[Mne_analysis] question about LCMV

Alexandre Gramfort alexandre.gramfort at telecom-paristech.fr
Wed Dec 14 15:43:42 EST 2016
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cc Andrea would recently looked a lot at this code.

stc.data contains the output of the filter and taking the magnitude if non
fixed orientation is used. I am not sure how to call this. Maybe Andrea can
you how he refers to this.

if you apply LCMV to 2 conditions you should use the same noise cov and
data cov
in which case the filters are the same and the stc.data are definitely

my 2c

On Wed, Dec 14, 2016 at 6:21 PM, daisy <smartcandies at 163.com> wrote:

> Hi, experts
> I have some questions  when I computed LCMV beamformer on evoked data.
> Could anyone help me?
> (1)I use this command:stc=lcmv(evoked_con1,forward,noise_cov,data_cov,reg=0.01).
> Then I can plot the source time courses(stc). The xlabel is time(ms). But
> what is the ylabel? Because the beamformer weight was normalized by noise,
> according to the paper of Van Veen in 1997, the ylabel should be neural
> activity index. But for one example in the gallery(http://martinos.org/
> mne/stable/auto_examples/inverse/plot_lcmv_beamformer_
> volume.html?highlight=lcmv), the ylabel is LCMV value. Is the ‘lcmv
> value’ same with ’neural acitvity index’ or ‘pseudo-z value’(Robinson and
> Vrba 1999)?
> (2) If I apply LCMV beamformer on evoked data of two conditions, then I
> can get two stc files. Can I compare them directly? For example, calculate
> the difference of time course of these two conditions in given time and
> location? Is it meaningful?
> Thank you!
> -Best
>  Xiaoxu
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