# LCMV with common spatial filter?

**URL:** <https://mne.discourse.group/t/lcmv-with-common-spatial-filter/2193>\
**Category:** Mailing List Archive (read-only)\
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**Created:** [May 20, 2020, 10:43am UTC](https://mne.discourse.group/t/lcmv-with-common-spatial-filter/2193 "2020-05-20T10:43:05Z")\
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**Author:** ![system](https://global.discourse-cdn.com/free1/uploads/mne/original/1X/85cc6bd2b69cb698a166dc6d880fb550510d0144.jpeg) [@system](https://mne.discourse.group/u/system)\
**Post date:** [May 20, 2020, 10:43am UTC](https://mne.discourse.group/t/lcmv-with-common-spatial-filter/2193/1 "2020-05-20T10:43:05Z")

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Dear MNE experts,

We use LCMV for localization of visual gamma oscillations in several  
experimental conditions. We expect that the power will differ between  
conditions, but that in all these conditions the source will be  
approximately in the same area. Therefore, we would like to use a common  
spatial filter for all conditions.

We calculated noise\_cov and data\_cov on the full data and then applied the  
resulting common filter to separate conditions, as described in ?examples?:  
[https://mne.tools/0.15/auto\_examples/inverse/plot\_lcmv\_beamformer\_volume.html](https://mne.tools/0.15/auto_examples/inverse/plot_lcmv_beamformer_volume.html)

This approach visibly reduced signal power in comparison with using  
specific filters for each condition.

We have earlier used the common spatial filter with LCMV beamformers in  
Fieldtrip and it worked well. However, I guess there is different approach  
to assessment of covariance in the Fieldtrip.

What approach to calculation of the LCMV spatial filter would you  
recommend us to use in the MNE?

Best,

Elena

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**Author:** ![system](https://global.discourse-cdn.com/free1/uploads/mne/original/1X/85cc6bd2b69cb698a166dc6d880fb550510d0144.jpeg) [@system](https://mne.discourse.group/u/system)\
**Post date:** [May 22, 2020, 7:23pm UTC](https://mne.discourse.group/t/lcmv-with-common-spatial-filter/2193/2 "2020-05-22T19:23:13Z")

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hi Elena,

make\_lcmv compute the filters and apply\_lcmv allow you to apply them  
to any condition. it's the recommended way when you compare conditions.

are you observing different results on the same data between Fieldtrip and MNE?

we have just published  
[https://www.sciencedirect.com/science/article/pii/S1053811920302846](https://www.sciencedirect.com/science/article/pii/S1053811920302846)

Amit Jaiswal, Jukka Nenonen, Matti Stenroos, Alexandre Gramfort,  
Sarang S. Dalal, Britta U. Westner, Vladimir Litvak, John C. Mosher,  
Jan-Mathijs Schoffelen, Caroline Witton, Robert Oostenveld, Lauri  
Parkkonen,  
Comparison of beamformer implementations for MEG source localization,  
NeuroImage, Volume 216, 2020,

and our results show very similar results between packages.

HTH

Alex