Hello, I’m working on connectivity analysis of EEG signal. After measuring the connectivity by Granger Causality or Phase Transfer Entropy when I visualized the connectivity matrix in circular maps the threshold value of the scouts changed based on the connectivity matrix.
Can you please tell me how the connectivity threshold changes automatically?
Is it adaptive threshold or how can I find the adaptive threshold?
Because If I manually changed the threshold from scout bar the connectivity links increasing with low threshold and vice versus.
Hello,
The minimum and maximum values of the threshold slider in the Display tab are the minimum and maximum values of the file. The behavior of this slider is therefore different depending on the file. There is no adaptative/automatic thresholding done on these connectivity graphs.
On top of this, there might be issues with negative values… This graph display suffers from many bugs and has to be redesigned completely. For a proper display of these connectivity matrices, I recommend you use the default option “display as matrix”. If you need this graph to be thresholded: export the values to Matlab, set to zero the values you don’t want to see, and replace the existing file with your modified matrix.
See the forum links at the bottom of this page for help:
http://neuroimage.usc.edu/brainstorm/Tutorials/Connectivity