[FieldTrip] DICS: fixed orientation of sources option

andrea brovelli andrea.brovelli at univ-amu.fr
Thu Nov 15 17:28:46 CET 2012

Dear all,

I have a question regarding the option "fixedori" of DICS (the code  
from lines 292 to 306 in beamformer_dics.m).

If I get it right, you implemented the situation when the first  
singular value lambda1 is much greater that the second singular value  
lambda2 of Cs (Cs is given by eq. 4 of Gross et al., 2001, PNAS).

I checked in my data and this is not the case. Maybe my data is just a  
very special case, but I find that the first is a little larger that  
the second. Here they are:

lambda1 = 0.5380;
lambda2 = 0.2921;
lambda3 = 0.0000;

After eq. 9 in Gross (2001), it says that if lambda1 >> lambda2 does  
not hold, the trace of Cs should be used instead.

So, has it been implemented in Fieldtrip somewhere ? And, if not,  
would you know how to do it ?

Thanks a lot



More information about the fieldtrip mailing list