[FieldTrip] lambda regularization using Neuromag data

Hyojin Park hjpark05 at snu.ac.kr
Tue Oct 23 16:06:10 CEST 2012

Dear all, 


I'm working on LCMV beamforming using Neuromag data applied with Maxfilter. 

I am using 204 gradiometer sensors. 


I have rank deficiency problem, maybe because of Maxfilter since it reduces
the rank.

When I checked the data, the rank is 60. 

I removed EOG and ECG components using ICA. 

2 or 3 components in sum in most subjects.

So for some, the rank is 58, for some, it's 57. 


When I tested with different lambda from 0% to 10%, (or above, even 100%), I
got the same warning ('covariance matrix is rank deficient'). 


Does anyone have suggestions for which lambda is most appropriate in this
case? Or any other useful advice/experience for how to apply beamforming in
combination with Maxfilter? 


Thank you in advance.

Hyojin Park

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.science.ru.nl/pipermail/fieldtrip/attachments/20121023/170301cd/attachment-0001.html>

More information about the fieldtrip mailing list