You should keep in mind that both a single dipole (in the ECD option) and a cortical patch (in the IMG option) can effectively summarize the activity of an extended cortical area and not just a single point, because EEG and MEG have a much lower spatial precision than fMRI. So effectively you can think of it as a ROI centered at the coordinates you specify.

Vladimir

2010/11/29 飞鸟 <[log in to unmask]>

Dear all,
　　Recently, I am using the SPM toolbox developed by your group in my research work. But a probelm confused me heavily, so I send this email to seek for your help.

What confuses me is that why don't we extract the signal from a ROI but from a fixed MNI coordinate when analysis EEG/MEG data with the method of DCM. Would it be more accurate if we select a ROI just as the DCM for fMRI do to extract signal?

　　Waiting for your help, your reply will be appreciate! Best wishes to you!

Haoran Li (Ms.)

Brain Imaging Lab
Research Center for Learning Science,
Southeast University,China

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