[FieldTrip] phase difference between sources

Jan.Hirschmann at med.uni-duesseldorf.de Jan.Hirschmann at med.uni-duesseldorf.de
Thu Sep 6 15:06:02 CEST 2012

Dear fieldtrip experts,


I was wondering how to get the mean phase difference between two sources A and B at a particular frequency f (mean across data segments). My idea was to use dics and to say cfg.refdip=A and cfg.keepcsd='yes'. Then I would get C, the cross spectral density between A and B, which is a 3x3 matrix with complex entries. Joachim Gross wrote that one could estimate csd in the dominant direction as the trace of C. So I guess I could get the phase difference by angle(trace(C)). Is this correct? If I wanted to use SVD to estimate the dominant direction instead of the trace, how would I get the phase difference then? And finally, if I wanted to have coherence not with the dipole orientation that maximizes power but with the orientation that maximizes phase difference, how would that work?


Thanks for any remarks!




Jan Hirschmann

MSc Neuroscience

Institute of Clinical Neuroscience and Medical Psychology

Heinrich Heine University Düsseldorf

Universitätsstr. 1

40225 Düsseldorf


Tel: +49 (0)211 81 18415

Fax: +49 (0)211 81 19033


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