为静息态功能磁共振成像数据的分析增添新的视角。
