Dear Francois and all,
I am sorry for so many questions.
Recently, I have been learning how to conduct PAC value and do statistical analysis at source level of epileptic though Brainstorm. My operation procedure is as follows:
Import the MRI of each individual
Import .fif MEG file of each subject and refine MRI registration using head points
Add event of spike
Preprocess data using 0.1-70Hz band-pass filter, 50Hz notch filter and ICA
Import in dataset using spike event
Generate cortex surface using Overlapping spheress
Select "No noise modeling" to prepare noise covariance
Compute soure using the following settings
Extract source estimation to Matlab and compute the PAC of theta-gamma using modulation index
Replace the field “ImageGridAmp”, “Comment”, “Time” with PAC value, “'Extract values: [-0.000s,0.000s]” and 0 respectively
Import modified structure from Matlab
Project source to default anatomy
Put the subjects into their respective groups in process2 and select ft_sourcestatistics
Because I just want to learn the process and want to see the results, I set the p-value and cluster alpah as 1. The results are as follows.
However, when I open the “FT t-test unequal cluster [0ms]: sub01/Extract values: [-0.000s,0.000s] (2) vs. sub02/Extract values: [-0.000s,0.000s] (5)”, it gives the message as follow: BST> All values are null. Please check your input file.
The Clusters on the right panel are also empty. In addition, the Time is displayed as [0,1]ms
Sorry this is so long. I unable to figure out the problem or if I am doing anything wrong. Could you check it for me and point out the mistakes. Thank you in advance for your assistance.
Checked how your band-pass filter alters the shape of your spikes before using this filter blindly.
Make sure the ICA components you are removing do not include any of the spiking activity you are interested in.
BST> All values are null. Please check your input file.
This means nothing is significant in your test.
I'm sorry I can't help you much with FieldTrip functions. If you have specific questions about the inputs of ft_sourcestatistics, please ask them on the FieldTrip support channels (put a breakpoint where this function is called in process_ft_sourcestatistics.m in order to report all the values used in input): https://www.fieldtriptoolbox.org/support/
In addition, the Time is displayed as [0,1]ms
This means there is no time dimension in your dataset.
This seems correct for a PAC analysis...
Thanks for your advice. I have one more question though.
I set cluster alpah as 0.05 and number of randomizations as 1000 when I use ft_sourcestatistics. The command window shows that 16 positive clusters and 377 negative clusters were found, as shown in the diagram below.
However, when I set the significance level α as 1 in the Stat tab, only 6 clusters are shown on list of Clusters.
So, what kind of clusters will be displayed on list of Clusters? Is there any other factor besides the level of significance?
Thank you again for all the help.