Paper:Altered Functional Connectivity in Default Mode Network in Absence Epilepsy: A Resting-State fMRI Study.
Data analysis:
1、 DMN Identification: 以PCC的功能连接pattern来定义DMN。
2、 比较患者与对照两组间的DMN功能连接,得出DMN的改变。
3、 Region-wise Functional Connectivity in DMN:比较DMN内区域之间的功能连接。在这一步,想请教各位老师如下问题:
1、 For the frontal lobe, however, a very large cluster obviously included four different DMN regions (dorsal medial prefrontal cortex, ventral medial prefrontal cortex, left and right superior frontal gyri). Therefore, it was separated into four nodes. A total of 12 DMN nodes were defined.
2、 Mean time series were extracted by averaging the time series of each peak voxel and its nearest 26 neighbors. The resulting time series were correlated between nodes of each subject, and then an 12×12 correlation matrix for each subject was obtained.
3、 Two-sample two-tailed t-tests were performed on all 66 possible connections represented in the 12×12 correlation matrices between patients and controls. The statistical significance level was set to P<0.05 (FDR-corrected).
文章再比较区域间功能连接后另作Graph Definition and Visualization,这一步看的挺晕,是否可以帮忙解释解释?
In terms of the probability of the observed zij > Z under the null hypothesis that zij is less than an arbitrary value Z, the threshold Z was defined. Because the multiple, nonindependent tests were for 66 possible connections among the 12 regions, the threshold P < 0.05 (FDR-corrected) was applied for multiple comparison tests. In other words, a layout of undirected edges was shown only under zij > Z for each subject and group.


1. 从这段话来说,看不出作者是怎样对一个大cluster进行分区的。
2. 可能是作者找不到更好的定义ROI的办法,所以采用周围26个体素的办法。个人认为不如使用定义小球的办法。
3. 12X12 矩阵(其中只有12*11/2的有效无素),采用FDR校正是比较常见的方法。
4. 我的理解,12X12 矩阵经FDR校正后,定义为Graph并显示。

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