[FieldTrip] lambda regularization using Neuromag data

[Hyojin Park]

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

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