[FieldTrip] What does minimum-norm estimate tell me + correlation in the source space

[runna90 at 126.com]

Dear Harold,
I am very sorry that I am not writing to reply your question but to request you something about minimum norm estimate because I am a rather new fieldtripper. I noticed that you have got results applying MNE, thus I think you must be more experienced! I followed the tutorial at http://www.fieldtriptoolbox.org/tutorial/minimumnormestimate and did source reconstruction with  MEG data acquired from ctf 275 system. But I got stuck in here
. Source model: Co-registration of the source space to the sensor-based head coordinate system, 
I could not find the file named ‘orig-nomask.mgz’ under the mir folder. Would you tell me in which step should this file be created? And how to create this file?

Best regards,

Runnan





> 在 2016年3月10日，08:40，Harold Cavendish <harold.cav89 at gmail.com> 写道：
> 
> Dear FieldTrip users,
> 
> I have a few questions regarding source localisation and statistics:
> 
> 1. Suppose I'm doing source reconstruction of ERP using minimum-norm estimate; one condition, multiple subjects. I'm using ft_sourceanalysis() and getting rather meaningful results which I visualise via ft_plot_mesh().
> 
> What is the validity of this result? I understand there are many individual dipoles spread over the cortical sheet and we're estimating best fit to the data given the conductance model while minimising overall power, but what does this actually tell us? If I find an area with higher power, what conclusions can I draw?
> 
> 2. Can I compute a correlation between the result in the source space and a behavioural variable? Perhaps even specify a region of interest? If yes, is this approach considered to be valid?
> 
> I want to see if e.g. the power of the reconstructed activity in the source space averaged over a time window correlates with my behavioural variable.
> 
> Thank you!
> 
> Best regards,
> Harold
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