[Eeglablist] How many dipoles to fit?

[Igor Riecansky]

Dear EEGLAB community,

 

I am starting to use DIPFIT2 to localize brain sources of PCA/ICA EEG
components. I face a problem to decide how many dipoles to fit, i.e. one
unilateral vs two bilateral symmetrical. Some papers simply always assume 2
symmetrical sources. However, if component's topography is highly
asymmetric, this seems not to be justified. Furthermore, in case of a
symmetric topography one could often reasonably assume both one unilateral
or two bilateral sources both originating from brain structures close to the
midline. Of course, solutions may substantially differ for one and two
sources. What is you experience and practice? How do you solve this problem?
Do you use any quantitative test? Residual variance is always lower when two
sources are fitted compared to one source. Is there some rule to consider
this reduction as significant, or can the reduction of residual variance be
statistically tested?

 

I will greatly appreciate any feedback and help. Thanks.

 

 

Igor

 

-----------------------------

Igor Riecansky, MD PhD

SCAN-Unit

Institute of Clinical, Biological and Differential Psychology

Faculty of Psychology

University of Vienna

Liebiggasse 5, A-1010 Austria

Tel.: +43-1-4277-47 509

Room No. O3.28

E-mail: igor.riecansky at univie.ac.at

 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://sccn.ucsd.edu/pipermail/eeglablist/attachments/20110527/2fc7d632/attachment.html>