My data is that the subjects are asked to listen to continuous stories, and then the meg responses are recorded.
Each subject listens to 8 stories, each story has about 8 minutes (500ms).
I am doing notch filtering at 60hz and 120hz and low-pass filtering from 0-100hz on the data.
Then I import the mri t1 image of the data, use cat for cortex segmentation, and then generate the bem model.
In addition I generated open meeg bem head model, calculated noise covariance using all data, and then used sloreta for source localization analysis (constrained to scalp surface, using meg grad and meg mag data).
But the results show that my brain has essentially no activation, I browse from the beginning of the data to the end of the data and there is still no visible activation in any brain region.
I would like to ask where am I going wrong? Or how should I do source estimation analysis for this type of data?
Unfortunately, I won't be able to help you debugging your entire processing pipeline through this forum.
If you have a specific question about one function, please report it precisely, with screen captures of the database explorer and the figures illustrating your problems.
But the results show that my brain has essentially no activation, I browse from the beginning of the data to the end of the data and there is still no visible activation in any brain region.
If you are using minimum norm estimates, you should always see "something". The values are never zero. Make sure your amplitude threshold is not too high.
If you have methodological questions related with the source estimation, get back to the introduction tutorials: https://neuroimage.usc.edu/brainstorm/Tutorials
I'd recommend you base your analyses based on strong hypotheses derived from the literature in your field. Computing random source estimates from 8min-long recordings hoping to see something may not take you anywhere.
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Thank you very much for your time and your reply.
I did adjust the amplitude threshold as you said and I can see the activation now.
I will adjust my thinking to fully report my process and ask more specific questions.